Lessons
Learned
NaturalGas
EPA POLLUTION PREVENTER
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From Natural Gas STAR Partners
COMPOSITE WRAP FOR NON-LEAKING PIPELINE DEFECTS
Executive Summary
Composite wrap is a permanent, cost-effective pipeline repair technology, suitable for non-leaking defects such
as pits, dents, gouges, and external corrosion. Composite wrap can be performed on an operating pipeline with-
out taking it out of service. This repair technique is quick and generally less costly than other repair options, and it
permanently restores the pressure-containing capability of the pipe when properly installed.
Composite wrap can serve as an alternative to the traditional pipeline repair practices such as pipeline replace-
ment or the installation of full-encirclement steel split sleeves. Compared to these traditional practices, composite
wrap repairs are generally less expensive, time consuming, and labor intensive. In the case of pipeline replace-
ment, composite wrap repair has additional advantages of avoiding customer service interruptions and eliminat-
ing methane emissions associated with the venting of the damaged pipeline.
Using composite wrap as an alternative to pipeline replacement often saves enough gas to pay back repair
costs immediately. One Natural Gas STAR partner reported completing 2 to 65 composite wrap repairs per year
on pipelines 10" and larger, saving 52Q thousand cubic feet (Mcf) to 27,500 Mcf of methane per repair.
Between 1993 and 1999, this partner saved 106,133 Mcf by choosing composite wrap over pipeline replace-
ment.
Method for Reducing
Gas Loss
Volume of Natural
Gas Savings (Mcf)
Value of Natural Gas
Savings2
Cost of
Implementation3
Payback
Composite Wrap Repair1
3,960
$11,880
$3,963
Immediate
'Repair of a 6" defect on a 24" diameter pipeline operated at 350 psig with 10 miles between shut-off valves.
2Assumes natural gas price of $3/Mcf.
includes labor, equipment and materials, and indirect costs. Note that cost of pipeline replacement for this example is $22,746, including cost of purge gas
(nitrogen at $4/Mcf). See Exhibit 5 for more details.
This is one of a series of Lessons Learned Summaries developed by EPA in cooperation with the natural gas industry on superior
applications of Natural Gas STAR Program Best Management Practices (BMPs) and Partner Reported Opportunities (PROs).
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Technology
Background
Non-leaking pipeline defects such as corrosion, dents, gouges, pits, and
cracks can cause pipelines to rupture. According to the U.S. Department of
Transportation (DOT), there are three primary methods of repair for non-leak-
ing defects on steel pipelines:
* Cut out damaged segment and replace with new pipe.
* Install a full-encirclement steel split sleeve over the damaged area.
* Install a composite sleeve over the damaged area.
Both the pipeline replacement and steel sleeve installation procedures are
expensive, time-consuming, and labor-intensive. Pipeline replacement
requires that the affected portion of the line be shutdown, often resulting in
service interruption. The gas in the line is then purged, the affected segment
is cutout, and a new segment of pipeline is welded into place. Steel sleeves
are typically used to repair leaking or weakened pipe without shutdowns.
The damaged pipeline is excavated, the pipe exterior is cleaned, and the
stainless steel split sleeve is bolted or welded into place.
Use of composite wrap as an alternative to pipeline replacement can reduce
safety risks, decrease pipeline downtime, save gas for sale, and decrease
methane emissions to the atmos-
phere. Composite wrap systems
allow pipeline repair without shutting
down gas flow, purging the pipeline,
or cutting into the pipe. Composite
wrap systems operate by transferring
Two Classes of Full-Encirclement
Sleeves
Type A: Steel sleeves are not welded around
the circumference to parent pipe.
Type B: Steel sleeves are welded around the
the hoop stress from the defect circumference.
through a high compressive strength
filler to a composite sleeve, which is
wrapped around and bonded to the pipe. Composite wrap sleeves are con-
sidered Type A full-encirclement repairs (see the Text Box).
Composite Wrap Variations
Many variations of composite wrap systems are available. Composite wrap
systems use different materials for wraps and adhesives, and some systems
use epoxy polymers and curing agents. Examples include Clock Spring®,
StrongBack, Armor Plate®, and PermaWrap™. Each has certain advantages:
* Clock Spring® is a three-part system in which the sleeve itself is com-
posed of glass fibers and polyester resin.
* The StrongBack system is water activated, and can be applied to wet
surfaces.
* Armor Plate® produces varieties of wrap systems that can be used in a
wide range of conditions including high or low pressure, high or sub-
freezing temperature, and under water.
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* PermaWrap™ (manufactured by WrapMaster, Inc.) has a feature to allow
detection of a previous wrap by a smart pig, so operators will not have
to uncover pipeline segments that have already been repaired.
Most manufacturers offer installation videos, training assistance, and pipe
defect analysis software. Composite wrap technologies are advancing rapid-
ly, and partners are encouraged to look for the best system for their needs
once they decide to repair a non-leaking pipeline using composite wrap. For
a partial list of manufacturers, see the References section at the end of this
study.
Clock Spring® Repair
As noted above, there are several variations of composite wrap repair sys-
tems. One that has been used for many years by several Natural Gas STAR
partners is the Clock Spring® system.1 This section will expand on the mate-
rials, installation technique, and special considerations of this system.
A Clock Spring® composite
wrap consists of three parts:
1. A high-strength, unidirec-
tional composite structure
of glass fibers and a poly-
mer base;
2. A fast curing, high-
performance, two-part
adhesive system; and
3. A high compressive-
strength, load-transferring filler compound.
The composite structure. The composite wrap laminate layers are nominal-
ly 0.062" thick and have a glass fiber content ranging from 60 to 70 percent
by weight. One wrap will cover a one-foot length of pipe. The composite
wrap is wound 8 times around the pipe creating a Vz" thickness of reinforc-
ing material. The length of the spiral strip varies for each pipe diameter.
Clock Spring® composite wrap is available for pipelines between 4" and 56"
in diameter.
Source: Clock Spring® Company L.P
This study focuses on Clock Spring® in order to simplify the economic analysis
described later in this document. The Natural Gas STAR Program does not claim that
this particular composite wrap system is any better, or worse, than any of the others
available on the market.
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Adhesive. The two-part adhesive is an epoxy methyl methacrylate, which is
used to hold the repair in place.
Load transfer (filler). In pipeline repair, the composite wrap works by
sharing the hoop load carried by the pipe wall. This load is efficiently trans-
ferred to the composite by the filler. The external defect is filled with the
high-compressive strength filler material to prevent the weakened pipe wall
from further yield. The filler material is a methacrylate with a compressive
strength exceeding 800 psi.
Installation. Training is required to ensure proper installation of a composite
wrap system. For the Clock Spring® composite wrap system, the pipeline
rehabilitation process includes the following steps:
1. Filling the external defect with the filler material.
2. Winding eight layers of composite sleeve around the pipe with adhe-
sive applied between the layers.
3. Tightening the composite wrap sleeve onto the pipe with a tension
strap.
4. Allowing the adhesive to cure for about two hours.
5. Coating the repaired pipe to prevent corrosion or ultraviolet radiation
damage (depending on whether the pipe is buried or not).
6. Reburying the pipeline (if applicable).
Once installed, the filler, adhesive, and composite bond together to form a
permanent repair that the manufacturer estimates will last at least 50 years.
In some situations, the entire project, from excavation to reburial, can be
completed in as little as 4 hours. A trained two-person crew can complete
an installation in as little as 30 minutes, excluding curing time.
There are several important points to keep in mind when installing a Clock
Spring® system:
* The maximum operating temperature for the standard Clock Spring®
system is 130°F under worst-case conditions of fully saturated soil.
* Internal gas temperatures up to 180°F can be accommodated in a mod-
ified version of the Clock Spring® system.
* If the Clock Spring® system is used above ground, a protective coating
is required due to the UV sensitivity of the material.
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Economic and
Environmental
Benefits
Decision
Process
* While the Clock Spring® repair can be made at full line pressure, manu-
facturers recom-mend that line pressure be reduced during repair.
Reducing the pressure reduces the stress on the defect during repair. As
the repaired area ex-pands during repressuring, the hoop strain transfers
from the steel to the composite wrap, resulting in a greater load transfer.
* At least 2" of wrap must extend beyond the damage on either side of
the defect for the Clock Spring® system to adhere to the parent pipe.
Therefore, a single 12" sleeve can be used to repair a defect up to 8"
long. For damage longer than 8", multiple composite wrap sleeves are
butted adjacent to each other to cover the length of the damage (a Vz"
gap can remain between butt joints). In the U.S., up to 15 Clock Spring®
sleeves have been butted side-by-side to repair defects on pipelines
between 16" and 30" diameter at 800 to 900 psi.
Using composite wrap as an alternative to pipeline replacement can yield
significant economic and environmental benefits:
* Avoidance of costs associated with ensuring uninterrupted service
during a repair, such as installing bypasses or temporary service lines.
* No methane is vented to the atmosphere. Using composite wraps
eliminates the income lost through methane losses.
* Easier and faster installation without the need for special equipment or
highly skilled labor, such as welders. A single composite wrap can be
installed by a trained two-person crew within 30 minutes. Curing time
is approximately 2 hours.
* Ability to perform repairs at full line pressure, although vendors rec-
ommend reducing line pressure for repair.
Using the five steps discussed below, partners can determine the methane
savings and economics of choosing composite wrap over pipeline replace-
ment. The cost analysis for composite wrap in Step 2 is also useful for com-
parison with steel sleeve repairs, if sleeving is your corporate practice.
Step 1: Determine suitable application. Typical non-leaking defects suit-
able for composite wrap repair include dents, gouges, and external corro-
sion. Defects of up to 80 percent loss of wall thickness can be repaired with
composite wrap. There are no pressure limits on the use of composite wrap.
Composite wrap can also be used to repair internal corrosion on a tempo-
rary basis. If the source of corrosion is eliminated, the repair can be deemed
permanent.
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When considering the use of com-
posite wrap, important decision fac- Five StePs .for Evaluating Composite
tors include the depth and length of Wrap RePair:
wall loss or deformation, yield 1. Determine suitable application;
strength, defect depth, defect axial 2 Ca,CU|ate cost for composite wrap repair;
length, pipeline diameter, wall thick- 3 Estimate methane savings;
ness, and pipeline operating pressure. 4 Ca|cu|ate cost of pipe|jne rep|acement; and
While detailed field measurements are
5. Evaluate the economics.
needed to make a final decision as to
whether composite wraps will restore
the pipe to American Society of Mechanical Engineers (ASME) standards,
software programs such as GRIWrap® can be useful in determining the suit-
ability of composite wrap for a given repair job. Composite wrap may be an
ideal choice for non-leaking defects when repair is urgently required, must
be completed quickly, and no backup gas supply is available.
If it is determined that composite wrap repairs are not applicable and that
cut-and-replace pipeline repair will be performed, partners should consider
other techniques recommended by the Natural Gas STAR Program to
reduce the methane emissions from a pipeline undergoing repairs. See
Lessons Learned Study "Using Pipeline Pump-Down Techniques to Lower
Gas Line Pressure Before Maintenance."
Step 2: Calculate cost for composite wrap repair. The cost of composite
wrap repair can range greatly depending on the length of the defect and the
pipeline diameter. The primary costs for installing a composite wrap sleeve
are labor costs, equipment and materials, and indirect costs such as permits
and inspection services. According to vendors contacted for this study, a
two-person crew can install a single Clock Spring® composite wrap in a 1/2
hour. As a rough estimate, assume 21/2 hours per person per composite
wrap (1/2 hour per installation plus 2 hours curing time). For a more compre-
hensive estimate of the duration of repair, include the time required for exca-
vation, installation of composite wrap, adhesive curing time, drying time for
coatings, and pipeline reburial. One partner reports using an estimate of 16
hours from excavation to reburial for repairs requiring up to 4 composite
wraps. Estimates should also include direct costs for consumable repair
materials (e.g., composite wrap kit and coatings) and indirect costs such as
inspection services and permits.
Clock Spring® composite wrap kits contain many of the items needed to
conduct the repairs, including the sleeve, the adhesive, the filler, a roller
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applicator, and application brushes. Cost may range from $432 for a 4"
pipeline kit to nearly $2,000 for a 56" pipeline kit. Some additional equip-
ment, such as a cinch bar and strap, and a spool feeder, will also have to be
purchased. This equipment, however, can be used for multiple repairs and
the costs can be spread over the lifetime of the equipment. For more infor-
mation on composite wrap kits, please refer to the Appendix.
Kits from other manufacturers will contain different equipment. Although this
study does not compare the economics of all of the available composite
wrap systems, the marketplace is quite competitive. The following economic
analysis incorporates cost information provided by Clock Spring®. Partners
are encouraged to search for the composite wrap system that best meets
their needs, and to use the methodology described in this Lessons Learned
study to perform their own economic analysis.
Exhibit 1 shows the most common labor and equipment costs used in es-
timating the cost of a composite wrap repair. One-time costs for training and
purchasing reusable equipment are excluded as they are assumed to be
similar or less than their equivalent costs for a pipeline replacement project.
Please note that these labor rates may not be applicable to all types of com-
posite wrap repair. Partners should consult the composite wrap manufactur-
ers before finalizing cost estimates.
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Exhibit 1: Calculating the Cost for Installing a Composite Wrap
Given: To repair a 6" non-leaking defect on a 24" pipeline, operating at 350 psig, assume
16 hours to complete project1 using the following labor categories2. Assume costs for
engineering management and planning to be 25% of field labor.
C|abor = cost of labor
Hourly rate of field labor category
Operator = $34/hr
Pipeliner =$31/hr
Apprentice = $21/hr
Ceqilip = cost of equipment
Cost of individual equipment
Composite Wrap Kit = $878 for 1 kit
Backhoe = $36/hr
Sandblasting Equipment =$10/hr
Pipeline coatings (5% composite kit) = $44
^direct = indirect costs such as field inspection crew, permits, etc.
(Assume 50% of total equipment and labor cost3)
(1) Calculate Cost of Labor
Clabor = Engineering management cost + Field labor cost
Field Labor Cost = hourly rate * time required to complete work
= ($34+ $31 +$21)* 16
= $1,376
Engineering management cost = 0.25 * $1,376 = $344
Clabor =$344 +$1,376 = $1,720
(2) Calculate Cost of Equipment
^quip = Cost of consumable materials (Composite wrap kit and coatings) +
Cost of renting/using equipment on-site
= $878+ $44+ ($36* 16)+ ($10* 16)
= $1,658
(3) Calculate Indirect Costs
^indirect = Cost °f permits, inspection services, right-of-way related expenses
= 0.5 * (Clabor + Cequip) = 0.5 * ($1,720 + $1,658)
= $1,689
(4) Calculate Total Cost of Repair
Total Cost of Repair = Clabor + Cequip + Cindirect
= $1,720+ $1,658+ $1,689
= $5,067
1 Partner supplied information.
2 Quick, P. "Economics of Pipeline Repair," The Southern Gas Association Transmission Operating
Conference, New Orleans, LA, July 2001.
3 Derived from Boreman, David. J. et.al. "Repair Technologies for Gas Transmission Pipelines,"
Pipeline and Gas Journal, March 2000.
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Step 3. Calculate methane savings. Composite wrap repair is not used to
address active methane leaks. The amount of gas saved is the amount of
gas that would have been vented had a pipeline replacement strategy been
implemented. Replacement requires the shutdown of pipeline and isolation
of the damaged portion of pipe with the use of shut-off valves. The distance
between shut-off valves is prescribed by DOT regulations and can be up to
10 miles in remote locations. Methane in the isolated pipeline segment is
generally vented to the atmosphere.
As shown in Exhibit 2, the volume of gas that would be saved by using
composite wrap instead of pipeline replacement can be calculated through
the use of a simple formula that takes into account the pipeline pressure,
length of the isolated section, and the cross sectional area.
Exhibit 2: Calculating Methane Savings with Composite Wrap Repair
Given: A pipeline company performs a composite wrap repair on a 24" pipeline, operat-
ing at 350 psig, with 10 miles between shut-off valves.
D = Inside diameter of pipeline (inches)
L = Length of pipeline between shut-off valves (feet)
P = Pipeline pressure (psia for low pressure1, psig for high pressure)
Pmetnane = Current methane market price ($3/Mcf)
Vmetnane = Volume of methane emissions
(1) Calculate Volume of Methane Emissions
Methane Savings with Composite wrap = Methane Emissions avoided from Pipe
Replacement
Vmetnane = Volume of methane savings with composite wrap for line under pressure
1,000
1,000
= 3,690 Mcf
(2) Calculate Value of Methane Savings
Value of Methane Savings with Composite wrap = Vmethane * Pmetaie
= 3,960 Mcf * $3/Mcf
= $11,880
Source: Pipeline Rules of Thumb Handbook, 5th Edition, 2002.
1 Pipeline pressure of 50 psi or less is considered low pressure.
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Step 4. Calculate cost of pipeline replacement. Calculate cost of pipeline
replacement. Costs associated with pipeline replacement can be grouped
into three categories:
* Purge procedures.
* Labor and equipment costs.
* Additional indirect expenses associated with pipeline replacement, such
as the cost of advertising if gas service is to be shutdown, relighting
customer pilots, inspection services, and permits.
After pipeline replacement, there is a need to purge a repaired segment
before bringing it back on-line, requiring the purchase and use of inert
gases, such as nitrogen. Exhibit 3 shows how to calculate costs from purge
procedures, by multiplying the volume of required purge gas by the gas
price.
Exhibit 3: Calculating Purge Procedure Costs for Pipeline Replacement
Given: Assume a 24" pipeline case operating at 350 psig, with shut-off valves 10 miles
apart.
D = Inside diameter of pipeline (inches)
L = Length of pipeline between shut-off valves (feet)
Vp = Volume of the pipeline segment
Ppgas = Current purge gas market price ($/Mcf)
Vpgas = Volume of purge gas
(1) Calculate Volume of Purge Gas
Vpgas = Volume of purge gas1 used during pipeline replacement procedure
= Vp* 1.2 (restoring line + 20% wasted)
= I
[
n*D2*L
'1.2
4*144*1,000
'3.14*242*52,800N1 *i 2
576*1,000 J
= 199Mcf
(2) Calculate Cost of Purge Gas
Purge Gas Cost = Vpgas * Ppgas
= 199Mcf *$4/Mcf
= $7961
11nert gas assumed to be nitrogen at $4/Mcf.
10
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Exhibit 4 shows how to calculate the labor and equipment costs of a pipe
replacment project. In general, the costs associated with pipeline replace-
ment are usually higher than those associated with composite wrap repair.
Given: A pipeline company has detected a 6" non-leaking defect on a 24" diameter
pipeline operating at 350 psig. The shut-off valves are 10 miles apart. Replace 72" of
pipeline1.
Assume a 40-hour job2 and the following labor and equipment classes and hourly rates3.
Assume costs for engineering management and planning to be 25% of field labor.
Hourly Rate of each Labor Category
Welder = $35/hr
Operator = $34/hr
Pipeliner =$31/hr
Apprentice =$21/hr
Cost of Equipment
Crane/Boom Truck = $36/hr
Welding Rig = $20/hr
Backhoe = $36/hr
Steel Pipe4 = $50/ft
Coatings5 = $303
(1) Calculate Cost of Labor
Cost of Field Labor = ($35 + $34 + $31 + $21)/hr * 40 hr
= $4,840
Engineering Management Cost = 0.25 * $4,840 = $1,210
Total Labor Cost, Clabor = $4,840 + $1,210 = $6,050
(2) Calculate Cost of Equipment
Total Equipment and Material Cost, Cequip
= ($36 + $20 + $36)/hr * 40 hr + $50/ft * 6ft + $303
= $4,283
(3) Calculate Indirect Cost
Indirect Cost = cost of permits, inspection services, right-of-way related expenses6
^direct = (Assume 40% of total equipment and labor cost)
= 0.4 * (Clabor + Cequip)
= $4,133
(4) Calculate Total Cost
Total Cost = Clai,or + Cequip + Clndirect
= $14,466
'Replace at least three times the pipe diameter. Information based on partner reported information.
2Time required to replace pipeline from excavation to reburial. Based on partner reported information.
Assumes 1 work-week (5 days, 8 hours/day). Excludes overtime.
3Quick, P. "Economics of Pipeline Repair," The Southern Gas Association Transmission Operating
Conference, New Orleans, LA, July 2001.
'Assumes $50/foot. Partner reported information.
5Basis: Oil and Gas Journal, "Composite Wrap Approved for U.S. Gas-Pipeline Repairs", Oct 9,1995.
Used three times the cost listed for a 2-foot split sleeve.
'Derived from Boreman, David. J. et.al. "Repair Technologies for Gas Transmission Pipelines,"
Pipeline and Gas Journal, March 2000.
11
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Step 5: Evaluate the economics. The comparison shown in Exhibit 5
examines the cost of replacing a segment of damaged pipeline and the cost
of repairing the defect with composite wrap for two scenarios. In both
cases, the defect has been found on a 24" pipeline at 350 psig. The only
difference is the length of the defect; in the first case, it is 6" long, and in the
second, 234" long. These two examples are chosen because the first, short
defect represents the most typical repair, and the second, long defect, repre-
sents a scenario where the cost of composite wrap repair exceeds the cost
of pipeline replacement.
Site excavation and reburying the pipeline are activities common to both
repair options. To simplify the analysis, the costs for such common activities
are assumed equal and are excluded.
The remaining costs for labor and materials are unique to each repair op-
tion. Exhibit 5 lists major costs for each repair. A crane or boom truck is
unique to pipeline replacement and is included in the basic analysis.
Once the replacement segment is aligned and welded in place, there is typi-
cally a 24-hour wait before it can be tested to ensure the welds are secure.
The analysis in Exhibit 5 assumes that the testing is completed within the
specified period.
This analysis shows that composite wrap repair results in significant
methane, nitrogen, and labor savings. The cost of the composite wrap kits is
low for the first scenario, as only one repair kit is needed for the 6" defect. In
the 6" defect case, methane savings alone cover the cost of composite
wrap repair, and the payback is immediate.
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Exhibit 5: Comparison of Pipeline Replacement and Composite Wrap
Economics
Given: 24" diameter pipeline operated at 350 psig1 with 10 miles between shut-off valves.
Methane Lost
Purge Gas (Mcf)
Number of Composite
Wrap Kits
Cost of Methane
Emissions3
Cost of Purge Gas4
Labor5
Equipment and
Materials6
Indirect Costs
Total Cost of Repair
Most Economical
Option
6" Defect
Composite
Wrap Repair
0
0
1
$0
$0
$1,720
$922
$1,321
$3,963
X
Pipeline
Replacement
3,960
199
0
$11,880
$796
$4,350
$2,843
$2,877
$22,746
234" Defect
Composite
Wrap Repair
0
0
202
$0
$0
$3,440
$18,440
$10,940
$32,820
Pipeline
Replacement
3,960
199
0
$11,880
$796
$6,525
$7,280
$5,522
$32,003
X
'Equivalent to the reduced pressure at which composite wrap repair would be performed.
2 Based on the number of composite wraps side-by-side less 2" needed on each end of the first and
last sleeve to adhere the composite wrap to the parent pipe.
3Assume methane at $3/Mcf.
4Assume nitrogen at $4/Mcf.
5 Pipeline Replacement: Assume 40 hours (no overtime) to complete 6" project, 60 hours (no over-
time) for 234" project. Composite Wrap Repair: Assume 16 hour to complete 6" project and 32 hour
to complete 234" project. Labor rates as shown in Exhibits 1 and 4. Labor for the pipeline replace-
ment excludes operator, as assumption made that operator's primary role would be related to exca-
vation and reburial. No similar adjustments made for labor categories for composite wrap.
'Excludes cost of backhoe and sandblasting equipment shown in Exhibits 1 and 4. For 234" defect,
assume 39 ft of replacement pipeline (double the length of defect).
For the 234" defect case, 20 composite wrap kits are butted together and
equipment costs increase approximately 20-fold over the short defect case,
while they increase by a factor of 2.5 for pipeline replacement. Methane sav-
ings and lower labor costs in the composite repair are offset by high materi-
als costs—this results in more comparable costs for both repair options.
It is important to note that in some circumstances (i.e., certain long defects),
pipeline replacement is the most cost-effective repair option, despite the gas
losses. Some Natural Gas STAR partners, however, have chosen composite
wrap over pipeline replacement in these circumstances, underscoring that
cost is not the only factor that influences the selected repair option. As the
13
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following case study from a Natural Gas STAR partner illustrates, urgency of
repair, availability of a back-up gas supply, and speed of repair influence the
final decision.
Partner Experience with Composite Wrap Repair
One Natural Gas STAR partner reported completing more than 300 composite wrap
repairs of non-leaking defects on transmission lines larger than 10" since 1995. In one
situation, the partner repaired a 20" defect on a pipe by butting together two composite
wrap sleeves. Since the damaged pipe was near a creek bed, not having to open the
pipeline (as would have been the case with a segment replacement), prevented any water
exposure to the pipeline interior and avoided all the attendant complications. Two trained
personnel installed the composite wrap and reburied the pipeline in four hours. The entire
repair, from excavation to reburial, was completed in two days, and the line was never out
of service.
For this partner, cost is often a secondary consideration in selecting composite wrap over
pipeline replacement. Primary considerations include:
* Can the repair be completed without taking the pipeline out of service? This is
important in areas where there is no back-up gas source.
* How quickly can the repair be completed? Composite wrap repair usually requires
two days, while five to seven days are common for pipeline replacement.
* Can the repair be completed safely? Operators are always concerned when repairs
such as composite wrap or steel sleeves are performed on a "live" pipeline.
Composite wrap presents no additional safety concerns compared to steel sleeve
repair.
Lessons
Learned
Composite wrap repair can cost-effectively eliminate methane emissions
associated with repairing certain non-leaking defects on pipelines. Partners
offer the following lessons learned:
* Composite wrap repair can be used for permanent repair of non-leaking
defects on pipelines and temporary repair of defects caused by internal
corrosion.
* Composite wrap repair results in methane savings as it eliminates the
need to shutdown damaged pipeline and vent methane to the atmos-
phere prior to repair.
* Methane savings may be sufficient to cover the costs of composite wrap
repair and result in immediate payback.
* Composite wrap may be an ideal choice for non-leaking defects when
repair is urgently required, must be completed quickly, and no back-up
gas supply is available.
* During repair, the pipeline can usually operate at pressures at least half
of full pressure, which avoids potential service interruptions, revenue
losses, and vented gas costs.
* The light weight of the composite wrap material makes it relatively easy
to install. Two lower-skilled technicians can complete a repair in a few
hours without welding, cutting, or special handling equipment.
14
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* Composite wrap eliminates costly delays for specifying and procuring
metal sleeves or pipe segments to repair the pipeline.
* Composite wrap restores the pipe's original pressure capabilities and
improves its resistance to further structural deterioration.
* Tests of segments repaired with composite wrap indicate continuous
cathodic protection.
* Many companies now supply composite wrap systems, each with its
own advantages, so it is important to shop around.
* Record methane emissions reductions achieved through this approach
and include reductions in Natural Gas STAR Program reports if your
company's prior policy was to replace sections of damaged pipeline.
Armor Plate, Inc., .
References
ASME B31G, Manual for Determining Remaining Strength of Corroded
Pipelines: Supplement To B31 Code-Pressure Piping, 1991.
Boreman, J. David, et al., Repair Technologies for Gas Transmission Pipe-
lines, Pipeline and Gas Journal, March 2000.
Columbia Gas Transmission and Columbia Gulf Transmission, personal con-
tact.
EPA Partnership, Columbia Energy Reports Significant Reduction in Meth-
ane Emissions, November 2000.
Furrow, M. L, U.S. Department of Transportation, personal contact.
Gas Research Institute, Summary of Validation of Clock Spring9 for Per-
manent Repair of Pipeline Corrosion Defects, GRI-98/0227.
Leewis, Dr. Keith, Gas Technology Institute, personal contact.
McAllister, E.W., Pipeline Rules of Thumb Handbook, 5th Edition, 2002.
Mohitpour, M. et al., Pipeline Rehab Responding to Regulatory Pressures,
Technological Advances, Oil and Gas Journal, January 20, 2003.
Oil and Gas Journal, Composite Wrap Approved for U.S. Gas-Pipeline
Repairs, October 9, 1995.
Quick, Porter, Economics of Pipeline Repair, The Southern Gas As-sociation
Transmission Operating Conference, New Orleans, Louisiana, July 2001.
15
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The Clock Spring® Company L.R, .
The StrongBack Corporation, .
Tingley, Kevin, U.S. EPA Natural Gas STAR Program, personal contact.
U.S. Environmental Protection Agency. Lessons Learned: Using Pipeline
Pump-Down Techniques to Lower Gas Line Pressure Before Maintenance
(EPA430-BOO-007, December 2000).
WrapMaster, Inc., .
16
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Appendix
Clock Spring Composite Wrap
Pipeline Products
Pipeline Size
4"
6"
8"
10"
12"
14"
IB-
IS"
20"
22"
24"
26"
28"
30"
32"
36"
40"
42"
44"
48"
56"
Cost of Composite
Wrap Kit (2001)
$432
$402
$466
$508
$549
$599
$649
$717
$794
$859
$878
$924
$969
$998
$1,051
$1,129
$1,331
$1,386
$1,488
$1,668
$1,951
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Composite Wrap Kit Contents
• Composite wrap sleeve (12" wide x 1/2" thick when installed)
• Adhesive
• Load transfer filler
• Roller applicator
• Double-sided adhesive starting pad
• Alignment blocks
• Application brushes, paint tray liners, stir stick, Jiffy mixer, trash bags
• An optional, specially designed installation stand
Source: The Clock Spring® Company L.P. Clock Spring® is a registered trademark of NCF Industries
Inc. All rights reserved. Manufactured under license from NCF Industries Inc. The Clock Spring
symbol is a trademark of Clock Spring Company L.P.
Miscellaneous One-time
Cost Equipment
(not included in cost of kit)
Standard Cinch Bar and Strap
H.D. Cinch Bar and Strap
Cinch Straps
Spool Feeder
Temperature Gage w/Magnetic Base
Shore "A" Hardness Tester
Complete Cinch Bar and Strap
Training - Excluding Travel Expenses
$150
$225
$25
$350
$32.50
$350
$150
$750
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&EPA
United States
Environmental Protection Agency
Air and Radiation (6202J)
1200 Pennsylvania Ave., NW
Washington, DC 20460
EPA430-B-03-017
July 2003
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