WATER POLLUTION CONTROL RESEARCH SERIES 11024 FLY 06/71
Heat Shrinkable Tubing
as
Sewer Pipe Joints
ENVIRONMENTAL PROTECTION AGENCY • WATER QUALITY OFFICE
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the results and progress
in the control and abatement of pollution of our Nation's waters. They provide
a central source of information on the research, development and demonstration
activities of the Water Quality Office of the Environmental Protection Agency,
through in-house research and grants and contracts with the Federal, State
and local agencies, research institutions, and industrial organizations.
Previously issued reports on the Storm and Combined Sewer Pollution Control
Program:
11023 FDB 09/70
11024 FKJ 10/70
11023 12/70
11023 BZF 06/70
11020 FAQ 03/71
11022 EFF 12/70
11022 EFF 01/71
11022 DPP 10/70
11024 EQG 03/71
11020 FAL 03/71
11024 DOC 07/71
11024 DOC 08/71
11024 DOC 09/71
11024 DOC 10/71
11040 GKK 06/70
11024 DQU 10/70
11024 EQE 06/71
11024 EJC 10/70
11024 EJC 01/71
11024 FJE 04/71
11024 FJE 07/71
11023 FDD 07/71
Chemical Treatment of Combined Sewer Overflows
In-Sewer Fixed Screening of Combined Sewer Overflows
Urban Storm Runoff and Combined Sewer Overflow Pollution
Ultrasonic Filtration of Combined Sewer Overflows
Dispatching System for Control of Combined Sewer Losses
Prevention and Correction of Excessive Infiltration and
Inflow into Sewer Systems - A Manual of Practice
Control of Infiltration and Inflow into Sewer Systems
Combined Sewer Temporary Underwater Storage Facility
Storm Water Problems and Control in Sanitary Sewers -
Oakland and Berkeley, California
Evaluation of Storm Standby Tanks - Columbus, Ohio
Storm Water Management Model, Volume 1 - Final Report
Storm Water Management Model, Volume II - Verification
and Testing
Storm Water Management Model, Volume III -
User's Manual
Storm Water Management Model, Volume IV - Program Listing
Environmental Impact of Highway Deicing
Urban Runoff Characteristics
Impregnation of Concrete Pipe
Selected Urban Storm Water Runoff Abstracts, First Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, Second Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, Third Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, July 1971 -
June 1971
Demonstration of Rotary Screening for Combined Sewer
Overflows
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HEAT SHRINKABLE TUBING
AS SEWER PIPE JOINTS
by
The Western Company
of North America
2201 North Waterview Parkway
Richardson, Texas 75080
for the
WATER QUALITY OFFICE
ENVIRONMENTAL PROTECTION AGENCY
Project No. 1102^ FLY
Contract No. 14-12-854
June 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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EPA Review Notice
This report has been reviewed by the Water Quality
Office, EPA, and approved for publication. Approval
does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or
recommendation for use.
11
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ABSTRACT
Preliminary testing had indicated that commercial sewer pipe might be
coupled in tight waterproof joints using the heat shrinkable plastic
tubing (HST) developed and used extensively in the electronics and
aerospace industries. Laboratory studies of such materials and joints
were conducted to determine their characteristics and their operational
and economic feasibility. A wide variety of HST materials and joints
were tested in addition to conventional joints for clay, concrete and
asbestos-cement pipes.
The results of both small scale tests and full scale tests using com-
mercial 8 inch sewer pipe indicated that a polyolefin with a polymeric
base hot melt adhesive produced the most durable, watertight joints
and were significantly superior in performance compared to existing pipe
joining mechanisms. In addition, the cost analysis indicated that HST
joints are economically feasible and compare favorably to conventional
joints when considering both material and installation costs. The HST
joint requires no significant departure from current installation practice
and is equally adaptable to repair of installed commercial pipe and
joints. Field development and in-use demonstration of the HST system
is recommended.
This report is submitted in fulfillment of Contract 14-1Z-854 between the
Environmental Protection Agency and The Western Company of North
America.
iii
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CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 5
IV Objectives 9
V Current Practice and Materials H
VI Small Scale Laboratory Testing 17
VII Full Scale Testing
VIII Cost Effectiveness 61
VIX Pipe Repair 65
X System Application 67
XI Acknowledgments 73
XII References 75
XIII Glossary 77
XIV Appendices 79
v
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FIGURES
_Page_
1 Heat Shrinkable Tubing Recovered Over Bell and
Spigot Pipe 6
2 Heat Shrinkable Tubing Boot Used to Connect
House Laterals 8
3 Billion Dynomometer, Tensile Test Apparatus 18
4 Budd Press, Shear Test Apparatus 18
5 Internal Pressure Test Apparatus 19
6 Thermal (Hoop) Pressure Test Apparatus 2/0
7 Small Scale Internal Pressure Test Results 24
8 Small Scale Shear Test Results 25
9 Small Scale Tensile Test Results 26
10 Small Scale Thermal (Hoop) Pressure Test Results 27
11 Clay Bell and Spigot Joint Chemical Resistance
Test Results 29
12 Concrete Bell and Spigot Joint Chemical Resistance
Test Results 30
13 Asbestos-Cement Joint Chemical Resistance Test
Results 3J
14 Clay Compression Coupling Chemical Resistance
Test Results 32
15 FEP Teflon HST Chemical Resistance Test Results 33
16 Polyolefin HST Chemical Resistance Test Results 34
17 Polyvinyl Chloride Chemical Resistance Test Results 35
18 TPS 1000 Polyethylene with Adhesive Chemical
Resistance Test Results 37
19 WRS Polyethylene with Adhesive Chemical Resis-
tance Test Results 38
20 Butyl Adhesive Tape Chemical Resistance Test
Results 39
vi
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Fage
21 Full Scale Test Apparatus 44
22 Full Scale Tensile Test Results 49
23 Full Scale Shear Test Results 50
24 Full Scale Internal Pressure Test Results 51
25 Full Scale Deflected Internal Pressure Test
Results 52
26 CC150 Hot Melt Adhesive Chemical Resistance
Test Results 54
27 Placing the Heat Shrinkable Tubing Joint Around
the Plain-End Pipe Joint 55
28 Heating the HST Joint With Gas Torch 55
29 Completed HST Sewer Pipe Joint 56
30 FEP Teflon Joint With Asphaltic Base Adhesive
During Shear Test 57
31 HST Joint and Concrete Pipe Alter Shear Test 58
32 HST Joint on Clay Pipe After Shear Test 59
33 Special Polyolefin HST Joint Test 59
34 Cross Section of HST Joint 68
35 Assembling HST Joint in the Trench 70
36 Proposed Equipment for Assembling HST Joints
Above Ground 71
vii
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TABLES
Page
1 Chemical Resistance Test I 22
2 Chemical Resistance Test II 28
3 Currant Direct Pipe Manufacturing Cost 63
4 HST Joint Material Cost 63
viii
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SECTION I
CONCLUSIONS
1. The coupling of commercial sewer pipe, both butt-end and bell and
spigot, with watertight joints using heat shrinkable plastic tubing is
feasible and economically practical. Used in conjunction with a hot
melt adhesive it can surpass in physical and chemical strength any of
the conventional joints presently being used with clay, concrete, and
asbestos-cement nonpressure sewer pipe.
2. Existing test standards for conventional pipe and joints do not provide
a means for uniform comparison between types and are not directly re-
lated to in-use needs. These standards are based on the capabilities of
the materials used.
3. Of the conventional materials tested, the asbestos-cement pipe and
joints tended to perform the best in tests exceeding standard limits.
While the existing clay compression coupling joint was most similar in
configuration to the HST joint concept evaluated, the cost of the com-
pression coupling was the greatest of all joints tested.
4. Of the materials tested, an irradiated polyolefin and polymeric base
hot melt adhesive, such as TPS 10750 tubing by Raychem Corp. and
CC 150 adhesive manufactured by H. B. Stuck Adhesives, Inc. , were
the two components best suited for sewer joint use.
5. The cost to a contractor for HST joint materials, including the ad-
hesive, is estimated at approximately $1.75 per joint for an 8 inch
diameter pipe, provided demand justifies sufficiently large volume
production of HST. The cost will vary with the size of the pipe.
6. Installation costs for sewer pipe construction are primarily dependent
on the size of the pipe and not the type of joint. Available statistics
indicate that labor costs account for about 24. 0 percent of the total
sewer investment cost. These costs are associated with width and
depth of trench, ground conditions and weight to be handled.
7. Some reductions in sewer installation costs can be anticipated using
HST joints. These are all related to elimination of the bell through
reduced breakage in handling, elimination of the need for undercutting
the trench bottom, backfill tamping under the pipe, etc. Opportunities
for improvements in sewer line placing methods (and cost reductions) may
exist, based on the strength of the HST joints.
8. The only added installation cost associated with the use of HST joints
is a heat source. The cost of providing this equipment will vary depend-
ing on the sophistication employed. However, a simple, but adequate,
hand operated device could cost as little as $50.
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9. The HST joints can be installed using unskilled, or semi-skilled
labor. There need not be any significant departure from current
installation practice.
10. Available statistics indicate that the cost of joint materials
account for about 23. 3 percent of the total sewer investment cost.
The statistics do not directly identify these costs on a per joint or
unit length basis.
11. The key element in the economic evaluation of HST joints is the
cost of providing the bell and joint materials for conventional joint
systems. A definite determination of these costs (and the cost
reductions possible through elimination of the bell and materials)
cannot be made at this time due to the proprietary nature of such infor-
mation.
12. The direct manufacturing costs for 8 inch clay and concrete pipe
can be estimated at $3. 35 and $2. 91 respectively using quoted sales
prices and industry operating statistics. The added costs, improved
joint characteristics and reductions in repair and maintenance costs
associated with the use of HST joints must be compared with poten-
tial reductions in existing manufacturing costs (and resulting sales
prices) available through the elimination of the bell and joint materials
in conventional systems.
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SECTION II
RECOMMENDATIONS
The polyolefin heat-shrinkable tubing should be spotted with a heat
sensitive paint to insure that enough heat reaches all surface areas of
the joint. A heat sensitive paint, which changes colors at a prescribed
temperature would aid both the installer and the inspector of the sewer
line in determining that all of the joint was heated sufficiently.
The tubing should be sized as close to the outer diameter of the pipe as
convenient placement will allow to reduce shrink time and product cost.
The hot melt adhesive should be applied to the inside of the HST
material by the manufacturer to ease installation and storage.
One end of each section of plain-end pipe should have a bumper mater-
ial permanently attached to it to reduce chipping and cracking of the
sewer pipe during and after installation.
The heat source should be gas, either from a torch or a catalytic heating
device to eliminate the need for electricity in the trench. The heating
device should encompass the heat shrinkable tubing joint in order to
shorten shrink time and maintain a uniform shrinkage of the HST
material.
Field installation of test sewer lines with the recommended HST joints
should be initiated at as early a date as possible to permit observation
of the joints under full use and aging, compare performance with in-
stalled conventional joints and verify installation procedures. Such a
demonstration should be conducted over a period of at least two years.
Uniform test standards for sewer pipe should be developed. These
standards should be based on in-use needs and requirements and not
the capability of materials used. Such standards would provide incen-
tive and a basis for development and use of improved materials and
systems.
Development of new concepts in sewer construction techniques promising
improvements in cost and quality of work should be pursued. Develop-
ment of such concepts, based on the strength of HST joints, should be
initiated once the performance of HST joints is verified in field use.
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SECTION III
INTRODUCTION
Purpose and Scope
The purpose of this program was to determine the feasibility and in-
stallation requirements for using heat shrinkable plastic tubing (HST)
as a sewer pipe joint mechanism. This was accomplished through a
systematic laboratory analysis of materials and procedures applied to
three types of sanitary sewer pipe on the market today. The bases of
comparison were the conventional sewer pipe joints now in use.
It was not the purpose of this program to develop or recommend new
test procedures for sewer pipe joints, evaluate existing pipe materials,
or demonstrate definitive installation practices for the HST system.
Background
For several thousand years sewage has been transported in some form of
collection system. From the Roman period to the early 1900's the pri-
mary objective was to get the sewage of communities out of sight and out
of the way. Today, with the population of the United States growing at
a rate of 100, 000 people per month, it is no longer possible to rid our
cities of their sewage by simple diversion to the outskirts of the more
populated areas. All sewage must be disposed of and returned to the
environment in a form acceptable to all plant and animal life. The
standards of disposal are continually becoming more stringent.
One of the most significant problems with sewage collection systems in
cities today is the exfiltration of sewage and infiltration of water through
deteriorated or leaking lines. Infiltration of rain water into a sewer
system after a heavy rain costs local taxpayers thousands of dollars each
year as a result of excessive demand placed on the system. Environ-
mental degradation results from overflows in the line and at the treatment
plant. 1> 2>3 J4"5 More tangible costs result from the added investment in
capacity of lines and plants to treat this overburden. In turn, the ex-
filtration from a sewer line in dry weather deposits raw sewage beneath
communities or permits uncontrolled drainage without treatment.
The joint between each section of sewer pipe can be identified as a
primary source of exfiltration and infiltration in a sewer system. 2>3>4>5
The conventional joint system also presents several inherent difficulties
to sewer contractors and pipe shippers. It is subject to:
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Breakage of the bell In shipment,
installation.
storage, and
Higher costs resulting from the bulkiness of the
bell in shipment and storage.
Time lost in undercutting the trench to receive
the bell.
Bell breakage resulting from the backfilling oper-
ation and in later soil shifting.
After considering these facts, it becomes evident that a sewer line
without the bell might eliminate many of the problems and costs
facing the sewer industry, provided a watertight joint can be made.
It was proposed that a sewer line composed of plain-end (without bells)
sewer pipe could be laid and heat shrinkable plastic tubing (HST) posi-
tioned at the joints. Heat would then be applied to the tubing, and the
HST would shrink in diameter around the pipes forming a tight water-
proof joint. An added feature of the proposed system would be that an
existing supply of bell and spigot pipe could also be used while re-
taining the benefit of a waterproof seal. By using a heat shrinkable
sleeve over a conventional bell and spigot joint, the plastic will shrink
tightly around the bell and spigot to form a strong leakproof joint as
shown in Figure 1.
Figure 1. Heat Shrinkable Tubing Recovered Over Bell and Spigot Pipe
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The joining capacity of the HST could not be limited only to straight
lengths of pipe, but had to be adaptable to wyes, tees, skew joints,
etc. In addition, one of the operating problems faced by pipe installa-
tion crews is the connection of house laterals or tie-ins where no
adapter has been placed in an existing line. By using an HST boot or
adhesive wrap, these connections might be efficiently secured and
sealed. Figure 2 depicts this latter situation.
The most common types of sewer pipe in use today are clay, concrete,
composition (asbestos-cement), plastic, and cast iron. It was the
intent of this program to unite the strength of these pipes with the
waterproof sealing capabilities of heat shrinkable tubing. The program
concentrated on applications with clay, concrete, and asbestos-cement
pipes as these represent the majority of below ground sewer installa-
tions.
Program Description and Approach
Due to the large number of heat shrinkable materials currently on the
market, it was necessary to structure the initial portion of the program
as an identification and screening process. As part of this first phase,
a review of the literature on heat shrinkable materials was conducted to
identify a complete list of candidate materials, their manufacturers,
product characteristics, existing applications and use practices. Per-
formance measures and a test scheme to develop those measures for
each material were developed.
All potential materials as well as the components of conventional sewer
pipe joints were exposed to a series of chemical resistance tests. The
heat shrinkable materials were subjected to tests for physical properties
and strength as joints on controlled specimens of small diameter (1 inch
I. D. ) pipe. The materials which performed best under these screening
tests were selected for full scale tests on commercial sewer pipe.
The second phase of the program consisted of tests for physical proper-
ties and strength of three HST materials as joints on 8 inch diameter
commercial sewer pipe of clay, concrete and asbestos-cement. The same
tests were also performed for the conventional joints currently used with
each of the pipe types so that direct comparisons could be made.
The second phase also included an investigation of the cost of HST
materials, conventional sewer pipe joints and sewer construction to
identify the economic feasibility of the proposed joint concept.
During the final portion of the program an evaluation was made of the
potential of the HST joint for installed sewer pipe and joint repair. In
addition, systems and methods for installation of HST joints were identi-
fied and evaluated based on the test experience and current practice.
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HOUSE LATERAL
00
HST BOOT
8" SEWER MAIN
Figure 2. Heat Shrinkable Tubing Boot Used to Connect House Laterals
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SECTION IV
OBJECTIVES
A group of six specific objectives was defined for the program. From
these objectives a plan of operation was developed which guided the
conduct of the investigation and evaluation. The emphasis of the ob-
jectives is on the comparison of the heat shrinkable joint concept with
existing systems rather than establishing absolute measures of evalua-
tion.
1. Determine the feasibility of the heat shrinkable joint concept by
. identifying potential HST materials and potential limitations on
their suitability relative to -
cost
special chemical and physical characteristics
manufacture of special size and shapes
formulation changes for special properties
delivery capability
. defining the characteristics of the proposed application -
soil loads
sewage composition
current standard joint tests and requirements
pipe properties
installation methods
. conducting laboratory evaluations of the identified HST
materials to rank and screen the candidates relative to -
physical properties and strength
chemical properties and resistance
. conducting laboratory evaluation of conventional joint
materials for chemical properties and resistance for
comparison with the HST materials
2. Select the four most promising HST materials resulting from the
feasibility study for further test, evaluation and comparison with
conventional joints.
3. Determine the extent of improvement in joint performance using
the four candidate HST materials as compared to conventional
joints by:
conducting tests for physical properties and strength of the
HST joints on commercial 8 inch sewer pipe.
. conducting tests for physical properties and strength of
conventional joints on commercial 8 inch sewer pipe.
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4. Determine the cost effectiveness of HST joints by comparing
material and installation costs with relevant costs using
conventional joints.
5. Define the applicability of HST joints to use in repair of
installed sewer lines.
6. Recommend the best HST materials, application methods and
associated equipment for further testing and demonstration
based on optimum joint performance and ease of installation.
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SECTION V
CURRENT PRACTICE AND MATERIALS
Heat Shrinkable Tubing
Heat shrinkable tubing begins as ordinary plastic or rubber compounds
which are then extruded into sections of tubing. The irratiated types of
HST are bombarded with high energy electrons to link the molecules
providing a high temperature burn point for the material. Non-irratiated
tubing does not exhibit resistance to high temperature. The tubing is
then heated and stretched in diameter, but not in length. After it cools,
it retains the expanded diameter. As a result of this process, when the
HST is reheated, it will recover in diameter only.
If a length of 8 inch diameter tubing is expanded to 16 inches, it will
conform to any shape between the 8 inch and 16 inch diameters, when
reheated. This characteristic gives the HST the ability to form a tight
fit around both the bell and the barrel of the sewer pipe as shown in
Figure 1. At the present time, HST is primarily used for covering elec-
trical components and roll covers. The materials offer flexibility, tem-
perature resistance, and chemical resistance, all of which are necessary
for applications in a sewer system.
The tubing can also be provided with an inner liner of hot melt adhesive.
At normal temperatures these adhesives are smooth, non-tacky and re-
semble a plastic coating on the tube. As the tube is heated for shrinking,
the adhesive changes in character, becomes tacky, and adheres to sur-
faces with which it comes in contact. After cooling, the adhesive
solidifies once again forming a tight bond with the contact materials.
An optimum system of this sort requires that the adhesive suitable for
proper bonding with the contained material have a melt point consistent
with the recovery temperature of the HST used.
There are a host of materials classified as "heat shrinkable" manufac-
tured by a wide range of organizations. The materials are offered in
a variety of characteristics and sizes. However, due to their applica-
tions to date, the majority of tube products are available in small
diameter (less than 3 inches). Appendix I represents the most pertinent
results of a review of literature, manufacturers and information relating
to heat shrinkable materials and tubing. This review coupled with inter-
views with manufacturers and suppliers formed the basis for selecting
candidate materials.
Heat Source
The proper heat source is important in reducing shrink time and providing
even shrinkage of the material. The temperature at which the heat shrink-
able tubing will begin to recover varies for different types of HST from
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150°F to 650°F. In addition, there is an upper limit of temperature
above which each material will burn. Considering these variations,
four heating devices were considered during the program.
A hot air gun6 was used during the first part of the small scale labora-
tory testing. The main body of the heat gun consists of a small air
blower and heating coils. It is powered by electricity and develops
heat up to 1000°F. The heat gun delivers hot air at 8. 82 cubic feet per
minute at a velocity of 1400 feet per minute. It requires 115 volts AC
and 20 amps of electricity. The hot air gun is adequate for recovering
tubing up to 2 inch expanded diameter.
An iodine quartz lamp7 emits infrared heat up to 750°F. It requires 115
volts and 2. 1 amps of electricity. The manufacturer stipulates approxi-
mate bulb life at 2, 000 hours. The iodine quartz lamp was not used
during this program, but representatives were consulted on its abilities
and limitations. The lamp easily recovered HST up to 2 inch expanded
diameter. In order to recover an 8 inch piece of HST, however, several
lamps would be needed to maintain shrink time at two or three minutes.
Both the hot air blower and the iodine quartz lamp require electricity.
In sewer pipe joint applications this would require a generator at the
installation site and electricity down in the trench. The equipment
necessary to link several of these heating devices together to encompass
the joint would be bulky and hard to handle. Additional costs would arise
from repair of air blowers and electric generators. After making these
observations, gas heaters appeared better suited to the HST sewer pipe
joint concept.
Using a hand held propane torch,8 8 inch HST joints can be recovered in
less than three minutes. With a torch pressure of 4. 0 psi the torch
will deliver a yellow-orange flame 20 inch in length. The approximate
heat output would be 83M btu/hr, at a propane consumption rate of
5. 1 Ibs/hr. By removing the torch head and attaching a hinged collar
with rows of small gas jets circling the inner diameter, an even heat
could encompass an HST joint. No electricity would be needed in the
trench and there would be no moving parts to repair.
Catalytic heaters9 offered another source of heat derived from propane or
butane gas. A catalytically active metal screen converts the gas to infra-
red energy and in turn supplies heat to recover the joint. The screen
encompasses the joint material to provide uniform shrinkage of the HST.
Like the gas torch, it requires no electricity and has no moving parts.
Sewer Pipe Joints
Pipe connections used by the sewer industry today include mortar, asphal-
tic base materials, lead, rubber gaskets, "O" rings, bands, clamps, and
numerous other combinations and variations used in conjunction with a
12
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bell and spigot or tongue and groove coupling mechanism. All of these
joints are designed to provide two things, a leak proof seal and flex-
ibility. With any type of bell and spigot or tongue and groove joint,
shifting soil or improper trench preparation can cause unnecessary
stress on the pipe or a deflection of the sewer pipe past a maximum for
which its joint is designed resulting in a leak at the joint. The problem
of flexibility is further restricted by pipe alignment, which must be
maintained to prevent obstructions in the sewer line and provide full
capacity of the pipe installed.
In general, the manufacturers of various types of sewer pipe (clay, con-
crete, cast iron, etc. ) have each developed, and provide as part of the
pipe, a complete joint mechanism, or recommend materials and proce-
dures to be used in fabricating a joint.
Sewer Pipe Installation
The installation of sewer pipe is often considered to be a simple task.
This opinion probably stems from the assumption that anyone can dig a
ditch. Physically digging a ditch is not all that is involved in making
a good excavation. The width of the trench must be determined by the
type of soil, depth of laying, type and size of pipe and excavating
equipment, and the space required to allow workmen to backfill thor-
oughly around and under the pipe. Consideration must be given to safe
operation, water fill up, proper backfill and supports. Several types of
trenches can be prepared for pipe installation:
1. flat bottom trenches, where backfill is tamped
or not tamped
2. trenches having blocks to support the pipe and
the backfill is tamped or not tamped
3. trenches having bottoms shaped to fit the bottom
of the pipe
Due to the presence of the bell on the majority of sewer pipe, the latter
two types of installations are generally required. When supports are
used, it is necessary to backfill and tamp beneath the pipe. Without
this, the backfill overburden will create undesirable stress on the pipe
and the bell due to the void left beneath the pipe. This condition leads
to pipe cracks, cracked and broken bells and leaks. When supports are
not used and bottom shaping to fit the bell is not accomplished, the same
conditions can also develop.
Handling the pipe above ground and placing it in the trench are important
considerations. Permitting the bell or spigot to strike objects or other
pipe contributes to cracking and chipping, seriously affecting the
quality of resulting joints.
13
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Finally, improper backfilling and compaction can break the pipe or joint
once in the ground or deflect or dislocate it exceeding the joints' flexi-
bility and destroying its seal.
It is evident that installation practice is critical to joint performance.
The practice must match the needs of the materials. The best designed
joint is useless if total installation is not accomplished properly.
Joint Requirements
To satisfy a broad range of performance requirements, the pipe industry
utilizes a number of different joints. Pipe joints can perform a variety
of functions depending upon the type of pipe and its application. The
selection of a proper joint may be determined by the performance required
of it. Joints can be designed to provide:12
1. Resistance to infiltration of ground water and/or
backfill material.
2. Resistance to exfiltration of sewage.
3. Control of leakage from internal or external heads.
4. Flexibility to accommodate lateral deflection or
longitudinal movement without creating leakage
problems.
5. Resistance to shear stresses between adjacent
pipe sections without creating leakage problems.
6. Hydraulic continuity and a smooth flow line.
7. Controlled infiltration of ground water for subsurface
drainage.
8. Ease of installation.
The primary source of definitive standards of performance for sewer pipe
joints are those set forth by the American Society for Testing and
Materials (ASTM) specifications. Specifications are given by types of
pipe material and joint mechanism and for sizes of pipe of each type.
During this program, clay, concrete and asbestos-cement pipes were
used in testing. The following ASTM specifications were found to be
relevant to the test program:
ASTM C425 66T Compression Joints for Vitrified Clay
Bell and Spigot Pipe
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ASTM C443 70 Joints for Circular Concrete Sewer and
Culvert Pipe, Using Rubber Gaskets
ASTM C428 69a Asbestos-Cement Nonpressure Sewer
Pipe
ASTM C584 66T Compression Couplings for Vitrified
Clay Plain-End Pipe
Pertinent extracts from these specifications are given in Appendix II.
Various sewer design and construction manuals were also reviewed, 10>n>12
however, the ASTM's were found to be the most pertinent and formed
the basis for the tests conducted during the program.
ASTM specifications have been particularly useful over the years in
helping to standardize industrial processes and products. By establish-
ing a basic level of performance for a product, they benefit manufacturers
as well as users. The standards are, in general, based on the capabil-
ities of a material or design as sponsored by a technical committee and
accepted by the Society.
It should be noted that there are some shortcomings or inconsistencies
in all specifications for sewer pipe joints. The most significant of
these is that all sources of these specifications permit some level of
leakage for new installation. Design manuals refer to leakage as "de-
sign infiltration" (or exfiltration), or "permissive infiltration" (or ex-
filtration). All assume some leakage as acceptable presumably under
potential operating conditions. It would be expected that such built-in
leakage would only increase with aging. In addition, the ASTM's specify
different standards for the different pipe materials. For example, one
type of pipe joint must withstand a hydrostatic pressure of 10 psi for
10 minutes while another must withstand only 4. 3 psi for 60 minutes to
meet specifications. As a result, the two pipe joints cannot be readily
compared as to performance for use in a given installation. Both,
however, are being used interchangeably on the job for the most part.
While these specifications are adequate for establishing base line manu-
facturing standards, they do not present a uniform standard relative to
on-the-job performance. It is recommended that attempts be made to
establish uniform standards based on the requirements and needs of the
job.
Loading and Forces
Sewer pipe is installed in relatively narrow trenches and covered with
earth backfill to the original ground surface. Load on the pipe develops
as the backfill settles and is equal to the weight of the material above
the top of the pipe minus the shearing or frictional forces on the side of
the trench. If the size of the pipe, width of the trench, and depth of
the trench are known, one can easily determine soil loads from prepared
15
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charts developed by the pipe industry.
While soil loads are important to pipe manufacturers in the design of
pipe to withstand high external loads, they were not considered of great
importance in the HST pipe joint evaluation. (In this respect soil load
was considered distinct from shear forces, which result from soil shift-
ing). Since the concept involved joining ends of pipe, the HST would be
supported by the pipe structure which in turn supports the overburden
and external hydrostatic pressure.
The shear forces which act upon a sewer system are critical to pipe
joints. If the soil beneath a pipe settles, support is provided only by
the joints on both ends or to the next supported pipe section. The
overburden must be supported by the joint strength or extreme deflection
and failure can occur.
During periods of infiltration or other peak loads, hydrostatic heads
develop. The ASTM specifications recognize each of these conditions
as well us the combined effect. Internal hydrostatic forces produce
longitudinal tensile forces within the pipe. This condition has negligible
effect when considering a pipe buried in the ground, but is quite impor-
tant when considering a test stand evaluation. Due to the forces present,
the pipe will attempt to separate at its weakest point in tension (the
joint) and must be constrained.
Sewage Composition
Sewage composition can vary widely between different geographic areas.
In order to produce a synthetic or manufactured sewage for laboratory
experimentation, several Environmental Protection Agency s> 13) 14»15 publi-
cations and ASTM specifications (Appendix B) were consulted. The com-
ponents of presently accepted synthetic sewage were the basis for the
chemical resistance tests conducted in this program.
16
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SECTION VI
SMALL SCALE LABORATORY TESTING
Test Procedures
The small scale laboratory testing conducted as Phase I of the program
was essentially a screening process for a large group of HST materials.
The test procedures used for the screening were established after con-
sidering available information relating to such factors as soil loads,
sewage composition, installation procedures, and joint requirements.
Material Preparation
All test specimens of HST had an expanded diameter of 1. 25 inch to
2 inches and a recovered diameter of 1 inch. Upon receiving a sample
of HST from the manufacturer, several preliminary steps were followed.
1. The HST was cleaned of any dirt or oil collected
during shipping.
2. The HST was cataloged and cut in 3 inch pieces.
3. The manufacturer1 s data sheet was consulted for
the recommended application procedures.
4. Specimens were recovered with hot air and with
a gas torch to determine the best heat source for
each material.
5. Each type of HST was checked for flammability.
Upon completion of these preliminaries, the HST was ready for the small
scale laboratory tests. There were two groups of tests. The physical
property tests revealed the mechanical strength of the HST materials,
while the chemical resistance tests showed any vulnerability to chemi-
cals or bacterias.
Pipe Preparation
For the sake of reproducibility in testing and adaption to test apparatus,
porcelain coated cold rolled steel pipe was used as simulated sewer
pipe for the screening tests. Each pipe was 8 inches long and 1. 20 inch
in outside diameter. This simulated sewer pipe had several advantages
over other various substitutes for sewer pipe in this size. A controlled
bonding surface was available. The threaded end made it adaptable to
test apparatus. It could withstand higher pressures than the HST joints.
It was reusable.
17
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Tensile Test
The objective of the tensile test was to determine the force necessary
to longitudinally separate the joined pipe. A Dillion Dynamometer was
used to measure the force necessary to part the joint. For the tensile
test, the Joint was formed with HST and pipe caps were placed on the
threaded end of each pipe. The joint was then placed into the Dynamo-
meter by attaching the pipe ends to the two opposing heads. Force was
applied until the joint separated. The highest reading in pounds was
taken and converted into psi using the formula:
psi = P £ (3. 14 x D x L)
A tensile test is not incorporated in the ASTM's since pipes in the
ground are butted together and constrained from longitudinal movement.
The test was included in the program to evaluate the relative grip strength
of recovered HST. Consideration was also given to the potential for dif-
ferential movement between sewer lines and house laterals.
Figure 3. Dillion Dynamometer
Tensile Test Apparatus
Figure 4. Budd Press. Shear Test
Apparatus
18
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Shear Test
The shear test was conducted to record the amount of pressure necessary
to separate the joint with forces applied perpendicular to the joint, such
as with differential settlement. A Budd Press was used in this test by
mounting holding blocks on the two opposing heads. Each holding block
was 10 in. x 4 1/2 in. x 3 1/4 in. with a hole slightly larger than the
outer diameter of the test pipe. One holding block was mounted on the
stationary head of the press and the second block was mounted to the
moveable head of the press, with the holes in alignment. The HST pipe
joint was inserted through the aligned holes and the press closed to
apply shear loads perpendicular to the joint axis. When the joint se-
parated, a failure was noted and the pressure in pounds recorded. To
determine what shear load the 1 inch HST joint had to withstand to model
full scale joint action, calculations were made based on the basic
Stress = Load/Area formula. These calculations are detailed in Appendix
C.
Internal Pressure Test
For the small scale internal pressure test, a bladder accumulator was
used to maintain a constant pressure over a wide range of values. The
test specimen, line, and one side of the accumulator were filled with
water. The opposite side of the accumulator was connected to an air
compressor. Air forced into the accumulator applied pressure to the
sealed water system on the opposite side. Any leakage of the joint was
noted as a failure and the pressure recorded.
Figure 5. Internal Pressure Test Apparatus
19
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Thermal (Hoop) Pressure Test
This test was designed to determine the amount of hoop pressure exerted
by the HST as it shrinks around the outer surface of the pipe. The hoop
pressure and rigidness of the HST would be necessary to maintain pipe
alignment. In conducting this test, a stainless steel pipe 17 inches
long and 11/4 inch outside diameter was used. The pipe was cut down
both sides from the ends to the middle leaving a 1/4 inch pivot point in
the center. A dial indicator was mounted on one end and calibrated to
pounds of pressure applied to the opposite end. The test procedure
consisted of placing the HST on the end of the stainless steel pipe and
shrinking it. An initial reading was taken immediately after recovery
and a secondary reading was taken after the HST cooled. By using the
formula psi = P , (2 x T x L), the reading in pounds was converted to
psi applied by the HST.
Figure 6. Thermal (Hoop) Pressure Test Apparatus
20
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Chemical Resistance Tests
Although an HST material may have had the right physical characteristics
for a sewer joint, it would still be of little use if it could not withstand
the chemicals which pass through it on a daily basis. Based on a review
of actual industrial, city, and recommended synthetic sewage each of the
HST materials was subjected to the tests shown in Table 1 for 1000 hours.
Specimen preparation for the chemical resistance tests began by cutting
each piece into half inch widths. Each one was then heated to its re-
covered diameter and weighed on a triple beam balance. The size of
each specimen was measured by a vernier caliper. After all data was
logged, the specimens were placed in a separate glass vial and half
submerged with a chemical solution. The glass vials were in turn placed
in ovens set at various temperatures. The bacteria, fungus, and enzyme
cultures were predeveloped and each specimen was suspended, half
submerged, in the broths.
Materials Tested
Whenever possible, two name brands of each type of material were ac-
quired for testing. It was felt that different manufacturing procedures
and compounds could produce variations in physical and chemical
properties. Appendix D lists all materials tested during the program by
generic name, trade name and manufacturer.
Physical Properties
Results of the Physical Properties Tests are presented in Figures 7-10.
It was found during the preliminary testing and literature search that some
heat shrinkable tubing, as supplied by the manufacturer, was unsuit-
able for use. Both of the neoprene HST tested were canceled after the
preliminary tests. Extreme care had to be used to keep this material from
getting too hot during shrinkage or the outer surface would bubble and
burn. They would not recover to their original diameters and large gaps
formed between the HST and the pipe. Neoprene is a very good insula-
tor for electricity and this material is largely used for wire coverings.
For this application, it is heated in an oven over a prolonged period of
time and satisfactory covering is obtainable. For a pipe joint, however,
this procedure is not practical and testing was discontinued.
As with the neoprenes, similar problems arose with the TFE Teflons.
Both of the TFE Teflons exhibited curling of the ends, uneven shrinkage,
and large gaps between the HST and pipe. Since a leak proof seal was
not possible, testing was discontinued.
21
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Chemical
HCL Acid
H20 (Tap)
H2S
Alconox (Soap)
Hydrogen Peroxide
Sodium Hypochloride
Sodium Hydroxide
Calcium Hydroxide
Gasoline & Naptha
Motor O il
Isopropyl Alcohol
Methyl Alcohol
Uric Acid
Urea compounds
Bacteria
Enzymes
Fungus
Mixture
99.75 parts water
.25 acid
99.75 parts water
.25 acid
100%
Saturated
99.00 parts water
1.00 soap
99.00 parts water
1.00 oxidizer
99.00 parts water
1.00 chlorene
99.00 parts water
1.00 alkali
99.00 parts water
1.00 alkali
50% each
100%
100%
100%
1.00
.50
98. 50 parts water
Each separate
with water
Temperature
125°F
125°F
125°F
125°F
125°F
125°F
125°F
125°F
125°F
Room Temperature
125°F
Room Temperature
Room Temperature
125°F
100°F
Table 1. Chemical Resistance Tests I
22
-------
Since most HST is used to cover electrical wiring and components, it
was not always possible to find two manufacturers of an HST material
over 1 inch diameter. This was the case with polyvinyl chloride (PVC)
HST. Several companies manufacture PVC HST, but not up to 1 inch
recovered diameter. After testing the only PVC material received which
would fit the test apparatus, it could not be determined if this material
could be made to work on 8 inch diameter pipe. The thermal pressure
test yielded low values, which showed that a tight fit was not developed.
The PVC also failed the internal pressure tests because of the small
recovery ratio, although it did recover uniformly.
The two polyolefin HST materials passed all tests except for the internal
pressure tests. This material had a very short recovery time (less than
15 seconds on 1 inch diameter) and would not burn when heated with a
propane torch. It is very inexpensive and easily available in sizes up
to 60 inch diameter. After applying an adhesive to the inside of the
polyolefin, it withstood a maximum internal pressure of 60 psi for two
hours with no leakage.
Only one silicon rubber HST was tested. It passed all of the physical
property tests and had very good flexibility.
Overall, the FEP Teflons were the best type of HST tested. They had the
highest thermal pressure and internal pressure test results (without adhe-
sives). They passed the other two physical property tests, were easy to
handle, and recovered very quickly.
Viton also appeared easily adaptable to sewer pipe joints. It was more
flexible than the teflon, and maintained almost equal test results. It
recovered easily and resisted moderate flame.
The Kynar HST material presented some of the problems previously en-
countered with the neoprenes and TFE Teflons, uneven shrinkage with
gaps between the pipe and tubing, curling of the ends, plus splitting
when excessive heat was applied. It was very difficult to get enough
joints to test, due to the splitting of the kynar where it was cut. It
passed all tests with the exception of the internal pressure tests. After
evaluating this material, it was felt to be unsuitable for pipe joints due
to brittleness, gaps and air pockets formed on the pipe, and difficulties
of application.
Chemical Resistance
After completing the chemical resistance tests (Table 1) and evaluating
the results, some discrepancies were noted. Materials such as teflon
and polyolefin which should have had no change in size or weight,
showed as much as a 25% change in some chemicals. It was determined
that the error inherent in the triple beam balance used was large compared
23
-------
PSI
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Figure 7. Small Scale Internal Pressure Test Results
24
-------
Lbs.
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Figure 8. Small Scale Shear Test Results.
25
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PSI
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Figxire 9. Small Scale Tensile Test Results
26
-------
CD
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Figure 10. Small Scale Thermal (Hoop) Pressure Test Results
21
-------
to the specimen weight. Possible changes in specimen weight were
lost in measurement error. A second chemical resistance test series,
as described by Table 2, was conducted on the materials which showed
the most promise from the physical property tests.
Chemical
Isopropyl Alcohol
Hydrochloric Acid
Calcium Hydroxide
Sulfuric Acid
Gasoline
Sodium Hypochloride
Mixture
100%
99. 75 parts water
. 25 acid
99. 86 parts water
20 oxidizer
99. 75 parts water
25 acid
100%
99. 00 parts water
1. 00 bleach
Temperature
Room Temperature
125°F
125°F
125°F
Room Temperature
125°F
Table 2. Chemical Resistance Tests II
Four samples of FEP teflon, polyolefin, and polyvinyl chloride were ex-
posed to each chemical. The specimens were cut into three inch lengths
and three of the four were heated in an oven to produce complete re-
covery. The fourth specimen was left in its expanded form to check for
changes due to improper shrinkage. The specimens were then weighed
on a torsion beam balance to the nearest . 001 gram. In lieu of measur-
ing the size with the vernier calipers, a water displacement procedure
was used. A 25 ml graduate was filled to the 15 ml point and the speci-
mens were then placed inside. The new water line was recorded with
the difference being the amount of volume of the material. This would
indicate absorption of the solution or loss of material to solution during
the tests. Upon removal from the chemical tests, a close visual exami-
nation of the specimens revealed any cracks or changes in flexibility.
Specimens of the gasket material presently being used in commercial pipe
joints were also tested using this procedure. Each was weighed and
sized in the same manner as the HST. Both the HST specimens and the
commercial gasket materials were subjected to the chemical tests for
1000 hours each. The results of the second Chemical Resistance Tests
are presented in Figures 11 - 17.
28
-------
-S
fO
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w
50
40
30
20
10
0
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-20
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Weight o
Sizo
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TJ
Figure 11. Clay Boll and Spigot Joint Chemical Resistance
Tost Results
-------
c
O
o
.-1
%
50
40
30
20
10
-10
-20
-30
o
A
.Weight £
Size
a
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rochloric Acid
oxide
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Figure 1Z. Concrete Bell and Spigot Joint Chemical Resistance
Test Results
30
-------
(C
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50
40
30
20
10
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.Weight
Size
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Figure 13. Asbestos-Cement Joint Chemical Resistance Test Results
31
-------
CO
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.Weight
Size
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Figure 14. Clay Compression Coupling Chemical Resistance Test
Results
32
-------
50
40
30
20
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r? 10
10
w
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Figure 16. Polyolefin HST Chemical Resistance Test Results
34
-------
(0
O
50
40
30
20
10
w
en
O
-10
-20
-30
.Weight %
Size
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Figure 17. Polyvinyl Chloride Chemical Resistance Test Results
35
-------
The gasket material used with clay bell and spigot pipe turned the iso-
propyl alcohol yellow, while the specimen exposed to the sodium
hypochlori.de was covered with small hairline cracks. The concrete bell
and spigot gasket material also developed cracks from exposure to the
sodium hypochloride, but turned the isopropyl alcohol red as did the
asbestos-cement gasket material. The latter showed no other signs of
wear.
The clay pipe compression coupling showed the largest degree of change
after the chemical resistance tests. The specimen in isopropyl alcohol
gained 15/16 inch in length. The gasoline specimen gained 7/8 inch in
length. The specimen placed in the sodium hypochloride turned the
solution a cloudy gray and displayed signs of dissolving in the bleach.
The submerged half of the specimen was sticky and easily scraped away.
The HST materials generally performed well in the chemical resistance
tests with the exception of hydrocarbon solutions. Of these, two exhi-
bited a weight loss. The FEP Teflons displayed excellent chemical
resistance.
Adhesives
Recognizing the sealing and bonding improvements an adhesive might
impart to the HST joint, tests of three available adhesives were con-
ducted during Phase I testing. Two of these were found to be available
on polyethylene tubing.
The first polyethylene HST had a petroleum base adhesive which remained
soft and sticky after cooling and separated from the contact surface
under relatively low pressure. It was also easily dissolved by hydro-
carbon solution.
The second type consisted of an irradiated polyethylene HST with a non-
irradiated polyethylene liner. With heat applied, the tube shrinks and
the inner liner melts to form a snug watertight seal. The chemical
resistance tests, however, indicated that this adhesive would be un-
satisfactory for use in a sewage system.
The third adhesive tested was a butyl adhesive tape sealant. A strip of
the tape was wrapped around the end of each pipe at the joint and the
HST recovered around it. The physical properties tests indicated it would
form a strong waterproof joint, however, the tape was highly soluble in
gasoline and oil. The results of the chemical tests for these materials
are as shown in Figures 18 - 20.
36
-------
w
w
50
40
30
20
10
0
10
-50
Weight
Size
o
s-,
a
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en
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J-H
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in
fO
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&
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2
O
CO
Figure 18. IPS 1000 Polyethylene with Adhesive Chemical Resistance
Test Results
37
-------
(0
O
w
w
O
50
40 .
30
20
10
0
-10 .
-20 .
-30 .
Weight
Size
opropyl Alcohol
w
i— i
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3 s 3
< X <
o 2 o
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2 ffi 3
° S rn
2 §
t 'G
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E (0
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Gasoline .
^-^
tn Hydrochloride
3
•pH
T3
o
CO
Figure 19. WRS Polyethylene with Adhesive Chemical Resistance
Test Results
38
-------
(0
O
50 .
40 .
30
20
"
10
0
-10 .
-20 .
-30 .
D ^
/ — """" S
/ °
/ L
V
E
D
CD ®
• — I Tl Jli TJ r-"
j=j "5* '" "o* 3
Weight 8 ^ 8 n §
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, JH o
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lium Hydrochlori
CO
Figure 20. Butyl Adhesive Tape Chemicals Resistance Test Results
39
-------
As a result of these tests, the search for additional adhesives was con-
tinued in an attempt to identify more suitable products.
Materials Selection
At the completion of Phase I testing had been conducted on twelve types
of HST. Forty-one manufacturers and distributors had been consulted on
the possibilities of using various types of HST in a sewer system, and
an extensive literature search had been conducted to develop as much
information as possible about the technology of heat shrinkable tubing.
Visits were made to the manufacturers of clay, concrete and asbestos-
cement pipe to develop their interest in the program, and to gather
additional information on adapting HST materials to use in a sewer system.
The Phase I activities were designed primarily to evaluate the use of HST
materials as a sewer pipe joint. At the end of this phase, it was con-
cluded that the use of HST as a material and method for joining sewer
pipe was a reasonable and practical approach to eliminating infiltration
of groundwater and exfiltration of sewage through a joint source. The
HST products which responded to heat quickly, recovered uniformly, and
had immunity to chemical and bacterial attack were considered as
candidates for the full scale tests of Phase II.
After comparing the test results of HST with and without adhesives, it
appeared that the addition of heat activated adhesive would add consi-
derable strength to the joint. The adhesive would fill any flow channels
created on the rough porous surface of the sewer pipe and still retain the
flexibility of the HST.
The HST materials considered for Phase II were polyolefin, FEP teflon,
polyvinyl chloride (PVC), silicon rubber, and viton. The FEP teflons
were chosen for their high thermal pressure test results and resistance
to chemical attack. This material is very expensive, but if it could be
manufactured on a large scale, indications were the price would drop
sharply. It responded very quickly to hot air and gas torch heating
devices, and had a high degree of flexibility.
The polyolefin heat shrinkable tubing also responded quickly to various
heat sources and was highly resistant to scorching and burning. This
feature makes it easy for a man under pressure of time to slap these
joints together. It has a high degree of chemical resistance and resists
cutting and punctures after shrinkage. After consulting the manufacturer,
it was found that this material in the 8 inch recovered size could be
marketed at less than $2. 00 per foot on a large volume basiu. Consider-
ing the test results, economics, and ease of application, this material
was chosen for Phase II.
40
-------
The physical property test results on the polyvinyl chloride HST were
not very impressive. After debating the test results of Phase I, it was
decided that a smaller recovered diameter would have given a tighter
fit on the simulated sewer pipe. The pipes were 1. 2 inch in diameter
and the manufacturer listed the recovered diameter of the HST at 1 inch.
If the recovered diameter of the HST had been smaller (3/4 in. ) a tighter
seal would have been obtained. Unfortunately, a smaller recovered
diameter is available only in a smaller expanded diameter which would
not fit the pipe. These diameter discrepancies could be corrected by
the manufacturer for economic order sizes. The PVC tubing did recover
uniformly and have the chemical resistance necessary. It was felt that
it would work in Phase II particularly if used with an adhesive.
The fourth HST material considered for Phase II was silicon rubber. It
had a good chemical resistance to all chemicals except for high con-
centrations of hydrocarbons, such as gasoline and alcohol. Since there
are often strong solvents in industrial sewage, this material was not
carried into Phase II. In addition, an 8 inch recovered diameter tubing
is not manufactured at this time, which would have further complicated
testing arrangements.
The viton HST had the highest shear resistance of any HST material with-
out an adhesive. It withstood 460 Ibs. shear load, 15 psi internal
pressure, and had a hoop pressure of 62 psi. The chemical resistance
test results were a very low percentage (less than 9%), and the material
recovered easily under moderate heat. The cost of this material was the
only weak point. After consulting the manufacturer, it was found that
the cost of this material could not be lowered to within a price range
that would make it practical for large scale sewer installation. Raw
polyolefin compounds used to make HST cost the manufacturer approxi-
mately $. 25 per pound. The raw viton compounds cost the manufacturer
approximately $ 11. 00 per pound. This would make the viton 44 times
more expensive before extrusion and other manufacturing costs.
41
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SECTION VII
FULL SCALE TESTING
T'est Procedures
All of the joints, both commercial and HST, were made using 8 inch
diameter commercial sewer pipe. The three types of pipe used were
clay, concrete, and asbestos-cement. A reference in this report to a
"concrete joint" will be to a joint assembled using commercial concrete
pipes and the bell and spigot joint assembly supplied with it. A
reference to a "concrete HST joint" will be to a joint using plain-end
sections of concrete pipe and heat shrinkable tubing. This terminology
will also apply to the clay and composition (asbestos-cement) pipe as
well.
The full scale laboratory physical property tests involved testing each
type of commercial joint under the ASTM procedures for that specific
joint, and then increasing the loads and pressures on the joint until
leakage occurred. An additional test for tensile strength of the joint,
for which there is no ASTM specification, was also conducted. Upon
completion of the commercial joint tests, a second series of tests was
conducted on HST joints following the same procedures as used on the
commercial joints.
Since the change in size from 1 inch to 8 inch diameter would not change
the chemical resistance or thermal (hoop) pressure of the HST material,
these tests were not incorporated into Phase II full scale testing. Four
different physical strength tests were conducted. Tensile, shear, inter-
nal pressure, and deflected internal pressure tests were used.
Test Facilities
The test stand for 8 inch sewer pipe was designed to allow all testing
to be conducted with one piece of multi-purpose equipment. Provisions
for the internal pressure tests, deflected internal pressure tests, shear
tests, and tensile tests were incorporated in the stand which is depicted
in Figure 21. The pipes could be mounted horizontally for the internal
pressure test. One end of the joint could be elevated upon completion
of the internal pressure test for the deflected internal pressure test. The
frame-work supporting one pipe could be lowered and a hydraulic jack
mounted above the pipe to conduct the shear test. One of the pipes could
be mounted on rollers and connected to the tensile-pull apparatus for the
tensile test. This equipment was used for all full scale testing.
43
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1. Tension Apparatus
2. Plain-End Pipe
3. HST Joint
4. Hydraulic Shear Jack
5. Expandable Packer
6. Water Pressure Gauge
7. 0-15 psi Regulator
8. Retractable Pipe Support
Figure 21. Full Scale Test Apparatus
-------
Internal and Deflected Internal Pressure Tests
In conducting the internal pressure and deflected internal pressure tests,
the Joint was assembled and pipe plugs were placed in the open ends of
the pipe. The pipes were then chained together to prevent their separa-
tion by hydrostatic pressure, and filled with water. Following the speci-
fications in the ASTM for each particular Joint, the internal pressure was
maintained for the prescribed length of time. Upon completion of this
test the pressure was increased at the rate of 1 psi per minute until the
joint leaked or the pressure reached a maximum of 15 psi. The psi
maximum resulted from the amount of pressure the pipe plugs could
withstand without leaking. If the Joint failed the internal pressure test,
a new Joint assembly was used to conduct the deflected internal pressure
test. Three specimens of each Joint were subjected to each test using
this procedure.
Shear Test
The only requirements for a shear test were incorporated into the clay
plain-end and clay bell and spigot pipe ASTM. Inspection of the ASTM
for concrete rubber gasket Joints and asbestos-cement Joints revealed
that there is no shear test for these two types of joints. In order to
maintain uniformity in testing, shear tests were conducted on these
joints following the ASTM requirements for "Compression Joints for
Vitrified Clay Bell and Spigot Pipe", C425-66T.
Tensile Test
The tensile test was included in the program because of various connec-
tions in a sewer line which might tend to drop or separate, such as
house-laterals and elbows. In establishing a procedure for the tensile
test, the test apparatus was modified to allow one pipe to rest on rollers
to reduce the friction produced by the pipe weight opposing the applied
tensile force. The other pipe was mounted stationary on the pipe rack
and tension was applied until the joint separated. At the point of sepa-
ration, the highest reading on the dynamometer was noted. Application
of tensile force was continued until that necessary to pull the pipe along
the rollers was determined. To determine the actual tensile force neces-
sary to separate the joint, the force needed to pull the pipe was sub-
tracted from the amount of force used to separate the pipe joint. The
tensile test was limited to 900 pounds due to the strength of the sewer
pipes. When the test apparatus was attached to the pipe tight enough to
surpass 900 pounds of tension the pipe would crack or break in com-
pression.
45
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Heat Source
Q
A propane torch, Raychem Model FH-2606, was used to heat all of the
HST joints during the full-scale testing. The torch flame was a soft
yellow-orange and could be adjusted to varying temperatures.
Materials Tested
During the full scale laboratory testing, tests were conducted on clay
bell and spigot pipe with a rubber gasket, concrete bell and spigot pipe
with a rubber "O" ring, asbestos-cement pipe with rubber gaskets, and
plain-end clay pipe with compression couplings. The HST joints were
tested in conjunction with sections of clay, concrete, and asbestos-
cement plain-end pipe. All testing was accomplished under uniform
conditions following the procedures previously outlined. A complete
listing of all materials used in the testing is included in Appendix D.
To directly compare the performance of HST joints and conventional
joints on 8 inch commercial pipe, the test results shown in Figures 22 -
25 are grouped for all joints tested by type of test. Actual test results
for each joint are tabulated in Appendix E.
Conventional Joint Test
Of the three types of commercial joints tested, the asbestos-cement per-
formed the best. It was tested according to the procedures and require-
ments as outlined in ASTM, C427-69a, "Asbestos-Cement Nonpressure
Sewer Pipe". Three joints were subjected to each test. Since the joint
and the pipe are separate pieces, only the collar was replaced if the
joint leaked. None of the asbestos-cement joints failed the physical
property tests. Test results for this joint are given in Appendix E, Table
1.
It was noted that the lubricant used to join the pipes could easily pick
up dirt and debris during installation, which might cause joint leakage.
Also, the asbestos-cement pipe barrels did not sweat or seep water from
the hydrostatic pressure as did the clay and concrete pipe.
The clay bell and spigot pipe joints were tested following the specifica-
tions of ASTM C425-66T, "Compression Joints for Vitrified Clay Bell and
Spigot Pipe. " Heavy sweating was noticed on the pipe barrels while
under pressure. The specifications require a hydrostatic pressure of
4. 3 psi for one hour. All joints passed the ASTM requirements. Test
results for this joint are given in Appendix E, Table 2.
46
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The concrete pipe with rubber gaskets was not as successful as the
other two types of pipe and joints. It was tested following the pro-
cedures outlined in ASTM, C433-70, "Joints for Circular Concrete
Sewer and Culvert Pipe, Using Rubber Gaskets". Two of the three
joints of this type met and surpassed the ASTM requirements. The third
joint leaked during the internal pressure test. The joint was dis-
assembled and checked for cracks or debris in the joint, and reassem-
bled with a new rubber gasket. The deflected internal pressure test
was then conducted on this joint. Leakage occurred at a pressure less
than 10 psi. The joint was disassembled, cleaned, and reassembled
with another new rubber gasket for the shear test. The joint withstood
the internal pressure of 10 psi until the shear load was applied, at
which point it failed again. The concrete pipe also experienced heavy
sweating and pin-head squirts of water sprayed two to three inches out
from the barrel of the pipe. The results of these tests are tabulated in
Appendix E, Table 3.
The ASTM, C584-66T, "Compression Couplings for Vitrified Clay Plain-
End Pipe", stipulates that a coupling shall be fabricated with a stop
ring which serves to properly position the pipe in the coupling and
which acts as a cushion between the mating ends of the pipe". This
stop ring, which prevents chipping and cracking of the ends of the pipe,
was not provided in the couplings purchased for testing. When pur-
chasing this type of joint it should be stipulated that the ring be in-
cluded to insure longevity of the sewer system. Test results are given
in Appendix E, Table 4. The compression coupling joint did not appear
to have as much physical strength or chemical resistance (Figure 14) as
some of the other joints tested, but it did possess a high-degree of
flexibility. The bell-less design of this system would ease installation
and trenching, but the cost of the joint mechanism is high in comparison
to the other types of joints tested.
Heat Shrinkable Tubing Test
To provide a significant incentive for adaption and use within the sewer
industry, it was recognized that the HST joints should surpass the per-
formance requirements of the conventional joint systems. After evalua-
ting the ASTM specifications for joints and the conventional test results
the following requirements were established for testing of the HST joints:
1. Withstand without leakage a hydrostatic pressure of
10 psi for one hour in straight alignment.
2. Withstand without leakage a hydrostatic pressure of
10 psi for one hour when deflected 1/2 inch per foot
of pipe length.
47
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3. Withstand, without leakage, a hydrostatic pressure
of 10 psi for one hour with a shear load of 150 pounds
per inch of nominal diameter applied over an arc of
not less than 120 degrees and along a longitudinal
distance of 12 inches.
4. Have a tensile strength of at least 376 pounds, twice
that developed by the conventional joints.
Heat shrinkable tubing with a recovered diameter of 8 inches or smaller
and an expanded diameter of 11 inches or greater was not readily avail-
able. Discussions with various HST manufacturers stimulated their
interest in the program and resulted in the procurement of 8 inch
recovered polyolefin and FEP teflon HST at nominal charges. As a mar-
ket for 8 inch heat shrinkable polyvinyl chloride tubing had not pre-
viously been established, this material was not available. Rally
Industries of California undertook to supply the 8 inch PVC tubing for
the cost of set up and tooling expenses. Hence, the program was
limited to testing polyolefin, FEP teflon, and polyvinyl chloride (PVC)
HST materials during Phase II.
The initial full scale tests of 8 inch HST joints in conjunction with
plain-end commercial sewer pipes identified some serious problems. It
was found that none of the HST joints gave a shrink fit tight enough to
fill the depressions and minute grooves on the outer surface of the three
types of sewer pipe. Leakage did not occur with the 1 inch diameter
pipe in Phase I due to the smooth surface contact between the HST and
glazed pipe. Flow channels which resulted from indentations and
bumps on the outer surface of the sewer pipe were easily distinguished
when hydrostatic pressure was increased. Experiments were conducted
using "O" rings and various gasket combinations to eliminate the
problems, but these were generally found to be unsuitable solutions.
At the conclusion of small scale testing, the search for a suitable hot
melt adhesive material had been continued. These materials were felt
to offer the greatest adaptability to the HST sealing need. They will
flow when melted to seal the indentations and bumps, and are generally
economical. As a result of the continuing search, several important
characteristics of the adhesive were identified. The two most important
factors involved in a marriage between the HST pipe joint and a hot melt
adhesive are chemical resistance and flow temperature. The flow tem-
perature of a hot melt adhesive is the temperature at which the adhesive
turns from a solid to a semi-liquid. At this point, the adhesive begins to
flow and fill any depressions or cracks. To insure that the adhesive is
completely melted, the flow temperature should be lower than the shrink
temperature of the HST joint. The chemical resistance of the hot melt
adhesive must also exceed the strength of any chemicals that are found
in a sanitary sewer system.
48
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49
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50
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51
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52
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The two above factors combined create a problem. As the flow tempera-
ture of the hot melt adhesive is lowered, so is the chemical resistance.
In attempting to match a low flow temperature and a high degree of
chemical resistance, over 20 adhesive manufacturers were consulted.
Of the adhesives received and tested, most exhibited more than suffi-
cient strength to pass the physical property tests. None of these
materials, however, could withstand strong hydrocarbons such as 100%
concentrations of gasoline and alcohol. As this concentration was
severe and highly unlikely in a sewer system, those adhesives with the
most suitable chemical characteristics were subjected to the physical
property tests.
The hot melt adhesive which displayed the most favorable overall
characteristics with the HST materials in Phase II was the CC150 by
Stuck Adhesives. This was subjected to the physical property tests in
con junction with polyolefin, FEP teflon, and PVC heat shrinkable tubing
on clay, asbestos-cement, and concrete pipe. This adhesive is a
polymeric type with a flow temperature of 350°F. It had a good chemical
resistance to all chemicals except for high concentrations of gasoline
and alcohol as shown in Figure 26. The CC150 has a 6 month storage
life. The cost of the adhesive material for one joint would be less than
$.25.
An investigation was also made into dry, heat activated epoxies. A
heat activated epoxy with the same working characteristics as a hot
melt adhesive would give a better chemical resistance. Several adhesive
manufacturers and distributors were contacted for additional information
on dry epoxies and resins. An epoxy which would react at a temperature
between 200°F and 500°F in approximately three minutes could not be
found.
Preliminary full scale tests were conducted on the HST joints with
adhesives using 12 inch and 8 inch tubing lengths. It was found that
there was no measurable loss of joint strength by reducing the length to
8 inches. As a result, 6 inch lengths were tested, however, uniform
alignment on the pipe was difficult and would hamper ease of installa-
tion in actual use. In addition it was found that the 8 inch length of
HST and adhesive resisted longitudinal movement from hydrostatic
pressures. Chaining or otherwise securing the pipes during testing was
not necessary as with conventional joints.
The series of photographs presented as Figures 27 - 29 demonstrate the
process of assembling the HST joints tested. The joint shown was
formed in an elapsed time of three minutes. A heat source which would
encompass the joint heating uniformly would reduce recovery time to
less than three minutes.
53
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Figure 26. CC150 Hot Melt Adhesive Chemical Resistance Test Results
54
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Figure 27. Placing the Heat Shrinkable Tubing Joint
Around the Plain- End Pipe Joint
Figure 28. Heating the HST Joint With Gas Torch
55
-------
Figure 29. Completed HST Sewer Pipe Joint
The polyolefin HST bonded readily with the CC150. The polyolefin
could withstand sufficient heat to allow the adhesive to completely
melt and flow into the pores of the sewer pipe. This allowed a good
bond to be formed with both the HST and the pipe. Results of the poly-
olefin tests are tabulated in Appendix V, Tables 5-7.
Since FEP teflon is basically a release agent, the hot melt adheslves
would not adhere to it. The only adhesives which would bond with it
were the gummy asphaltic base types. These adhesives were found
unsuited for the application due to their lack of chemical resistance and
low tensile strength. The manufacturer of FEP teflon responded with
specimens of etched FEP teflon which also refused to adhere to the hot
melts. If a suitable heat activated epoxy could be substituted for the
hot melt adhesive, a bond could be obtained with this HST. Figure 30
shows a typical test and indicates that the FEP teflon is acceptable for
joint use provided a suitable adhesive can be made available. Since
adhesives which will bond to the teflon do not exhibit acceptable
chemical resistance, testing was not pursued further and no test
results are presented.
56
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Figure 30. FEP Teflon Joint With Asphaltic Base
Adhesive During Shear Test
As the polyvinyl chloride (PCV) HST was not available in a size appro-
priate for Phase II testing, it had to be specially manufactured for this
program. Due to manufacturing difficulties the material was not
received until the last month of testing. The tubing was formed from
flat sheets which were wrapped and bonded to form a sleeve with the
appropriate recovered diameter and wall thickness.
This tubing required a relatively low level of heat over an excessive
time period (45 minutes) to melt the adhesive without ruining the tubing.
This was felt to be impractical and heat resistance would have to be
improved to make this tubing useable for sewer pipe joints. As a
result of these observations, no tabulated data was obtained. Since heat
shrinkable PVC tubing had not been manufactured in this size before, it
was expected that some changes would have to be made in order to ob-
tain a working product. Unfortunately, these changes could not be com-
pleted within the time constraints of the program.
The heat shrinkable tubing best suited for sewer joints appears to be the
polyolefin. When used with a hot melt adhesive, the polyolefin HST
joint is far superior to conventional pipe joints currently being used by
the industry. The physical property test results presented in Appendix E
and Figures 22-25 indicate the strengths that can be obtained using this
material. The only failures from this system would result from an attack
by strong hydrocarbon solutions on the hot melt adhesive.
57
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Figure 31 shows the result of increasing shear load to 5700 pounds on
plain end concrete pipe with this joint. There was no Joint leakage at
any time during the test. Figure 32 shows similar results obtained
with clay pipe. The pipe broke under a load of 5300 pounds. Prior to
breaking, there was no leakage from the joint. One additional test was
performed on the clay pipe with a polyolefin adhesive joint. This test
is depicted in Figure 33. The total load on the pipe was 995 pounds.
Figure 31. HST Joint and Concrete Pipe After Shear Test
It is recommended that a test sewer line be installed to demonstrate
the actual performance of the polyolefin/hot melt adhesive system over
a significant time period and to verify installation procedures on the
job. This should be accomplished at a location suitable for controlled
monitoring and observations in direct comparison with installed con-
ventional joints.
58
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Figure 32. HST Joint on Clay Pipe After Shear Test
Figure 33. Special Polyolefin HST Joint Test
59
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SECTION VIII
COST EFFECTIVENESS
The purpose of the program described in this report was to determine the
technical feasibility of the HST joint and identify the best joint system.
The emphasis of the program was placed on joint performance and sim-
plicity of installation compared to existing systems. It was not the
purpose of the program to necessarily produce a less expensive joint.
Presumably a better joint, in terms of performance, would have a higher
value and could cost more. Savings would accrue through less degrada-
tion to the environment, lower sewer cleaning and repair costs and
lower system investment costs through infiltration elimination. The
intent of the program was to identify a new system that performed better
and would be economically practical compared to existing systems.
The investigation of sewer joint costs relevant to evaluation of the HST
concept was divided into two catagories, those costs associated with
installation, equipment and procedures, and those costs related directly
to the materials. To develop these costs, contractors, pipe manufac-
turers, municipal authorities, published data and statistics were con-
sulted.
Installation Costs
Analysis of the information developed, revealed that the cost of in-
stallation varies considerably geographically and from job to job. 16 The
variation results primarily from changing labor rates, trench depth re-
quirements and soil conditions. In addition, none of the national data
and statistics found delineated cost per joint or cost per unit length
directly. Although considerable detail was provided, individual cost
items were consistently related to total job cost and not to quantities
utilized. The statistics indicated that construction labor accounts for
about 24. 0 percent of capital investment in sewer lines, while pipe and
joint materials account for 23. 3 percent. Contractors were also extremely
reluctant to disclose detailed information on their operating costs. For
these reasons, it was not possible to adequately quantify the impact of
HST joints on installation costs. Some conclusions pertaining to poten-
tial differences in costs can be made, however.
Trench depth and width (determinants of equipment and labor costs)
should not change appreciably using HST joints. Manpower and placing
equipment required to assemble a joint are determined primarily by pipe
size and not type of joint. Therefore, the major installation costs for
HST should be comparable to conventional systems.
61
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Some savings using HST could be anticipated. Undercutting for the bell,
or tamping backfill under the pipe where blocks are used, could be
eliminated without a bell. In addition, costs due to breakage of the bell
in shipping and handling are currently reflected in the cost of construc-
tion and might be reduced. Repair costs for excavation and replacement
necessitated by bells broken in use from soil shifting and shear loads
must also be considered. It is evident that some reduction in installa-
tion and future operating costs might be anticipated by eliminating the
bell.
The only added equipment cost associated with using HST is a small,
portable heat source, the cost of which is estimated at less than $50.
More sophisticated devices could cost more, however, they might also
offer reduced installation time and, therefore, lower the cost of con-
struction.
Material Costs
To evaluate HST joint material costs, it was necessary to develop the
cost of providing conventional joints, primarily that of the bell and
coupling materials. Manufacturers of each type of pipe were contacted.
Various estimates for the direct manufacturing costs associated with
the bell arrangement ranged from cost unknown, to no cost, to 50 percent
of the cost. All sources were unable to reveal the actual costs involved.
In analyzing the economic impact of HST joints on sewer material costs
8 inch clay and concrete bell and spigot pipes 5 feet in length were
taken as examples in the discussion throughout the remainder of this
section. The clay pipe was assumed to have a rubber gasket joint, the
concrete an "O" ring joint.
A review of business statistics for related manufacturing organizations
revealed that the current direct manufacturing cost for such pipes should
be about $3. 35 for clay and $2.91 for concrete as shown in Table 3. 17> 18
This is based on a price to contractors of $5. 00 and $4. 35 respectively
($ 1. 00 and $. 87 per foot) from recent manufacturers' quotes for truck-
load quantities. That portion of cement pipe manufacturing costs result-
ing from the bell and joint materials could not be determined. However,
it is possible to identify what those costs would have to be for HST
joints to be substituted in the system.
The manufacturers of the polyolefin and polyvinyl chloride HST used in
full scale testing indicated that the price of those materials to a con-
tractor could be less than $ 1. 50 per joint if demand was sufficient to
justify large volume production. The actual volume basis for that price
was not disclosed. Adding to that price the cost of providing adhesive
(estimated at one pound per joint) at a quoted price of $.25 per pound,
the total cost to a contractor for HST joint materials would be about
$1.75 per joint as shown in Table 4.
62
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Clay Pipe1 Concrete Pipe 2
Price to Contractor $5. 00 $4. 35
Manufacturer's Gross
Margin 1. 65 1.44
Direct Manufacturing
Cost $3.35 $2.91
Note:
1. 8 inch diameter x 5 feet with rubber gasket coupling.
2. 8 inch diameter x 5 feet with "O" ring coupling.
3. 33 percent of sales average.
Table 3. Current Direct Pipe Manufacturing Cost
Cost per 8 inch Joint
HST Tubing Cost to Contractor $1.50
Applied Adhesive Cost . 25
HST Joint Materials Cost to
Contractor $1.75
Table 4. HST Joint Material Cost
If there were no final price difference between conventional joints and
HST joints, the direct manufacturing cost would have to be reduced by
about $1.75 per 8 inch pipe through elimination of the bell and existing
joint materials to accommodate the cost of HST and adhesive. Thus a
cost reduction of 52% for clay pipe and 60% for concrete pipe would be
required for equal price substitution. Only the individual pipe manu-
facturers know to what extent such reductions might be achievable.
If the cost of the conventional systems cannot be reduced by eliminating
the bell and joint materials, the total 8 inch joint cost would be in-
creased by $1.75 or about 35 percent for clay pipe and 40 percent for
concrete. With pipe and materials representing 23. 3 percent of sewer
capital cost, the use of HST joints in this case would increase total
investment cost by about 8 to 9 percent. It was concluded that the
actual economics must fall somewhere between the two cases presented.
63
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As an example, if direct pipe manufacturing costs could be reduced by
25% using the HST system, total project cost increases of about 4 to 5
percent would have to be absorbed by the community. This would amount
to about $4, 500 on a $ 100, 000 project. At a cost of capital of 8 percent,
this added investment would cost the community $423 per year ($1. 16
per day) over a 25 year investment life.
Likewise, to maintain economic equality with conventional joints, the
added investment for HST would be expected to produce savings of the
amount identified above ($ 1. 16 per day). Based on the pipe size and
cost used in Table 3 and its relation to total project cost, a $ 100, 000
project could provide approximately 4. 4 miles of conventional 8 inch
sewer line. Assuming an allowable infiltration rate of 100 gallons per
inch diameter per mile per day is experienced as a result of joint leakage,
the total infiltration in the line would amount to 3, 520 gallons per day.
To be economically comparable to conventional joints the HST system
would have to eliminate maintenance and incremental treatment costs
related to that line and infiltration. The total of all costs eliminated
would have to amount to $423 per year ($ 1. 16 per day or $.27 per mile
per day) in this example.
The key element in evaluating the economics of HST joints was felt to
be the savings or credit allowed for elimination of the bell and conven-
tional joint materials. There is some reason to believe that HST joints
can be substituted with little, if any, added investment cost to the
community. A final determination of this fact cannot be made at this
time due to the proprietary nature of the required information. Likewise,
it is not possible to present a definite quantitative determination of
installation costs based solely on laboratory evaluation. From the
information that is available, it was concluded that HST joints are
feasible. The analysis suggests that potential cost differentials will
fall within a range that is economically practical. Joint performance
and installation costs must be finally determined in field use. Manufac-
turers must verify the cost of materials in the market place.
64
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SECTION DC
PIPE REPAIR
As part of this program, an evaluation was conducted to consider methods
for repairing broken or cracked joints using HST. It was felt that when
a decision had been made to replace a badly broken or leaking joint,
repair by an HST sleeve or wrap-around HST collar could simplify the
operation.
In order to replace a conventional bell and spigot pipe, the pipes ad-
jacent to the joint have to be pulled to allow the spigots to slip into
the bells. This procedure results in four disturbed joints instead of
two. By breaking away the cracked pipe and installing a plain-end
pipe with HST joints, the adjacent pipes are not disturbed.
If the joint is leaking, but not broken, a wrap-around heat shrinkable
collar could seal it. The material is received in flat strips of nonirra-
diated polyolefin. They are then wrapped around the pipe and the over-
lapping ends are heated until they fuse together. After the seam is
made, they can be recovered around both the bell and barrel sections
of the pipe. The wrap-around forms of HST are relatively new and their
full potential is not known. Since this is a new product, specimens were
not available for testing before completion of the program.
The labor and equipment involved in replacing a broken pipe or joint
constitutes at least 50% of the repair costs. The cost of repair mater-
ials is minor in comparison.5>16 As a result, sealing a leaking joint
which is not broken or cracked by excavating the line and using HST
materials may not be economically practical. One of the other sealing
methods currently being used by the industry to seal joints internally
might be better suited due to the high costs of uncovering the sewer line.
If excavation is necessary, either the HST sleeve or wrap-around HST
with adhesive would form a tighter and more durable joint than conven-
tional joint systems as indicated by test results in this program.
65
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SECTION X
SYSTEM APPLICATION
In designing an overall system for the installation of an HST joint
sewer line, several considerations must be made. These involve the
HST material to be used, the adhesive to be used and where the ad-
hesive is to be applied, the heat source to be used, and the method
of assembling the joint. As a result of the work accomplished in this
program, a recommendation for each of these components can be made.
A cross section of the recommended joint is shown in Figure 34. It is
recommended that the basic HST joint system identified be demonstrated
in actual field use and installation procedures verified.
HST Material and Adhesive Design
The heat shrinkable tubing acquired for the Phase II tests had an ex-
panded diameter large enough to fit the bell of a sewer pipe and re-
covered small enough to fit the barrels of all three types of sewer pipe
tested. By matching recovered and expanded diameters more closely
to the outer diameter of plain- end pipe, material costs and recovery
time could be reduced.
The addition of heat sensitive paint to the outer surface of the HST
would insure that ample heat is applied to the tubing. Heat sensitive
paint changes color when it reaches a predetermined temperature. This
would make any cool spots stand out and aid both installers and inspec-
tors of the pipe joint.
The adhesive can be on the interior surface of the tubing or placed on the
outside surface of the sewer pipe during manufacture. This would ease
and speed installation of the joints. Using tubing with adhesive pre-
applied to the interior surface is recommended as storage and handling
conditions for the adhesive would be better. In addition, some tubing
is currently manufactured with adhesives and already a part of the manu-
facturing process.
Heat Sources
The recommended heat source is gas, either from a torch or catalytic
heating device. 8> 9 These types of heating devices eliminate the need for
electricity in the pipe trench and loss of heat as with hot air blowers in
high winds. The heat source should be able to encompass the HST joint
to achieve uniform shrinkage, standardized joint quality and a minimum
installation time.
67
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Bumper
Heat Shrinkable Tubing
CO
Hot Melt Adhesive
Figure 34. Cross Section of HST Joint
-------
Sewer Pipe Modifications
Although HST materials perform equally well on bell and spigot or
plain end pipe, it is recommended that plain end pipe be specified
and used. Reductions in total installed cost through elimination of
the bell, closer sizing of unrecovered HST to the pipe and greater
ease of placing the HST may be experienced. As previously mentioned,
the barrel ends of the pipe should not be butted together. This could
result in chipping and cracking of the pipe ends during installation and
from shifting soil loads. A bumper surface of suitable material should
be manufactured on one end of each sewer pipe. When the pipes are
installed there would be one bumper at each joint. Besides cushioning
the ends of the pipe, the bumper would reduce eddies in flow over the
joint.
Installation Procedures for HST Joints
Only minor changes in equipment and procedures presently being used to
install sewer lines would be required to install HST joints. Instead of
recessing the bottom of the trench to receive the bell on commercial pipe,
the pipe ends for the HST joint would have to be temporarily elevated
3 to 4 inches with blocks to allow the heat to reach the lower side of
the joint. After the tubing recovered, the blocks would be pulled out
and the pipes would drop into place. The heat shrinkable tubing re-
quires approximately 5 to 10 minutes to cool at room temperature.
During this time, it is still very soft and flexible and final positioning
of the pipe can be accomplished. See Figure 35.
A proposed system for assembling HST joints above ground was con-
sidered and is depicted in Figure 36. Such a system could cut labor
costs and installation time. The equipment involved in this process
would include a flat bed trailer with the heating device and materials
loaded on it. Two sections of pipe would be positioned on rollers with
the HST around the joint. They would then pass through a heat chamber
and the HST would be recovered around the pipe ends. The rollers would
then carry the joint through a refrigerated water bath to set the hot melt.
After the bath, the joint would be cooled sufficiently to allow the pipes
to be lowered into the trench from the vehicle. The vehicle could move
forward one pipe length at a time providing a continuous operation. By
using this procedure, narrower trenches could be used in some instances
and there would be minimum requirements for men working in the trench.
The characteristics of the HST joints, particularly tensile strength, offer
the opportunity for significant changes and improvements in current sewer
construction practice. These opportunities should be evaluated and
demonstrated. It is recommended that further investigation and develop-
ment of systems such as that described be initiated upon field use
verification of the basic HST joint concept.
69
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Plain-End Sewer Pipe
Installed
HST Joint
Heat
Installation
Blocks
Expanded HST
Joint
Figure 35. Assembling HST Joint in the Trench
-------
.Refrigerated Water
Tanks
Plain-End Pipe
Generator
Gas Jets Inside
Heater Encompass
Joint.
Pipe Joint
Figure 36. Proposed Equipment for Assembling HST Joints Above Ground
-------
SECTION XI
ACKNOWLEDGMENTS
We would like to thank the Water Quality Office of the Environmental
Protection Agency for their assistance during this program. In particular,
we wish to thank Mr. W. A. Rosenkranz, Chief, Storm and Combined
Sewer Pollution Control Branch; Mr. George Putnicki, Director, Office
of Contracts & Grants for Research, Development & Demonstration,
Region VI; and Mr. Robert Killer, Deputy Director, Office of Contracts
&: Grants for Research, Development & Demonstration, Region VI.
We also express our appreciation to the many companies and individuals
who furnished comments and information pertaining to products and prac-
tices related to the program. In particular, we would like to thank E.
I. Dupont De Nemours fc Company, Can-Tex Industries Division of
Harsco Corporation, Raychem Corporation, and Rally Industries for their
assistance and products furnished for the program.
73
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SECTION XII
REFERENCES
1. U. S. Department of the Interior, FWPCA, The Cost of Clean Water,
Vol. II, U. S. Government Printing Office, (Jan. , 1968).
2. U. S. Department of the Interior, FWPCA, The Cost of Clean Water
and its Economic Impact. Vol. 1, 2, 3, U. S. Government Printing
Office, (Jan. , 1969).
3. U. S. Department of the Interior, FWPCA, The Economics of Clean
Water. Vol. 1, U: S. Government Office, March, 1970.
4. Hayes, Seay, Mattern & Mattern, Engineering Investigation of Sewer
Overflow Problem, Water Pollution Control Research Series 11024
DMS, (May, 1970).
5. Western Company of North America, Improved Sealants for Infiltration
Control, Water Pollution Control Research Series, WP, (Aug., 1969).
6. Master Appliance Corp. , Model HG 751 Heat Gun, data sheet, Racine,
Wisconsin, (May, 1970).
7. T. C. Products, Model 1000 F Versalite, data sheet, Mountainview,
California, (June, 1970).
8. Raychem Corporation, FH-2605 Torch, data sheet, Menlo Park, Cali-
fornia, (Jan. , 1969).
9. Raychem Corporation, Model CH-3002A Catalytic Heaters, data sheet,
Menlo Park, California, (Jan. , 1969).
10. Babbitt & Doland, Water Supply Engineering, McGraw-Hill, Inc.,
(1955).
11. American Society of Civil Engineers and WPCF, Design and Construc-
tion of Sanitary and Storm Sewers. WPCF Manual'.No. 9, 1969.
12. H. F. Peckworth, Concrete Pipe Handbook, American Concrete Pipe
Association, (1951).
13. Merrimack College, Proposed Combined Sewer Control by Electrode
Potential. Water Pollution Control Research Series 11024 DOK,
(Feb., 1970).
14. Burgess & Niple Limited, Stream Pollution and Abatement from
Combined Sewer Overflows, Water Pollution Control Research
Series, 11024 FKN, (Nov. , 1969).
75
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15. Avco Economic Systems Corp., Combined Sewer Overflow Abatement,
Water Pollution Control Research, Series 11024, (June, 1970).
16. U. S. Department of Commerce, BDSA, Construction, Distribution of
Water & Waste Water Utilities Capital Expenditures in 1964. U. S.
Government Printing Office, (Dec. , 1966).
17. Dun & Bradstreet, Cost of Doing Business and Key Business Ratios,
(1969).
18. Internal Revenue Service, Statistics of Income, 1968: Corporation
Income Tax Returns, Catalogue 526, U. S. Government Printing
Office, 1970.
76
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SECTION XIII
GLOSSARY
HST - Heat shrinkable tubing.
Recovered Diameter - The inner diameter of the HST after it shrinks.
Recover - In reference to HST, to shrink.
Expanded Diameter The inner diameter of the HST before it is heated
and shrunk.
House Laterals - The sewer line which connects a building to a main
sewer line.
77
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SECTION XIV
APPENDICES
Page No.
A. Heat-Shrinkable Tubing Literature Review .... 76
B. American Society for Testing and Materials
Pertinent Extracts from Specifications Relevant
to Sewer Pipe Joints 80
C. Conversion Formula for Phase I Shear Test .... 86
D. Materials Utilized and Tested 88
E. Full Scale Test Data 91
F. Technical Data Submitted by Rally Industries
Pertaining to the 8 Inch Recovered Polyvinyl
Chloride Heat Shrinkable Tubing Manufactured
by Them for This Program 94
79
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APPENDIX A
HEAT-SHRINKABLE TUBING
LITERATURE REVIEW
81
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HEAT-SHRINKABLE POLYMERS
A Literature Search
Prepared By
Martha Betes
Literature Searcher
U.S. SEARCH NO. 620
May 21, 1970
SOUTHERN METHODIST UNIVERSITY
INDUSTRIAL INFORMATION SERVICES
SCIENCE LIBRARY
A STATE TECHNICAL SERVICES ACT PROGRAM
83
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HEAT-SHRINKABLE POLYMERS
Introduction
A survey of a portion of the technical and marketing literature on heat-
shrinkable plastics and rubber has been completed, as you requested.
Emphasis was placed on tubing, but citations on both film and tubing
were included due to the scarcity of material on the latter. Mechanical
and chemical properties of heat-shrinkable tubing, shapes and sizes
available, manufacturers, and tube-shrinking devices were of interest.
The following sources were used in the course of the search:
Applied Science and Technology Index, 1964 - April, 1970.
Chemical Buyer's Guide, 1970.
A Directory of Information Resources in the United States,
1965.
Directory of Special Libraries and Information Centers,
1968.
Modern Plastics, January - April, 1970.
Modern Plastics Encyclopedia, 1970.
Plastics and Polymers, 1969 - February, 1970.
Plastics Monthly, 1968-1969.
Plastics Technology, 1969 - April, 1970.
Thomas Register, 1969.
In addition, recent issues of Business Periodicals Index, Chemical
Abstracts, Electrical and Electronics Abstracts (Science B),
Engineering Index, Gas Abstracts, Instrument Abstracts, the NASA
report literature, Paper Chemistry Institute Abstracts, Petroleum
Abstracts, and the U.S. Government Research and Development Reports
were scanned. Also various other directories, texts, and encyclo-
pedias were consulted but yielded no pertinent information. Patents
as such were not searched, but relevant ones were noted during the
survey. No single comprehensive listing of manufacturers of heat-
shrinkable tubing and/or films was found, but isolated names were
uncovered. We could have copied all the manufacturers the various
kinds of polymers known to be used in the shrink process, but this
did not seem worthwhile because these same polymers (such as PVC
and polyethylene) are used in so many other ways. However, this
can be done if you wish, and also a patent search can be undertaken
upon your authorization.
The report is divided into four major sections, with the first two sub-
divided into two parts each. The first covers heat-shrinkable tubing,
with Part A noting full-length articles and Part B abstracts and citation.
Section II is comprised of material on heat-shrinkable films such as
those used for packaging and wrapping. Parts A and B correspond to
those of Section I. Section III covers manufacturers, both of equipment
85
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and polymers, while Section IV highlights research centers and special
libraries which you might consult for further information. The citations
in IB and HE are arranged chronologically, most recent first, while
Section III and IV are arranged alphabetically by name of the company
or center. Separate from the search itself is a guide to heat-shrinkable
plastics located in the journal Electronic Engineer, March, 1969.
It is hoped that this report will be of use in your project.
INDUSTRIAL INFORMATION SERVICES
86
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SOUTHERN METHODIST UNIVERSITY
HEAT-SHRINKABLE POLYMERS
ABSTRACTS AND CITATIONS
1. Hauck, Jack E. , "Heat Shrinkable Tubing and Moldings,"
Materials in Design Engineering, (Feb., 1965).
2. Newey, A.B. , '"Elastic Memory" Causes Heat Shrinkable
Plastics to be Effective Protective Coatings, ' Materials
Protection. No. 7, (August, 1968).
3. "Plastic Heat Shrinkable Tubing, " Materials in Design
Engineering, (Jan., 1966).
4. Hamilton, W.O. and others, "Thermal Expansion of Epoxies
Between 2 and 300° K, " Research fa Science Instrumentation,
No. 39:645-8, (May, 1968^
5. Jackson, C.A. , Beason, E.G., Duncan, D.G., "Patent,
Packaging Articles with Heat Shrinkable Tubing,." To Phillips
Petroleum Co. US 3, 410. 394, (Nov., 1968).
6. Jablin, J.N., "Shrink on the Insulation," Radio-Electronics,
No. 38:61+ N, (1967).
7. Ragolia, A.J. , "Dimensional Stability of Acrylic Resins, "
Modern Plastics, No. 43_107- 10+ Jl, (1966).
8. "Plastic Heat Shrinkable Tubing, " Materials in Design
Engineering, No. 63:26, (Jan. , 1966).
9. Wood, S., "Coming Market for Shrink Film-Industrial Packaging, "
Modern Plastics, No. 1, pp 110-13 (Jan., 1969).
10. "The Coming Market for Shrink Film: Industrial Packaging, "
Modern Plastics, (Jan., 1969).
11. Emus, R.W., "Apparatus for Heat Shrinking Biaxially Oriented
Polymer Films." W. R. Grace & Co. , No. US 2, 427, 789,
(Feb., 1969).
12. Tiernan, J. , "Now a Low-Plasticized PVC Shrink Film, "
Borden Inc. , pp81-2 (June, 1969).
87
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APPENDIX B
AMERICAN SOCIETY FOR TESTING AND MATERIALS
PERTINENT EXTRACTS FROM
SPECIFICATIONS RELEVANT TO SEWER PIPE JOINTS
ASTM C594-66T (Accepted 11-16-66)
COMPRESSION COUPLINGS FOR VITRIFIED CLAY PLAIN-END PIPE
(Minimum Requirements)
TABLE 1 - TESTS FOR RUBBER MATERIALS
Test
Chemical resistance
1 N sulfuric acid
1 N hydrochloric
acid
Tensile
strength
Hardness
Accelerated
oven aging
Compression set
Water absorption
Ozone resistance
Low t emperature
brittle point
Test Requirements
no weight loss
no weight loss
1000 psi min
450% min
elongation at break
60 1 5
decrease of 10%
max of original
tensile strength
decrease of 10%
max of original
elongation
decrease of 25%
max of original
deflection
increase of 5%
max of original weight
rating no. 1
no fracture at
-40 F
ASTM Test Method
D 5435
D 4125
D 22405
(Shore A durometer)
D 57 33 (7 days at
70 1 C)
D 3953
Method B
(70 C for 22 hr)
D 47 I3 as follows:
immerse 0. 075 by
2 by 2 in. in dis-
tilled water at 70C
for 7 days.
D 117 I3
D 7463
89
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5. Test Requirements for Joints
5. 1 Pipe joints shall meet the following requirements:
5. 1. 1 The pipe joints shall be designed in a manner to achieve a
residual compression of at least 30 psi between the coupling and the
pipe barrel.
5. 1. 2 The joint shall exhibit sufficient flexibility to allow the
following deflections without visible leakage when tested with an
internal 10-ft head of water (4. 3 psi) for a period of 1 hr for each test
condition. The tests shall be performed at temperatures of the water,
pipe and atmosphere within a range of 60 to 75 F. These tests will be
construed to demonstrate exfiltration characteristics.
5. 1. 2. 1 Test Condition I.-- The ends of the test line (two lengths
of joined pipe) shall be restrained against longitudinal movement. The
pipe shall be deflected in any direction for the distances stated in Table
2. The deflection shall be the distance the free end of one pipe moves
away from the center line in any direction while the other pipe remains
fixed.
5. 1. 2. 2 Test Condition II: Coupling without Shear Ring—There shall
be no leakage when tested under conditions outlined in 5.1.2 if the
jointed ends shall be deflected relative to one another in any direction,
either longitudinally or perpendicularly to the pipe axes a distance of
1/24 in. /in. of pipe diameter.
TABLE 2 - DEFLECTION PER FOOT OF PIPE LENGTH
Deflection per Foot of
Nominal Diameter, in. Pipe Length, in.
4 to 12, incl 1/z
15 to 24, incl 3/8
27 to 36, incl i/4
5. 1. 2. 3 Test Condition II: Coupling with Shear Ring--Instead of the
deflection test specified in 5. 1. 2, the following shear test on couplings
with shear rings may be substituted. When a weight of 150 Ib/in. of
nominal diameter is uniformly applied over an arc of not less than 120
deg and along a longitudinal distance of 12 in. at the end of the pipe
immediately adjacent to the coupling of the assembled joint, there shall
be no leakage when tested under the conditions outlined in 5. 1. 2. 2.
The pipe in this laboratory test shall be supported on adequate blocks
placed immediately behind the coupling.
6. Field Performance and Acceptance
6. 5 Joints shall sustain a maximum limit of 0.40 gal/in. of diameter/
hr/100 ft of line when field tested by actual infiltration conditions. If
exfiltration testing is required or necessary, the joints shall perform
equally well, except that an allowance of an additional 10 per cent of
90
-------
gallonage shall be permitted for each additional 2-ft head over a basic
2-ft minimum internal head.
ASTM C 425-66T (Accepted 11-16-66)
COMPRESSION JOINTS FOR VITRIFIED CLAY BELL AND SPIGOT PIPE
(Minimum Requirements)
TABLE I - TESTS FOR PLASTIC MATERIALS
Test
Chemical resistance
1 N sulfuric acid
1 N hydrochloric acid
Test Requirements
no weight loss
no weight loss
ASTM Test Method
D 543
TABLE 2 - TESTS FOR RUBBER MATERIALS
Test
Chemical resistancw
1 N sulfuric acid
1 N hydrochloric acid
Tensile strength
Hardness
Accelerated oven aging
Compression set
Water absorption
Ozone Resistance
Test Requirements
no weight loss
no weight loss
2000 psi min.
500% min elongation
at break
35 min
50 max
maximum decrease
of 20% of original
tensile strength
maximum decrease of
25% of original
elongation
maximum decrease
of 16% of original
deflection
maximum increase
of 5% of original
weight
Rating no. 1
ASTM Test Method
D 543'
D 4123
D 22403(Shore A
Durometer)
D 5734 (7 days at
70 4 l C)
D 3954, Method B
(70 C for 22 hr)
D 47 I4 as follows:
Immerse 0. 075 in.
by 2 in. by 2 in.
in distilled water
at 7OC for 7 days
D 11714
91
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TABLE 3 - DEFLECTION PER FOOT OF PIPE LENGTH
Deflection per foot
Nominal Diameter, in. Pipe Length, in.
4 to 12, incl ya
15 to 24, incl 3/8
27 to 36, incl V4
6. Test Requirements for Joints
6. 1 Pipe joints shall meet the following requirements:
6.1.1 The joint shall exhibit sufficient flexibility to allow a deflec-
tion in any direction per ft of pipe length for various pipe diameters as
stated in Table 3, and the joint, when deflected, shall show no visible
leakage when being tested under an internal 10-ft head of water pressure
(4. 3 psi). The ends of the test line shall be restrained only in an a-
mount necessary to prevent longitudinal movement. The deflection shall
be measured as the distance the free end of one pipe moves away from
the center line in any direction, while the other pipe remains fixed.
6.1.2 The pipe joints shall present sufficient resistance to shear
loading to meet the following test: when a weight of 150 Ib/in. of
nominal diameter is uniformly applied over an arc of not less than 120 deg
and along a longitudinal distance of 12 in. at the spigot end of the pipe
immediately adjacent to the bell of the assembled joint, there shall be
no visible leakage when an internal 10-ft head of water pressure (4. 3 psi)
is applied for a period of 1 hr after application of the shear load, with the
temperature of water, pipe, and atmosphere within a range of 60 to 75
deg F. The pipe in this laboratory test shall be supported on adequate
blocks placed immediately behind the bell. This test shall be construed
to demonstrate exfiltration characteristics.
7. Field Performance and Acceptance
7. 5 Joints shall sustain a maximum limit of 0.40 gal/in. of diameter/
hr/100 ft of line when field tested by actual infiltration conditions. If
exfiltration testing is required or necessary, the joints shall perform
equally well, except that an allowance of an additional 10 per cent of
gallonage shall be permitted for each additional 2-ft head over a basic
2-ft minimum internal head.
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ASTM c 428-69a (Accepted 11-14-69)
ASBESTOS-CEMENT NONPRESSURE SEWER PIPE
Joint Tightness
5. (a) The purchaser by designation with his order may require that
assembled pipes and couplings pass the following performance tests
without leakage:
(1) Straight Alignment--A hydrostatic pressure test shall be made on
an assembly of two sections of pipe, properly connected with a coupling
in accordance with the joint design. An equivalent alternative may be
a single pipe with a coupling on each end. The assembly shall be sub-
jected to an internal hydrostatic pressure 10 psi (0.7 kgf/cm2) for 10 min
and any leakage shall be considered a failure of the test requirement.
(2) Maximum Deflected Position--Upon completion of the test for
pipes in straight alignment in accordance with Section 5(a) (l), deflect
the test sections 5 deg for 12 in. and smaller diameters and 3 deg for
14 in. and larger diameters (with one half of the deflection being between
each pipe and the coupling) and subject it to an internal hydrostatic pres-
sure of 10 psi (0.7 kgf/cm2) for 10 min. Any leakage shall be considered
a failure of the test requirement.
(b) Test one sample of at least one size unless some other arrangement
is made with the purchaser by designation with his order. At the option
of the purchaser, the sample of the pipes and couplings to be tested may
be selected by him. Instead of requiring performance of these tests, the
purchaser may require the manufacturer to certify that the pipes and coup-
lings will pass the tests enumerated in this section.
ASTM C 443-70 (Accepted 2-6-70)
JOINTS FOR CIRCULAR CONCRETE SEWER AND CULVERT PIPE,
USING RUBBER GASKETS
Note l--The purchaser of pipe with rubber gasket joints should
carefully investigate the adequacy and performance of the rubber
gasket joint proposed for use. The infiltration or exfiltration in
a pipe line made with these joints should not exceed 0.60 gal/in.
(0.002 m3/25 mm) of internal pipe diameter per 100 ft (30.48 m) of
pipe line/h, where the maximum hydrostatic head at the center line
of the pipe does not exceed 25 ft (7. 62m). The purchaser may spe-
cify other infiltration or exfiltration requirements.
8. Performance Requirements for Joints
8. 1 The purchaser may require that assembled joints pass the follow-
ing performance tests without leakage at the joints:
93
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8. 1. 1 Pipes in Straight Alignment--Hydrostatic pressure tests on
joints shall be made on an assembly of two sections of pipe, properly
connected in accordance with the joint design. At the option of the
purchaser a second such test may be required. Suitable bulkheads may
be provided within the pipe adjacent to and on either side of the joint,
or the outer ends of the two joined pipe sections may be bulkheaded.
No mortar or concrete coatings, fillings, or packings shall be placed
prior to water-tightness tests. After the pipe sections are fitted together
with the gasket or gaskets in place, the assembly shall be subjected to
an internal hydrostatic pressure of 10 psi (1 kg/cm2) for 10 min. Mois-
ture or beads of water appearing on the surface of the joint will not be
considered as leakage. At the manufacturer's option, the test period
may be extended up to 24 h.
8. 1. 2 Pipes in Maximum Deflected Position--Upon completion of
the test for pipes in straight alignment in 8. 1. 1, the test sections shall
be deflected to create a position 1/2 in. (12.7 mm) wider than the assem-
bled position on one side of the outside perimeter of each joint and shall
be subjected to an internal hydrostatic pressure of 10 psi for 10 min.
Moisture or beads of water appearing on the surface of the joint will not
be considered as leakage.
94
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APPENDIX C
CONVERSION FORMULA FOR PHASE I
SHEAR TEST
Stress = Pounds of shear load / Area in sq. inches = PSI
This formula can compare the shear load applied to the 1 inch diameter
HST with a wall thickness of 0. 035 inch to an 8 inch HST joint with a
wall thickness of 0. 122 inch. By taking a cross section of the HST
joint at the shear point and finding the area of that material, the area
can be divided into the shear load to determine the PSI of that load.
EXAMPLE:
If the 8 inch diameter HST joint has:
1. Wall thickness = 0. 122 inch
2. Inner diameter (I. D.) = 9. 75 inches
3. Outer diameter (O. D. ) = I. D. +2 (wall thickness) = 9. 99 inches
4. Load = 1200 pounds ASTM specification
Stress = Load / Area
Area = 3. 14 / 4 (O. D. )2 - (I. D. )2
Area = 3. 14 / 4 (99. 8) - (95. 1)
Area = 3. 69 sq. in.
Stress = 1200 Ibs. / 3.69 sq. in. = 325.2 PSI
Knowing that an 8 inch sewer pipe has 325 PSI at 1200 pounds shear load,
the minimum load for the 1 inch HST joint can be determined. The same
procedure is followed.
The 1 inch diameter HST joint has:
1. Wall thickness = 0. 035 inch
2. I. D. = 1. 2 inches
3. O. D. = 1. 27 inches
4. Load = 43 pounds
Stress = Load / Area
Area = 3. 14 / 4 (O. D. )2 - (I. D. )2
Area = 0. 13 sq. in.
95
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Stress = 43 pounds / 0. 13 sq. in. = 330 PSI
Note that the 8 inch HST joint must withstand 325 PSI under 1200 pounds
of shear load, and that the 1 inch HST joint must withstand 330 PSI under
43 pounds of shear load. Consequently all 1 inch HST joints must
withstand a minimum of 43 pounds shear load, or the joint is a failure.
96
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APPENDIX D
MATERIALS UTILIZED AND TESTED
HEAT SHRINKABLE TUBING
Laboratory Testing
Brand
Generic Name Designation Manufacturer
Polyolefin RNF 100
Polyolefin HK 2
Poly vinyl Chloride FIT 105-2
Raychem Corporation
Rally Industries Inc.
Alpha Wire Corporation
Silicon Rubber
Neoprene
Neoprene
FEP Teflon
FEP Teflon
TFE Teflon
TFE Teflon
Viton
Kynar
Polyethene &
Adhesive
Polyethene &
Adhesive
Silastic 1412 Dow Corning Corporation
NT-2
Raychem Corporation
Penntube VII Penntube Plastics Inc.
FEP 177 E. I. Dupont De Nemours & Co.
SMT II Penntube Plastics Inc.
Zeus Industrial Products Inc.
Penntube I Penntube Plastics Inc.
Raychem Corporation
Raychem Corporation
TPS 1000 Raychem Corporation
WRS Raychem Corporation
97
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Full Scale Testing
Brand
Generic Name Designation
Polyolefin
FEP Teflon
Poly vinyl Chloride
TPS 10750
Manufacturer
Raychem Corporation
E. I. Du Pont De Nemours & Co.
Rally Industries Inc.
ADHESIVES
Laboratory Testing
Brand
Generic Name Designation
Butyl Adhesive
Tape
Hot Melt
Hot Melt
SFTS 1
TPX 327
394 A
Manufacturer
Sigma Industries Inc.
Raychem Corporation
Raychem Corporation
Full Scale Testing
Brand
Generic Name Designation
Hot Melt
Manufacturer
Hot Melt
Adhesive Tape
Hot Melt
Hot Melt
Hot Melt
Hot Melt
CC 150
SFTS 1
DA- 2
80-5322-0
Superseal
Electro-
Stix I
Stuck Adhesives Inc.
Sigma Industries Inc.
3-M Company
Paisley Products, Inc.
Electro- Seal Corp.
Electro -Seal Corp.
M5L
Eastman Chemical Products Inc.
98
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Full Scale Testing (cont. )
.Generic Name
Hot Melt
Epoxy
Epoxy
Film Adhesive
Epoxy
Brand
Designation
M5W
Plastilock 729
Plastisol 370-569
367-147 Sealant
CPRL 367-109
Manufacturer
Eastman Chemical Prod. Inc.
B. F. Goodrich Adhesive Prod.
B. F. Goodrich Adhesive Prod.
Hysol Corp.
Hysol Corp.
COMMERCIAL SEWER PIPE JOINTS
Full Scale Testing
Type
Clay, Bell and Spigot Pipe
Asbestos-Cement Nonpressure
Sewer Pipe
Concrete, Rubber Gasket
Clay, Compression Couplings
Manufacturer
Can-Tex Industries
Johns-Manville Transite Pipe
Gifford-Hill Pipe Company
Can-Tex Industries
99
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APPENDIX E
FULL SCALE TEST DATA
Test No.
1.
2.
3.
Average
Internal
PSI
15.0
12.4
13. 0
13.5
Table
Deflected
Pressure Internal Pressure
PSI
15.0
15.0
10.5
13.5
Shear
LBS
3600
2900
3800
3400
Tensile
LBS
146
65
174
128
1. Asbestos -Cement Test Results
Test No.
1.
2.
3.
Average
Internal
PSI
15. 0
11.5
12.6
13. 0
Table 2 .
Deflected
Pressure Internal Pressure
PSI
12.0
10.4
8.5
10.3
Clay, Bell and Spigot, Test
Shear
LBS
2400
2600
1900
2300
Results
Tensile
LBS
68
195
137
133
Test No.
1.
2.
3.
Average
Table
Internal Pressure
PSI
Failed
15.4
13.7
9.7
3. Concrete and
Deflected
Internal Pressure
PSI
Failed
11.0
9.2
6.7
Rubber Gasket Joint
Shear
LBS
Failed
3400
2600
2000
Tensile
LBS
105
271
188
188
Test Results
101
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Test No.
1.
2.
3.
Average
Deflected
Internal Pressure Internal Pressure
PSI PSI
9.7
8. 5
10.4
9.5
Table 4. Clay,
11.3
7.7
10. 0
10. 0
Shear
In.
7/16
3/8
9/16
7/16
Tensile
LBS
61
78
94
78
Compression Coupling Test Results
Test No.
1.
2.
3.
Average
Table 5.
Deflected
Internal Pressure Internal Pressure Shear
PSI PSI LBS
15.0
15.0
15. 0
15.0
Polyolefin HST,
15. 0
15. 0
15.0
15.0
CC150 adhesive, and
Failed
5300
2800
4100
Clay plain-
Tensile
LBS
900
900
900
900
end Pipe
Test No.
1.
2.
3.
Average
Deflected
Internal Pressure Internal Pressure
PSI
15. 0
15. 0
15. 0
15.0
Table 6. Polyolefin
Asbestos- Cement
PSI
15.0
15.0
15.0
15. 0
Shear
LBS
4800
5600
5100
5200
Tensile
LBS
900
900
900
900
HST, CC150 Adhesive,
and Plain- End Pipe
102
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Test No.
1.
2.
3.
Average
Internal Pressure
PSI
15. 0
15.0
15. 0
15.0
Table
CC150 Adhesive,
Deflected
Internal Pressure
PSI
15. 0
15.0
15. 0
15. 0
7. Polyolefin HST,
and Concrete Plain- End
Shear
LBS
5700
2800
4400
4300
Pipe
Tensile
LBS
900
900
900
900
103
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APPENDIX F
TECHNICAL DATA SUBMITTED BY RALLY INDUSTRIES PER-
TAINING TO THE 8 INCH RECOVERED POLYVINYL CHLORIDE
HEAT SHRINKABLE TUBING MANUFACTURED FOR THIS PROGRAM
105
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HEAT SHRINK RIGID PVC SLEEVING
INTRODUCTION
A sub-contract to develop a heat shrink sleeve from Rigid PVC was
established under prime contractor, WESTERN RESEARCH CORP., Richard-
son, Texas. The prime development project involved a method of pro-
ducing heat shrink sleeves of rather large dimensions for sealing butt
joint ceramic clay or cast iron pipe subject to seismic shifts and
other joint hazards.
GENERAL SPECIFICATIONS
1. The basic sleeve material must have low water absorption
properties and good resistance to petroleum hydrocarbons and
chemicals.
2. The sleeve requires sufficient tensile strength and elongation
to resist a finished joint bending test involving one fixed length
while the second length is moved through an arc of 1" per foot
of length.
3. The sleeve must be capable of shrinking using hot air methods
from an original inner diameter of 11" to a final diameter of 8"
and affect a sealed joint using accepted hot melt adhesives that
will melt during the heat shrink process.
HEAT SHRINK THEORY
The most probable structure of useful polymers is a random tangled
arrangement of long chain molecules. Structural strength is dependent
upon intermolecular attractive forces and the inability of the molecular
chains to move freely.
If the molecular structure is stretched in a relatively cool state, re-
alignment of the molecular structure occurs and the stresses are locked
in by intermolecular forces which resembles crystal structure. The
molecular locking areas are called spherulites or crystalites.
A second way to lock in molecular stresses is through the use of chemi-
cal cross links. In rubber this is accomplished through "vulcanization"
with sulfur bridges. Direct carbon to carbon bonds occur in adjacent
molecular chains through the use of peroxide crosslinking agents or by
electron beam irradiation of certain polymers.
The locked in stresses can be relaxed by heating the structure above its
"glass transition temperature" which allows molecular rearrangement or
107
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shifting of the chain structure back to its original dimensions, resuming
its original tangled relaxed state.
Advantage can be taken of this principle by inducing stresses in rigid
PVC by stretching at a relatively low temperature. The stresses are
locked in by intermolecular forces - crystalites - and relaxed to
shrink to its original dimensions by heating above its glass transition
temperature (above 170°F).
STRUCTURE
a.) Plastic Sheeting
To apply the concept, rigid Type II PVC sheeting is stretched
approximately 100% in the longitudinal direction and at a
temperature of 190-250°F. This is accomplished by speeding
up the take off of the calender train during sheet production.
The stretched sheet when relaxed at 210° F will shrink up to
30% of its original calendered dimension and at 330°F the sheet
will shrink up to 50% of the calendered stretched length (100%
based on the final relaxed dimensions).
b. ) Adhesive
The adhesive requirements are very rigorous involving the
following points :
1. ) Maximum specific adhesion to rigid PVC.
2. ) Heat resistance to above 300°F to maintain bond strength
during shrink process.
3. ) Sufficiently thermoplastic to allow shrinkage to occur
at temperature of 200°F-300°F.
c. ) Hot Melt
The hot melt affects the seal between the sleeve and the pipe.
Besides forming a hot melt seal during the heat shrink process,
the hot melt must be resistant to water, chemicals, hydrocar-
bons, etc.
PRODUCTION PROCEDURE
Shrink sleeves are produced by wrapping and bonding stretched PVC sheet-
ing on a circular mandrel of the desired dimensions.
In this way sleeves of any dimension can be made with minimum tooling
cost. The dimensional change will be directly proportional to the shrink
built into the PVC sheeting.
108
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Sleeve building procedure follows :
a.) Building Mandrel
A collapsible mandrel can be built from relatively light sheet
metal locked to the proper initial dimensions (inner diameter).
This design should permit good internal heat transfer and
sufficient inner peripheral collapse to permit removal of the
finished sleeves. Accurate, constant sectional dimensions of
the mandrel are necessary to guarantee accurate wrapping
geometry.
b.) Cement Application
Cement can be applied by brush, spray or roller coat to the
sheeting. In this particular construction two coats of a
30% solids polyester cement was applied to produce approxi-
mately 1 mil dry film thickness. A single coat of the same
cement was applied to the opposite side of the sheet and
allowed to air dry for a minimum of 15 minutes before assembly.
c. ) Mandrel Wrapping
Dry coated sheeting having a length equivalent to the number
of circumferential wraps required for the proper thickness plus
30% of circumference for overlap reinforcement. It is neces-
sary to align the sheet and the mandrel properly in order to
produce a smooth tight wrap, free of wrinkles and potential
trapped air.
d.) Pressure Application
Ply to ply pressure is necessary to produce an intimate contact
to guarantee fusion of the cement films during the heat bonding
process. This also prevents the laminate from uncoiling during
the heat bonding process. The necessary pressure is applied
by stretching an external rubber sleeve over the coiled lami-
nated structure. A pressure sleeve of temperature resistant
rubber designed for medium modulus properties will supply suf-
ficient bonding pressure when elongated approximately 50% and
has a sectional thickness of . 060" to . 090".
e. ) Heat Bonding Cycle
The assembled mandrel with the dry adhesive coated PVC sheet-
ing, prepared with the external rubber pressure sleeve, is
placed in a forced draft air oven and heated 15 minutes at 250°F.
The actual attained temperature of the sleeve is in the order of
109
-------
200-2300F. The heat causes the PVC sheeting to shrink suf-
ficiently to apply the additional necessary pressure for
structural ply bonding.
The dry adhesive film coating is heat activated at 210°F to 220°F
which fuses the structure into a tight uniformly bonded sleeve.
After coating, the mandrel is unlocked, slightly collapsed and
the sleeve removed and trimmed to 8" or whatever specified
lengths.
FINAL TESTING
a.) Inspection
The sleeves are checked for blisters or non-laminated areas.
This can be done by flexing the sleeves. Any non-laminated
areas produce a distinctive frictional or "cracking" sound.
b.) Percent Shrink Vs. Temperature
Typical sleeve sections are placed in circulating air ovens
at 200°F and 300°F for 15 minutes.
Minimum percent shrink as measured by circumferential dimen-
sions before and after heat treatment follow:
% Shrink - minimum
200°F 20%
300°F 50%
c.) Mandrel Shrink
To an 8" diameter (OD) sheet metal mandrel two strips of hot
melt adhesive (cross section 1/4" x 1/2") is wrapped around
the test mandrel 7-1/2" apart. An 11" ID PVC shrink sleeve
is centered on the prepared 8" mandrel and placed in an oven
5 minutes at 275°F.
The PVC sleeve must shrink tightly onto the mandrel producing
a sealed structural simulated joint. The hot melt must exude
from the end of the sleeve forming a continuous seal.
ADDITIONAL DESIGN POSSIBILITIES
1. Evaluate heat activated cements that can be cast into films
which in turn can be coiled as an interleaf between PVC plies
and heat fused as described above.
110
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2. Evaluate high temperature resistant pressure sensitive adhe-
sives such as Silicones that would allow simple pressure
wrapping of sleeves and heat shrinking at 300 °F.
3. Investigate mechanical riveting using metal or plastic gussetts
and rivets at the PVC ply overlap area. Gussett seals could
be made using extra hot melt sealant in this area.
4. Better hot melt design would be achieved by heat shrinking
annular grooves circumferentially around the PVC sleeves to
contain a preformed ring of hot melt sealant.
This could be done during the heat setting process of the ad-
hesive over a shaped mandrel containing annular ribs.
5. A heat shrink heating device should be designed to distribute
hot air at 350oF to 400°F in a flow pattern from one end of
the sleeve to the other with air flow outside and inside of the
sleeve for uniform heating.
This could be designed as a split hot air oven with an outside
annular space of 2"-3" greater than the shrink sleeve. Hot
air from a gas fired oven would be forced through and over the
sleeve affecting rapid and even heat transfer eliminating most
of the heat sink problems of the cold pipe.
Considerable development is needed to develop field methods
for delivering uniform heat to the sleeve to produce an even
uniform shrink without the necessity of heating the pipe or the
great out-of-doors.
Ill
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.Access/on Number
Subject Field & Group
08G
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
The Western Company of North America
Title
HEAT SHRINKABLE TUBING AS SEWER PIPE JOINTS
1 Q Authors)
Beale, Gerald D.
Sweet, Stephen M.
Harts el, Gerald D.
16
21
Project Designation
EPA Water Quality
(11024 FLY)
Office Contract No. 14-12-854
Note
22
Citation
Water Pollution Control Research Series 11024 FLY 06/71
23
Descriptors (Starred First)
ij M n ii |j
sewers, sewer joints, sanitary, infiltration, construction costs, sewer repair,
water pollution
25
Identifiers (Starred First)
Heat shrinkable tubing, hot melt adhesives, sewer joint tests
Abstract Preliminary testing had indicated that commercial sewer pipe might be coupled
in tight waterproof joints using the heat shrinkable plastic tubing (HST) developed and
used extensively in the electronics and aerospace industries. Laboratory studies of such
materials and joints were conducted to determine their characteristics and their operational
and economic feasibility. A wide variety of HST materials and joints were tested in
addition to conventional joints for clay, concrete and asbestos-cement pipes.
The results of both small scale tests and full scale tests using commercial 8 inch sewer
pipe indicated that a polyolefin with a polymeric base hot melt adhesive produced the
most durable, watertight joints and were significantly superior in performance compared
to existing pipe joining mechanisms. In addition, the cost analysis indicated that HST
joints are economically feasible and compare favorably to conventional joints when
considering both material and installation costs. The HST joint requires no significant
departure from current installation practice and is equally adaptable to repair of installed
commercial pipe and joints. Field development and in-use demonstration of the HST
system is recommended.
27
Abstractor
Gerald D. Harts el
utio
tton
e Western Company of North America
WR:I02 (REV. JULY 1969)
WRSI C
SEND TO:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 20240
* OPO: 1969-359-339
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Continued from inside front cover....
11022 08/67
11023 09/67
11020 12/67
11023 05/68
11031 08/68
11030 DNS 01/69
11020 DIH 06/69
11020 DES 06/69
11020 06/69
11020 EXV 07/69
11020 DIG 08/69
11023 DPI 08/69
11020 DGZ 10/69
11020 EKO 10/69
11020 10/69
11024 FKN 11/69
11020 DWF 12/69
11000 01/70
11020 FKI 01/70
11024 DDK 02/70
11023 FDD 03/70
11024 DMS 05/70
11023 EVO 06/70
H024 06/70
11034 FKL 07/70
11022 DMU 07/70
11024 EJC 07/70
11020 08/70
11022 DMU 08/70
11023 08/70
11023 FIX 08/70
11024 EXF 08/70
Phase I - Feasibility of a Periodic Flushing System for
Combined Sewer Cleaning
Demonstrate Feasibility of the Use of Ultrasonic Filtration
in Treating the Overflows from Combined and/or Storm Sewers
Problems of Combined Sewer Facilities and Overflows, 1967
(WP-20-11)
Feasibility of a Stabilization-Retention Basin in Lake Erie
at Cleveland, Ohio
The Beneficial Use of Storm Water
Water Pollution Aspects of Urban Runoff, (WP-20-15)
Improved Sealants for Infiltration Control, (WP-20-18)
Selected Urban Storm Water Runoff Abstracts, (WP-20-21)
Sewer Infiltration Reduction by Zone Pumping, (DAST-9)
Strainer/Filter Treatment of Combined Sewer Overflows,
(WP-20-16)
Polymers for Sewer Flow Control, (WP-20-22)
Rapid-Flow Filter for Sewer Overflows
Design of a Combined Sewer Fluidic Regulator, (DAST-13)
Combined Sewer Separation Using Pressure Sewers, (ORD-4)
Crazed Resin Filtration of Combined Sewer Overflows, (DAST-4)
Stream Pollution and Abatement from Combined Sewer Overflows •
Bucyrus, Ohio, (DAST-32)
Control of Pollution by Underwater Storage
Storm and Combined Sewer Demonstration Projects -
January 1970
Dissolved Air Flotation Treatment of Combined Sewer
Overflows, (WP-20-17)
Proposed Combined Sewer Control by Electrode Potential
Rotary Vibratory Fine Screening of Combined Sewer Overflows,
(DAST-5)
Engineering Investigation of Sewer Overflow Problem -
Roanoke, Virginia
Microstraining and Disinfection of Combined Sewer Overflows
Combined Sewer Overflow Abatement Technology
Storm Water Pollution from Urban Land Activity
Combined Sewer Regulator Overflow Facilities
Selected Urban Storm Water Abstracts, July 1968 -
June 1970
Combined Sewer Overflow Seminar Papers
Combined Sewer Regulation and Management - A Manual of
Practice
Retention Basin Control of Combined Sewer Overflows
Conceptual Engineering Report - Kingman Lake Project
Combined Sewer Overflow Abatement Alternatives -
Washington, D.C.
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