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Evolution of Epoxy Pipeline Technology

Ian Fordyce, Principal Consultant, Oil & Gas

Contents

• Introduction• Epoxy Repair Sleeves

• Pipelines• Domed repairs on fittings

• Epoxy End Seals• Grouted Tees

• Hot tap fittings• Repair of illegal taps

• Road Crossings – alternative to thick wall pipe• Conclusions

Introduction

• During the early 1980’s British Gas developed the epoxy sleeve pipeline repair technology that is suitable for most pipeline defects

• The physical properties of the epoxy that was developed was so good that the original technology has been further developed over the years to create branch connections, sleeved pipeline end seals and leak repair solutions

• This paper provides an overview of the evolution of epoxy based pipeline technology covering all of the various applications and the benefits of use

Epoxy Repair Sleeves

• During the 1980’s British Gas started the development of the Epoxy Sleeve Repair Technology

• The epoxy sleeve is used on pipeline defects such as corrosion, dents, gouges, cracking, small minor leaks

• 30 years on, it still remains one of the only pipeline repair methods that is suitable for girth weld defects.

Epoxy Repair Sleeves

The epoxy sleeve repair supports and strengthens damaged pipelines without interrupting the product flow. Each fitting comprises two oversized half shells, which are either welded or mechanically joined to fully encircle the damaged section of pipeline. The annulus is then sealed at both ends prior to injecting with epoxy grout. This results in a repair that is usually stronger than that of the adjacent undamaged pipe material. On completion of a repair the shell can be linked to the pipeline for cathodic protection.

Epoxy Repair Sleeves

• The effective damage depth should be no greater than 80% of the pipe wall thickness with deepest point being no greater than 90%

• A dent/defect combination must not have a dent depth greater than 9% of the pipelines diameter or a defect depth greater than 12.5% of the pipe wall thickness

• A pressure reduction of 15% is usually required prior to an installation, although, under some circumstances this isn’t required

• The pressure must not be increased until 24 hours after the installation is complete. This 24 hour period allows the epoxy to sufficiently cure so that stresses in the defect area are transferred into the repair sleeve during re-pressurisation

Epoxy Repair Sleeves – Small diameter applications

• The epoxy repair sleeve has been designed for small diameter applications typical of valve body vent and sealant line corrosion

• Sealant line repair sleeves have been qualified for pressures of 689 barg (10,000 psig) in order to accommodate sealant injection pressure

Epoxy Repair Sleeves – Domed repairs on fittings

• In recent years, the epoxy repair sleeve has been adapted to completely encapsulate damaged or corroded fittings by means of a domed repair

• The design is based on the principles and concepts of the traditional epoxy repair sleeve whereby the fitting is split into two half shells

• The branch half shell has a welded dome end that is placed over the damaged fitting and bolted, along the longitudinal flanges, to the lower half shell. The remaining gap is then flooded with epoxy grout providing a permanent repair to the pipework

Epoxy End Seals

• Excessive corrosion has been found on carrier pipes where end seals have failed and water has entered the sleeves

• The introduction of a nitrogen charge into a sleeve annulus creates an inert, non-corrosive atmosphere for the carrier pipe, and was considered to have many benefits over the grouts and gels used at the time

• Prior to the introduction of using thick wall pipe for road crossings thousands of steel sleeves were installed during the 1960’s and 1970’s

• During the early 1960’s sleeves were typically air filled with the ends sealed to prevent the ingress of soil and water

Epoxy End Seals

• An epoxy end seal has been developed which allows for retrospective nitrogen filling of sleeves already installed within a pipeline network

• This illustrates the epoxy end sleeve sealing the void between the sleeved section and carrier pipe to enable the pipeline sleeve annulus to be filled with nitrogen

Epoxy Grouted Tees

• The Grouted Tee is a novel method of installing a branch connection onto a live pipeline

• The technology was developed in 1997 based on the well established epoxy filled repair sleeve

• Welding new connections onto live pipelines is hazardous and in some cases impossible due to high flow rates

• The Grouted Tee connection is bonded to a live pipeline without interrupting or adjusting the pipeline product supply

Epoxy Grouted TeesPipeline Welding Issues

• Safety related to hot work• Large crew of highly skilled welders required• Maintaining temperatures where high flow

rates • Typically 30% pressure reduction required• Operational delays can affect planning &

scheduling• Thick wall pipe WT > 32mm requires PWHT• Thin wall pipe requires strict procedure and

specially trained welders• Ovality & misalignment can cause welding

difficulties

Epoxy Grouted TeesMajor Components

Epoxy Grouted Tees

• The saddle seal is the main pressure containment component that is energized when the two halves of the shell are bolted together

• All Grouted Tee fittings are sized to allow an even gap between the bore of the shell assembly and the outside diameter of the parent pipe

• This annular gap is filled with the same epoxy grout to that of epoxy repair sleeves

• The saddle seal is the main pressure containment component that is energized when the two halves of the shell are bolted together

• All Grouted Tee fittings are sized to allow an even gap between the bore of the shell assembly and the outside diameter of the parent pipe

• This annular gap is filled with the same epoxy grout to that of epoxy repair sleeves

Epoxy Grouted Tees Qualification Programme

• Structural Loading• Pressure containment • Combined loadings • Thermal stress, sustained & fatigue

• Materials Selection• Seal - Fluid compatibility • Grout – Ambient and Environmental Temperatures• Long term assessment (40 years design life)

• Traffic Loading• 1.5 million cycles simulating a 12.5 tonnes vehicle at 1m depth of soil cover

Epoxy Grouted Tees – External Verification

Crude Oil Pipelines

• ASME B31.3• ASME B31.8• IGE / TD / 1• IGE / TD / 12• PD 8010

Gas transmission

Subsea Grouted Tee

Grouted Tee Case Study36” x 36” – UK National Grid Feeder 7

5 men / 3days operation

Grouted Tee Case Study 42” x 18” Class 600 - Feeder 13

• High demand for the gas (high flow rate)• No interruption to the pipeline operation• Grouted Tee installation time – 7 hours• Estimated welding time for 42” split tee –

3 days

Grouted Tee Case Study 20” Stopple - Sao Paulo Brazil

High flow – Thin wall pipelines

Thin Wall Application – 20” diameter 6mm wall thickness

Grouted Tee Case Study 8” x 8” – Windsor, London

Critical adjacent pipeline (aviation fuel) – no hot work

Grouted Tee Case Study 20” x 24” – Gateshead, North of England

Heavily corroded cast iron

Grouted Tee Case Study Multiple Branch Tees

Epoxy Grouted Tees Repair of Illegal Hot Tap Connections

• The Grouted Tee can be used to support a cut out and replacement operation or a single hot tap repair

• The fitting is installed without the requirement of on-site welding which eliminates the hazard of hot work operations in close proximity to a potentially fragile illegal hot tap connection

• Removing the requirement of welding activities on a live pipeline also eliminates the high risk of potential burn through on thinner wall pipelines during installation

Cost comparison between welded and Grouted Tee fittings

The total costs for welded split tees and Grouted Tee connections are generally comparable. Although the physical cost of the Grouted Tee is considerably more expensive than the welded split tee alternative, the installation costs are considerably less with the total cost being less at larger diameters and only slightly more expensive throughout the lower range

The total costs for welded split tees and Grouted Tee connections are generally comparable. Although the physical cost of the Grouted Tee is considerably more expensive than the welded split tee alternative, the installation costs are considerably less with the total cost being less at larger diameters and only slightly more expensive throughout the lower range

Road Crossings – Heavy Wall Replacement Alternative

• Current pipeline specifications require heavy wall pipe to be used for areas along a pipeline which are exposed to higher external forces such as road and rail crossings

• Traditional means to replace standard wall with heavy wall pipe is extremely expensive if the operation requires the pipeline to be decommissioned

• This practice may also be hazardous if using flowstop and bypass procedures

Road Crossings – Heavy Wall Replacement Alternative

• During 2013, GL Noble Denton supported National Grid in the first variation of this whereby a modified epoxy sleeve was designed and developed to create an assembly of sleeves covering up to 80m of 48” diameter pipeline

• The concept was to provide a cost effective and safe means to create a protective barrier around the pipeline over a specified length

Road Crossings – Heavy Wall Replacement Alternative

• Standard epoxy repair sleeve specifications were adopted to provide a design that would provide a protective barrier and transfer stress via pressure increase throughout the remaining life of the pipeline

• Overlapping sleeve sections covered the gap between each epoxy repair sleeve providing complete protection throughout the length of the road crossing

Road Crossings – Heavy Wall Replacement Alternative

• Following the successful completion of the project the IGEM (Institution of Gas Engineers & Managers) standards committee in the UK are now looking to include the epoxy sleeve assembly option as a suitable alternative to replacing with thick wall pipe

• The proposed approach will be added to the list of possible changes when a panel meets for the next revision of IGEM/TD/1 – Recommendations on Transmission and Distribution Practice, Steel Pipelines for High Pressure Gas Transmission, Edition 6

Conclusions

• Overall, epoxy pipeline technology has evolved over the last 30 years and will continue to provide solutions to the complex problems faced by operators in the oil and gas industry. Although epoxy pipeline technology was originally developed to provide repairs to pipeline defects it has demonstrated its versatility with the design principles and concepts being adopted for range of client requirements

• With the economic necessity of maintaining production and reducing risk ever more prevalent in the oil and gas industry, the use of epoxy technology will become increasingly important going forward

Conclusions

• The key advantages of epoxy pipeline technology are as follows:

• Eliminates all welding works on site during installation • Significantly reduces installation time on site• Higher probability of scheduled installation• Minimise risks of live pipeline intervention• Completely independent to parent pipe materials • Can be adopted to an array of projects and manipulated to many different uses • Infinite length of pipeline can be covered in a road crossing • Large range of diameters can be covered with an installation • Economic gains made through limiting risk to product flow• Suitable for very thin wall pipelines and applications on high strength steel

pipelines• Unique in that the technology can be modified for specific client requirements

For further information visit www.gl-nobledenton.com

Thank you for your attention!

ian.fordyce@gl-group.com