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Sandwich solution for damaged pipe

A new composite pipe repair method joins a growing number of asset life extension techniques designed to save cost and cut risk without disrupting operations.

Advances in composite materials have enabled numerous applications for oil and gas infrastructure repair and maintenance. Add to the list TSG/Pipe Repair with Sandwich Plate System (SPS), a new offering from UK-based TSG Marine.

The technology provides an alternative to crop-and-replace pipe repair, eliminating potentially hazardous “hot” work and allowing the pipeline to remain in service during repairs.

The TSG system makes use of the SPS developed by UK company Intelligent Engineering.

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The composite material, which comprises two metal plates bonded with a polyurethane elastomer core, has been used to repair offshore structures such as platforms and floating production, storage and offloading (FPSO) hulls.

In the TSG pipe repair system, the “sandwich” consists of the prepared section of the damaged or corroded pipe, a metal clamshell that clamps around the pipe, and the elastomer, which is pumped into the cavity between. The elastomer forms a protective lining that maintains a bond with the original pipe.

The clam shells, which are manufactured in standard one-metre lengths, are bolted in place and fitted with gaskets and seals for the injection process.

A small specialist team is dispatched for the procedure, which can be done much faster than traditional pipe repair, says TSG Marine managing director Allan Syme.

“This is a pragmatic response to common pipework corrosion problems,” he says.

“The industry requires efficient and effective asset life extension options. We are operating in an environment where we are requiring our engineering structures and equipment to operate beyond their intended design life.”

Allan Photo: Allan Syme, TSG Marine

"This is a pragmatic response to common pipework corrosion problems."
Allan Syme, TSG Marine

The TSG/Pipe Repair with SPS system was developed to restore the original design life of corroded pipework, he says.

“This is achieved as the repair methodology tackles structural integrity, containment and corrosive protection.”

The one-metre sections may be connected at the flanges to form longer repair sections, or bolted on later if corrosion “creeps” along the pipe.

The original pipework under a repaired section may, in fact, completely erode — but the elastomer will remain as a corrosion and thermal barrier, while the outer shell is designed to contain the system pressure of the original pipework.


TSG has a track record with SPS, having used the composite technology to make deck repairs

“The concept for this application for SPS,” Syme explains, “came when considering a particularly challenging pipe repair project, where at that time, given the repair location, the only available option seemed to be replacement.

"Replacement of that particular pipe required the shutdown of a large plant and the resulting costs. We therefore set out to develop a permanent repair method that could be installed in-service and be classed as permanent.

“As our intention was to launch in the oil and gas market, we wanted to ensure a broad range of applications and therefore sought to develop a ‘no hot works’ solution.”

1709.TSG10.jpg CORROSION CONTAINED: The SPS technology creates a “sandwich” when elastomer is injected between the corroded or damaged pipe and a metal clamshell covering. Photo: TSG Marine

TSG sought input from a major client, Syme says, “which generously shared information on the types of issues they were having and the limitations that would apply when making repairs, especially in hazardous areas”.

The client wanted a method that would eliminate hot work, yet result in a repair “that could be regarded as permanent rather than temporary”, he says.

“We identified the real constraints and developed a system that we hope covers most of the issues raised.”

TSG used this year’s Offshore Europe conference and exhibition in Aberdeen as an occasion to announce that the TSG/Pipe Repair with SPS had received DNV GL verification.

While verification tests, carried out as part of the technology qualification process, were not conducted on a working pipeline, Syme says, “the repair method has been designed on the basis that the original pipe will continue to corrode.

1709.TSG18 ADD-ON: Standard one-metre sections may be bolted together to repair longer sections of pipe. Each clamshell section is affixed with a data plate containing operational condition information and a unique serial number linked to TSG Marine’s configuration management system. Photo: TSG Marine

“As part of the testing programme we simulated this scenario by machining out the original pipe to leave just the elastomer core and the outer clamshells.

"This demonstrated that the TSG/Pipe Repair with SPS not only offers structural integrity, but also containment and corrosive protection.”

The technology qualification as it stands applies to pipes carrying fresh water or seawater, he says.

“However, we will be seeking to expand the range to other media shortly and will be working with our clients and the verification authorities to achieve this.”

1709.TSG5.jpg BOLTED DOWN: When bolted in place, the clamshell covering provides equal or greater pressure containment capacity as the original pipe. Photo: TSG Marine

The product is designed for a temperature range of -20°Celcuis to 80°C, but can be adapted for more extreme conditions “on a case-by-case basis”, he adds.

The repair methodology would not be suitable for some applications — in pipe that is subject to high velocity turbulent flow, for example, or one that contains abrasive materials that could erode the elastomer if the original pipe corroded through its entire thickness.

“However, all other applications could be considered, subject to a gap analysis being carried out and any additional approvals being sought, as required,” Syme says.

TSG is aiming the product at the UK continental shelf oil and gas market, he says. But “we consider it could prove an effective repair solution in a large number of other markets and industries where the ability to restore the system to original design life without having to shut the process down or break containment will be attractive”, he notes.

“We see TSG/Pipe Repair with SPS sitting in the space between temporary repair methods and traditional crop-and-replace.”

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