NEWS RELEASE from FURMANITE International

Composite repairs provide solution to corrosion damage

When replacement of a 30 inch hydrocarbon gas pipeline suffering external corrosion in multiple locations on Shell’s Leman Alpha platform was established as impractical, Furmanite was able to provide a repair designed for a substantial life, using the latest carbon fibre composite repair technology.

Furmanite, the specialist technical services company, designed and installed a total of over 28 metres of bespoke-engineered repairs at some 17 locations along the carbon steel export header gas line on the southern North Sea platform, where the corrosion had caused wall thinning. Fourteen different repair designs were required, ranging in length from 1 to over 4 metres and involving various complex geometries including elbows, branches and stabbings.

Given the numerous damaged areas, the only other option – to cut and replace the line – would have led to increased safety concerns and logistics issues, rendering it impractical. Instead, the carbon fibre repairs, designed against the line’s design pressure of 99 barg and temperature of -10 to +70 degrees C, fully restored pressure containment and structural strength, using repair thicknesses of only 8mm rising to 27mm in some areas. Repairs of this type can provide exceptional strength (up to ten times that of steel) whilst adding only minimal weight (at less than a quarter the density).

The example is indicative of a capability that represents high value in the North Sea and is set to see rising demand, given the region’s ageing assets, a high proportion of which were recently highlighted by the United Kingdom Health and Safety Executive (HSE) as being in poor condition.

Furmanite’s composite repairs are typically applied on-line with no disruption to production, although in this case they were applied during a shutdown which ensured the strength of the composite would be fully utilised. Because no hotwork is required, the repairs could be carried out without needing to drain the line.

Tight access restrictions and awkward geometries (requiring more complex design engineering and installation expertise) posed challenges at a number of the repair locations. The fact that the composite repairs require no prefabrication, involve lightweight materials, and are applied in a layering process needing only a hand’s width clearance, helped in meeting these challenges.

Commenting on the principle of being able to repair corrosion damage in-situ, Shell mechanical engineer Andrew Dickson said: “The ability to repair the external defects in this fashion for this specific case has removed the numerous risks of a cut-out and replace scope. The installation of the repairs was completed in an extremely effective manner.”

“Being able to provide repairs to corrosion-damaged lines and infrastructure components and avoid the high cost and logistical issues of cutting and replacing, or providing a solution where replacement is impractical, is one of the primary advantages of this technology,” Furmanite business manager Graham McKay said.

“Moreover the composite repairs will not corrode, and will prevent further corrosion occurring where they are applied. Composite repairs are one of a number of technologies and services we can offer to help operators keep ageing assets operating efficiently and safely, while minimising downtime, representing high value.”

Sarah Manwaring-White, Keep in Touch Ltd,
Tel: +44 (0)1451 844 488
Email: sarah_mw@keepintouch.co.uk