The document provides an overview of the evolution of epoxy-based pipeline repair technology developed by British Gas in the 1980s. It describes how epoxy repair sleeves can be used to repair pipeline defects such as corrosion and cracks without interrupting product flow. Over time, the technology has been adapted to create branch connections using epoxy grouted tees and to replace pipeline sections under roads with epoxy sleeves as an alternative to heavy wall pipe. The epoxy solutions provide benefits such as eliminating on-site welding and allowing repairs without reducing pipeline pressure.

1. Evolution of Epoxy Pipeline Technology
Ian Fordyce, Principal Consultant, Oil & Gas
www.gl-nobledenton.com

2. 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

3. 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

4. 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.

5. 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.

6. 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

7. 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

8. 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

9. Epoxy End Seals
• 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
• 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

10. 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

11. 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

12. Epoxy Grouted Tees
Pipeline 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

13. Epoxy Grouted Tees
Major Components

14. 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

15. 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

16. Epoxy Grouted Tees – External Verification
Gas transmission
Crude Oil Pipelines
Subsea Grouted Tee
•
•
•
•
•
ASME B31.3
ASME B31.8
IGE / TD / 1
IGE / TD / 12
PD 8010

17. Grouted Tee Case Study
36” x 36” – UK National Grid Feeder 7
5 men / 3days operation

18. 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

19. Grouted Tee Case Study
20” Stopple - Sao Paulo Brazil
Thin Wall Application – 20” diameter 6mm wall thickness
High flow – Thin wall pipelines

20. Grouted Tee Case Study
8” x 8” – Windsor, London
Critical adjacent pipeline (aviation fuel) – no hot work

21. Grouted Tee Case Study
20” x 24” – Gateshead, North of England
Heavily corroded cast iron

22. Grouted Tee Case Study
Multiple Branch Tees

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. Thank you for your attention!
For further information visit www.gl-nobledenton.com
ian.fordyce@gl-group.com