Product Details Supplier Info More products

Furmanite has won the Pipeline Industries Guild award for the ‘Most Significant Contribution to Subsea Pipeline Technology’, for its ultra high-pressure subsea pipeline repair clamp design.

This design was developed for high-pressure 16 and 18in sea water injection-pipeline and riser systems, to be held as a contingency repair measure for emergency deployment.

Furmanite provides Furmaseal high-pressure repair clamps for rapid and economical on-line leak sealing, consisting of a split sleeve fitting installed to cover the damaged section and bolted to seat and compress the elastomer seals.

In this instance, the design pressure of 520bar required a successful hydro-test at almost 800bar – an unprecedented pressure-loading on a split-repair clamp.

The need to accommodate a variation in pipe diameter of 7mm presented a further challenge.

Adam Thistlethwaite, engineering manager at Furmanite, said: ‘Designing a split joint to withstand a test pressure of 780bar is a significant challenge, as a balance must be achieved between code compliance, flexibility and manufacturing cost and feasibility.

‘Elastomeric seals are prone to extrusion under load and given the high pressures involved it was necessary to carry out detailed analysis of the clamp body.

‘A double seal system was used to allow safe testing of the pressure boundary by pressurising the inter-seal annulus.

‘This allows a pressure test to be carried out on installation to ensure the seals are correctly activated, without having to pressure test the entire clamp cavity and pipeline along the length of repair, which can cause problems.’ Extremely high mechanical forces are required in the seal system to withstand a 780bar test pressure, with seal compression pressures of more than 1,800bar needed, demanding a complex high-strength anti-extrusion system.

The anti-extrusion system can also support the seal over the entire variation of pipe diameters.

The repair clamp is hinged and hydraulically actuated, to aid diver installation.

Anodes are fitted to provide corrosion protection.

View full profile