abstract of papers:- - online portalportal.malaysiangas.com/document/publication/... · abstract of...

Abstract of Papers:-

Long Term Durability of Clock Spring Repairs – Recent Removals and Examinations

The Clock Spring repair system was the subject of a rigorous Research and Development

program conducted under the management of the Gas Research Institute (GRI). The

program extended over a decade and considered long term degradation.

As part of this program an extensive field validation program was required by the US

Department of Transportation. This requirement was added to verify the laboratory

experimental results and to provide and to validate the real world behaviour on actual

pipelines. Statistical sampling was required and a matrix of various soil types, location and

environmental conditions were created as the basis for the field validation study. The

results were published in the public report GRI 1998-0032. This peer reviewed report was

relied upon by the industry and regulators as the basis of documentation to suggest

amended code language for both liquid and natural gas pipeline which was subsequently

proposed and adopted in CFR 192 and 195.

Abstract of Papers (cont’d) :-

Over two decades of time has past since the GRI established the first steering committee of

industry experts to design the scope and methods of the investigations. Subsequently

several hundred thousand Clock Spring repairs have been made. Units have been installed

in many countries and in almost all conceivable environmental conditions.

The purpose of this paper is to document where various repairs have been taken out of

service and to document the subsequent investigations and findings in respect to the

condition and overall effectiveness of the repair.

Clock Spring®

Long Term Durability of Clock Spring

Repairs: Recent Removals and

Examinations

Darren Looi

Asia Pacific Representative

Clock Spring Company, L.P.

Abstract

With over 20 years of commercial

experience and over 750,000 repairs

installed in over 72 countries the purpose of

this paper is to case study recent removals

of Clock Spring repairs from high pressure

pipelines and riser service and to

substantiate the original test and validation

data and acceptance of Clock Spring as a

permanent repair system.

The history

The removals

The conclusions

The History

The R+D of Clock Spring started in the early

1980’s and was driven by actual pipeline

operators who were interested in a repair

alternative to:

- Welded steel sleeves

- Hot tapping / cut and replace

The History

Industry pre-requisites were established:

- Repair had to be proven to be permanent

- Easy and quick to install for all pipe diameters

- No hot work

- No shielding of C.P

- No shut down of pipeline operation

Industry pre-requisites cont….

- Suitable for use in all environments andsoil types.

- A standard off the shelf product to suit alldefects of up to 80% metal loss on anyoperating pressure pipeline.

The History

Industry pre-requisites cont….

- Validated with a mathematical modelwhich allows permanency to beconfirmed in accordance to variousdefect assessment criteria (B31.G,modified and effective area), classlocation and based on material propertiesderived from an extrapolation of a 50 yearperformance.

The History

The History

A steering committee wasestablished under the auspices of theGas Research Institute (GRI) andincluded:

- The GRI

- Battelle

- South West Research

- Kiefner & Associates

Steering committee cont….

- Stress Engineering Services

- North Western University

- ITW – Devcon

- PRCI

- Pipeline Operators

- NCF Industries

- The Clock Spring Company, L.P.

The History

The History

In addition the US DOT/OPS providedtheir own requirements and pre-requisites for an acceptable repairdesign including:

• Tensile tests

• Stress rupture tests

• Lap shear strength

• Durability

• Burst pressure testing

• Adhesive testing

• Fatigue testing

• Field tests

• Durability tests

The History

The GRI R+D program took 10 years and involved both in-

depth laboratory and in-field testing to determine if a

composite product could meet the established industry,

GRI and DOT pre-requisites and provided thorough

evaluation of:

- The most suitable fibre type and architecture

- Resin matrix

- Adhesive and filler systems

Composite Coil

• Composite coil

• E-glass filaments

• Polyester resin

• Memory matrix

• Conforms tightly to

pipe

• Unidirectional

filaments

• Hoop reinforcement

Adhesive

• Methyl Methacrylate

Polymer

• Proprietary composition

• 1200 psi lap shear

strength

Filler

• High compressive strength• Greater than 8,000 psi

compressive strength

• Transfers load from the pipe to the Clock Spring

History

Throughout the 10 year R+D program

topical reports were released by the GRI

for peer review and evaluation.

The GRI stated in 1998 “Several years ago

the research team proved the durability of

the Clock Spring product through

hydrostatic testing and accelerated

corrosion testing.”

History

“These laboratory predictions indicated that

Clock Spring can provide safe repairs

beyond 50 years. However to further verify

its performance required that repaired

sections remain buried for up to 7 years in

actual operating conditions.”

History

“Through this recent field based research

we confirmed repairs will last at least 50

years but we feel that most repairs will last

much longer.”

History

Following this work the DOT accepted the

use of alternative repair technologies for

high pressure oil and gas transmission

pipeline service providing the pipeline is

“repaired by a method that can permanently

restore the serviceability of the pipe as

shown by reliable engineering tests and

analyses.”

History

Many other recognised approvals werealso given allowing the acceptance ofcomposite repair sleeves including:

ASME 31.4

ASME 31.8

API 1160

API 570

History

Clock Spring has now been used

for over 20 years in all regions of

the world.

Africa

Middle East

U.S.A.

Asia

In all environments

The History

Offshore

Desert

Tropical

Underwater

The History

For many applications

Tank Farms

Refinery

Pipe Supports

Structural

The Removals

CASE 1

Location: North America

Pipeline: High pressure natural gas 30”

Repair made in: 2005

Removed in: 2010

The Removals

Reason for removal:

An OLI survey performed in 2009 indicated

corrosion growth under the repair.

Conclusion:

The units were difficult to remove and well

bonded in place. No new corrosion under

the repair was identified.

The Removals

CASE 2

Location: Asia

Pipeline: 20” oil export pipeline.

Initial repair: significant dent due to poor

backfill.

Repair made in: 2006

Removed in: 2010

The Removals

Reason for removal:

Operator decided to cut and replace the

section to allow safe passage of future OLI

surveys.

Repair excavation

Installed Clock Spring after coating removal

Cutting the coil into sections for removal

Cuts in both 3 and 9 o’clock positions

Removing the cut sections by chisel

Crowbars used to prise the coil from the pipe

Layers of the bonded Clock Spring and filler on

the pipe

Final coil removal

Removing the filler from the pipe surface using a

chisel

Final filler removal – no corrosion present

The removed Clock Spring sections including the

original molded filler from the dent section

The Removals

CASE 3

Location: North America

Pipeline: 30” oil pipeline.

Initial repair: 1995 external corrosion and

potential reinforcement of SCC.

Removed in: 2010

The Removals

Reason for removal:

Evaluation of performance of Clock Spring

repair.

Conclusion:

The unit had to be sand blasted and pry

bars used to remove the various layers of

the coil. The coil was well bonded within

each layer and to the carrier pipe.

Conclusion cont….

No evidence of any active corrosion, no

evidence of any cathodic disbondment or

cathodic shielding effects. After 15 years of

service the repair remained sound and

durable.

The Removals

CASE 4

Location: Middle East

Pipeline: 18” high pressure high

temperature oil riser in the splash zone.

Initial repair: 1997 external corrosion.

Removed in: 2006

The Removals

Reason for removal:

The riser was selected for shut down and

replacement and client decided to evaluate

the repair performance.

Conclusions:

The repair was well bonded to the riser and

very difficult and time consuming to remove.

After 9 years …….

Coil cut away in sections to be removed

Cleaning to remove filler, adhesive and fibre still

bonded to the riser

Final preparation for UT inspection

Conclusions

Several more case studies are availableand reported in the correspondingtechnical paper.

- As part of the initial validation processthe US DOT required the GRI to conductlong term field validation.

- This was conducted over a 7 yearperiod and was an integral part of theoverall permanent repair acceptanceand validation of the Clock Springproduct.

Conclusions

- The findings in the above case studiesand removals of repairs with up to 15years operating service are consistentwith the original reported anddocumented long term testing asconducted in the 10 year GRI program.

Conclusions

Conclusions

- The operational history of the case

studied repairs shows the GRI made

sound technical decisions in terms

of the composite architecture used

and the constituent components

within the Clock Spring repair.

- The approvals attributed to the use of a

long term, tested composite repair

sleeves for reinforcement of corrosion

and mechanical damage on high

pressure pipeline and riser systems

has been validated.

Conclusions

Questions ?

Darren Looi

Asia Pacific Representative

Clock Spring Company, L.P.

Darren.Looi@clockspring.com