United States
       Environmental Protection
 Office of Solid Waste
and Emergency Response
     (5104 A)
 EPA 550-F-09-004
  September 2009
            Rupture Hazard from Liquid Storage Tanks

The Environmental Protection Agency (EPA) is issuing this Alert as part of its ongoing
effort to protect human health and the environment by preventing chemical  accidents.
We  are striving to learn the causes and  contributing factors associated  with chemical
accidents and to prevent their recurrence.  Major chemical accidents cannot be prevented
solely  through regulatory requirements.  Rather, understanding the  fundamental root
causes, widely disseminating the lessons  learned, and integrating these lessons learned
into safe operations are also required.  EPA publishes Alerts to increase awareness of
possible hazards. It is important that facilities, State Emergency Response Commissions
(SERCs), Local Emergency  Planning Committees (LEPCs), emergency responders, and
others  review this information and  consider whether  additional  action is needed to
address the hazards.

 Over the past few years, there have been
 several catastrophic failures of liquid
fertilizer storage tanks resulting in property
 damage and environmental contamination.
 These ruptures have Involved site-erected
 storage tanks with capacities ranging from
 500,000 to 2 million-gallons. In several of
 the tank failures cited in this alert, the tanks
 were built by either Carolyn Equipment
 Company ofFairfield, Ohio, or Nationwide
 Tanks, Inc. of Hamilton, Ohio. Both of these
 companies have since gone out business
 (Carolyn Equipment in 1990 and
 Nationwide Tanks in 1995.) This alert
 describes some  of the tank failures and
 identifies standards and precautions that
 apply to aboveground liquid storage tanks.
 While all users of aboveground liquid
 storage tanks should take appropriate steps
 to maintain tank integrity, owners of tanks
produced by these two manufacturers are
 advised to take extra precautions to guard
 against tank failure.

           3/1997 in Iowa: A 1-million gallon tank
           containing ammonium phosphate ruptured
           and released its contents. The walls of the
           ruptured tank fell onto two other tanks and
           broke their valves. One tank contained 1-
           million gallons of a nitrogen liquid fertilizer
           and the other tank held ammonium
           thiosulfate. Much of the release was
           contained by an earthen dike, but immediate
           construction of a secondary, temporary dike
           was necessary to keep the release from
           flowing into the nearby Missouri  River.
           Cleanup involved pumping the liquid out of
           the dikes and removing all contaminated

           7/1999 in Michigan:  A 1-million gallon
           tank full of ammonium polyphosphate
           ruptured and damaged three other tanks.
           Fortunately, the tanks were surrounded by
           earthen dikes lined with polyethylene. This
           minimized the environmental damage.
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Rupture Hazard from Liquid Storage Tanks
                        Revised September 2009
1/8/2000 in Ohio: A 1-million gallon tank
of liquid fertilizer ruptured and damaged
four adjacent tanks. The wave of liquid
broke a concrete dike wall and hit five
tractor-trailer rigs, pushing two of the rigs
into the river. A total of 990,000 gallons of
material were released.  More than 800,000
gallons of the liquid spilled into the Ohio
River. Sampling detected amounts of the
fertilizer mixture 100 miles downstream,
which is expected to increase algae growth
in the river. The  company has discontinued
use of seven other tanks purchased from the
same manufacturer.

3/8/2000 in Ohio: At the same facility, a 1.5
million gallon tank of ammonium phosphate
ruptured and damaged three nearby tanks
causing them to leak. Two of the damaged
tanks held phosphoric acid and the third one
held 'Ice-Melt', a magnesium chloride
mixture. The released liquid overflowed the
dike walls into nearby creeks. The four tanks
were dismantled after the incident. Over 1.8
million gallons of contaminant were
recovered, with an additional 450,000
gallons of contaminated water recovered
from the sewer system.  The release caused
evacuation of a nearby school, and the
public was forced to use bottled water
because of concern that the drinking water
supply may be contaminated by the spilled

11/12/2008 in Virginia: A 2-million gallon
tank of urea ammonium nitrate fertilizer
ruptured, seriously injuring two workers.
The released liquid fertilizer overtopped the
secondary containment  berm surrounding
the  tank, partially flooded an adjacent
residential neighborhood, and contaminated
the  southern branch of the Elizabeth River.
Nearby residents were ordered to evacuate
for  several days.

Hazard Awareness

Defective Welds
In the incidents cited, all of the above-
ground liquid storage tanks that failed
appeared to have had defective welds.
Several of the tanks were produced by either
Carolyn Equipment Company or Nationwide
Tanks Incorporated. Both companies have
since gone out of business. These tanks were
under warranty for only one year, and the
welding of the tanks was done by
subcontractors hired by the two companies.
The companies built tanks  in Michigan,
Ohio, Indiana, Illinois, Missouri, and Iowa
between 1980 and 1995. Because of
increased frequency in tank failures, the
Ohio Fire Division is creating a voluntary
registry of liquid storage tanks to help track
and prevent similar failures.

Chemicals Involved

The failed tanks have held  liquid fertilizers,
such as ammonium phosphate, which are not
considered hazardous and are not regulated
by the U.S. Environmental Protection
Agency. However, the failure of these tanks
can damage nearby tanks containing
hazardous substances and cause releases. In
some cases, accidents have involved tanks
containing hazardous materials like
anhydrous ammonia and phosphoric acid,
which are used to produce the fertilizer
ammonium phosphate.

Increased Hazard During First Fill

According to American Petroleum Institute
(API) Standard 653, "Tank Inspection,
Repair, Alteration, and Reconstruction,"
tanks are more likely to fail when being
filled to the maximum level for the first
time. Additionally, hydrostatic testing places
greater than usual stresses on a tank shell,
and therefore presents another potential
failure scenario. Facilities  should be aware
of the additional hazard associated with
initial fill and hydrostatic testing, and
develop procedures or policies to prevent or
mitigate failures that may occur at these
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Rupture Hazard from Liquid Storage Tanks
                        Revised September 2009
Hazard Identification

Facilities should evaluate their storage tanks
for potential catastrophic failure. Some of
the factors to consider include:

   Manufacturer's record for quality

   Evidence of weakened or defective

   Signs of corrosion around the base and
    direct contact with ground and exposed
    to moisture.

   Exposure to high winds or frequent

   Age of the tank.

   Close proximity to other storage tanks
    containing hazardous chemicals.


The failure of liquid storage tanks can stem
from inadequate tank design, construction,
inspection, and maintenance. Hazard
reduction and prevention starts with good
design and construction. The risk to tanks
already in service can be reduced through
tank maintenance and weld inspection. To
minimize effects from possible tank failures,
there should be a secondary containment
such as a dike or a berm surrounding the

Tank Design and Construction

The Fertilizer Institute (TFI) has published
uniform industry inspection and
maintenance guidelines  for aboveground
liquid fertilizer storage tanks. According to
the TFI guidelines, liquid fertilizer storage
tanks should be designed and constructed
according to API Standard 650, "Welded
Steel Tanks for Oil Storage," and
inspections of existing tanks should be based
on API-653, but with modifications for the
unique characteristics of tanks storing liquid
fertilizer. API-650 specifies an allowance
for corrosion and for the specific gravity of
the fertilizer liquid.

In each of the tank failures mentioned,
welding has been the main cause of failure.
To ensure durability and integrity, it is
imperative that the tank is welded correctly.
Several standards and specifications outline
the proper techniques and procedures for
welding, including API-653.

Operational Hazards and Maintenance

Tank buyers should insist on seeing the
tank's inspection record. Although tanks
should undergo a rigorous inspection by a
recognized  inspection authority before a
manufacturer's job is complete, the tanks
should still  be closely inspected by the buyer
prior to purchasing the unit. For liquid
storage tanks, the most important item to
look for is complete  penetration and
complete fusion of the welds joining shell

Once a tank has been purchased, it becomes
the tank owner's duty to regularly inspect
the tank. Inspection intervals may be set by
using a risk-based inspection theory, as
indicated by API-653.

Various inspection methods can be used for
those tanks already in service.  Radiography
is the technique applied to all tanks designed
to API-650 to ensure that complete
penetration and fusion of welded joints has
occurred. Unfortunately, this procedure
cannot detect poor mechanical properties in
the welded  regions. This and other standards
cover what types of joints must be checked
by a radiograph, as well as the number of
tests that must be done.

Additional inspections may be done visually
or by several other methods. A vacuum box
can identify localized problems. The
vacuum box, approximately 6 inches by  30
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Rupture Hazard from Liquid Storage Tanks
                     Revised September 2009
inches, is tightly sealed to the tank surface,
and pressure is applied. Automated
ultrasonic testing can be applied to all shell
welds to examine for cracks, fusion,
penetration, and porosity with greater
resolution than radiography. It is also now
possible to  conduct floor scanning while the
tank is full. Combined with chemical
analysis and hardness testing, field
replication  can assess the toughness, or
resistance to brittle failure of a weldment.

If damage is found during an inspection, this
needs to be assessed in accordance with the
methodology described in API Std 579-
1/ASME FFS-1 "Fitness for Service." Any
tanks that do not meet the acceptance
requirements set by API Std 579-1/ASME
FFS-1 should be repaired or replaced.

Steps for Safety

Here are some additional ways to prevent
rupture  of liquid storage tanks:

    Realize the inherent risk of using and
    maintaining any storage tanks.

    Ensure that employees are aware of the
    hazards associated with the failure of a
    liquid storage tank.

    Avoid overfilling tanks.

    Perform regular inspections of tanks. Be
    sure to  look for all possible risks.

    Follow up on problems identified during
    inspections by  conducting repairs or, if
    necessary, replacing the tank.

    Replace, repair, or modify any and all
    tanks not meeting the standards set forth
    in API-Std 579-1/ASME FFS-1

    Be on the alert for new tank regulations,
    standards, or recommended practices.

    Locate  storage tanks and design and
    construct their  secondary containment
systems so as to separate the contents of
a leaking or collapsing tank from the
rest of the facility and to prevent any
leakage from going offsite.

Develop an emergency plan that
addresses a catastrophic tank failure.

Identify the manufacturers of the tanks
on the property, being careful to identify
any tanks built by either company
mentioned in this alert. NOTE: If tanks
were manufactured by Carolyn
Equipment Company or Nationwide
Tanks of Hamilton, take the following
actions immediately:

  - A close external inspection should
    be made for leaks, corrosion, or any
    anomalies in the surface of the tank.
    Vent(s) should be checked for any
    blockages by foreign materials, such
    as snow or ice. The majority of the
    failures have occurred during the
    winter months, when steel becomes
    more brittle and when vents can
    become blocked by snow and ice. If
    liquid is drawn out of the tank when
    vents are  plugged or restricted, a
    vacuum may be  pulled on the tank
    causing it to  collapse inward.

  - If you find evidence of leakage or
    corrosion during the inspection, the
    tank should be taken out of service
    and if possible, drained.

  - If there is no evidence of leakage  or
    corrosion, arrange for an external
    evaluation by a qualified inspection

  - Depending on the results of the
    evaluation, arrange for an internal
    inspection immediately or within  the
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Rupture Hazard from Liquid Storage Tanks
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 Information Resources

 References with information about the
 hazards of catastrophic storage tank failures
 and methods of minimizing them are listed
 below. Regulations potentially applicable to
 storage tanks and codes and standards that
 may be relevant are also included. A
 Chemical Safety Alert on catastrophic fires
 and explosions in storage tanks is available

 Statutes and Regulations

    Clean Air Act Section 112(r)(l) -
    General Duty
    EPA's Risk Management Program  Rule
    [40 CFR 68]
    OSHA Process Safety Management
    Standard [29 CFR 1910.119]
    EPA Spill  Prevention, Control and
    Countermeasure Plan regulations [40
    CFR 112]

 Investigation Reports and Safety Videos

 The U.S. Chemical Safety and Hazard
 Investigation Board (CSB) is an independent
federal agency charged with investigating
 industrial chemical accidents.  The  CSB
 conducts root cause investigations of
 chemical accidents affixed industrial
facilities, publishes investigation reports,
produces safety videos, and makes
 recommendations to plants, regulatory
 agencies, industry organizations, and labor

 Investigation Report: Allied Terminals, Inc.
 - Catastrophic Tank Collapse, Report No.

 U.S. Chemical Safety and Hazard
 Investigation Board
 2175 K Street, NW, Suite 650
 Washington, DC 20037-1809
 Phone: 202-261-7600
 Web site: http://www.csb.gov
Codes and Standards

The Fertilizer Institute (TFI) has published
guidelines for inspection and maintenance
ofaboveground liquid fertilizer storage

Aboveground Storage Tanks of Liquid
Fertilizer: Recommended Inspection

The Fertilizer Institute
820 First Street, N.E., Suite 430
Washington, DC 20002

The American Petroleum Institute (API) has
tank standards and guidelines on safe
API Standard 579-1/ASME FFS-1 - Fitness
for Service

API Standard 620 - Design and
Construction of Large, Welded, Low-
Pressure Storage  Tanks

API Standard 650 - Welded Steel Tanks for
Oil Storage

API Standard 653 - Tank Inspection,
Repair, Alteration, and Reconstruction

American Petroleum Institute
Washington DC 20005
Phone: 202-682-8000
Web site: http://www.api.org

The American Society of Mechanical
Engineers (ASME) has the Pressure Vessel
Code and other codes relevant to tanks and
storage vessels:

American Society of Mechanical Engineers
1828 LStNW, Suite 906
Washington DC 20036
Phone: 800-843-2863
or 202-785-3756
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Rupture Hazard from Liquid Storage Tanks
                      Revised September 2009
Codes and standards: 212-705-8500
Accreditation and certification programs:
Web site: http://www.asme.org

The American Society of Nondestructive
Testing (ANT) certifies welding and non-
destructive examination (NDE) and non-
destructive testing (NDT) inspectors:

American Society of Nondestructive Testing
P.O. Box 28518
1711 Arlingate Lane
Columbus, OH 43228
Phone: 800-222-2768
Web site: http://www.asnt.org
The American Welding Society (A WS)
certifies welding inspectors with the
designation AWS QC-1 (Quality Control)
Welding Inspector and has guidelines on
safe welding.

American Welding Society
550 NW LeJeune Road
Miami, FL 33126
Phone: 800-443-9353
or 305-443-9353
Web site: http://www.amweld.org
                         For More Information:

     Call the Superfund, TRI, EPCRA, Risk Management Program,
                        and Oil Information Center
                       800-424-9346 or 703-412-9810
                    TDD 800-553-7672 or 703-412-3323

                       Visit the OEM Home Page at:
   Notice: The statements in this document are intended solely as guidance.
   This document does not substitute for or change any applicable statutory
   provisions or regulations, nor is it a regulation itself. The guidance it provides
   may not be appropriate for every situation.
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