United States
Environmental Protection
Agency
Solid Waste And
Emergency Response
5403G
EPA510-B-98-004
August 1998
&EPA
Test Protocol For Evaluating
Integrity Assessment
Procedures For Underground
Storage Tanks
Printed on Recycled Paper
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CONTENTS
Foreword Page 1
Acknowledgments Page 4
Quality Assurance Project Plan, including Appendices Section 1
Results of Evaluation Forms Section 2
Instructions for Filling Out Results Forms Section 3
"Guidance on Alternative Integrity Assessment Methods ..." Memorandum . Section 4
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FOREWORD
\ ' ' '' '
How to Demonstrate That Integrity Assessment Procedures For Steel USTs Meet EPA's
Recommended Performance Standards
The Environmental Protection Agency's (EPA's) regulations for underground storage
tanks (USTs) require that all substandard UST systems be upgraded, replaced, or closed by
December 22, 1998. These regulations require that steel tanks without corrosion protection
must be assessed for structural integrity. Then cathodic protection, lining, or both must be
added to meet corrosion protection requirements. The federal UST regulations at 40 CFR §
280.21 (b)(2) state that an assessment method may be used to ensure the integrity of steel tanks
prior to upgrading with cathodic protection if one of two things is true. One is if the
assessment method is specifically listed in the regulations. The other is if the agency.
implementing the UST program determines that an alternative assessment method prevents
releases in a manner that is no less protective of human health and the environment than those
listed.
Deciding whether an alternative method of integrity assessment will prevent releases
in a manner that is no less protective than the methods listed in the regulations has not been
easy. Vendors of such alternative methods have based their performance claims on a wide
variety of test methods and data bases. EPA issued guidance on July 25, 1997, titled
"Guidance on Alternative Integrity Assessment Methods for Steel USTs Prior to Upgrading
with Cathodic Protection," to assist states and local implementing agencies in determining
what alternative assessment methods to allow. In this guidance, EPA recommends that after
March 22, 1998, implementing agencies allow alternative (non-human entry) integrity
assessment methods as meeting the December 22, 1998 requirements, but only if they meet
one of two options..
The first option is a national standard code of practice. Although the American
Society for Testing and Materials developed an emergency standard (ASTM ES 40) for
performing such methods, it has lapsed and a replacement standard has not been finalized.
The second option is a successful third-party evaluation against specified criteria. The
purpose of this document is to provide a protocol for evaluating alternative integrity
assessment procedures, in a form that is readily available via EPA's distribution channels, and
that is consistent with the July 1997 guidance.
EPA will not test, certify, or approve specific vendor procedures for assessing the
structural integrity of steel tanks. Instead, the Agency is describing how implementing
agencies may determine that an alternative integrity assessment method (not listed in the
regulations) meets the performance standard of preventing releases in a manner that is no less
protective of human health and the environment than those listed in the regulations.
Conducting evaluation testing to demonstrate this level of release prevention is the
responsibility of the vendor of such integrity assessment procedures, in conjunction with an
independent third-party testing organization. In ah evaluation and certification process, a
vendor contracts with a third party for evaluation. The third party conducts the evaluation and
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writes a report on the findings for the vendor. The vendor can then provide a copy of the
report to UST owners and regulators, showing that the procedure meets EPA's recommended
performance criteria. This information should be provided to UST owners and operators, who
must keep the evaluation results on file to show compliance with regulatory requirements.
Within the third-party evaluation option, EPA recognizes two distinct ways to
determine that an integrity assessment procedure meets the federal recommended performance
criteria and should be considered to prevent releases in a manner that is no less protective than
the methods listed in 40 GFR § 280.21 (b)(2)(i) though (iii):
1. A qualified independent third party evaluates a vendor procedure by using
EPA's standard test protocol and certifying that the procedure meets specified
performance criteria regarding detection of perforations and of either internal
or external damage, or;
2. A qualified independent third party evaluates a vendor procedure by using a
test protocol deemed equivalent to the EPA test protocol by a nationally-
recognized association or independent third-party testing laboratory.
This document discusses both "integrity assessment methods" and "vendor
procedures." The usage here is that a "method" is a general technology (such as robotic
devices or diagnostic modeling). A method may be described in a national standard code of
practice (such as those from ASTM) and encompass multiple vendor procedures. A "vendor
procedure" is an application of such a technology, typically marketed under a trademarked
brand name. A vendor procedure must be successfully evaluated and certified by a third party.
However, such evaluation is not necessarily recommended for each individual contractor who
is the local provider of a vendor procedure.
Evaluation Process
In an evaluation and certification process, a vendor contracts with a third party for
evaluation. This third party should be a qualified test laboratory, university, or not-for-profit
research organization with no financial or organizational conflict of interest. Based on the
nature of EPA's performance criteria, evaluations will likely be qualitative, but quantitative
evaluations also are acceptable. The evaluation should be performed first without and then
with any information about the leak status of the tank divulged to the vendor. The method's
performance characteristics, both with leak data and without, are determined, summarized on
a results form, sometimes called a "short form," and certified by the evaluator. For the
purpose of determining whether a vendor procedure meets the recommended performance
standards, the results of the procedure after incorporating knowledge about the leak detection
test results are to be used.
Implementing agencies should allow the use of those vendor procedures successfully
evaluated and certified by a qualified independent third party to meet specified performance
criteria regarding detection of perforations and detection or either internal or external damage.
However, those vendor procedures that were part of the 1996 field study conducted by EPA's
Edison, New Jersey lab can use applicable data generated in that study as part of a more
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comprehensive evaluation. In addition, even if a vendor follows a standard code of practice, it
may voluntarily put its procedure through this evaluation process in order to obtain
independent third-party documentation of performance.
EPA Standard Test Protocol
This document incorporates the peer-reviewed "Quality Assurance Project Plan ..."
(QAPP) prepared for EPA's engineering study, "Field Evaluation of UST Inspection
Assessment Technologies," conducted in 1995 and 1996. With the associated reporting
forms, this document is considered a Standard Test Procedure, similar to EPA's Standard Test
Procedures for Evaluating Leak Detection Methods. The Agency recommends that
evaluations conducted in accordance with this document be considered valid. The original
QAPP called for an assessment method to be used on approximately 100 tanks, which are then
removed from the ground for testing and inspection. EPA now allows as few as 42 total
tanks, with at least 21 being unsuitable per the baseline testing.
'
Alternative Test Protocols Deemed Equivalent to EPA's
/ . '.''-'
Because of the nature of the vendor procedure, in order to take advantage of existing
data, or because of improved testing methods, an alternative evaluation protocol may be, more
effective in a particular case than the standard protocol developed by the EPA. Removal and
examination of tanks as detailed in the QAPP may not be necessary for all tanks in the
evaluation. An evaluation following a protocol different than EPA's may be performed by a
qualified third party as above. An approach that uses existing data to establish the baseline
status can be used in lieu of some physical testing if all relevant data requirements are factored
in. The development of other protocols is not precluded, but rather is encouraged. The
alternative protocols should be based on the same evaluation criteria as the QAPP, and the
results should include an accreditation by the association or third-party testing organization
that the evaluation was at least as rigorous as the EPA standard test protocol.
Evaluation Criteria
Within EPA's recommended option for evaluation, the criteria for proving tank .
integrity are as follows:
One of the following:
a) Detect external pits deeper than 0.5 times the required minimum wall
thickness, OR
b) Detect internal pits deeper than 0.5 times the required minimum wall
thickness AND any internal cracks or separations.
Note that a perforation of a tank is regarded as a pit that is deeper than the wall thickness,
whether it originated from the outside or the inside of the tank. Thus, perforations must be
detected under either (a) or ;(b). To meet the criterion, a method must demonstrate a
probability of detection of unsuitable (by one of the above criteria) tanks or sites of at least
95%. A site is considered unsuitable if any one of the tanks at the site is unsuitable. The
estimated probability of false alarm is to be reported, but there is no required level for this
probability. This is a change from the July 1997 guidance.
.3
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Human-Entry Inspection
This document is not intended to discourage the use of human-entry internal
inspection as an assessment method or tank lining as an acceptable upgrade option. EPA's
UST regulations allow for human-entry inspection and interior tank lining to be used as an
upgrade option for tanks lacking corrosion protection (40 CFR § 280.2 l(b)(l)). This
document addresses primarily methods not specifically listed in the federal regulations (see §
280.21(b)(2)(iv)), although human-entry inspection procedures can also be evaluated
according to this document.
ACKNOWLEDGMENTS
This document is based on the "Quality Assurance Project Plan Field Evaluation of
UST Inspection Assessment Technologies," which was produced for U.S. EPA's Office of
Research and Development by IT Corporation. EPA's Work Assignment Manager was
Carolyn Esposito of the National Risk Management Research Laboratory, IT's Project
Manager was Janette Martin, and the primary author was Jarius D. Flora Jr., Ph.D. of Midwest
Research Institute. The Foreword, Results of Evaluation forms, and instructions for the
Results forms were produced by Dr. Flora and David Wiley of EPA's Office of Underground
Storage Tanks (OUST). Paul Miller of OUST, Russ Brauksieck of the New York State
Department of Environmental Conservation, Pejman Eshraghi of the Arizona Department of
Environmental Quality, and Jeff Tobin of the Montana Department of Environmental Quality
all helped, via their participation in the ad hoc Integrity Assessment Evaluations Work Group,
to improve this document.
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SECTION 1
Quality Assurance Project Plan
Field Evaluation of UST Inspection Assessment Technologies
October 1995
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QUALITY ASSURANCE PROJECT PLAN
FIELD EVALUATION OF UST INSPECTION
ASSESSMENT TECHNOLOGIES
by
IT Corporation
11499 Chester Road
Cincinnati, Ohio 45246
and
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Contract No. 68-C2-0108
Work Assignment No. 4-17
JTN 764396 ;
for A,
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
2890 WOODBRIDGE AVENUE
EDISON, NEW JERSEY 08837-3679
Carolyn Esposito
Work Assignment Manager
' ! ' - ' t '
October 1995
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RREL QUALITY ASSURANCE PROJECT PLAN (QAPP) IMPLEMENTATION AGREEMENT
,'- ' f°F ' - ' '
RREL Gontracts/Inter-Agency Agreements/Cooperative Agreements/In-house Projects
RREL QA ID Number:.
Contractor:
RREL Project Category: "_ QAPP Revision Date:
QA Project Plan Title:
Field Evaluation-of U.ST Inspection/Assessment Technologies
QAPP contributors (i.e., QA and management personnel, including subcontractors, for extramural projects
and the EPA princiipal investigator for in-house projects) must sign below. Signatures should be acquired
before submitting the QAPP to EPA for review and written approval.
Name (print)
Role - Affiliation
Agreement Signature'
Date
C
IT
1 Any substantive change to the measurement, data-gathering, or data-generation activity must be documented
in a revision to the previously approved QAPP. Accordingly, this agreement must be revised, re-signed and
submitted with the QAPP revision. (Note: The term "substantive change" is defined as any change in an
activity that may alter the quality of data being generated or gathered.)
2 Signing here signifies agreement with all measurements, data-garnering, and data-generation activity, as
specified, in the QAPP. Above signatures indicate a commitment to implement the QAPP\ approved, in
writing, by the EPA. ,
RREL (IA)
March 1995
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Section No. QAPP List
Revision No. 1
Date: October 4.1995
Page: 1 of 1
Carolyn Esposito
Robert Amick
Janette Martin
Dennis O'Conner
Thomas Clark
J.D. Flora
C. Green
Thomas Barlo
Quinton Bowles
Bopinder Phull
Oliver Siebert
QAPP DISTRIBUTION LIST
EPA/NRMRL Work Assignment Manager
IT Project Manager
IT Work Assignment Leader
IT Senior Reviewer
IT QA Manager
MRI Project Manager
. MRI QA Officer
Project Work Group Member
Project Work Group Member
Project Work Group Member
Project Work Group Member
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Section No. Contents
Revision No. 1
Date: October 4. 1995
Page: 1 of 5
CONTENTS
Section
Contents List of Tables
Contents List of Figures
1.0 Project Description
2.0 Quality Assurance Objectives
3,0 Site Selection and Sampling
Procedures
4.0 Analytical Procedures and
Calibration
5.0 Data Reduction* Validation, and
Reporting
6.0 Internal Quality Control Checks
7.0 . Performance and Systems Audits
8.0 Calculation of Data Quality
Indicators
9.0 Corrective Action
10.0 Quality Control Reports to
Management .
11.0 References
Pages
1
1
21
8
10
2
7 ,
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No. .
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Revised
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10/04/95
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s
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10/04/95
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8/16/95
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8/16/95
10/04/95
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Section No. Contents
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CONTENTS (Cont.)
Section
Appendix A
Appendix B
Appendix C
Radiographic Testing Procedure
Baseline Testing Procedures and Data
Collection Forms
Vendors' Standard Operating
Procedures
Pages
18
13
Revision
No.
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Section No. Contents
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Table
1-1
1-2
2-1
2-2
3-1
4-1
4-2
5-1
5-2
Figure
1-1
-1-2
1-3
1-4
3-1
LIST OF TABLES
Title
Critical or Non-Critical Data, Measurements, Records
Performance Measures for Assessment Methods
'
Completeness Objectives for Vendor Tests
Quantitative QA Objectives for Baseline Test Procedures
Number of Measurements
Measurement, Type, and Equipment for Baseline Testing
of Tanks and Coupons
Scheduled Baseline Test Calibrations
Conclusion of Each Vendor Assessment Method
Sample Data
LIST OF FIGURES
Title .
Tentative Schedule for Work at an Individual Site
Tentative Schedule for Sites in the First Region
Tentative Schedule for Sites in the Remaining Four
Regions
Project Organization
Coupon History Form
P_ag£
1-9
1-11
2-4
2-5
3-3
4-2
4-2
5-5
5-5
Page
1-14
1-15,
1-16
1-21
3-10
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Section No. Content
Revision No. ]_
Date: October 4.
LIST OF ACRONYMS
ADQ Audits of Data quality
API American Petroleum Institute
ASME American Society of Mechanical Engineers
ASTM American Society for Testing Materials
CFR Code of Federal Regulations
CP Cathodic Protection
EPA Environmental Protection Agency
ES Emergency Standard
IT International Technology Corporation
MRI Midwest Research Institute
NACE National Association of Corrosion Engineers
NLPA National Leak Prevention Association
NRMRL National Risk Management and Research Laboratory
OHSA Occupational Health and Safety Administration
PCD Probability of Correct Decision
PD Probability of Detection
PFA Probability of False Alarm
QA Quality Assurance
QAO Quality Assurance Officer
QAPP Quality Assurance Project Plan
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QC Quality Control
SSPC Steel Structures Painting pouncil
TSA Technical Systems Audit
UL Underwriters Laboratory
UST Underground Storage Tank
WAL Work Assignment Leader (Contractor)
WAM Work Assignment Manager (EPA)
Section No. Contents
Revision No. 1
Date: October 4. 1995
Page: _5_ of _5_
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SECTION 1.0
PROJECT DESCRIPTION
Section No. 1
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1.1 Background
By December 22, 1998, all Underground Storage Tank (UST) systems must be replaced,
upgraded, or closed according to the current Federal Regulations for USTs (4QiCFR 280 and 281).
Owners and operators choosing to upgrade their UST systems via cathodic protection or cathodic
protection combined with an internal lining must determine the integrity of their system prior to
upgrading. This Quality Assurance Project Plan (QAPP) presents the experimental design and
criteria for evaluating the performance of four assessment methods for determining the suitability
of USTs for upgrading with cathodic protection. -
In order to be suitable for upgrading by cathodic protection alone (that is, without also lining
the tank), in accordance with 40 CFR Part 280, "Technical Standards and Corrective Action
Requirements for Owners and Operators of Underground Storage Tanks," the tank must be assessed
to ensure that it is structurally sound and free of corrosion holes [Section 280.21(b)(2)(I)j. For tanks
that are 10 years old, two alternative criteria for upgrading a tank with cathodic protection are stated
in the EPA regulations (CFR 280.21 (2)).
"(I) The tank is internally inspected and assessed to ensure that the tank is structurally sound
and free of corrosion holes prior to installing the cathodic protection system;"
"(iv) The tank is assessed for corrosion holes by a method that is determined by the
implementing agency to prevent releases in a manner that is no less protective of human
health and'the environment than subparagraphs (I) through (iii)."
Subparagraphs (ii) and (iii) of CFR 280.21 (2) refer to tanks less than 10 years old. By
December 22, 1998, when the Federal Regulation requires that all UST systems,must either be
"new" tanks, or be upgraded to new tank standards, or closed, there will be no tanks less than
10 years old that do not meet new tank standards.
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Section No. 1
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Determining the integrity of UST systems usually requires some type of internal inspection
or assessment. Past practices involved actual tank entry and internal inspection, and required
significant down time from normal operations. Recently the American Society for Testing Materials
(ASTM) Committee E-50 on Environmental Assessment and Subcommittee E50.01 on Storage
Tanks has issued an Emergency Standard Practice, ES 40-94, "Emergency Standard Practice for
Alternative Procedures for the Assessment of Buried Steel Tanks Prior to the Addition of Cathodic
Protection." The Emergency Standard Practice provides recommended minimum performance
practices for three alternative methods to internal inspection for assessing the suitability of
underground storage tanks for upgrading by adding cathodic protection. These three methods are
tank life/corrosion rate models, remote video camera tests, and robotic ultrasonic tests. These
v »
methods do not require human entry into the tank to determine the suitability of a tank for upgrading
with cathodic protection.
The three new methods include a site survey to collect basic tank and environment
information. This site survey includes items such as tank age, a check for stray d-c current, other
buried metal structures, tank material and electrical isolation, and tank leak and repair history. In
particular, the tank is also required to have passed a suitable leak detection test. These methods all
conduct basic site-specific tests of the tank environment including:
Stray current/corrosion/mterference
Soil resistivity
Structure to soil potential
SoilpH
Electrical continuity/isolation
In addition, other tests may be required by the corrosion expert including such measurements
as hydrocarbon, chloride, sulfide, and sulfate ion concentrations in soil and resistance of the tank
coating. Some methods have obtained approval from some State regulatory authorities; however,
other State agencies are withholding approval, pending an evaluation of performance claims for these
systems.
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Section No.._...'1
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The intent of the Emergency Standard Practice is to present alternative methods for
determining if cathodic protection is a reasonable and viable upgrading method for a particular tank.
To do this, a corrosion engineer must consider both the condition of the tank and the, condition of
the soil that forms the environment for the tank. This project is designed to evaluate the performance
' - f
of the three methods described hi the Emergency Standard Practice, as well as the existing method
of internal inspection, hi determining only the condition of the tank. The procedure for this
evaluation is to have vendors of each of the four methods apply that method to a set of underground
storage tanks and report their results. The use of the soil data to determine the soil's compatibility
with applying cathodic protection is beyond the scope of this project. ,
The tanks will then be removed and the actual condition of the tanks determined by a series
of baseline tests, some of which are destructive. It should be noted that the non-destructive tank
assessment methods are inherently limited to observing and making measurements from the ulterior
of the tank. The baseline tests will have both the inside and outside surface of the tank shell
available for determining the condition of the tank.
The performance of each method of tank assessment will be estimated by comparing its
conclusion as to whether each tank was suitable for upgrading with cathodic protection to the
condition of the tank determined by the baseline testing. The results of the comparison will be
summarized for all tanks in the study by calculating the proportion of correct decisions reached by
each tank assessment method. That is; the proportion of tanks for which each assessment method
agreed with the findings of the baseline test will be calculated and reported. The proportions of each
type of disagreement between the assessment methods and the baseline findings will also be
calculated and reported. Regulators may use these performance estimates in deciding which
methods to allow in then- jurisdiction. Tank owners may use this information to select a method of
assessment for then- tanks. .
1.2 Vendor Assessment Methods to Be Evaluated
The four vendor methods below are used to evaluate the structural soundness of the tanks.
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1.2.1 Non-invasive Tank Life/Corrosion Model Tests (i.e., modeling)
This method examines the environment in the specific vicinity of the tank. A statistical
model is used to determine a relationship between the aggressiveness of the environment and the rate
of corrosion. The site-survey and site-specific tests noted above are to be conducted in more detail
for this method than'for the others. For example, the stray current measurements use a
microprocessor-controlled data acquisition unit taking data samples at 5-sec intervals. The soils data
are based on samples collected at 2-ft intervals fix>m two or more holes bored at least as deep as the
bottom of each of the tanks.
The data input to the model include the results of the analysis of soil samples as well as
various electrical measurements (e.g., structure to soil potential). The statistical model is required
to have been developed on at least 100 sites with at least 200 tanks that were excavated and
inspected by a corrosion expert. The model must also include factors such as presence of a water
table, annual precipitation and average temperature.
The output of the model includes an estimated leak-free life of the tank (which must have a
standard deviation of no more than 1.5 years) and an estimated probability of corrosion perforation.
Tanks with an age less than the estimated leak-free life and with a probability of corrosion
perforation less than 0.05 (5%) may be upgraded by the addition of cathodic protection using an
appropriately designed cathodic protection system. This method is described in ASTM ES 40-94.
1.2.2 Invasive Robotic Ultrasonic Tests (i.e., ultrasonic)
Following the site-survey and site-specific tank environment tests, the robotic ultrasonic
equipment is installed in the tank through an existing opening (typically 4 in. in diameter). The tank
will be prepared according to the vendor's specifications (in their written procedure) by the vendor.
The robotic ultrasonic equipment is used to take discrete, located measurements of wall thickness
on at least 15% of the entire tank interior surface. These measurements are designed to be uniformly
distributed over the, tank surface (excluding man-way entries). The data from a mathematical
corrosion prediction model are used to forecast when each tank is expected to leak. The tank is
considered suitable for upgrading with cathodic protection if there is no pitting greater than 50% of
the minimum recommended wall thickness and the average metal wall thickness of each 9 ft2 is
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greater than 85% of the minimum recommended wall thickness. This method is described in ASTM
ES 40-94. In the event that one of the selected tanks does not have an opening large enough for the
robotic ultrasonic equipment, a larger opening will be cut in the tank, since such an opening will be
cut for the internal, inspection anyway.
1.23 Invasive Remote Video Camera Tests (i.e., video)
- This method also uses the basic site survey information and the site-specific measurements
described above. In addition to those, this method consists of inserting a remotely operated video
camera and. suitable lighting source into the tank. The tank will be prepared according to the
vendor's specifications (in their written procedure) by the vendor. This video system must be
capable of recording a video survey of the ulterior surface of the tank.\ The, detailed requirements
of the video system are included in ASTM ES 40-94. (
The video system is used to survey the interior of the tank to allow the operator to first
determine that the tank is sufficiently clean for effective video inspection. Then the camera is
controlled to systematically record a visual inspection of the internal tank surfaces, with a recorded
voice override and text input to document the direction and location of the view arid comment on
» '_-,'... .
findings. The corrosion tester using the video will document any evidence of corrosion including:
Perforations .'..'...
Rust tuberculation
Streaks .; -..'..'..
Discoloration ./ ' .
Pitting " . .
Scaling or delaminations
.' Weld corrosion
Cracks
Passive films
Based on this visual examination using the video camera, review of the site-specific
environmental data, and tank age, the examming corrosion expert makes a determination of whether
any evidence exists for corrosion or deterioration that would indicate that the tiank is not suitable for
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, Section No. 1
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upgrading with cathodic protection, whether the tank requires further inspection by other recognized
procedures, or whether the tank is suitable for upgrading with cathodic protection. In the event that
one of the selected tanks does not have an opening large enough for the robotic ultrasonic equipment,
a larger opening will be cut in the tank.
1.2.4 Invasive Internal Inspection (Le., inspection)
Determination of tank structural integrity has most commonly been accomplished by means
of human inspectors physically entering properly prepared tanks and using various inspection
techniques. Current practice is to perform a visual inspection either alone or in combination with
other measurements. The techniques that have been used in an internal inspection include: (a) visual
inspection for holes, cracks, and deformation, (b) "hammer test," involving striking the inside of the
tank with a ball peen hammer to identify structurally weak areas and/or judging the relative thick or
thin area by the resonant sound produced; © ultrasonic transducer measurement of the wall
thickness; (d) magnetic particle testing for cracks; and (e) various combinations of the previous
methods. The visual inspection, and to a lesser extent visual inspection in conjunction with UT
testing, is commonly performed by applicators of ulterior tank linings.
The internal inspection requires physical entry into a tank. Typically the top of the tank must
be exposed by excavation and an opening (minimum 18 in by 18 hi) cut in the top of the tank. The
tank must be ventilated to provide a breathable atmosphere and to eliminate any fire hazard. Persons
entering the tank must wear protective clothing and be supplied with air from a tank or outside
source. Sludge must be removed from the tank and the tank cleaned and abrasively blasted prior to
performing the visual inspection. The vendor must follow all applicable OHSA and other regulatory
requirements. Generally the internal inspections follow the guidelines in American Petroleum
Institute (API) 1631, "Interior Lining of Underground Storage Tanks, 3rd Edition, April 1992,"
National Leak Prevention Association (NLPA) 631 "Entry, Cleaning, Interior Inspection, Repair and
Lining of Underground Storage Tanks," or NLPA 632 "Internal Inspection of Steel Tanks for
Upgrading with Cathodic Protection Without Lining."
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Date: October 4.1995
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1.3 BASELINE TESTS (i.e., Baseline)
The vendor test methods are all done with the tank in the ground and consequently are
limited to the interior of the tank. Corrosion and pitting may occur on the outside of the tank. The
baseline tests are conducted from both sides of the tank after it has been removed from the ground
to establish the actual condition of the tank. This internal and external method is similar to the visual
inspection method, with several additions. The internal vertical diameter is measured while the tank
is still underground, then the tank is excavated and moved for additional measurements and an
access hole is cut in one^nd. The original location of the diameter measurement is recorded, and
the internal vertical and horizontal diameters of each end are measured, then the amount of shell
deformation is calculated. A grid pattern using 3 ft by 3 ft grids is marked on the inside and outside
of the tank, and both the ulterior and exterior (before and after abrasive blasting) are visually
inspected. The purpose of the inspection is to detect surface discontinuities such as cracks, holes,
and pits, and to describe the amount and type of any corrosion observed. The written procedure that
is applicable for this examination is that provided in Section 3.3. Photographs are used to document
the condition. When rust plugs are detected, they are removed. The depths of the visually deepest
pits are measured.
Ultrasonic measurements are conducted to determine wall thickness. This testing is done
primarily from the inside of the tank, but may also be done from the outside. An ultrasonic test is
made at the approximate center of each marked grid. Additional ultrasonic readings may be taken
in any grid section based on field crew observation and judgement. Wall thicknesses will also be
measured by drilling a sentry hole and using a through-wall micrometer. The minimum required
initial wall thickness for each tank will be determined by the tank size in accordance with
Underwriters Laboratory (UL) 58 "Standard for Steel Underground Tanks for Flammable and
Combustible Liquids."
The results of the baseline measurements are used with the criteria hi Section 2.2.3, "Criteria
': i
for Upgrading," to classify the tank as suitable or unsuitable for upgrading with cathodic protection.
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Section No. 1
Revision No. 1_
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1.4 STATEMENT OF PROJECT OBJECTIVES
The primary objective of the project is to determine the performance, i.e., proportion of
correct decisions, of the four tank assessment methods. First, the four assessment methods will be
conducted by vendors. Second, a baseline test on the same tanks will be conducted by the
contractor. Third, the conclusion of each assessment method will be compared with the baseline
findings. Fourth, the measure of performance of each tank assessment method and their 95%
confidence intervals will be calculated.
The critical and noncritical data, measurements, and records for the four vendor methods and
the baseline tests are provided below in Table 1-1. The equipment used for the baseline testing is
also listed. *
Table 1-2 classifies the tanks by the vendor's results and the actual tank condition. The cells
where the vendor's result agrees with the actual condition are correct decisions, while those where
the results disagree represent errors. The proportion of correct decisions is the number of tanks
classified hi the upper left and lower right cells of Table 1-2 divided by the total number of tanks.
Four secondary objectives of the project are to estimate the proportions of false alarms,
correct detection, missed detections, and correct approvals. A false alarm occurs if a vendor's result
fails a tank that is suitable for upgrading (by cathodic protection). A correct detection occurs if a
vendor's result fails a tank that is not suitable for upgrading. A missed detection occurs if a vendor's
result indicates that a tank is suitable for upgrading, when, in fact, its actual condition does not
qualify it for upgrading. A correct approval occurs if the vendor's result approves a tank for
upgrading and the tank is actually suitable for upgrading. Additional secondary objectives are given
in Subsection 2.1.
1.5 EXPERIMENTAL DESIGN
One hundred tanks will be used in the study. This number constitutes a statistically valid
population of tanks for assessing the performance of the vendor assessment methods. The total
number of tanks to be included hi this study was set by determining the number required so that the
expected half-width of the 95% confidence interval for the probability of false alarm and probability
of correct detection would be 0.15. That is, the objective of estimating the performance parameter
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Section No. 1
Revision No. 1
Date: October 4.1995
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to within at least ±0.15 with 95% confidence would be met. This led to the selection of a sample'
size of 100 tanks, of which approximately half would be found suitable for upgrading with cathodic
protection, as sufficient to meet this objective.
Table 1-1. Critical or Non-Critical Data, Measurements, Records
Required Data/Measurement/Record ,
Modeling: , .
,
Tank identification .
Conclusion (suitable or unsuitable for upgrading with CP)
Raw data from soil and electrical measurements , .
Expected Life of the Tank
Probability of corrosion hole
Ultrasonic:
Tank identification
Conclusion (suitable or unsuitable for upgrading with CP)
If tank not suitable, reason for conclusion
Data base of ultrasonic wall thickness measurements (and locations)
Maximum pit depth found
Average wall thickness for each 3 ft by 3 ft area
Results of their prediction model
Video:
Tank identification ;
Conclusion (suitable or unsuitable for upgrading with CP)
If tank not suitable, reason for conclusion
Presence of pits or rust tubercles on opposite surface of > 0.125 in diameter
A copy of the video tape record ..'..-'
Location of any perforations or corrosion identified by the video inspection as significant
TYPE
C
C
NC
NC
NC
C
C
NC
NC
NC
NC
NC
C
C
NC
- NC
NC
NC
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Section No. 1
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Date: October 4.1995
Page: 10 of 21
Table 1-1. Critical or Non-Critical Data, Measurements, Records
Required Data/Measurement/Record
Inspection:
Tank identification
Conclusion (suitable or unsuitable for upgrading with CP)
If tank not suitable, reason for conclusion
Location of any perforations, deep pits, or thin walls identified
Any quantitative measurements developed, e.g., wall thickness measurements
Baseline:
Tank identification
Presence of perforations
Location of perforations using grid system developed by tape measure
Depth of pit for 5 deepest pits using depth micrometer
Location of 5 deepest pits'
Diameter of pits on interior using a ruler
Wall thickness measurements using throughwall micrometer
Wall thickness measurements using an ultrasonic instrument
Tank diameter (vertical and horizontal) using tape measure
Presence of observed cracks in welds
Location of cracks in welds
Internal and external detailed inspection results
Results of any external laboratory tests recommended by field crew (e.g., radiography or
sectioning of steel coupons)
Photographic documentation of each tank
TYPE
C
C
NC
NC
NC
C
C
NC
C
NC
NC
C
C
C
C
NC
NC
NC
NC
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Section No. 1
Revision No. 1
Date: October 4.1995
Page: IT'of 21
Table 1-1. Critical or Non-Critical Data, Measurements, Records
Required Data/Measurement/Recqrd
TYPE
Owner:
Result of leak tests
NC
Age of tank
C = Critical
NC = Non-critical
NC
Table 1-2. Performance Measures for Assessment Methods
Vendor's result
Actual condition
«
Tank suitable for
upgrading
Pass
Correct Approval (Approved a tank
suitable for upgrading)
Fail
False Alarm (Failed a tank suitable for
upgrading)
Tank not suitable
for upgrading
Missed Detection (Incorrectly passed a tank
not suitable for upgrading)
Correct Detection (Failed a tank not
suitable for upgrading)
To assure that the environmental conditions at the tank sites would be representative of
conditions in the United States, the contiguous 48 states were divided into 5 regions. The 100 tanks
will be selected with an equal number of 20 from each of the 5 regions.
The Northwest region was chosen to represent cool, wet climates and a range of soil types.
The Southwest region represents the hot, dry conditions with sandy soils typical of that area. The
Midwest region represents agricultural soil types with hot summers, cold winters, and moderate
precipitation. The Northeast region represents densely populated urban areas with rocky soils and
climates typical of New England, and the Southeast region represents hot, wet climates with the
typical red clay and other soil types found in that region.
EPA will arrange with tank owners to identify tanks previously scheduled for removal that
can be used in this project. The tanks selected will be steel tanks that have not been cathodically
protected or lined. The tank owners will be asked to supply data on the age of each tank, its size or
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Revision No. 1_
Date: October 4.1995
Paqe:JL2 of 21
volume, the leak detection history, and any other information available. In planning, it has been
assumed that all tanks at a given site (within a geographic region) would be scheduled for removal.
A tank site is the specific location of the study tanks, for example, a gas station. In order to control
the cost, all tanks to be removed at a given site will be included hi the study. It is estimated that
there will be an average of 3 tanks per site, leading to approximately 7 sites per geographic region
to supply the 20 tanks. In order to obtain a variety of soil types and environmental conditions, at
i S , " - . f
least 6 sites within each region will be used to provide the 20 tanks.
EPA will develop a list of available tanks and sites within each region. If there are more than
20 tanks within a geographical region, this list will be reviewed to select the tanks and sites for use
in the project. The representativeness of the set of tanks is not completely under the control of the
project. In addition, the tanks to be used do not need to represent the population of tanks. Ideally,
approximately half of the tanks to be used should be suitable for upgrading by cathodic protection
and about half should not be suitable. This would make the estimation of the two performance
parameters about equally precise. To achieve representation of these two classes of tanks as well
as possible, the tanks will be selected from the list of eligible tanks by selecting equal numbers of
tanks from those that have recently passed a leak detection test and those that have not, if there are
enough tanks hi each group to allow this. If very few tanks have not passed recent leak detection
tests, then about half of the tanks selected will be the oldest available. The suitability of tanks for
upgrading with cathodic protection will not be known or determined until the baseline tests are
conducted. Selecting tanks from these groups is an attempt to obtain approximately equal numbers
of tanks in the suitable and unsuitable groups.
All tanks selected for use in the study will be tested by each of the four tank assessment
* 1
methods to be evaluated. The vendors of the methods will supply their reports including conclusions
as to the suitability for upgrading as well as supporting data. The supporting data should be
sufficiently documented to identify the reason for disqualifying a tank, and, if a specific problem is
found, the location in the tank of that problem. The vendors of each method will first present their
1 " * ' ' , , " , " ' i
conclusions in the absence of knowledge about the results of a leak test on the tank. Such
conclusions may be stated conditionally on the results of the leak test. After the conclusions of each
method without knowledge of the leak status of the tank have been stated, the leak test results will
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Section No.
Revision No.
DateLOctober4
Page:.J2_of_2J_
be supplied to the vendors. The vendors will then prepare second conclusion reports incorporating
- the results of the leak detection test. Thus, each method will provide two sets of results for each
tank, one without knowledge of the leak test result on the tank, and one incorporating the results of
the leak detection test.
* -
After the tank has been assessed using each of the four methods, the tank will be removed
from the ground and subjected to baseline tests, some of which will be destructive. These tests will
determine the condition of the tank based on four primary parameters:
Presence or absence of holes
Depth of pits, if found , \-
Wall thickness
Cracks in welds
These four primary parameters will be used to determine if a tank is suitable for upgrading
with cathodic protection. Because there is no single standard criterion for judging a UST suitable
for upgrading with cathodic protection, the determination of suitability will be made using several
different criteria, as listed in Section 2.3. For a given criterion, the probability of false alarms for
each method will be estimated as the proportion of tanks judged to pass by the criterion applied to,
the baseline data which the method reported as unsuitable for upgrading. The probability of
detection for each method will be estimated as the proportion of tanks failed by that method that are
also judged to fail by the criterion applied to the baseline data. Two sets of conclusions will be
reported by the methodr-with and without knowledge of the leak test results. Separate estimates will
be made for each set of conclusions compared to each of the 4 criteria for the tank.
1.6 SCHEDULE
Three tentative schedules are presented as Figures M through 1-3. Figure 1-1 is the
tentative schedule for work at an individual site; Figure 1-2 is the tentative schedule for all the sites
at the first region; and Figure 1-3 is the tentative schedule for all the sites at each of the remaining
regions. The comments below provide the assumptions made in developing these schedules. A
minimum of 6 sites per region are required. For the schedule and budget, 7 sites per region were
used. . -
-------
Pump 1
Robotic Ultrasonic
Remote Video
Noninvasive
Excavate, Open Tanks,
Desludge
Sandblast
Internal Inspection
Pull Tanks
Sandblast, Open End
Baseline Tests
Makeup Day
Site Schedule
1
2
3
I
4
I
Wor
5
I
kDay
6
7
8
I
9
I
10
a. ao ea
QJ CD tO
55-37 SEV gtauz »cd 1 072605
Figure 1-1. Tentative Schedule for Work at an Individual Site
CO
-------
s
1
3
2
Regional Test Schedule
First Region
Identify Sites
Training & Mobilization
Scheduling
Site 1
Site 2
Site3
Site4
SiteS
SiteB
Site?
Final Lab Work
1
2
3
l
V
4
5
Week
6
1
(
7
8
9
,_
l l
10
1 I
11
- ' .
I
-O O 3O C/3
Q) Q) CD CD
ca I-*- < r>
N
Figure 1-2. Tentative Schedule for Sites in the First Region
cr
CD
CO
CO
01
-------
Regional Test Schedule
Remaining Regions
Identify Sites
Mobilization
Scheduling
Sitel
Site 2
Site 3
Site 4
SiteS
Site 6
Site?
Final Lab Work
1
2
3
4
Week
5
6
7
,_
I 1
8
1 1
9
1
-a a 3D co
m o> re n>
CO r* < O
'
*MT >EV ^iw K anew
Figure 1-3. Tentative Schedule for Sites in the Remaining Four Regions
2. '
=>
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Section No. __
Revision No. ,
, - Page:_lZ_of_21_
1.6.1 Site Schedule
fl Id" It T' 7 SfeS * * KSimWm ^ "^ >0 working days ,o complete al,
neldworkby^vendorsand^eresearch.ean,. !t is assumed that each si* contains 3 tanks !, ^
^--^-^d**^;^^^^^ °
construct contractors, ^ One slack day per site, shown as a makeup day has been
*
.
of the tanks wil, be done by the tank owner^r prior to conducting vendor
^hrnmary purgmg may a!so have occurred, bu, addinona, purging wffl be needed for a few hours
after the s*rt. Tie Mowing additional assumptions also control the schedule
1.6.1.1 Modeling
I, is assumed to thework of ^ vendors on site can be accompUshed in , day. However,
the data coUect-on reouired by the vendor does not require access to the tank, per se nor does it
.n^erewit.theworkof^othervendors. Tr^ore, can be done any time during thefet week
(before the tanks are excavated).
1.6.1.2 Ultrasonic
vendor cotad both be a, the site the same day, testing on a-temate tanks. Nevertheless, a total of
2 days for the two methods has been allocated.
1,6.1.3 Video
Ine vendor wil, r^e about a day a, Me site. However, mis vendor and the robotic
boateaaesitete^^^on
1.6.1.4 Inspection
methods has been aUocated.
on,oto
lnspectio,
^
otters are sttllunder test. Specific assumptions are as follows-
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Section No. _. 1
Revision No. _ 1
Date:J)ctober4.
e:_l£_of.2L_
1.6.1.5 Baseline
. . A total of 4 day, has been allotted to the baseline testing, including the necessary r^
work. This preliminary work includes pulling the tanks, perhaps relocating the taks, abrasive
blastag ft. exterior of ft. tanks, and cutting open one end of each tank. Specific assumptions
as follows:
are
Pulling of the tanks (and relocating them if necessary) should require 1 day and is
unlikely to be significantly overlapped with other activities.
bCen 8ll?Catod t0 Sbrasive blasting «* ext£rior of each tank and
been allocated to conducting the baseline tests on each of the three
1.6.2 Regional Test Schedule for the First Region
It is assumed that the field work at the 7 ^ sites in the &st region will require 1 1 weeks of
effort following approval of the QAPP. The primary assumptions deal with matters beyond the
contractor's direct control. These are that EPAcan identify the sites within 3 weeks, that the tank
owners/operators can comply with the contractor's schedule, and that the vendors and construction
subcontractors can comply with the contractor's schedule. The other assumptions are as follows.
1. Final safety and related training and mobilization will require approximated
2 weeks, and can occur simultaneously with EPA's efforts to *
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2.
3.
4.
Section No. 1
Revision Mo. 7
Date: October 4.1995
Pane: 19 of 21
Scheduling the sites, vendors;, and construction subcontractors can start as soon as
some of the sites are identified, and can continue after field work has started at some
sites. ',.'-'', ' . * '
Each site requires 10 working days of field work. However, work can be staged, so
that work can be ongoing at more than one site at a time. A 1 -week overlap has been
assumed for the first four sites, and a half-week overlap for the last three, as the
various participants become more adept at their roles.
1 " ~~ ' f -
- " ' ' %
About a week and a half has been allocated to complete the lab work after all field
work is completed.
1.6.3 Regional Test Schedule for the Remaining Regions
The assumptions made for the first region remain essentially valid for the remaining regions.
However, because of the experience gained by the research team and the vendors in the first region,
, . , ^ - . y . .
the work in each of the remaining regions can be conducted somewhat more expeditiously. It is
estimated that work at the first site can begin after 2 weeks, even though all 7 sites may not yet have
been selected. Work at the various sites can be overlapped somewhat more than hi the first region.
It is expected that field work in the remaining regions may proceed more rapidly than in the first
region. As a result of all these assumptions, it is estimated all work at each remaining site can be
completed in 9 weeks, compared with 11 weeks for the first region.
1.7 Project Organization and Responsibilities
The project organization and lines of authority and responsibility are presented in Figure 1-4.
Ms, Carolyn Esposito (Telephone: (908) 906-6895) of the EPA NRMRL is the EPA Work
Assignment Manager (WAM) and will oversee all activities conducted hi this project. Ms. Esposito
will review the draft QAPP, and review the final report to determine if the project objectives and QA
requirements have been satisfactorily addressed. Mr. Guy Simes is the EPA Quality Assurance
Officer (QAO). Guy Simes will review the QAPP or assign a designee to review the QAPP to
'
ensure that all QA requirements have been satisfactorily addressed.
Mr. Robert Amick (Telephone: (513) 782-4759) is the IT Project Manager for this contract.
Mr. Amick will provide overall review of the quality, budget, and timeliness of work conducted in
this project. Ms. Janette Martin (Telephone: (513) 782-4956) is the IT Work Assignment Leader
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Section No. 1
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Date: October 4.199S
Page: 20 of 21
(WAL) responsible for ensuring the completion of the project and for providing project status
information to the EPA WAM. She has ultimate responsibility for ensuring project quality and
timeliness. Mr. Tom Clark (513-782-4700) is the IT QAO for the Cincinnati office. He will monitor
the project activities to ensure the proper conduct of analyses, data reduction, and data reporting.
Mr. Dennis O'Conner, and members of a Work Group formed specifically for this Work Assignment,
will provide expert technical expertise and oversight during this study.
Ms. Martin will be assisted hi conducting the technical work by IT technical staff and
personnel from IPs subcontractor, Midwest Research Institute (MRI). The MRI Project Manager,
Dr. J.D. Flora (816-753-7600), is responsible for technical oversight of the work conducted by MRI
and will report to the IT WAL. Ms. Carol Green (816-753-7600) is the MRI QAO. She will conduct
or direct audits as required hi the QAPP.
Communications during this project will be maintained through weekly telephone calls
between the IT WAL and the MRI Project Manager, and the IT WAL and the EPA WAM. The IT
Quality Assurance Officer and the Health and Safety Officer will be included in the calls and provide
technical assistance as required during the project. If a serious problem arises, IT and MRI will
immediately discuss the problem over the telephone, possible corrective actions will be discussed,
and the selected actions will be carried out.
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Section No, _J_
Revision No. 1
Date: October 4.1995
Page: 21 of 21
Work Group Members
Thomas -Barb, Ph.D.
Quinton Bowies, Ph.D.
Bopinder Phull, Ph.D.
Oliver Siebert, P.E.
IT Technical Staff
MRI Health
& Safety Officer
James McHugh, CIH
On-Site Subcontractors
abrasive blasting
, leak detection
EPA Work Assignment
Manager
Carolyn Esposito
IT Project Director
Robert Amick, P.E.
IT Work Assignment
Leader
Janette Martin
MRI Project Manager
Jairus Rora, Ph.D.
MRI Technical Staff
EPA QA Officer
IT Senior Reviewer
Dennis O'Conner
FT Health
& Safety Officer
Larry Verdier, CIH, CSP
IT Quality
Assurance Officer
Thomas Clark
MRI Quality
Assurance Officer
Carol Green
Commercial Labs
Figure 1-4. Project Organization.
MWI6417-2-3-SW5-O
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Section No. _
Revision No.
Date: October 4.1
Page: 1 of 8
SECTION 2,0
QUALITY ASSURANCE OBJECTIVES
2.1 Overall QA Objectives
The primaiy purpose of this study is to evaluate the performance of four different methods
for determining the suitability of steel underground storage tanks for upgrading with cathodic
protection. The findings of each tank assessment method will be compared with the results of
baseline:tests that determine the actual status of the tank.
The primary project objective is to estimate the proportion of correct decisions made by each
vendor assessment method with a 95% confidence interval having a half-width of 0.15 or less. ;.
For example, an estimated proportion of correct decisions of 0.85 with a 95% confidence
interval of (0.78, 0.92) would meet this objective.
To do this, the following secondary objectives must be met:
« A statistically valid number of tanks must be tested. (See Subsection 15,
Experimental Design.) For design purposes, 100 tanks are to be tested arid between
45 and 55 of these tanks should be found to be suitable for upgrading by cathodic
protection. .
Vendors must follow established protocols and procedures. (See Subsection 2.2,
Evaluation and Documentation of Vendor Protocols and Procedures.)
'. The data collected from each vendor method and the baseline tests for each tank and
coupon must be. thoroughly documented and sufficiently complete so that the
conclusion reached may be reconstructed. (See Subsection 2.2.2, Documentation of
Observed Procedures.)
The precision of the baseline tests of the 5 deepest pit depths and the precision of the
through-wall thickness measurements must be within specified criteria as proof of
the reliability of the baseline tests. (See table 2-2, Quantitative QA Objectives for
Baseline Test Procedures.)
Vendor results must be compared to the criteria for judging an underground storage
1 tank to be acceptable for upgrading with cathodic protection. (See Subsection 2.2.3,
' " Criteria for Upgrading.) ,
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Section No.
Revision No.
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Page:_2_of_E_
Each tank must be classified according to its status for upgrading with cathodir
protection as detexmined by the baseline tests and as.repSed by^e vendor's
assessment method. (See Table 1-2, Perfonnance MeLres for Ass
Documentation of Vendor Protocols and Procedures
Evaluation and documentation of vendors protocols and procedures are important to:
V^fy^ttheprotocolsandprocedires^
Establish to vendor field crews both understand and follow the written protocols
and procedures so that the data are properly evaluated, interpreted and arcSved
2.2.1 Comparison of Vendor Protocols to Applicable Standards
Prior to participation of a vendor in this program, the vendor will submit a written protocol
that describes the purpose and principles of the method. This document will generally also contain
the following information:
1.
2.
3.
4.
5.
6.
7.
Scope and applicability of the method
List of reference publications
Delineation of applicable permits and local approvals
Personnel training requirements
General safety requirements
Step-by-step procedures
Methodology for inspection and compliance to specifications
The contractor will review the vendor's protocol and compare it to any consensus standards
such as thoseoftheAmericanPetroleumlnstituteCAPI), American Society for Testing and Materials
(ASTM), American Society of Mechanical Engineers (ASME), Underwriters Laboratory (UL), and
EPA Federal Register, and will make an engineering judgment that the protocol meets'any
appropriate and minimal standard, and/or note any discerned deficiency.
2.2.2 Documentation of Observed Procedures
Prior to the observation of the vendors' operations the contractor will devise a check list of
the step-by-step procedures as delineated in the vendor's protocol. The ^afeiSf keep a log of the
observed procedures for comparison with the protocol. In addition to this check list, the contractor
will note any other information deemed pertinent. As an example, note will be made of the type and
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Section |\lo.
Revision Mo.
model of equipmenWnstanentation utilized, abrasive material and specifiers used during
abrasrve blasting, maintenance and/or calibration of equipment, adequacy of data obtained, and
.,. record keeping.
For each vendor's operation the contractor will providea succinct summary providing
conclusions and recommendations.
23 Criteria for Upgrading
There is currency no single standard criterion for judging an underground storage tank , be
acceptableforupgradingbyfteadditionofcamodicprotection. Consequent*, the determination
of the acceptability of a tank for upgrading based on the baseline tests will be made using four
drfferen, criteria. These are listed below. Bom forms of me vendor's conclusions wi,l be compared
to each of these four criteria and the results summarized
~"
suitable. (This requirement is specified in the Federal Regulations.)
Criterion!: To b<
"-*
0.240 in. Note: Requirement(a) implies that there can be noperforations
Quantitative QA Objectives
For the vendor tests, only completeness objectives can be estabUshed. For the baseline tests
bothprecisionand completeness objectives ^^.~4^to£^^^^ .
Criterion 4:
2.4
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, : Revision No. 1
Date: October 4.1995
Page: 4 of 8
» » ,
from a tank. A location grid is used to document the position of the measurements and various
features. Completeness objectives for the four vendor tests are provided in Table 2-1. Objectives
for the baseline tests are provided in Table 2-2.
Table 1-2 classifies the tanks by the vendor's results and the actual tank condition. The cells
where the vendor's result agrees with the actual condition are correct decisions, while those where
the results disagree represent errors.
A correct decision occurs if a vendor's result agrees with the baseline finding about
the tank's suitability for upgrading with cathodic protection.
A false alarm occurs if a vendor's result fails a tank that is suitable for upgrading (by
cathodic protection).
A correct detection occurs if a vendor's result fails a tank that is not suitable for
upgrading.
A missed detection occurs if a vendor's result indicates that a tank is suitable for
upgrading, when, in fact, its actual condition does not qualify it for upgrading.
A correct approval occurs if the vendor's result approves a tank for upgrading and
the tank is actually suitable for upgrading.
Table 2-1. Completeness Objectives for Vendor Tests
Type of test
Modeling
Video
Ultrasonic
Inspection
Subject
Data, measurements, records,
conclusions, reason for failing
Data, measurements, records,
conclusions, reason for failing
Data, measurements, records,
conclusions, reasons for failing
Data, measurements, records,
conclusions, reasons for failing
Completeness (%)
100
100
100
100
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Settion No. 2
Revision Wo. _J_
Date: October 4.1995
B: 5 of 8
Table 2-2. Quantitative QA Objectiyes for Baseline Test Procedures
Critical
measurement
Pit Depth
Wall thickness
Wall Thickness
through 5/8" sentry
holes (for nominal
quarter in steel tank)
Pit Diameters
(maximum and
minimum if not
circular)
Location by grid
system
Tank diameter
Equipment
Depth Gauge
Micrometer Model
449AZ-3R, L.S.
Starrett Company
Ultrasonic Thickness
Gauge Model
DM4DL,
Krautkramer Branson
Company using a 0.38
in transducer and
EXOSEN 30 couplant
Throughwall
Micrometer,
Inspectors
Micrometer Model
175RLZ.L.S. Starrett
Company)
Ruler (common
source)
Tape measure
(common source)
Tape measure or tank
gauge stick (common
source)
Sensitivity and
Reporting units
(in)
0.001
0,001
0.001
0.0625
0.5
0:0635
ty"
Precision (in)
0.01
NA ;
0.01
NA
NA
NA
Completeness
(%)
100
100
100
100
100
100
*
NA = Not Applicable
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Section No. 2
Revision No. 1
Date: October 4.1995
Page: 6 of 8
i
For this study, the accuracy of a tank assessment method is defined as the probability that
the method correctly determines that a tank is suitable for upgrading with cathodic protection. The
reliability of a tank assessment method is defined as the probability that the method correctly.
.!',' ;
identifies a tank that is unsuitable for upgrading with cathodic protection. Thus, among tanks
suitable for upgrading, the proportion of tanks correctly passed and incorrectly failed by each
assessment method must be estimated. Naturally the sum of these two proportions is 100%.
Similarly, among tanks not suitable for upgrading, the proportion of missed detections and correct
detections must be estimated for each assessment method. Again, these two proportions add to
i **
100%. .
A measure of performance of an assessment method, combining both aspects of performance,
is the overall correct rate of an assessment method. The overall correct rate is the proportion of
tests hi the upper left cell and the lower right cell of Table 1-2 among all tests. The complement of
this is the proportion of incorrect decisions among all tests.
The goal is to estimate the vendor's overall correct rate to within ±0.15 with 95% confidence.
In addition, the performance measures in Table 1-2 will be estimated to within ±0.15 with 95%
confidence. This is referred to as the 95% confidence interval for the proportion having a half-width
of 0.15 or less. For example, for a false alarm rate of 50%, it will be possible to estimate the False
Alarm Rate of 0.5 ±0.15 (or 50% ± 15%) with 95% confidence. The confidence interval will be
smaller for values of the proportion close to zero or one.
In order to estimate these proportions, the study must contain both tanks suitable for
upgrading and unsuitable for upgrading. If the numbers of suitable and unsuitable tanks in the stu,dy
are equal, the estimation of the two error rates would be based on the same sample sizes and so be
of about equal precision. However, since the actual condition of the tanks in the study will not be
known until the baseline tests have been run, these sample sizes cannot be chosen hi advance.
The number of tanks to be used in the study was chosen to provide the required amount of
data to estimate these proportions with the stated confidence and length of the confidence interval.
Assuming that approximately half of the tanks are found to be suitable for upgrading by the baseline
tests, the denominator for estimating the probability of false alarm (PFA) and the probability of
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detection (PD) will each be approximately SO. The maximum width of the confidence interval
would occurif the estimated proportion is 0.5. Using the normal approximation to the binomial, the
half-width of the confidence interval in this case is
W=1.96y'(0.5)2/n
where the number 1.96 came from the normal distribution for a two-sided 95% confidence interval.
If W is specified as 0.15, this equation can be solved for n to yield 43. Thus, the total sample size
of 100 tanks, which is expected to provide about 50 tanks suitable for upgrading and 50 that are not
suitable for upgrading, should be sufficient to meet this objective.
It should be noted that if the methods actually produce a relatively small false alarm rate and
a high rate of detection, then the width of the confidence intervals will actually be shorter than the
worst case used for estimating the sample size.
2.5 Qualitative QA Objectives
Comparability of data will be assured by use of the same brand of equipment by all of the
baseline field crew members. In addition, all baseline field crew personnel will be proficient in the
measuring and recording methods using the equipment.
2.6 What If QA Objectives Are Not Met
The primary QA objective would not be met if the proportion of tanks found suitable for
upgrading differs substantially from 50%, this will affect the estimates of some of the performance
parameters. In the most extreme case, if no suitable tanks were found, the study would be unable
to estimate the correct approval rate (the proportion of suitable tanks correctly identified by each
assessment method). This extreme case is unlikely. If, say, the suitable group is much smaller than
the unsuitable group, then the confidence interval for the correct approval rate would be larger than
expected. The confidence interval for the correct detection (of unsuitable tanks) would be shorter
than expected. The confidence interval for the overall correct rate would not be affected, although
it would be based on a slightly different combination of correct approvals and correct detections.
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Other QA objectives would not be met, for instance, if triplicate measurements of pit depth
did not meet the precision objectives. This would reduce the statistical confidence level of the study
and possibly cast doubt on the conclusions reached concerning the tank. An overall outcome would
be a weaker study with the possibility of the study gaming less acceptance from industry and
i. '
regulators.
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SECTION3.0
SITE SELECTION AND SAMPLING PROCEDURES
3.1 Site Selection
Tanks will be selected by the contractor from an EPA list of a tank population provided by
the industrial and corporate community. Ideally, approximately half of the tanks selected will be
suitable for upgrading and half will not. The owner/operator of the tank will be asked to provide
information regarding the condition of the tank. Definitive data regarding whether a tank is suitable
for upgrading will not be known hi advance. Therefore, information provided by the owner/operator
(such as leak detection results, age, etc.) will be used to determine the approximate condition of the
tank.
Steel tanks that have not been eathodically protected or lined will be selected to provide a
population encompassing a wide range of tank conditions including:
Leaking tanks (tanks that have failed a leak-detection test)
Nonleaking tanks (tanks that have passed a leak-detection test)
, Tanks of unknown condition
Tanks in a variety of geographic locations
3.2 Sampling Locations
With regard to sampling strategy, results of vendor reports will be used to help identify areas
for conducting baseline tests. The tank will have a grid system applied, with each grid being
approximately 9 ft2. See Appendix, B for a figure showing the sampling grid numbering pattern
scheme to be used for all tanks. All grids will receive ultrasonic measurements. Lacking indications
of problem areas, randomly selected areas will be chosen for additional testing: The random
S ' .
selection will be stratified to include areas known to be problematic (i.e., beneath the fill pipe, top
of tank, bottom of tank, etc.). Baseline testing will consist of axis measurements, pit depth, wall
s- , - - . ,
thickness and pit diameter measurements.
A minimum of one and a maximum of five pit depth measurements will be made in each grid
of the tank on the exterior (if pits of apparent depth of least 0.05 in. are visually detected). On the
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interior of the tank a minimum of one and a maximum of five pit depth measurements will be made
on each grid of the tank for which pits of apparent depth at least 0.05 in. are visually detected.
Triplicate measurements will be made of the five deepest pit measurements for each tank. The
average and standard deviation of the pit depth for each of these five pits will be calculated.
Pit diameters of at least 0.125 in will be measured at the place on the inside of the tank
farthest from the remote video camera location. If the pit diameters on the surface furthest from the
point of access for the video camera are near 0.125 in, the field team will have the pit diameter
measured by two persons to confirm that the diameter either exceeds or is less than 0.125 in. If pit
diameters are substantially larger than 0.125 in, a single measurement will suffice. Pit depth (inside
or outside) and pit diameter (inside) are not necessarily measured on the same pit.
Ultrasonic tests of wall thickness will be made at the approximate center of each grid. For
any grid in which a thickness reading less than 90% of the minimum required wall thickness as
specified in UL 58 is obtained, the grid will be subdivided into nine smaller grids and readings will
be taken from each subsection.
In addition, approximately 1-ft2 coupons will be cut using a cutting torch from tanks which
have passed all on-site tests. Areas for sampling coupons will be selected by searching for areas of
greatest corrosion potential or observed corrosion and two coupons will be cut for each tank.
Coupons will be labeled according to the scheme described in Subsection 3.5, Sample Custody.
3.3 Baseline Testing
The baseline tests listed below will be performed. Appendix B provides field procedures and
forms for the baseline tests. The number of measurements of each type will be a function of the tank
size. Table 3-1 provides the approximate number of measurements of each type for a nominal 8000
gallon tank that is 8 ft in diameter and 21 ft long. The contractor's field crews may increase the
number of measurements based on observations and judgement if it appears that this would give a
more complete determination of the tank condition. Such a tank would have a grid with 66 locations
consisting of 8 sections around the circumference and 7 sections along the length of the cylinder plus
5 sections on each end consisting of a center circle and 4 sections around the outside of the central
circle.
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Table 3-1. Number of Measurements
<»
(b)
Measurement Type
Ultrasonic Wall Thickness
Pit Depth Gauge^
Pit Diameter0
Tank Diameter
Through-wall micrometer wall
thickness
Number^
66
162 - 690
10
2
'.'< 2
Based on a nominal 8000 gallon tank, 8 ft. diameter and 21 ft. long
Minimum number based on one pit depth measurement per grid square (66) plus triplicate measurement of 5 deepest
pits (15) for both interior and exterior. Maximum number based on five pit depth measurements per grid square
(330) plus triplicate measurements of 5 deepest pits (15) for both interior and exterior. Actual number may vary
depending on number of pits observed.
Up to ten pit diameters will be measured; actual number may vary depending on number and size of pits observed.
1... Prior to excavation and removal of the tank, axis measurements will be made with
a tape measure or tank gauge stick to document the vertical diameter of the tank.
This checks for the tank's "out of roundness" due to deformation and gives a gross
indication of tank condition.
The vertical diameter will be measured at the fill pipe from outside the tank while it
is still in the ground and this measurement recorded. After the tank has been
removed and an access hole cut in one end, the internal vertical diameter at the same
location will be measured. If this measurement agrees with the original measurement
to within 0.5 in, no substantial deformation occurred during removal. In this case,
, the horizontal diameter at that location will be measured. If the difference between
the original vertical diameter measured before removal and the horizontal diameter
is more than 2% of the average of these two diameters, the tank, will be judged to be
structurally deformed.
If the original vertical diameter measured before removal differs more than 0.5 in
from that measured after the tank is out of the ground, internal vertical and horizontal
diameters will be measured at each end (where the end caps provide additional
strength and would not deform). The average of these four diameter measurements
is used as the original diameter of the tank. If the original vertical diameter measured
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i , r
before removal differs from this average diameter by more than 2%, the tank will be
judged to be structurally .deformed.
The tank will be excavated and removed by the tank owner or their subcontractor.
The contractor's field crew will hose down the tank or carefully brush away loose
soil. The tank will have a 3 ft by 3 ft grid pattern applied to the exterior using a
combination of chalk lines and wax markers. The grid will be applied in the fol-
lowing manner:
The length of the tank in feet will define the number of horizontal grid
sections, which run longitudinally along the cylinder of the tank.
The circumference of the tank will be divided into as many equal segments
as the tank diameter hi feet.
Starting at the opened end of the cylinder, marks will be made every 3 ft for
a circumferential grid line. This provides the grid of the cylindrical surface.
Each end will have a center circle of 9 ft2 area defined (a radius 20.375 hi).
The remaining area will be divided into equal segments of about 9 ft2 each.
For example, an 8-ft diameter tank has about 45 ft2 of surface on each end.
Appendix B contains a figure showing the sampling grid numbering pattern
scheme to be used for all tanks.
A visual inspection of the exterior of the tank will be conducted after the grid has
been applied. The purpose of the inspection is to detect surface discontinuities such
as cracks, holes, pits, general corrosion, and other porosities in the tank. A data form
will be provided for documentation of the visual inspection. This inspection and
other visual inspections of the ulterior and exterior will follow the procedure
provided hi Appendix B. The type of examination is a direct visual examination.
The written procedure for this is provided in Appendix B and calls for viewing the
entire surface with the human eye at a light level of at least 161 lumen/m2 from a
distance of no more than 24 hi. A magnifying glass will be used to observe
questionable areas.
Still photography using a 35 mm camera with color film will be used to document
the tank condition Areas of discoloration, apparent corrosion, exterior evidence of
petroleum product, or obvious holes will be identified and referenced. Special
attention will be paid to the bottom of the tank and to the lower weld seams as well
as to bungs, fittings, and connections. If any rust plugs are identified, simple means
of extracting them will be made, such as with a screwdriver or hammer.
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4. The exterior of the tank will be abrasive blasted to bare metal (NACE 2 or SSPC-
SP10) and the grid will be reapplied. A second visual inspection of the tank exterior
will be conducted. This will be accompanied by still photography to document the
tank condition.
In making the baseline visual observations, the field personnel will characterize any
apparent corrosion according to the following descriptions:
Note presence, location, and approximate size of any perforations
, Pro vide an estimate of the nature and approximate percentage of area within
each grid location of a given type of corrosion
Note the presence, nature, and approximate density of shallow pits,
subjectively judged to be <0.05 in deep
. Note the presence, nature, and approximate density of deep pits subjectively
judged to be 0.05 to 0.10 in deep
Note the presence, nature, and approximate density of very deep pits
subjectively judged to be > 0.10 in deep
1 . s
Note the corrosion pattern, i.e., pits widely dispersed, isolated, overlapping,
or in line
Note an association of pitting with tank geometry or structural features, e.g.,
top of tank, bottom of tank, under a gauge sticking port, at an apparent sludge
line or ullage line, or associated with a weld, bend, or other stress risers
Note surface conditions such as general roughness, evidence of coating, rust
plugs, tubercles, and scale
Provide a characterization of corrosion product including color, loose or
tightly adhering, soft or hard, wet or dry, and any distinctive smell such as
that of hydrogen sulfide
" Provide a characterization of pits as concave and hemispherical, elongated,
vertical sides, undercutting, subsurface, narrow and deep, or horizontal
tunneling.
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Particular attention will be paid to those areas identified in the initial inspection and
to problem areas not earlier evident but made visible by the abrasive blasting. These
problem areas will be documented.
5. The end of the tank that was closest to the placement of the internal video camera
location will have an entry hole cut in it and the interior will have a grid applied as
previously described. The interior of the tank will have been abrasive blasted to bare
metal during the vendor assessment tests. A visual inspection of the interior of the
tank will be conducted. This will be accompanied by still photography to document
the tank condition. Areas of discoloration, apparent corrosion, or obvious holes will
be identified and referenced for specific area testing.
6. Ultrasonic measurements will be conducted to determine wall thickness. This testing
will be done primarily from the inside of the tank, but may also be done from the
outside. If areas of the inside are pitted or rough to the extent that the ultrasonic
instrument does not indicate a satisfactory coupling with the surface, the
measurement will be taken from the outside.
Each 3 ft by 3 ft area will be defined by the grid reference system for that tank
described in Section 3.5. An ultrasonic test of the wall thickness will be made at the
approximate center of each marked grid. The minimum required original wall
thickness for each tank will be determined by the tank size in accordance with UL
58. The thickness varies with tankage volume. Typically, the minimum required
wall thickness is expected to be 0.240 in for a tank with a nominal wall thickness of
0.25 in.
Any grid section in which an ultrasonic thickness reading less than 90% of the
minimum required wall thickness was obtained will be subdivided into nine smaller
grids. Then, a reading will be taken from each subsection. The average of these nine
readings will be taken as the average wall thickness of that section. The field crews
may elect to take additional ultrasonic readings in any grid section based on their
observations and judgement All readings taken in a grid section will be averaged
for the average wall thickness of that section.
7. Areas of the tank wall identified as likely to be thin will be marked. A portion of
these areas, to include the suspected thinnest wall sections, will be subjected to direct
physical measurement. This will be accomplished by drilling sentry holes through
the tank wall of 0.625 in diameter (for nominal wall thickness of 0.25 hi) to accept
a thickness gauge or micrometer. Burrs will be removed from the drilling by filing
or grinding. A micrometer will then be inserted through the hole and the thickness
measured directly. Duplicate wall thickness measurements will be made through the
sentry holes. If the ultrasonic measurement indicates that the wall thickness is less
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than 90% of the required minimum wall thickness, up to 5 direct thickness
measurements will be made using sentry holes to confirm the ultrasonic readings.
For each 3 ft by 3 ft grid area of the interior and exterior of the tank that has one or
more pits that are visually judged to be 0.05 hi deep or more, at least one pit depth
measurement will be taken with a depth micrometer and recorded. After these
measurements have been completed, the five deepest pits will be measured two more
times, giving triplicate measurements. For these 5 deepest pits, a measurement of the
remaining wall thickness will be attempted using the ultrasonic instrument from the
side opposite the pit. The ultrasonic instrument will be set hi a mode to store the
minimum thickness measured, and then used to scan acrossjthe area of the pit from
the opposite side of the tank wall.
In cases where the pit depth of the deepest pits cannot be accurately measured with
a depth micrometer (for example, the pit is on the curved section of the end wall
where it is welded to the cylindrical portion of the tank, or the pit in question is
surrounded by other pits or areas of severe corrosion such that the depth gauge has
no good bearing surface), the pit depth must be measured by other methods. At least
two of the following methods will be attempted:
a. Taking an ultrasonic measurement of the remaining wall thickness.
b. Drilling a sentry hole next to the pit and using a throughwall micrometer.
c. Cutting a coupon containing the pit from the tank and sending it to a
laboratory for sectioning and photomicrograpning (see following discussion).
In cases where the deepest pits are in an area of overlapping pits, so that the original
surface does not remain, the remaining wall thickness will be subtracted from the
required minimum wall thickness to give a depth. If the apparent original wall
thickness of the tank can be determined from a relatively uncorroded section of the
tank and if it exceeds the minimum wall thickness, the remaining wall thickness of
the pits will be subtracted from this value to give a determination of pit depth.
In cases where no perforations were found in the tank shell, coupon samples for
laboratory analysis will be taken. At least two coupons, measuring approximately
12 x 12 in, will be identified by the field crew and cut from the tank by the tank
removal subcontractor using a cutting torch. In all cases, the feature of interest will
be at least 2 in. from the edge of the coupon to avoid any effect from cutting the
coupon.. One coupon will be taken from the tank wall area that had the least wall
thickness as measured by the ultrasonic instrument. The second coupon will be taken
from the area that had the most severe corrosion hi the opinion of the field crew
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based on the visual inspection. For example, this might be an area of overlapping
pits on the exterior or an area along the bottom that had many small pits with
apparent or possible undercutting. Examples calling for. additional coupons may be
taken at the discretion of the field crew. Examples calling for additional coupons
would include but not be limited to corrosion along a weld, an apparent crack in a
weld, two distinct areas with different types of corrosion such as overlapping pits on
the outside and intergranular corrosion on the inside, or a deep pit whose depth could
not be measured satisfactorily by other methods.
The coupons will be permanently marked in the field for identification. Coupons
containing suspected weld cracks will be taken to H.R. Inspection Service, a
commercial laboratory in the Kansas City area, for radiography testing. See
Appendix A for the Radiographic Testing Procedure.
All coupons will be photographed at MRI, with marking applied to show the location
of interest. They will be subjected to wall thickness measurements by ultrasonic
and/or micrometer as well as pit depth measurements. If these measurements are not
definitive and if additional data are needed to classify the tank according to the
criteria in Section 2.3, smaller sections that contain the area(s) of interest will be cut
from the coupons at MRI. These smaller sections, along with copies of the MRI
photographs, will then be sent to Sherry Labs Oklahoma in Tulsa, Oklahoma for
sectioning and mounting. Photomicrographs will be taken by that lab and returned
along with the mounted specimens to MRI for definitive measurements of the wall
thickness, pit depth, and weld cracking. .
3.4 Sampling Equipment
Sampling equipment to be used for the baseline tests includes: drill with 5/8" bit (for sentry
holes), tape measure, chalk line, and wax marker (for gridding). All other equipment are for
measurements. Abrasive blasting equipment and an acetylene torch for cutting coupons will be
supplied by the tank contractor on site.
3.5 Sample Custody
The five regions will be assigned numbers as follows:
Rl Midwest
R2 Northwest
R3 Southwest
R4 Southeast
R5 Northeast
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Within each region, sites will be assigned numbers sequentially once the list of tanks and
sites has bqen identified., At each site, tanks will be assigned sequential numbers and identified by
location and size on a sketch of the site. Once a tank has had its grid marked on it, each grid section
will be identified by a letter and number as described hi Appendix B, and within each grid section,
each square foot will have a number from 1 to 9 assigned to it. Thus, each tank can be identified by
the region, site, and tank number; e.g., Rl, S2, Tl would denote tank 1 at site 2. in region 1
t " - t ', i ' '
(midwest). A location on that tank would be identified by a sequence of a letter and two numbers;
e.g., D-5-4 would denote square foot number 4 in the grid section that begins 15 ft from the opened
end of the tank apposition D around the circumference. This location scheme will be used to mark
the coupons to be cut from the tank. .
Sample coupons will be initially marked with chalk and engraved or punched on their surface
prior to leaving the site hi order to provide permanent identification. Coupon History Forms will
be provided to document sample collection and sample history for each coupon taken at each site.
Figure 3-1 provides an example of a Coupon History Form. Coupons and forms will then be
packaged and shipped according to DOT regulations.
The field crew chief will be responsible for samples during field sampling. Responsibilities
will include labeling samples and preparation of the sample documentation form. Samples will be
permanently marked by engraving or punching in the field and shipped to MRI. A sample history
form (Figure 3-1) will be prepared for each set of samples (one site's samples) and will travel with
the sample set as it is moved about for testing and analysis.
Each time a sample set begins to undergo testing, the sample history form will be reviewed
and samples checked for correctness and completeness. If problems with a sample set are discovered
(such as missing or incorrect samples) the nature of the problem will be noted on the sample history
form and reported immediately to the MRI Project Manager and MRIQAO.
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Section No. 3
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Figure 3-1. Coupon History Form
COUPON
NUMBER
REGION
SITE
TANK
COLLECTED
BY
DATE
COLLECTED
RECEIVED BY
DATE RECEIVED
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Section No. 4
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SECTION4.0
ANALYTICAL PROCEDURES AND CALIBRATION
4.1 EPA-Approved or Other Validated Standard Methods
The vendor methods are attached in Appendix C. The three new vendor methods (i.e.,
modeling, video, ultrasonic) are adapted from ASTM ES40-94. The internal inspection method is
adapted from API 1631, NLPA 631, or NLPA 632.
The baseline method has been summarized in Subsection 3.3. The baseline method consists
of visual inspections of the interior and exterior, depth, width, and thickness measurements,
evaluation of the type of corrosion, and the pit depth tests described in Subsection 3.3. The critical
measurement, type of measurement, and type of equipment used for the baseline tests are shown
below in Table 4-1. ~
4.1 Calibration K
The depth, micrometer will be calibrated at the beginning and end of measurements for each
tank and the zero readings reported. The average will be used to correct all readings for accuracy.
The through-wall micrometer will be calibrated at the beginning and end of measurements
for each tank and the zero readings reported. These will be used to correct the readings.
The ultrasonic gauge calibration will be checked upon instrument power-up and prior to
beginning each series of readings on each tank and its value recorded. If the calibration value is off
by more than 5%, a two-point calibration will be done to calibrate the instrument. The calibration
checks will be recorded by the field crew and reviewed at the data reduction stage. The calibration
of the ultrasonic gauge will also be checked on a portion of the tank that appears to have little or no
corrosion. A measurement of wall thickness on such an area will be made with the through-wall
micrometer using an edge or a sentry hole and also with the ultrasonic gauge. The two readings will
be compared and must agree to within ±.01 in. This will ensure that the steel of the tank is not
apprebiably different from that of the calibration block.
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Table 4-1. Measurement, Type, and Equipment
for Baseline Testing of Tanks and Coupons
Critical Measurement and Type
Pit depth (distance)
Wall thickness (distance)
Wall Thickness through 0.625 in sentry holes (distance)
Pit diameter (distance)
Location by grid system (distance)
Tank diameter (distance)
Equipment
Depth Gauge Micrometer
Ultrasonic Thickness Gauge
Throughwall Micrometer
Ruler
Tape measure
Tape measure or tank gauge stick
The baseline methods and forms are provided in Appendix B.
The calibration frequency and requirements are summarized in Table 4-2. The micrometers
- ,
will be checked before and after making measurements on each tank and the zero readings recorded.
The ultrasonic calibration will be checked on the 0.25-in standard before beginning a series of
readings. If it is more than 5% different from the standard, a two point calibration of the instrument
will be done and the calibration re-checked. The calibration reading will be reported.
Table 4-2. Scheduled Baseline Test Calibrations
Equipment
Depth
Micrometer
Through-wall
micrometer
Ultrasonic
Frequency
At the beginning
and end of
measurements
for each tank
At the beginning
and end of
measurements
for each tank
Prior to
measuring each
tank
Acceptance criteria
<0.01 in
< 0.01 in
< 5% relative to NIST
traceable standard
0.25 in
< + 0.01 in compared to
through-wall micrometer
Corrective action
If zero < 0.01, record and correct all
readings; if greater than 0.01 adjust
zero.
If zero < 0.01, record and correct all
readings; if greater than 0.01 adjust
zero.
Record calibration value. If greater
man 5%, recalibrate with 2 point
calibration and re-check.
Recalibrate to match micrometer and
re-check on NIST calibration block.
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; _
SECTION 5.0
DATA REDUCTION, VALIDATION AND REPORTING
5.1 Data Reduction .
The vendors are responsible for data reduction of their tests.
The MRI Project Manager is responsible for data reduction of the baseline tests. There are
four primary measurements to be made on each tank during the baseline test: tank diameter, pit
depth, pit diameter, and wall thickness.
For baseline tests each tank will be inspected for penetration and if any holes are found, the
presence, location, and approximate diameter of holes will be noted. The qualitative assessment of
corrosion on each 3 ft by 3 ft area of tank wall surface that is made as part of the visual inspection
will be reduced by providing a textual statement summarizing the condition of the tank in terms of1**
the amount and type of corrosion identified during the visual inspection.
The pit depth data will be reduced by reporting the maximum pit depth found for each tank.
If a tank has a corrosion hole, this will be deemed a pit completely through the tank wall thickness
and will be noted as a hole, with a numerical value that is the larger of the nominal wall thickness
(usually 0.25 in) or the largest wall thickness measurement observed on that tank. If a tank has a
hole, the deepest nonpenetrating pit depth will also be reported.
The five deepest non-perforating pits will be measured ultrasonically from the side opposite the pit
to measure the remaining wall thickness. The minimum wall thickness found in the area of the pit
will be used as the remaining wall thickness at the pit. This value will be subtracted from the larger
of the measured remaining wall thickness in the area of the pit and the required minimum wall
thickness (typically 0.240 in) to give another measure of pit depth. This will be compared to the pit,
depth measured by the depth micrometer and the larger value used to report the maximum pit depth.
This maximum will be reported as a percent of the required minimum wall thickness as well as in
the directly measured units.
The diameters of several pits, if any, on the interior surface of each tank at the maximum
distance from the internal video camera will be measured. Typically this surface will be the circular
end of the tank, which will generally be 8 ft in diameter. These data will be summarized by
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reporting whether any pits on that surface were found that were 0.125 in. in diameter or larger and
whether the internal video inspection identified them or not. While this is not a criterion for
determining whether the tank is suitable for upgrading, it is a requirement stated in ASTM ES 40-94
for the video inspection method.
The precision estimates of the triplicate determinations of pit depths for the 5 deepest pits
and the duplicate measurements of the wall thicknesses using the through wall micrometer will be
calculated and reported as standard deviations. The formula for precision calculations is provided
in Section 8.
The ultrasonic thickness measurements from each 3 ft by 3 ft area of tank surface will be
averaged using the arithmetic mean to provide an average wall thickness for the shell of the tank.
i, V , , ' ,
Any 3 ft by 3 ft section that is found to have a thickness measurement less than 90% of the required
i,< , , '
minimum wall thickness will have the average of the 9 measurements of wall thickness for that 3
ft by 3 ft area reported separately. The location of that section will be identified by its grid reference
and reported.
For each criterion for accepting a tank for upgrading, the performance measures described
in Section 2.0 will be calculated for each tank assessment method. A confidence interval for each
estimated proportion will be calculated and reported. If the sample size available to estimate the
proportion is sufficiently large, the normal approximation to the binomial will be used to calculate
the confidence interval. If the sample size is too small or the proportion is small, exact confidence
intervals based on the binomial distribution will be used. Formulas for these calculations are
provided below.
The 95% confidence intervals for the performance measures will be calculated using the
binomial distribution. Each performance measure will be estimated as the observed proportion of
tanks that were classified by the vendor hi a particular category. For example, suppose that the
baseline method determined that 50 tanks were suitable for upgrading. Each vendor's probability
of false alarm would be estimated as the proportion of those 50 tanks that the vendor concluded were
not suitable for upgrading. Let
Y,- = 0 if a vendor determined that the I-th tank was suitable for upgrading.
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Section No. 5
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Date: October 4.1995
Pane: 3 of 7
1 if a vendor determined that the I-th tank was not suitable for
upgrading. .
Ns - the number of tanks determined bythe baseline to be suitable for upgrading.
Then the probability of false alarm, PFA, is estimated as
The 95% confidence interval for PFA will be calculated using the binomial distribution. If
both
and
Nv=Ns-Nu
are both at least 5 or more, the normal approximation to the binomial will be used to calculate the
confidence interval.
That is, the confidence interval for PFA will be given by
PFA ± 1 .96JPFA(1-PFA)/NS
If the requirements for using the normal approximation to the binomial are not met, then
exact binomial confidence limits will be calculated. Denote the cumulative binomial distribution
by ". " -. ' ' . ' ' ./ ' '- ' : ' . .'
where the summation is on x from 0 to y, the observed number of events. In the equation nCx stands
for the combinatorial number of ways to choose x items from n items. That is
Then the lower confidence limit is found by solving the equation
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Section No. 5
Revision No. 1
Date: October 4. 1995
Page: 4 of 7
for p,. Generally the solution must be found iteratively The upper confidence limit is found by
solving the equation .
BiOwy) = a/2
for pb, where again the solution must generally be found interactively. The result is a two-sided
confidence interval with confidence coefficient 100%(l-a). In this example the number of events,
y, is the
where the Y,- were defined above. These formulas can be used to calculate the confidence intervals
for each of the estimated proportions hi the performance parameters.
5.2 Data Validation
The MRI Project Manager will be responsible for ensuring that validation checks are done
on the data reported. All raw data, including calibration and precision data, and calculated data will
be examined for completeness and compliance to all requirements and objectives. The calculated
data will be examined for accuracy. Any assumptions will be examined for reasonableness. Any
data affected by problems will be flagged hi the records and in the report as follows:
C (did not meet calibration requirements)
P (did not meet precision requirements)
T (did not meet completeness requirements)
X (did not meet compliance requirements; i.e., did not follow test protocol/procedures or
documentation requirements)
53 Data Reporting
The results of the vendor tests will be supplied to MRI hi reports. Calibration, quality control
checks, calculations, assumptions, and evaluation will be documented and retained in the project
files. The field crew leader will be responsible for preparing a data report containing the data
recorded on each tank. The Project Manager will be responsible for preparing the final report. The
data reported will include those shown previously in Table 1 - 1 . All baseline data for pit depth, pit
diameter, and wall thickness will be reported hi niches.
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Section No. 5
Revision No. 1
Date: October 4.1995
Page:_§_of_Z_
The conclusions of each assessment method will be presented in the report as shown below
(where n is planned to be 100):
Table 5-1. Conclusions of Each Vendor Assessment Method
1
BASELINE
SUITABLE
UNSUITABLE
VENDORRESULT
SUITABLE
nn
°21
n.i
UNSUITABLE
nn
«22
n.2
INCONCLUSIVE
nn
na
n.3
< '
ni.
n2
n
Such a table will be prepared for each of the four criteria listed in Section 2.3 and for both
versions of the vendor's conclusions (i.e. with and without knowledge of the results of the leak test)
To illustrate how the performance parameters are determined, assume a vendor produces the
data shown in Table 5-2, as compared to one of the evaluation criteria (e.g., presence or absence of
penetrations found in the tanks).
Table 5-2. Sample Data
BASELINE
SUITABLE
UNSUITABLE
- VENDORRESULT
SUITABLE
45
8
,53
UNSUITABLE
5
31
36
INCONCLUSIVE
5
6
11
,55
45
100
With these data, the following can be calculated:
Correct Decision Rate
= 76/100 = 0.76 ±0.084
Proportion of Correct Approval (Accuracy)
= n,,/nlf
= 45/55 or 0.81 8 ±0.104
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Section No. _JL_
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Proportion of Correct Detection (Reliability)
^n^/n^
= 31/45 or 0.689 ±0.138
Proportion of False Alarms
=.n12/n,.
-5/55 or 0.091 ±0.076
Proportion of Missed Detections
= n2,/n2>
= 8/45 or 0.178 ±0.1 14
Proportion of Inconclusive Results
= 11/1 00 = 0.11 ±0.063
Proportion of Inconclusives for Suitable Tanks
= n,3/nu
= 5/55 = 0,091 ±0.078
Proportion of Inconclusives for Unsuitable Tanks
= 6/45 = 0.133 ±0.101
The final report will also include a QA section that documents QA/QC activities and results.
1 . " \ , ''.'
This section will compare the QA findings to the QA objectives and will include a statement regard-
ing whether these objectives were met. If the objectives were not met for any measurements for
some tank, the impact of this will be assessed and reported. Since 'the purpose of these
measurements is to determine whether a tank is qualified for upgrading with cathodic protection,
assessment of any impact will be on whether that decision can be made adequately on the basis of
the data collected. For example, measurements of pit depth that do not meet the standard deviation
requirement would not affect the results if the tank has a corrosion hole, or if another pit also exceeds
the threshold for maximum pit depth.
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Section No. 5
Revision No. __]__
Date: October 4.199B
Paoe: 1 of 7
* ! "'*'." - '
Raw and final hard copy data will be stored as permanent records in MRI Archives.
Computer data will also be stored in MRI Archives, but the life is dependent on the media. Coupons
will be stored by the MRI Project Manager for a maximum period of 12 months after the final report
has been submitted, then disposed of according to IT directions.
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Section No. 6
Revision Wo. 1
Date: October 4.1995
Page:.
SECTION 6.0
INTERNAL QUALITY CONTROL CHECKS
6.1 Types of QC Checks
The field staff will be proficient in the use of the baseline equipment and procedures.
Replicate field measurements will be made as follows:
Triplicate depth measurements will be made for the five deepest pits (excluding
holes) on each tank and all three measurements and their average and.standard
deviation will be calculated and reported. In making the pit depth measurements, the
field crew will adjust the position of the depth gauge to obtain the maximum reading.
These data will be reviewed for consistency and the precision will be determined and
reported.
Duplicate wall thickness measurements will be made using the through wall
micrometer.
If the difference between the largest and smallest of the measurements exceeds 0.02
in, the measurements must be repeated.
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Section No. 7
Revision No. 0
Date: August IB.
Page:_j_of_2_
SECTION7.0
PERFORMANCE AND SYSTEMS AUDITS
The IT and MRI QAOs will conduct one or more Technical Systems Audits (TSAs) and the
MRI QAO will conduct one or more Audits of Data Quality (ADQs). Performance audits are not
appropriate to the scope of work and thus will not be conducted. Results of the audits by the MRI
QAO will be reported to the MRI Project Manager and[department management, the MRI Project
Manager will report the results to the IT Work Assignment Leader. Results of audits by the IT QAO
will be reported to the IT Work Assignment Leader. Audit results and any corrective actions taken
will be summarized hi the final report.
7.1 Technical Systems Audits
The IT and MRI QAOs will conduct technical systems audits during the initial phase of the
work assignment, and periodically thereafter. All components of the data gathering and management
' : ' &
system will be audited to determine if these systems have been properly designed to meet the quality
objectives. The technical systems audit will include a review of the adequacy of the experimental
design, the control procedures, and the analytical procedures. This review also includes compliance
to the QAPP, personnel qualifications, project management structure, adequacy and safety of the
facility and equipment, and the data management and reporting system. The systems audit will end
with a review of the report, actions taken by MRI Project Manager on inspections and follow-up
inspections, and an audit of the records at the completion of the study. IT and MRI will also
participate in any external audits scheduled by the EPA Work Assignment Manager during this
study. .
7.2 Audits of Data Quality
The audits of data quality, an important component of a total system audit, are the critical
evaluation of the measurement, processing, and assessment steps to determine if systematic errors
have been introduced into the system or if specific questions regarding the quality of the data need
to be resolved. During the data audit, the MRI QAO will audit either randomly selected data that
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Section No. Z_
Revision No. Q_
Date: August 16.1995
Page: 2 of 2
will be followed through the testing and reporting process, or audit all data hi question, if specific
questions of quality need to be resolved. In addition, the quality control and calibration data will be
audited. The audit verifies that the data-handling system is correct and assesses the quality of the
data generated to ensure that the data quality objectives are met.
The completeness of all the data will be checked by the MRI Project Manager after receipt
of data from each tank and field site.
73 Site Audits
The IT WAL, IT Senior Reviewer, and MRI Project Manager will conduct one site audit per
region to assess the field evaluation procedures, compliance to the QAPP, and field data reporting
procedures.
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Section No. 8'
Revision No. 0
Date: August 16.1995
SECTION 8.0
CALCULATION OF DATA QUALITY INDICATORS
- - .'*- ' '
This section describes the calculation of the data quality indicators that will be used on this
project. Sensitivity is defined as the smallest possible equipment measurement.
8.1 Precision
For the triplicate or duplicate measurements, the unit of precision will be the standard
- = ' - '- . . , ' - -v . . "
deviation of the replicate measurements, where the standard deviation is defined as follows:
C ~
where:
s
y,-
n
y
standard deviation
measured value of the ith replicate
number of replicates
mean of the replicate measurements.
8.2 Completeness
Completeness is defined as follows for all measurements
%C = 100% x ()
T
where: %C = percent completeness
V = number of measurements judged valid
T ?= total number of measurements.
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Section No..
Revision No,.
Date: August 16.1995
Page: 1 of 1
SECTION 9.0
CORRECTIVE ACTION
Corrective actions are required;for any major quality-related or compliance problem. Such
problems may be detected during routine inspections or by audits. The MRI Project Manager is
responsible for notifying the IT WAL, making sure actions are taken to prevent recurrence of such
problems, and that the actions taken are documented in a report to the MRI QAO and department
management. The MRI QAO must evaluate the effectiveness of corrective, actions taken and must
document the results in a report to the MRI Project Manager and department management. The MRI
Project Manager is responsible for providing these/results to the IT WAL, Typical problems and
actions to be taken are listed below.
If problems are due to lack of training, the MRI QAO and/or the MRI Project Manager will
implement the necessary training.
If the problems are due to lack of sufficient resources, the MRI Project Manager will inform
department management, who will then provide the required resources.
If the problems are due to inadequate planning, the plan will be modified, approved as
required, and then distributed to those on the distribution list.
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Section No. 10
Revision No. 0
Date: August 1G. 1995
Page:.
SECTION 10.0
QUALITY CONTROL REPORTS TO MANAGEMENT
The IT and MRI QAOs will be responsible for conducting systems audits early in the project;
The MRI QAO will be responsible for conducting data audits soon after the data become available
The IT and MRI QAOs will prepare written QA audit reports used to keep project and department
management informed. Such written reports will include items appropriate to this project, such as:
Items/areas audited and the results of the audits
QAPP changes or deviations, QA/QC problems, and recommendations for corrective action
Summary of any training and any improvements noted
Data quality assessment and limitations, and the possible impact on data quality
Followup and assessment of the effectiveness of any corrective actions taken
If major quality-related problems are detected during an audit, the IT and MRI QAOs will
immediately so inform the IT WAL and MRI Project Manager, then follow up,with a written report
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Section No..
Revision No..
Date: October 4.199R
Page:J_of_2_ ,
SECTION 11.0
REFERENCES
1. 40 CFR Part 280 and 281, "Technical Standards and corrective Action Requirements for
Owners and Operators of Underground Storage Tanks," 1988. These regulations stipulate
that in order to be suitable for upgrading by cathodic protection, a tank must be assessed to
ensure that it is structurally sound and free of corrosion holes.
2. ASTM Emergency Practice Standard ES 40-94, "Emergency Standard Practice for
Alternative Procedures for the Assessment of Buried Steel Tanks Prior to the Addition of
Cathodic Protection," 1995. This standard provides the following requirements for tanks to
be suitable for cathodic protection: no pitting greater than 50% of the minimum
recommended wall thickness; average metal wall thickness of each 1 m2 is greater than 85%
of the original wall thickness.
3. Section V, Article 9 of the ASME Boiler and Pressure Vessel Code (ASME SE-797). The
code provides a visual examination procedure consisting of viewing the entire surface with
the human eye at a light level of at least 161 lumen/m2 from a distance of no more than
61 cm.
4. ASTM Standard G1-90 (Re-approved 1994) "Standard Practice for Preparing, Cleaning, and
Evaluating Corrosion Test Specimens." This standard will be used as the reference for
marking and preparing coupons for testing.
5. ASTM Standard G 46-94, "Standard Guide for Examination and Evaluation of Pitting
Corrosion," 1994. This standard will be used as the reference for testing coupons for the
evidence of pitting corrosion. The guide is used for the corrosion examination tests.
6. ASTM Standard E 114, "Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by
the Contract Method," 1990.
7. ASTM Standard E 797, "Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo
Contact Method," 1990.
> ' ... , . '
8. API Standard 1631, "Interior Lining of Underground Storage Tanks," 3rd Edition, April
1992.
9. National Leak Prevention Association NLPA 631, "Entry, Cleaning, Interior Inspection and
Repair, and Lining of Underground Storage Tanks," Fourth Ed., 1991.
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Section No. 11
Revision No. 1
Date: October 4.1995
Pane: 2 of 2
10, Underwriters Laboratories Standard UL 58, "Steel Underground Tanks for Flammable and
Combustible Liquids," 1984.
11. H.R. Inspection Service, Inc., Shawnee, KS, "Radiographic Testing Procedure NDE-RT."
12. National Leak Prevention Association NLPA Standard 632, " Internal Inspection of Steel
Tanks For Upgrading with Cathodic Protection Without Lining," First Ed., 1990.
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Section No. App. A
Revision Wo. 0
Date: August 16.1995
Page: 1 of 18
APPENDIXA
Radiographic Testing Procedure
-------
NDE-RT REV. 4
MARCH 10, 1993
H. R. INSPECTION SERVICE, INC.
P. O. BOX 3280
6878 MARTINDALE ROAD
SHAWNEE, KANSAS, 66203
RADIOGRAPHIC TESTING PROCEDURE
NDE-RT '
THIS PROCEDURE HAS BEEN TESTED
AND APPROVED FOR USE BY
WILLIAMSON
ASNT TC1A LEVEL III
-------
NDE-RT RADIOGRAPHIC BESTING PROCEDURE
* - . " ' l'
TABLE OF CONTENTS
R-110
R-120
R-130
R-220
R-230
R-250
R-260
R-270
R-280
R-290
R-294
Scope .2
Safety Requirements 2
Applicable Documents.......................... .2
General Documents 3
Industrial Radiographic Films-, Screens, &
Radiographs ............3
Radiographic Sharpness 7
Image Quality Indicators 8
Radiographic Technique 11
Procedure REquirements 13
Evaluation of Radiographs ,13
Qualification of Radiographic Personnel......14
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RADIOGRAPHIC TESTING PROCEDURE
NDE-RT
R-110 SCOPE
RilO.l
The procedure covers thfe requirements for radio-
graphic examination of ASME codes including the
ASME Boiler and Pressure Vessel Code (Sections I,
V, and VIII) and ANSI/ASME B31.1 and B31.3.
R-120 SAFETY REQUIREMENTS
R120.1 Each installation or area where x-ray or radio-
active material is used shall have a radiation
survey made during the initial operation and any
other time when the conditions change, to assure
adequate personnel protection. In all instances,
.each person using the radiation source shall wear
a radiation film badge and a pocket dosimeter.
Personnel radiation exposure shall not exceed the
limits called for in Title 10, Code of Federal
Register.
R-130 APPLICABLE
Contract Specifications and Codes.
R130.1 ASME Boiler and Pressure Vessel Codes - 1992 ed.
1. Section I Power Boiler
Section VIII Pressure Vessels
Section V Nondestructive Examination
2
3
a. Article 1
b: Article 2
c. SE94 & SE142
R130.2 ANSI/ASME B31.1 Power Piping - 1992 ed.
** '''','
R130.3 ANSI/ASME B31.3 Chemical Plant and Petroleum
Refinery Piping - 1992 ed.
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R-220
R-221
GENERAL REQUIREMENTS.
Surface Preparation.
R- 2 21.1 Materials
Surfaces shall satisfy the requirements of the
applicable materials specifications, with add-
itional conditioning, if necessary, by any
suitable process to a degree that surface
irregularities cannot mask or be confused with
discontinuities.
R-221.1 Welds
R-230
R-231
When, required, the weld ripples or weld surface
irregularities on both the inside (where
accessible) and outside, may be removed by any
suitable process to such a degree that the
resulting radiographic image due to any
irregularities cannot mask or be confused with
the image of any discontinuity.
R-221.3 Surface Finish
The finished surface of all butt-welded joints
may be flush with the base materials or may have
reasonably uniform crowns, with reinforcement
not to exceed that specified in the referencing
Code Section (Par PW-35 of Section I & Table
127.4.2 of ANSI B31.1).
INDUSTRIAL RADIOGRAPHIC FILMS, SCREENS AND RADIOGRAPHS.
Film Selection.
Radiographs shall be made using film equal to or finer
grained than Type 2 of Recommended Practice SE-94,
R-232 Screens.
Except when restricted by the referencing Code Section,
intensifying screens may be used with the film types
specified in R-231,
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R-233 Film Processing.
R-233.1
a. Liquid x-ray developer, fixers, short stop and
Photo-Flo .shall be prepared in accordance with
manufacturer's recommendations.
b. Solutions shall be thoroughly stirred before
processing.
c. Development time shall be standardized based
on temperature and exposure technique must be
adjusted for the developing time.
d. Film shall be agitated during developing at one
minute intervals.
e. After development, the film shall be transferred
to the short stop for one minute. The film
should be agitated for the first 15 or 20 seconds
in the short stop.
f. After the short top the film shall be transferred
to the fixer and agitated for 10 seconds. They are
to remain in the fixer for ten minutes minimum or
twice the film-clearing time. Films shall not
remain more than 15 minutes in fresh fixer.
g. The film must be washed for a minimum of 30 minu-
tes to remove all residual fixer prior to drying.
h. The film shall be transferred to the Photo-Flo
solution for 90 seconds before drying.
i. All films shall be free from processing or other
defects which would interfere with proper inter-
pretation of the radiograph.
R-233.2 Quality of Radiographs.
7 .
All radiographs shall be free from mechanical,
. chemical or other blemishes to the extent that
they cannot mask or be confused with the image
of any discontinuity in the object being radio-
graphed. Such blemishes include, but are not
limited to:
a. Fogging.
b. Processing defects such as streaks,
water marks, or chemical stains.
c. Scratches, finger marks, crimps, dirt,
static marks, smudges or tears.
d. Loss of detail due to poor screen to
film contact.
e. False indications due to defective
screens or internal faults.
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, Radiographic Density.
R-234.1 Density Limitations of Radiographs.
The film density through the radiographic image of
the body of the appropriate penetrameter and the
area of interest shall be 1.8 minimum for single film
viewing for radiographs made with an x-ray source
and 2.0 minimum for radiographs made with a gamma-ray
source. For composite viewing of double film expos-
ures the minimum density shall be 2.6. Each radio-
graph of a composite set shall have a minimum density
of 1.3. The maximum density shall be 4.0 for either
single or composite viewing. A tolerance of 0.05 in
density is allowed for variations between densito-
meter readings.
R-234.2 Monitoring Density Limitations of Radiographs.
Densitometers shall be used for assuring compliance
with film density requirements and a national stand-
ard calibrated step wedge film shall be used for
checking densitometer calibration. Step wedge comp-
arison film may be used, for direct comparison with
production radiographs to show compliance with »
density requirements, as a permissable alternate
to the use of a densitometer as required above.
R-^235 Scattered Radiation.
. ' ! .
R-235.1 Back Scatter Check.
As a check on back-scattered radiation, a lead symbol
"B", with minimum dimensions of 1/2 inch in, height
and 1/16 inch in thickness, shall be attached to the
back of each film holder.
R-235.2 Excessive Scatter.
If a light image of the "B" appears on the darker
background of the radiograph, protection from back-
scatter if insufficient and the radiograph shall be
considered unacceptable. A dark image of the "B"
on a lighter background is not cause for rejection.
R-236 System of Identification of Radiographs.
A system of Radiograph identification shall be used to
produce permanent identification on the radiograph trace-
able to the contract, component, weld seam, or part
numbers, as appropriate. , In addition, the manufacturer's
symbol or name and the date of the radiograph shall be
plainly and permanently included on the radiograph. This
identification system does not necessarily require that
the information appear as radiographic images. In any
case, this information shall not obscure the area of
interest.
-------
R-237 Location Markers.
Location markers, which are to appear as radiographic
images on the film, shall, be placed on the part, not on
the cassette, and their locations shall be marked on the
surface of the part being radiographed or on a map in a
manner permitting the area of interest on a radiograph
to be accurately located on the part for the required
retention period of the radiograph and providing evid-
ence on the radiograph that the required coverage of the
region being examined has been obtained. Location
markers shall be placed as follows (see Fig. T-275):
R-237.1 Single-Wall Viewing.
R-237. 1.1 Source side markers.
Source side location markers shall be used
when radiographing the following:
Flat components or longitudinal joints
in cylindrical or conical components;
Curved or spherical components whose
concave side is toward the source and
when the source to material distance is
less than the inside radius of the
component;
" ,i , " ' / ' , ' ' ' ' ' - '
Curved or spherical components whose
convex side is toward the source.
a.
b.
c .
R-237.1. 2 Film Side Markers.
a. Film side markers shall be used when
radiographing curved or spherical
components whose concave side is toward
the source and when the source to mater-
ial distance is greater than the inside
radius.
b. As an alternate for source side markers
in R-237. 1.1 (a), film side markers may
be used when the radiograph shows cover-
age beyond the location markers to the
extent demonstrated by Fig. T-275 (e)
and when this alternate is documented in
accordance with R-293.
R-237 .1.3 Either Side Markers .
Either source side or film side location
markers may be used when radiographing curved
or spherical components whose concave side
is toward the source and the source to
material distance equals the inside radius
of the component.
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R-237.2
Double-Wall viewing.
R-250
R-251
For double-wall viewing at least one location
marker shall be placed on the outside surface
adjacent to the weld (or on the material in
the area of interest) for each exposure.
R-237.3 Location Marking with a Map.
/ '
When inaccessibility or other limitations
prevent the location of markers as stip-
ulated in R-237.1 and R-237.2, a dimension-
ed map of the geometric arrangement includ-
ing marker locations shall accompany the
radiographs and shall show that full coverage
has been obtained.
SHARPNESS OF RADIOGRAPHIC IMAGE.
Geometrical Unsharpness Limitations.
When requjired by the referencing Code Section, geometric
unsharpness of the radiograph shall not exceed the
following:
Material Thickness, inches
Under 2 - - . - .
2 through 3 - - - - - .
Over 3 through 4 - - -
Greater than 4 - - - -
Ug Maximum, inches
0.020
- - - - 0.030
- - - - 0.040
-- 0.070
Note: Material thickness is the thickness on which
the penetrameter is based.
R-252 Geometrical Unsharpness.
Geometrical unsharpness equals source size times thick-
ness over object to source distance.
' - . " '' - ' . FT
Ug =
where: D
Ug = geometrical unsharpness
F = source size, inches-the maximum effective dimen-
sion (diameter) of the radiation source (or
focal spot) in the plane of the distance D from
the weld, see table R-251.
T = thickness in inches of the weld or other object
being radiographed assuming the film is against
the weld or object; otherwise it is the thick-
ness of the weld or object plus the space
between the film and the weld or object.
D - distance in inches between the source and the
weld or other object being radiographed.
8
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TABLE R-251
Determination Factor
Length
Dia. X Length
1/32 X 1/32
1/32 X 1/16
1/16 X 1/16
1/16 X 3/32
1/16 X 1/8
.10 X .10
1/8 X 3/32
1/8 X 1/8
.Isotope Source Projected
F ='" inches
0.044
0.070
0.088
0.112
0.140
0.141
0.156
0.177
NOTE: Refer to Recommended Practice SE-94, Section 10, for a
method of determining geometric unsharpness. Alter-
natively, a nomograph as shown in Recommended Practice
SE-94 may be used.
R-253 Calibration of Source Size.
The equipment manufacturer's certification of the maximum
effective dimension of the source shall be acceptable.
R-260 Image Quality Indicators (IQI).
R-261 IQI (Penetrameter) Sensitivity.
Radiography shall be performed with a technique of suffi-
cient sensitivity to show the penetrameter image and the
specified hole, which are essential indications of the
image quality of the radiograph. The radiographs shall
also display the identifying numbers and letters.
R-262 IQI Design and Selection.
R-262.1 IQI Design.
Penetrameters shall be manufactured and identified
in accordance with the requirements or alternates
allowed in SE-142 and Appendices. ASME standard
penetrameters shall consist of those specified in
Table R-233.1.
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R-263
R-262.2 IQI Selection.
The essential hole size and designated penetrameter
shall be as specified in Table R-276.
A smaller hole or a thinner penetrameter than listed
for each range may be used, provided all other
requirements for radiography are met.
R-262.2.1 Welds With Reinforcements.
For welds with reinforcements the thickness on
which the penetrameter is based is the nominal
single wall thickness plus the maximum rein-
forcement permitted by the referencing Code
Section. Backing rings or strips are not to be
considered as part of the weld or reinforcement
thickness in penetrameter selection, i
R-262,2.2 Welds Without Reinforcements.
For welds without reinforcements the thickness
on which the penetrameter is based is the
nominal single wall thickness . Backing rings
or strips are not to be considered as part of
the weld thickness. . '_
Use of Penetrameters to Monitor Radiographic Examination.
R-263.1 Placement of Penetrameters.
a. Source Side Penetrameter (s ). The penetrameter (s) shall
be placed on the source side of the part being examined,
except in the condition described in R-263.1 (b) ...
b. Film Side Penetrameter (s ). Where inaccessibility
prevents hand placing the penetrameter (s) on the
source side, it shall be placed on the film side in
contact with the part being examined. A lead letter
"F" at least as high as the penetrameter .
identification number (s) shall be placed adjacent to
or on the penetrameter (s) , but shall not mask the
essential hole where hole penetrameters are used.
c. Penetrameter Location for Welds - Hole Type. The
penetrameter (s) may be placed adjacent to or on the
weld. The identification number (s) and the lead
letter
when used, shall not be in the area of
interest unless either part geometry makes it
impractical to place the penetrameter outside the
area of interest or the weld metal is not
radiographically similar to the base metal.
10
-------
d. Penetrameter Location for Welds - Wire Type. The
penetrameter (s) shall be placed on the weld so that
the length of the wires is perpendicular to the length
of the weld. The penetrameter(s) shall not be placed
in the area of interest unless conditions exist as
stated in R-2 6 3.1 (c).
R-263.2 Number of Penetrameters .
a. For components where one or more film holders are
used for an exposure, at least one penetrameter
image shall appear on each radiograph except as
outlined in R-263.2 (b) through (f).
b. If the requirements of R-261 are met by using
more than one penetrameter, one shall be in the
lightest area of the radiograph and the other
in the darkest; the intervening densities on
the radiograph shall be considered as having
acceptable density. If the density of the
radiograph anywhere through the area of interest
varies by more than minus 15% or plus 30% from the
density througth the body of the penetrameter,
within the miniTTOTn/maxlT'""" allowable density ranges
specified in R-234.1 then an additional penetrameter
shall be used bor each exceptional area or areas
and the radiograph retaken. When calculating the
allowable variation in density, the calculation
may be rounded to the nearest 0.1.
For cylindrical vessels or flat components where
one or more exposure cassettes are used for an
exposure, at least one penetrameter image shall
appear on each radiograph except where the
source is placed on the axis of the object and
a complete circumference or portion of the
circumference is radiographed with a single expo-
sure, in which case, at least three penetrameters
shall be spaced approximately 120 degrees apart.
When the source is placed on the axis of the
circumference and a portion of the circumference
(four or more film location) is radiographed
during a single exposure, at least three
penetrameters shall be used. One penetrameter
shall be in the approximate center of the
section exposed, and one at each end. When the
section exceeds 240 degrees, three penetrameters
spaced 120 degrees apart may be used. In each
case, additional film locations may be
required around the circumference to
establish 120 degree penetrameter spacing,
otherwise at least one penetrameter image shall
appear on each radiograph. Where portions of
longitudinal welds adjoining the circumferential
weld are being examined simultaneously with the
circumferential weld, additional penetrameters
shall be placed on the longitudinal welds at
11
-------
the ends of the sections most remote from the
source of those welds being radiographed. When
an array of objects in a circle is radiographed,
at least one penetrameter shall show on each
object image. ^
d. For spherical vessels, where the source is
located at the center of the vessel and one or
more exposure cassettes are simultaneously
exposed, at least three equally,spaced penetra-
meters per 360 degree circumferential seam plus
one additional penetrameter for each other seam
shall be used.
e. If the required penetrameter image and specified
hole does not show on any film in a multiple
film technique, but does show in composite view-
ing, interpretation shall be permitted only by
composite film viewing.
R-263.3 Shims Under Penetrameters.
a. A shim of material radiographically similar to
the weld metal shall be placed under the pene-
trameter if the weld reinforcement and/or back-
ing strip are not removed.
b. The shim thickness shall be selected so the
total thickness being radiographed under the
penetrameter is at least the same as the nprm-
inal single wall thickness plus the maximum
reinforcement permitted by the referencing Code
Section (if reinforcement is not removed) plus
backing strip (if not removed) and other thick-
ness variations such as in nozzle geometries.
c. When shims are used the plus 30% density
restriction of R-263.2 (b) may be exceeded,
provided the required penetrameter sensitivity
is displayed and the density limitations of
R-234.2 are not exceeded.
d. The shims dimensions shall exceed the penetra-
meter dimensions such that the outline of at
least three sides of the penetrameter image
shall be visible in the radiograph.
R-270 RADIOGRAPHIC TECHNIQUE.
R-271 Single Wall Technique.
R-271.1 Radiography, regardless of the configuration
of the material, shall be done using a single-
wall radiographic technique whenever pract-
icable. Penetrameter size and placement
shall be per R-262 and R-263,'as applicable.
12
-------
R=271.2 For complete radiographic coverage of cylind-
rical girth welds, a minimum of four expos-
vires 90 degrees apart is required when the
source is placed outside and the film inside
the object.
R-272 Double-Wall Technique
R-272.1 Double-Wall Viewing.
Unless otherwise specified, for materials and
for welds in pipe and tubes 3.5 inches (89 mm)
or less in nominal outside diameter, a technique
may be used in which the radiation passes
through two walls and the weld (material) in
both walls is viewed for acceptance on the same
film. For welds, the radiation beam may be off-
set from the plane of the weld at an angle suff-
icient to separate the Images of the source side
and film side portions of the weld so there is
no overlap of the areas to be interpreted in
which case a minimum of two exposures taken at
90 degrees to each other shall be made for each
joint. As an alternate, the weld may be radio-
graphed with the radiation beam positioned so
the images of both walls are superimposed, in
which case at least three exposures shall be
made at 60 degree to each other. For double-
wall viewing a source side penetrameter shall be
used and placement shall be as indicated in
R-263.1.
R-272.2 Single Wall Viewing.
a. For material and for welds in pipe and tubes
with a nominal outside diameter greater than
3.5 inches (89 mm), radiographic examination
shall be performed for single-wall viewing
only. An adequate number of exposures shall
be taken to ensure complete coverage.
b. For welds in pipe or tubes with a nominal
outside diameter 3.5 inches (89 mm) or less,
single-wall viewing may be used provided the
source is offset from the plane of the weld
certerline as outlined in R-272.1. As mini-
mum, three exposures 120 degrees apart shall
be required. A film-side penetrameter shall
be used and placement shall be as indicated
in R-263.1 (c) and (d).
R-273.3 Penetrameter Selection.
The designated hole penetrameter with
essential hole or wire diameter shall be
as specified in Table R-276.
13
-------
R-274 selection of Energy of Radiation.
R-274.1
R-274.2
X-Radiation. Except as provided in R-274. 3,
the maximum voltage used in the examination
shall not exceed the value shown in Figures
T-272.1(a), (b), or(c), as applicable.
Except as provided in R-274. 3,
thickness for which
Gamma Radiation.
the recommended
radioactive isotopes may be used is as follows:
Minimum Thickness (in.)
IT 392 f?o 60
0.75 1.50
0.65 1.3
2.5
Steel
Copper or Nickel
Aluminum
The maximum thickness for the use of radioactive
isotopes is primarily dictated by exposure time;
therefore, upper limits are shown. The minimum
recommended thickness limitation may be reduced
when the radiographic techniques used demonstrate
that the required radiographic sensitivity has
been obtained.
R-280 PROCEDURE REQUIREMENTS. .
R-281 Procedure Compliance Without a Written Procedure.
Compliance with the density and penetrameter image
requirements on production radiographs shall be consid-
ered evidence of qualification of the procedure used.
R-282 Requirements for a Written Radiographic Procedure.
When required by the referencing Code Section, a written
procedure shall contain, as minimum, the following tech-
nique variables: '
a. material and thickness range
b. isotope used or maximum x ray voltage
c. minimum source- to film distance
d. maximum source size
e. film brand or type
f. screens used.
R-290 EVALUATION OF RADIOGRAPHS.
" v- - . -
R-291 Facilities for Viewing Radiographs.
Viewing facilities shall provide subdued background
lighting of an intensity that will not cause troublesome
reflections, shadows, or glare on the radiograph. Equip-
ment used to view radiographs for interpretation shall
provide a light source sufficient for the essential
penetrameter hole to be visible for the specified density
range . The viewing conditions shall be such that light .
14
-------
from around the outer edge of the radiograph or coming
through low-density portions of the radiograph does not
interfere with interpretation.
R-292 Evaluation by Manufacturer.
Prior to being presented to the inspector for acceptance,
the radiographs shall be examined and interpreted, by
qualified Level II radiograhic personnel as complying
with the referencing Code Section and with radiographic
procedure. The qualified Level II or Level III radio-
graphic personnel shall record, on a review form accomp-
anying the radiograph, the interpretation of each radio-
graph and disposition of the material examined.
R-293 Radiographic Setup Information.
To aid in proper interpretation of radiographs, a sketch,
drawing, written procedure, or equivalent record shall be
prepared to show the setup used. The information shall
accompany each group of radiographs if the same informat-
ion applies. Reference to a standard setup is acceptable
if descriptions of this standard setup are readily avail-
able. As a minimum, the information shall include:
a. Number of films.
b. The data specified in R-236 and R-237.3 when
applicable.
R-294 QUALIFICATION OF RADIOGRAPHIC PERSONNEL.
R-295 Requirements.
Personnel shall be qualified in accordance with the
requirements of SNT-TC-1A, 1984 Edition.
a. NDT LEVEL I - An NDT Level I individual shall be
qualified to properly perform specific calibrations,
specific tests and specific evaluations according to
written instruction and to record the results. He
shall rece'ive the necessary guidance or supervision
from a certified NDT Level II or III individual.
b. NDT LEVEL II - An NDT Level II individual shall be
qualified to set up and calibrate equipment and to
interpret and evaluate results with respect to
applicable codes, standards and specifications. He
shall be thoroughly f amiliar with the scope and
limitations of the method and shall exercise assigned
responsibility for on-the-job training and guidance
of trainees and NDT Level I personnel. He shall be
able to prepare written instruction, and to organize
and report nondestructive testing investigations.
15
-------
c.
NOT LEVEL III - An NDT Level III individual shall be
capable of and responsible for establishing
techniques, interpreting code, standards and specif-
ication, and designating the particular test method
and technique to be used. He shall be responsible
for the complete NDT operation he is qualified for
and assigned to and shall be capable of evaluating
results in terms of existing codes, standards and
specifications. He shall have sufficient practical
background in applicable material, fabrication, and/
or product technology to establish techniques and to
assist the design engineer in establishing acceptance
criteria where none are otherwise available. It is
desirable that he have general familiarity with other
commonly used NDT methods. He shall be responsible
for the training and examination of NDT Level I and
Level II personnel for certification. The actual
administration of training and grading of examina-
tions may be delegated to a duly selected represent-
ative of the Level III individual and so recorded.
16
-------
TABLE T-233.1
PENETRAMETER DESIGNATION .THICKNESS,
AND HOLE DIAMETERS
Penetrameter
Designation
5
7
10
12
15
17
20
25
30
35
40
45
50
60
80
100
120
160
200
Penetrameter
Thickness
0.005
0.007
0.010
0.012
0.015
0.017
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.060
0.080
0.100
0.120
0.160
0.200
IT Hole
Diameter
0.010
0.010
0.010
0.012
0.015
0.017
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.060
0.080
0.100
0.120
0.160
0.200
2T Hole
Diameter
0.020
0.020
0.020
0.025
0.030
0.035
0.040
0.050
0.060
0.070
0.080
0.090
0.100
0.120
0.160
0.200
0.240
0.320
0.400
4T Hole
Diameter
0.040
0.040
0.040
0.050
0.060
0.070
0.080
0.100
0.120
0.140
0.160
0.180
0.200
0.240
0.320
0.400
0.480
0.640
17
-------
APPENDIX B
Baseline Testing Procedures and
Data Collection Forms
Ssction No. App. 6
Revision No. 1
Date: October 4.1995
Page: 1 of 12
-------
FIELD EQUIPMENT NEEDS
for Tank Inspections
1. Clip Board
2. Data Forms
3. Pens
4. Tape Measure (25 ft)
5. Chalk Sticks
6. Wax Marker
7. Chalk Line
8. Chalk Powder
9. Twine or Strong String
10. 6-ft Step Ladder
11. Extension Cords
12. Multiple Outlet Adapter
13. High Intensity Light (500 W)
14. Jack Knife
15. Hammer
16. Center Punch
17. Small Cold Chisel
18. Work Gloves
19. Camera
20. Film
21. Flash
22. Screw Drivers
23. Vise Grips
24. DM4 DL Ultrasonic Thickness Gauge
25. Couplant and Applicator
26. Calibration Blocks
27. Laptop Computer
28. Hand Calculator
29. Micrometer Depth Gauge
30. Micrometer Wall Thickness Gauge
31. Heavy Duty Drill Motor
32. 5/16 in Drill Bits (2)
33. , 5/8 in Drill Bits (2)
34. ' Safety Glasses with Side Shields
35. Oil Can
36. Extra Oil
37. Hand Files
38. Shop Vac (supplied by sandblaster?)
39. Drinking Water
40. Brush or Wisk Broom
41. Wire Brush
42. Hard Hats
43. First Aid Kit
-------
GENERAL INSTRUCTIONS FOR INSPECTING TANKS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Complete the Initial Tank Data and History form. .
After the tank is removed from the ground, have a 4-ft by 4-ft or larger opening cut in
one end for safe access.
If possible, allow the outside of the tank to dry off, if wet, and sweep or scrape off
excessive soil.
Grid the inside and outside of the tank to allow for future location references. See
special instructions for doing this.
On at least four locations (two inside and two outside, on opposite sides of the tank),
mark off and label the subsection lines for future reference. (See illustration for
guidance.)
Complete the Tank Welding Details form and the Tank Views chart.
Conduct internal and initial external inspection of the tank, using the Tank Visual
Inspection forms provided.
Conduct the ultrasonic inspection. The Krautkramer Branson DM4 DL ultrasonic
thickness gauge or equivalent should be used after checking its calibration. Preferably,
it should be used with its data logger capability and the data then-transferred to a PC'
Otherwise, use the Ultrasonic Inspection form. (Note, this step may be conducted before
or after steps 9 and 10.)
Have the exterior of the tank sandblasted.
Conduct a second exterior inspection of the tank, using the Tank Visual Inspection forms
provided.
Take pit depth measurements of the deepest pits found, using the Starrett micrometer
depth gauge and the Pit Depth forms provided.
Drill sentry holes. For 1/4 inch plate, first, drill a 5/16 in pilot hole, followed by a 5/8
in sentry hole. Back off the larger nut on the anvil side of the thickness micrometer and
pull anvil against spring tension until it can be rotated 90°. Then feed anvil through
sentry hole, rotate the anvil back to its normal position, and using the ratchet stop on the
spindle take a thickness measurement. Rocking the micrometer slightly will enable you
to get the minimum reading. Record reading on.the Wall Thickness forms provided
-------
INSTRUCTIONS FOR GRTODING THE TANK
1.
2.
3.
5.
6.
8.
The tank is to be divided into 3 ft by 3 ft (or less) segments with a grid work. First,
measure the diameter and length of the tank. In all of the following, the process may
be made easier if at some point the tank can be rolled 90° so you don't have to work on
the top of the tank.
The number of circumferential segments is equal to the diameter, in feet. Thus, an 8-ft
diameter tank should have 8 circumferential segments, a 10-ft diameter tank 10 segments,
etc.
The length of the tank should be divided into equal increments, with each increment to
be no more than one meter. Tanks eight feet in diameter should be divided
longitudinally as follows:
6,000 gal
8,000 gal
10,000 gal
12,000 gal
5 segments
7 segments
8 segments
10 segments
For the interior of the tank, determine the length of the arc needed for the grid. For
example, if the diameter is 8 feet, the circumference is IIxD = 301.6 in. One eighth of
this is 37.7 in, or approximately 37.75 in. Then, at both ends of the tank mark off with
chalk or a wax marker the eight (approximately) equal segments. It is best to start from
the top of the tank, as the top is more easily identifiable than any other reference.
Using a carpenter's chalk line, snap longitutinal grid lines between the marks placed in
step 4. .
Lay out the longitudinal segments. For example, for a 6000 gal tank, which is 16 ft
long, use 16/5 ft, or about 38.5 in! Make a set of marks this distance apart for the
length of the tank at three or four locations around the circumference (eg., at 60, 180,
and 300 degrees from the top). Then, using a piece of chalk or wax marker, draw a set
of circumferential grid lines through the marks. (There will be 4 such lines for a 16-ft
tank.)
The process on the outside of the tank is basically the same. It is recommended that the
initial marks at each end of the tank around the circumference be augmented with a
center punch or chisel, so they can be readily relocated after sandblasting or rain. A
carpenter's chalk line can be used for both the longitudinal and circumferential grids,
unless the surface is wet or extremely dirty. In that case, use a piece of regular string
as a guide and draw the lines with a wax marker.
For the circular ends of the tank, locate the center. Mark a vertical diameter and a
horizontal diameter, dividing the end into 4 parts. Mark a circle 20.3 in hi diameter in
the center. The center circle becomes one section, the other 4 sections are defined by
-------
the center circle and the vertical and horizontal marks. This gives approximately 9 ft2
areas for an 8-ft diameter tank. If it is necessary to divide the end into 1 ft2 areas, begin
with the vertical diameter and mark a vertical line every ft in both directions. Then
begin with the horizontal diameter and mark a vertical line every ft in both directions.
The result divides the end into 1 ft2 sections. A division into square feet for tanks of
different diameters is shown in the figure. ,
Note: 1 meter = 39.36 inches; 1 gallon = 231 cubic inches.
-------
Top
Opening
H _m_ A
E ^~ 1 D
Example Subgrids:
._.
.4_L5J_6.
7 I. 8 I 9
B2 Exterior
B2 Interior
4
r
HI
TJ
0)
c
(1)
Q.
o
<&--
0)
I
V
if
/
/
/
tf *
A
--
B
C
D
Nomenclature: This is subsection B2-9.
2
"
5
R
1
4
7
1
9
6
3
1
8 , 7
1
5 | 4
2 | 1
I
7 , 8
I
_4_L5_
1 ] 2
I
9
6
3
G2 Exterior
Note: Interior and exterior notations are identical for same portion of tank.
Also, notation does not change with rotation of tank.
G2 Interior
95-24 SEV gltuz Km 1 062095
-------
TOP
12FOOTDIA
10FOOTDIA
8FOOTDJA
6 FOOT DIA'.
LEFT
OUAORANTUNE
SUBDIVISION LINE
QUADRANT LIKE
SUBDIVISION LINE
RIGHT
BOTTOM FLOOfl OF TANK
-------
INSTRUCTIONS FOR COMPLETING TANK VIEW INFORMATION
1. Provide proper project tank identification number and location of site.
2, Sketch the locations of all tank openings. Show bung locations on the top, and indicate
their diameters (eg., 4 in or 2 in). Indicate the size and location of the manway. Sketch
the size, shape, and location of the tank end wall opening.
3. Show locations of all tank welds except the head joints. Include longitudinal and
circumferential welds on the cylindrical portion and any welds on the heads.
4. Sketch and label the grid system used on the two heads, with 4 or 5 sections per head.
5. Show the approximate locations of any holes visible before exterior sandblasting.
6. Indicate whether or not the tank had obviously been coated, locations where coating has
deteriorated or is missing, and the general condition of the coating.
7. Indicate the approximate locations of visually unusual sections of the tank prior to
exterior sandblasting, if any. This would include areas of major damage, discolored
areas, areas symptomatic of product leakage, etc.
8. Provide additional comments on your initial impression of the tank. See example below.
-------
Tank No.
Date:
Tank Location:
Data entered by:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
INITIAL TANK DATA AND HISTORY
Site contact, name and phone
Tank capacity, diameter, and length
Tank manufacturer ''
Tank nominal wall thickness
Tank serial no. or other identification
Tank age, if known
Product stored in tank.
Was cathodic protection used (yes/no) ?
Was tank coated internally (yes/no)?
Was tank coated externally (yes/no)? _
Backfill material ._
Evidence of product leakage in backfill
Leak and repair history, if available -
14. Other observations
-------
Tank No.
Date:
Tank Location:
Data entered by:
Internal/External
TANK VISUAL INSPECTION FORM
Sandblasted Q7N)
Page.
Grid ID
Hole Subgrid
Many Shallow Pits?
Comments
Percent Area Corroded
V. Deep Pit Subgrid
Pattern? '.
Subgrid of Large Dent.
Deep Pit Subgrid _
General Corrosion?
Grid ID
Percent Area Corroded
Subgrid of Large Dent.
Hole Subgrid
Many Shallow Pits?
Comments
V. Deep Pit Subgrid
Pattern? ______
Deep Pit Subgrid _
General Corrosion?
Grid ID
Percent Area Corroded
Subgrid of Large Dent,
Hole Subgrid
Many Shallow Pits?
Comments
V. Deep Pit Subgrid
Pattern?
Deep Pit Subgrid _
General Corrosion?
Grid ID
Hole Subgrid.
Many Shallow Pits?
Comments
Percent Area Corroded
V. Deep Pit Subgrid
Pattern?
Subgrid of Large Dent
Deep Pit Subgrid
General Corrosion?
Grid ID
Percent Area Corroded
Subgrid of Large Dent.
Hole Subgrid
Many Shallow Pits?
Comments I
V. Deep Pit Subgrid
Pattern?
Deep Pit Subgrid _
General Corrosion?
-------
Tank No.
Date:
Tank Location:
Data entdred by:
TANK WELDING DETAILS
1. Comparing with°-i racF
' jr*" ^ *a"*"~ * ^ "
J- 9 1 f ^*ij f i ^aaa^^ ~ i
. j |-l/2'Mm.(l2.7mm)
N0.4-MAX. DIAM No. 5- ALL DIAM. No. 6-ALL OIAM.
-J [ 5/32* <4 JO mm) Min. Stoorotion
F~°~1 ySCr t t 1 __J '
L . .. < 1 h-l/2" Min.
MJajmrnr
Na 7-MAX OIAM. 65- No 8.ALL D|AM.
(1.65 m)
B Overlap 1/2 inch (12.7 mm) minimum.
C Continuous welds.
CF AH lap welds shall be continuous full fillet welds..
0 Overlap 1/2 inch (12.7 mm) minimum for,
diameters 48 Inches (1.2 m) or less; 3/4 inch (19.1
mm) minimum for diameters over 48 inches (1.2 m).
E 1/2 inch (12.7 mm) minimum diameter lock weld,
not over 12 Inches (305 mm) apart.
T Tack weld 1 Inch (25 mm) spots, not over 12 inches
(305 mm) apart..
t Thickness of backup bar to be same as shell
thickness. .
HEAD JOINTS
^T-^^i^^)
N0.22 U N0.23 u N0.24 u
B Overlap 1/2 Inch (12.7 mm) minimum.
C Continuous welds.
CF Shan be continuous full fillet welds.
F Not less than five times head thickness minimum
1/2 inch (12.7 mm).
J Joint No. 21 Minimum thickness of 0.167 inch
(4.24 mm).
K Joint No. 22 Heads require bracing, (see No. 1
and 2 of Figure 6.2). Minimum thickness of 0.167
(4.24 mm).
T Tack weld 1 inch (25 mm) spot*, not over 12 Inches
(305 mm) apart.
t Minimum. 1 X shed thickness.
Heads may be fiat, dished, or cone. -
Height of cone heads not less than one-
twettth diameter.
-------
1 Tank No.
Date:
Tank Location:
Data entered by: |
ULTRASONIC INSPECTION FORM
Subgrid
Grid
Thick.
Thick.
Subgrid
Thick.-
Grid
Subgrid
Thick.-
Thick.
Subgrid
Thick. _
Thick.
Thick.
Grid
Subgrid
Thick.-
Subgrid.
Thick. _
Thick.
Thick.
Grid
Subgrid
Thick. _
Subgrid
Thick. _
Subgrid
Thick.-
Subgrid
Thick. _
Thick.
Grid
Subgrid
Grid
Subgrid
Thick. _
Subgrid
Thick. _
ThirV
Thick.
Subgrid
Thick. _
Subgrid
Thick. _
Subgrid
Thick. -
Subgrid
Thick. _
Thick.
Subgrid
Thick. _
Subgrid
Thick. _
Grid
Subgrid
Thick.-
Grid
Thick.
Thick.
Grid,
Thick.
Thick.
Grid
Subgrid,
Thick.-
Grid
Subgrid
Thick.-
Subgrid,
Subgrid.
Thick. _
Subgrid
Thick. _
Grid
Subgrid.
Thick. _
Subgrid
Thick.
Grid
Grid
Subgi
Thick.
Thick
Subgrid
Thick.-
-------
Section No. ftpp.C
Revjsion No. 0
Date: August 16.1995
Page: 1 of __
APPENDIXC
* .
Vendors' Standard Operating Procedures
(To be inserted upon receipt from vendors)
-------
-------
SECTION 2
Results of Evaluation Forms
-------
-------
Results of Evaluation Forms
Integrity Assessment Procedure for Steel USTs
, This form tells whether an integrity assessment procedure used .to assess steel USTs prior to
upgrading with cathodic protection meets the performance standards recommended by the
EPA. The evaluation is of a vendor procedure for assessing tank integrity, and was conducted
by a third party acting as a consultant to the vendor. The vendor procedure was evaluated
according to the Quality Assurance Project Plan (QAPP), "Field Evaluation of UST Inspection
Assessment Technologies" of October 1995 or equivalent protocol. The full evaluation report
includes a form summarizing the test data.
The evaluation consisted of the vendor applying the procedure to a number of tanks or sites.
After the vendor's conclusions were reported, the baseline results were determined by
removing the tanks from the' ground and inspecting the tanks. The baseline inspection .
determined that a tank was not suitable for upgrading if the tank had any perforations or had
any pits (either external or internal, depending on the assessment procedure) that were deeper
than ,50% of the required minimum wall thickness for tanks of that size.
Where the UST program implementing agency allows or requires evaluations for compliance,
UST owners and operators of steel tanks that have been upgraded by the addition of cathodic
protection should keep this form on file to prove compliance with the federal regulations.
Tank owners should check with State and local agencies to make sure that this form satisfies
their requirements.
Vendor Procedure
Procedure Name
Version ; '
Vendor Name
Vendor Address.
Vendor Phone __
-E-mail
Fax
Description of Procedure
This vendor procedure assesses the integrity of a steel UST by (give a brief description below
of the operating principles of the procedure):
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This procedure is operated in accordance with the following standard operating procedures or
national codes (List any applicable procedures and codes below):
Test Conditions During Evaluation
The evaluation used a total of.
ranged from years to
tanks at different sites. The ages of the tanks
. years with a mean average age of years.
Groundwater was found above the bottom of the tank at the time of the evaluation at
sites with tanks. The evaluation data included tanks with a minimum wall
thickness of 3/16 inch,.
nominal), and
.tanks with a minimum wall thickness of 0.24 inch (1/4
. tanks with a minimum wall thickness greater than 1/4 inch.
Evaluation Results
List the vendor's criteria for declaring a tank unsuitable for upgrading with cathodic
protection. Note that these are the criteria according to the vendor's standard operating
instructions, and not the EPA's evaluation criteria. (List below.)
In some cases, assessments done in the normal course of business are not completely
. i;; i a ' , ' ,.,'", , *
conducted only by a single vendor company. Instead, part or all of the assessment procedure
is conducted by a licensee or other company or person. The assessments within an evaluation
must not have more involvement of the original vendor that is seen in normal practice.
A licensee or other company or person besides the original vendor was was not
involved in the assessments that were a part of this evaluation. If licensee or other company
or person was involved, the nature and level of involvement was (describe below):
The evaluation resulted in data summarized in the table below. The data are reported in the
Reporting Form for Evaluation Data: Integrity Assessment Procedures for Steel USTs. Note
that some assessment procedures report results on a per tank basis, while others report on a
per site basis. See the instructions for an explanation of reporting on a per site basis. Indicate
by checking the appropriate box which reporting basis was used in this evaluation:
The evaluation data were reported on a O per tank D per site basis.
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BASELINE
VENDOR RESULT (without leak test knowledge)
SUITABLE
UNSUITABLE
INCONCLUSIVE
TOTAL
SUITABLE
UNSUITABLE
TOTAL
BASELINE
VENDOR RESULT (after inclusion of leak test results)
SUITABLE
UNSUITABLE
INCONCLUSIVE
TOTAL
SUITABLE
UNSUITABLE
TOTAL
Note that the performance estimates are to be interpreted as applying on a per tank or per site
basis, depending on the way that the data were reported. The results are based on the
calculations described in Section 5 of the QAPP "Field Evaluation of UST Inspection
Assessment Technologies." Based on the data summarized above obtained during the
evaluation, the following performance estimates were found based on the vendor's results
after including the results of any leak tests:
Correct Decision Rate
_%. (This is the number of tanks [or sites] declared
1.
suitable by both the vendor and baseline, plus the number declared unsuitable by both vendor
and baseline, divided by the total number of tanks [or sites] and converted to percent.)
The 95% confidence interval was from _____ to ___%.
2. Proportion of Correct Approvals (Accuracy)
_%.. (This is the number of
tanks [sites] ^.declared suitable by both the vendor and baseline, divided by the number found
suitable by the baseline tests, converted to percent.)
The 95% confidence interval was from to %. ,
3. Proportion of Correct Detections (Reliability)
_%. (This is the number of
tanks [sites] declared unsuitable by both the vendor and baseline, divided by the number
found unsuitable by the baseline tests, converted to percent. EPA recommends that this
proportion be 95% or greater.)
The 95% confidence interval was from 1 to %.
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4. Proportion of False Alarms.
_%. (This is the number of tanks [sites]
declared unsuitable by the vendor but found suitable by the baseline tests, divided by the total
number found suitable by the baseline tests, converted to percent.)
The 95% confidence interval was from to %.
5. Proportion of Missed Detections
_%. (This is the number of tanks [sites]
declared suitable by the vendor, but found unsuitable by the baseline tests, divided by the total
number found unsuitable by the baseline tests, converted to percent.)
The 95% confidence interval was from to %. ,
6.
7.
8.
Proportion of Inconclusive Results of total results.
The 95% confidence interval was from to _
Proportion of Inconclusive Results for Suitable Tanks.
The 95% confidence interval was from to
Proportion of Inconclusive Results for Unsuitable Tanks
The 95% confidence interval was from to _%.
In order to meet the performance requirements, the proportion of correct detections (the
proportion of unsuitable tanks correctly detected as other than suitable) must be at least 95%.
The proportion of correct detections is computed as 100% minus the percent reported in
number 5 above, and was %. Based on the results from this evaluation the procedure
(mark applicable box)
D does meet the performance standards, or
CD does not meet the performance standards.
Limitations on Results
The performance estimates above are only valid when:
The procedure is performed in accordance with the standard operating instructions
used in this evaluation; and
The procedure has not been substantially changed.
Other limitations specified by the vendor or determined during the evaluation are (list below):
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Evaluator Certification of Results
Procedure Name
Version ':
Vendor Name
I certify that the vendor conducted the assessment of the integrity of steel tanks prior to
upgrading with cathodic protection in accordance with the vendpr's standard operating
procedure, >
I also certify that this vendor procedure was evaluated according to the plan in "Field
Evaluation of UST Inspection Assessment Technologies" and that the results presented above
are those obtained during the evaluation. ,
I also certify that, outside this evaluation, I and my organization have no financial interests in
the vendor company, and that the vendor company has no financial interests in myself or my
organization.
Name (person)
Organization performing evaluation
Signature
Address of Organization
Date
Phone
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Vendor Certification of Independence
in ' . , . .'''',.':''
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Reporting Form for Evaluation Data
Tank Integrity Assessment Procedures for Steel Tanks
(Use as many pages as needed.) Page of .
(Indicate whether reported on tank or site basis by circling appropriate word in column 1 or 2)
Tank .
ID
Site
ID
-
Tank
Age
Baseline Results
Perforation
(Y/N)
Deepest Pit
Depth
(Indicate
internal or
external)
. .
Inspection
Conclusion
'_ >. ; .;
. .
-
Vendor Conclusion
Without
Leak Test
After Leak -
Test
7
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SECTIONS
Instructions for Filling Out Results Forms
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Instructions for Filling out Results Forms
The evaluation is based on the procedures outlined in the "Quality Assurance Proj ect
Plan: Field Evaluation of UST Inspection Assessment Technologies" (QAPP) of October 1995,
. or an equivalent protocol. The standard test procedure document supplements the QAPP and
provides instructions for completing the results form for the evaluation of a tank integrity
assessment method for steel USTs prior to upgrading with cathodic protection.
Vendor Procedure
' - h,. ''"."' v . , . ' - ._ f -
In this section, provide the name of the vendor procedure. This is usually a trademarked
name. If there is a version of the system or a date, list that under the version. The vendor name
is the name of the company that performs the assessment or supplies the specific procedure used
by licensees or users. The company's address and phone number should be supplied. An
optional FAX number and/or e-mail address could also be supplied.
Description of Procedure
Give a brief description of the type of assessment here. Examples might be an internal
video camera or a corrosion model. If the procedure is performed or operated according to an
industry standard code or standard operating procedure, give the appropriate reference(s) as the
answer in the next section. *
Test Conditions During Evaluation
-' ' v -
This section documents the conditions and data used in the evaluation. Record the
number of tanks investigated and the number of distinct sites. Typically all tanks in a single
excavation would be a single site. However if there were two separate tank excavations
separated by some distance, this could be two sites even if it was a single address or facility.
Report the youngest and oldest age of tanks in the study. Also report the average tank age. If
there are tanks with unknown ages, use the best approximation of age in computing the average
and the minimum and maximum. Report the number of tanks of different wall thicknesses. If
the wall thickness is not known, use the minimum required by the Underwriters Laboratory
Standard 58 based on the capacity of the tank.
The QAPP was developed on a per tank basis and called for investigating about 100
tanks. With an average of about 2.5 tanks per site, this would translate to about 40 sites. For
procedures that report on a site basis, the evaluation should include at least 42 sites, with at least
21 sites that were determined by the baseline tests to be unsuitable for upgrading. Note that this
will probably involve more than 21 tanks at these sites. No minimum requirement is specified
for the number of suitable sites. Procedures that report on a per tank basis should include at least
42 .tanks,- with a minimum of 21 unsuitable tanks as determined by baseline tests. .
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Evaluation Results
Describe briefly how the vendor determines that a tank is unsuitable for upgrading. For
example, the vendor's decision might be based on a visual review of the internal video of the
tank, or it might be based on the predicted life of the tank compared to its age based on a
corrosion model,
Indicate whemer the vendor procedure makes a determination separately for each tank, or
whether one decision is made that applies to the site (with possibly multiple tanks). If the vendor
reports results on a per site basis, the site as a whole is judged suitable for upgrading by the
addition of cathqdic protection or the site as a whole is judged unsuitable. If the vendor reports
on a site basis, the baseline results must also be reported on a site basis rather than on a per tank
basis. For this purpose the baseline testing results are interpreted to mean that a site is not
suitable for upgrading by the addition of cathodic protection if any of the tanks at the site is not
suitable. For a site to be judged suitable for upgrading, all tanks at the site must be suitable for
upgrading with cathodic protection.
The QAPP calls for the vendor to report findings first in the absence of information about
whether the tank has passed a leak detection test, and then again using the results of a leak
detection test. Correspondingly, the results form has a table for the vendor's conclusions in the
absence of knowledge about the leak detection test and a subsequent table for results including
that knowledge. The data to be entered in the table are described in detail with examples in
Section 5, page 5 of 7, of the QAPP.
Compute the percentages for items 1 though 8 as described in the QAPP, Section 5, pages
5 and 6 of 7, and report them in the indicated blanks. Note that these items are based on the
vendor's results including knowledge of any leak detection test results.
The performance requirements are based on the probability^ of correct detection. The
probability of a correct detection is computed as 100% minus the percent reported in item 5. For
example, if item 5 were computed as 2% (based on incorrectly declaring 1 unsuitable tank out of
50 unsuitable tanks as suitable), then the probability of correct detection would be 98%.
Mark the "does" box if the estimated probability of detection is at least 95%. Otherwise,
mark the "does not" box.
Limitations on Results
List any and all restrictions or special requirements of the procedure here. For example,
if there are any special cleaning requirements for the tanks hi preparation to performing the
assessment, these should be described here. Similarly, if the evaluation only reflected certain
situations, and not the full range of variables that might be encountered in the field, then these
should also be described as limitations.
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Certification of Results
Repeat the procedure name, version and vendor's name as indicated. Give the name of
the person in charge of the evaluation in the first position, followed by the name of the evaluating
organization. On the second line, the person in charge of the evaluation should sign the form.
This is followed by the address of the evaluating organization. On the next line, enter the date
followed by the evaluating organization's telephone number.
Vendor Certification of Independence
The vendor's representative should complete and sign.
Reporting Form for Evaluation Data
The QAPP contains detailed data reporting forms for the baseline inspections of the
tanks. The indicated data should be summarized for each tank on this .reporting form. This
includes the identification of the tank and site, whether or not each tank had a perforation, and
the depth of the deepest pit found during the inspection, leading to the inspection conclusion as
to whether the tank was suitable or not. Note that a specific procedure is required to assess only
one side of the tank shell, but must identify all perforations. The baseline conclusion should be
based on the deepest pit found on the same side of the tank shell (interior or exterior) that is
assessed by the vendor's procedure. The vendor's conclusions both without knowledge of the
leak test results and with that knowledge are also reported. These data form the basis for the
tables in the reporting form. , .
3
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SECTION4
"Guidance on Alternative Integrity Assessment Methods
for Steel USTs Prior to Upgrading with Cathodic Protection'
EPA Memorandum :
July 25,1997
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\
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
Mail Code 5401G
JUL 25 I997 -.""
OFFICE OF
SOLID WASTE AND EMERGENCY
RESPONSE
MEMORANDUM
SUBJECT:
FROM:
TO: ,.
Guidance On Alternative Integrity Assessment Methods,For Steel USTs Prior To
Upgrading With Cathodic Protection
: TxZLAtt-^
lopkins Virbick, Director
Office of Underground Storage Tanks
EPA UST/LUST Regional Program Managers
State UST Program Managers
, This memorandum provides guidance that pertains only to a relatively smallsubset of all
underground storagfe tanks (USTs). This subset>,of USTs consists of steel USTs that are not yet
protected from corrosion, that will not be internally lined to meet the 1998 deadline for corrosion
protection, and that will-be" assessed by alternative methods other than either human-entry
internal inspection or leak detection before cathodic protection is added.
In our memorandum of October 21, 1996, we recommended to UST program
implementing agencies that they continue to follow their current policies regarding allowed
integrity assessment methods for this subset of tanks until more information and guidance .
became available. On March 6, 1997, we circulated additional mformation and draft guidance.
Today's memorandum finalizes our guidance on this subject. The guidance promotes protective
and affordable integrity assessments while maintaining regulatory flexibility for implementing
agencies.
Guidance On The Use Of Alternative Integrity Assessment Methods
Federal UST regulations require that existing steel tanks without corrosion protection
must be assessed for structural integrity before cathodic protection can be Idded to meet
corrosion protection requirements. Basically, tanks that are not structurally sound must not have
their operational lives extended. Specifically, the federal UST regulations at 40 CFR
§ 280.21(b)(2) state that an assessment method may be used to ensure the integrity of steel tanks
prior to upgrading with cathodic protection if the assessment method is listed in the regulations
or if the implementing agency determines that an alternative assessment method prevents
releases in a manner that is no less protective of human,health and the environment than those
listed. Today's guidance pertains to determinations of alternative integrity assessment methods
that are not listed in the federal regulations.
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EPA recommends that implementing agencies determine that an alternative
integrity assessment method that meets either Option A or Option B below be considered to
prevent releases in a manner that is no less protective of human health and the
environment than the methods listed in 40 CFR § 280.21(b)(2)(i) through (Hi), which
include human-entry internal inspection and, for tanks less than 10 years old, certain leak
detection methods.
Option A. Ensure tank integrity by using an alternative integrity assessment method that is
in accordance with a standard code of practice developed by a nationally recognized
association or independent testing laboratory.
Option B. Ensure tank integrity by using a vendor-supplied procedure that has been
successfully evaluated and certified Jby a qualified independent third party to meet
specified performance criteria regarding detection of perforations and detection of
either internal or external damage. Within Option B, the criteria for proving tank
integrity are as follows:
1. Detect all perforations; and
2. One of the following:
a) Detect external pits deeper than 0.5 times the required minimum
wall thickness, OR
b) Detect internal pits deeper than 0.5 times the required minimum
wall thickness AND any internal cracks or separations.
To meet a criterion, a method must demonstrate a probability of detection of at least
95 percent and a probability of false alarm of no more than 5 percent.
After March 22,1998, EPA recommends that implementing agencies approve the
use only of alternative integrity assessment methods meeting either Option A or Option B.
Before March 22,1998, agencies should maintain their current policies for alternative
integrity assessment methods that do not meet either Option A or Option B. Also, before
March 22,1998, agencies should allow upgraded tanks that have used alternative integrity
assessment methods meeting either Option A or Option B to select a leak detection method
from those available after March 22,1998 (as discussed below in today's guidance).
This guidance is not intended to discourage the use of human-entry internal inspection as
an assessment method or tank lining as an acceptable upgrade option. EPA's UST regulations
allow for interior tank lining to be used as an upgrade option for tanks lacking corrosion
protection (40 CFR § 280.21(b)(l)). This guidance addresses only § 280.2l(b)(2)(iv), which
regards methods not specifically listed in the federal regulations.
The Difference Between "Method" And "Vendor-Supplied Procedure"
Option A addresses "integrity assessment methods" and Option B addresses "vendor-
supplied procedures." Both "methods" and "procedures" share the common essential task of
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verifying the integrity of the tank, but they differ in the guidance as follows. A "method" is a
ji> " ,
general technology (such as the use of robotic devices of diagnostic modeling) that is in
accordance with a standard code of practice. A "vendor-supplied procedure" is an application of
a technology, usually marketed as a patented brand name and procedure. Under Option B, a
"vendor-supplied procedure" must be successfully evaluated and certified by a third party. .
However, the guidance does not recommend the certifying of'each individual contractor who
may be the local provider of a "vendor-supplied procedure." .
Option A: Standard Codes Of Practice
Option A recommends that each alternative integrity assessment methocl comply with a
standard code of practice developed by a nationally recognized association or independent testing
laboratory. Compliance with a standard code is a requirement in almost all other areas of the
federal UST technical regulations. Codes of practice are often updated over time, and so the
code used must be the code applicable at the time that the alternative assessment is conducted.
The American Society for Testing and Materials (ASTM) has been the most active code
body for alternative integrity assessments. A standard is being drafted by a joint task group
under Subcommittees E50.01 on Storage Tanks and GO 1.10 on Corrosion in Soils. The first
draft of the "Standard Guide for Three Methods of Assessing Buried Steel Tanks" was recently
balloted, and is very similar to the expired ASTM ES 40, "Emergency Standard Practice for
Alternative Procedures for the Assessment of Buried Steel Tanks Prior to the Addition of
Cathodic Protection." Since balloting is within G01.10 only, interested parties should contact
ASTM's Robert Held at (619) 832-9719 for information about participating in this standard
development activity.
Although ASTM committees have been the most active, other nationally recognized
associations and independent testing laboratories are not precluded from developing standard
codes of practice. ,
Option B: Evaluation And Certification Process
Option B recommends that each vendor-supplied procedure intended to ensure tank
integrity must receive third-party evaluation and certification that it meets criteria for
establishing the integrity of a tank. Implementing agencies should allow the use only of those
vendor-supplied procedures successfully evaluated and certified by a qualified independent third
party to meet specified performance criteria regarding detection of perforations and detection of
either internal or external damage. -
In an evaluation and certification process, a vendor first contracts with a third party for
evaluation. This third party should be a qualified test laboratory, university, or not-for-profit
research organization with no financial or organizational conflict of interest. Based on the nature
of the performance criteria, evaluations will likely be qualitative, but quantitative evaluations
also are acceptable. The evaluation is performed first without and then with information about
the leak status of the tank divulged to the vendor. The method's performance characteristics,,
both with leak data and without, are determined, summarized on a "short form," and certified by
the evaluator. Owners and regulators can then use this documentation, along with other
information, to make decisions mat are right for their particular situations. ~
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We have determined that an independent evaluation and certification process is already
available for use in the UST community. This finding is based on discussions with vendors and
third-party evaluators and industry's experience with other UST system technologies.
In an evaluation, the determination of whether or not a vendor-supplied procedure meets
the criteria may be based in part on leak detection data. This is allowed because protectiveness is
based on the performance of the complete vendor-supplied procedure, and leak detection results
often play a large role in integrity assessments. However, the performance of a vendor-supplied
procedure without inclusion of leak detection data should still be reported on the short forms for
informational purposes.
As is clear from the recommendations, no integrity assessment methods or vendor-
supplied procedures that have been in use before March 22, 1998 should be "grandfathered" or
considered exempt from following a standard code or from evaluation after March 22, 1998.
However, those vendor-supplied procedures that were part of the 1996 field study conducted by
EPA's Edison lab can use applicable data generated in that study as part of a more
comprehensive evaluation. In addition, even if a company follows a standard code of practice, it
may voluntarily put its vendor-supplied procedure through this evaluation process in order to
obtain independent third-party documentation of performance characteristics.
Evaluation Protocols For Option B
More detailed information on evaluation can be found in the "Quality Assurance Project
Plan" (QAPP) prepared for EPA's engineering study conducted in 1995 and 1996. We consider
the original QAPP written for the EPA field study to be a viable, peer-reviewed evaluation test
protocol. We recommend that evaluations conducted in accordance with it be considered valid.
However, removal and examination as detailed in the QAPP may not be necessary, at least not
for all tanks used in an evaluation. An approach that uses data in lieu of physical testing can be
used if all relevant data requirements are factored in. An evaluator may choose alternative
evaluation protocols or procedures, because of the potentially high cost of following the QAPP to
the letter or because of special characteristics of the vendor-supplied procedure under evaluation.
(The QAPP calls for an assessment method to be used on approximately 100 tanks, which are
then removed from the ground for testing and inspection.) The development of other protocols is
not precluded, but rather is encouraged.
We have investigated the EPA/private sector Environmental Technology Verification
program, and found that it probably cannot provide assistance in the needed time frame. EPA
will Hot be involved in the writing of additional protocols or in the funding of evaluations.
However, EPA staff will be available to comment on draft protocols and to provide guidance to
implementing agencies. In addition, we will provide optional summary forms, or "short forms,"
for the QAPP, as suggested by commenters. These will help industry give implementing
agencies and owners relevant information in a consistent and understandable format.
Evaluation Criteria In Option B
The criteria in Option B above are based on those found in the QAPP. On each criterion,
methods must demonstrate a probability of detection of at least 95% and a probability of false
alarm of no more than 5%. Note that 100% accuracy is not specified. We have found it
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protective and cost-effective to rely on a series of multiple, complementary, and high-quality
measures to achieve the greatest protection at a reasonable cost.
In addition to a mandatory criterion on perforations, a method must pass evaluation of a
criterion for either external or internal damage. We structured the criteria in this way based
partly on consistency with internal (human-entry) inspection standard codes. In addition, these
criteria are based on our belief that not allowing the upgrading of tanks with either significant
interior or exterior damage (unless they are repaired) yields significant benefits over the costs
incurred. We do not believe, however, that the additional cost of assessing a tank for both
internal and external damage provides a net benefit in significantly greater protection.
A criterion for loss of wall thickness over a wide area of the tank is not included, because
our research found that failures due to uniform corrosion are very rare. Likewise, a criterion for
tank deformation is not included, because it is generally found to be an issue only in fiberglass
tank installations.
c
Recommended Commencement Date
Setting the recommended commencement date of March 22, 1998 allows time for
standards to be developed and evaluations to be conducted, and comes before a significant
portion.of the anticipated assessment work. We extended the date proposed in our draft guidance
in response to comments requesting more time. Note: the December 22,1998 deadline for all
existing UST systems to meet spill, overfill, and corrosion protection requirements will not be
extended.
Monthly Leak Detection Not Required
We earlier proposed to include stand-alone monthly leak detection monitoring in
combination with the integrity assessment options. However, this monitoring is no longer part of
our recommendation for integrity assessment methods fulfilling Option A or vendor-supplied
procedures fulfilling Option B. We deleted monthly monitoring based on technical merit,
consistency, and simplicity. We believe that if an integrity assessment method complies with
either a standard code of practice or evaluation procedures as described above, then leak
detection monitoring beyond that required in the federal regulations is not warranted on a
nationwide basis, and we have not found performance data that indicates otherwise. In addition,
deleting the additional monitoring brings all assessment methods in line with each other and
simplifies the compliance picture. "'.-
If the implementing agency follows today's guidance, compliant USTs (correctly
upgraded through alternative assessment, cathodic protection, protected piping, and spill/overfill
protection) could follow the requirements of § 280.41(a)(l) allowing either stand-alone monthly
monitoring or, for up to ten years, the combination of inventory control and tightness testing
every five years. Note that the period during which this combination leak detection method is
valid may be less than 10 years if the tank itself meets the 1998 standards for corrosion
protection before other UST system components meet 1998 standards for spill, overfill, and
corrosion protection, as clarified in our memorandum of July 25, 1997, "Applicability Of A
Combination Leak Detection Method For Upgraded Underground Storage Tanks."
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Recommendation Against Leak Detection As An Integrity Assessment
The question of whether leak detection alone should be used to assess older tanks prior to
upgrading with cathodic protection has been raised from time to time. We received numerous
comments on this subject, nearly all in agreement that leak detection alone is not sufficient.
Although we recognize the important role leak detection generally plays and allow the use of
leak detection results in evaluations of integrity assessment methods, EPA does not recommend
that leak detection alone be'considered sufficient to assess the integrity of USTs 10 years old or
older.
State Program Approval
A decision either to adopt or not adopt EPA's recommendations regarding integrity
assessment would not affect the status of state program approval or of an application for
approval. This is because EPA is providing recommendations only and not amending its
regulatory criteria for state program approval. \
Federal And State Consistency ,
We hope mis guidance is accepted by implementing agencies because there are benefits
to having consistency across jurisdictions. However, EPA recognizes that State and local
requirements may differ from Federal requirements. We have included in Attachment 1
additional items that implementing agencies may consider in developing their integrity
assessment policies.
Guidance Intended To Ensure Quality Of Integrity Assessments
EPA believes today' s guidance will benefit the UST community and protect human
health and the environment by ensuring quality alternative integrity assessments that can lead to
extended operational life of older steel tanks. Option A can ensure that alternative integrity
assessment methods are valid by being in accordance with national codes of practice. Option B
can ensure that vendor-supplied procedures have met rigorous third-party evaluation and
certification. However, for these Options to be most successful, UST owners will need to be
informed to use only methods that meet code or vendor-supplied procedures that have been
certified. Implementing agencies should make concerted attempts to inform their UST owners
about what they need to look for to make sure they get a reliable integrity assessment.
Acknowledgments
Our March 6 draft guidance package sought input on the general approach, specific
evaluation criteria, costs of evaluations, compliance and enforcement implications, and timing. I
thank the state and EPA representatives who provided comments to our draft, including those
from Arizona, District of Columbia, Michigan, Tennessee, and EPA's Office of General
Counsel. I also thank the many other individuals and organizations that provided comments.
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Disclaimer
EPA's Office of General Counsel advises that the policies set out in this document are not
final agency action, but are intended solely as guidance. They are not intended, nor can they be
relied upon, to create any right, benefit or trust responsibility, enforceable by any party, in
litigation with the United States.
cc:
^ EPA UST/LUST Regional Program Managers' Supervisors
OUST Program Directions Team
OUST Desk Officers .
Betty Arnold, OUST Compendium
Carolyn Esposito, EPA NRMRL, Edison, NJ
Dariiel Sullivan, NRMRL, Edison, NJ
Kathy Nam, EPA OGC
Joan Olmstead, EPA OECA
Larry Magni, American Petroleum Institute
Dennis Rounds, Chair, ASTM Subcommittee E50.01
Susan Canning, ASTM Staff Liaison, Committee E50
Richard Huriaux, DOT Office of Pipeline Safety
Shelley Leavitt Nadel, NACE International
Marc Katz, National Association of Convenience Stores
Chappell Pierce, OSHA Directorate of Safety Standards Programs
Bob Renkes, Petroleum Equipment Institute -
John Huber, Petroleum Marketers Association of America
Mark Morgan, Petroleum Transportation & Storage Association
Roy Littlefield, Service Station Dealers of America
Tom Osborne, Society of Independent Gasoline Marketers of America
John Worlund, Converse Environmental Consultants Southwest
James Bushman, Bushman and Associates
Michael Baach, Corrpro Companies
George Kitchen, International Lubrication and Fuel Consultants
Derick Sharp, National Leak Prevention Association
John Piazza, Southern Cathodic Protection
Bud Mattox, Tanknology-NDE
Warren Rogers, WRA Environmental
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ATTACHMENT!
......
ADDITIONAL ITEMS FOR CONSIDERATION IN
DEVELOPING INTEGRITY ASSESSMENT POLICIES
Agencies that implement underground storage tank programs may find the following items
useful in conjunction with EPA's guidance in constructing their integrity assessment policies:
* Requiring certain documentation be submitted by vendors to UST owners or implementing
agencies (or both). An example for human-entry assessments following NLPA 631 is Form
CF-2, "Internal Inspection Affidavit," which must be maintained by the owner, according to
the standard. An example for an alternative assessment would be a certification by the
. vendor that the work meets code or a short form summarizing the evaluation and limitations
of a particular method.
* Requiring that companies, individuals, or both be licensed in order to perform assessments.
* Requiring monthly stand-alone leak detection monitoring following assessment and upgrade.
* Limiting the time between assessment and upgrade (for example, limit the time to six
months),' ,
* Putting mechanisms in place to make the vendor responsible for a tank failure due to
improper assessment. , .
* Reviewing each vendor-supplied procedure before allowing it to be used, even if a vendor
claims the procedure complies with a standard code of practice, to ensure the procedure
meets all requirements of the code and of the agency.
G:\Share\OUST\TechIsue\ImegAss\I_A_Gui 11 .wpd
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