J-tube cluster for Petrogas' new gasfields.

Aiming to continue its domestic gas supply, Petrogas E&P develops the A15 and B10 gas fields near the A12CPP platform in the northern part of the Dutch North Sea.

Petrogas develops two gas fields with two identical platforms. Both platforms will be connected via new pipelines to the existing pipeline infrastructure in the area. In addition, the platforms have been connected via two new control umbilicals to the existing A12 central processing platform (CPP).

Power, data, hydraulic and methanol cables with a length of 13 kilometers and 10 kilometers will be buried on the seabed and routed to the CPP via a cluster of 3D curved J-tubes.

For the realization of the J-tube cluster, Petrogas came to Kersten. "Initially, we approached Kersten to produce the induction pipe bends," says Nick Verhoef, Project engineer at Petrogas "However, it soon became clear that Kersten was also an interesting party for the J-tube cluster." Kersten could make the entire construction as well as meet the short lead times.
"We bent three J-tubes into a complex 3D shape with small tolerances. Everything had to be just right because once on site, little to nothing could be adjusted," explains Martijn Rozemeijer, Area Sales Manager at Kersten. "Our engineers worked closely with Petrogas and thought along to achieve the optimal result".

Verhoef is very pleased with that cooperation. "The cooperation was very pleasant. There is an enormous amount of experience at Kersten and they used it to the full in this project. Together with Petrogas, Kersten even optimized the design of the J-tube construction!" Eventually, the job became more and more complete for Kersten. "In the end, we manufactured the entire J-tube construction with platform, messenger wires, shim plates and anodes.," says Rozemeijer.

For the J-tube cluster, Kersten bent steel tubes (S355J2H) of Ø168, Ø273 and Ø323mm into a 3D shape, fitted them with transition pieces, bellmouths (from Ø323 to Ø874mm) with clamps on the J-tubes to mount the J-tube to the platform, assembled them and provided them with an inner and outer coating. The welds are 100% NDO-tested.
The J-tubes were transported to the offshore site and sunk to the seabed where they were picked up with a winch, carefully tilted and raised to the platform. Underwater divers clustered the J-tubes and mounted to the platform.

About Petrogas

Petrogas is one of the top five offshore gas operators in the Netherlands. Petrogas onshore office is located in Rijswijk and together with its onshore logistic base at Beverwijk, managing offshore logistics via Den Helder. Petrogas E&P Netherlands has interests in offshore blocks on the Dutch Continental Shelf.
www.petrogasep.com

About Kersten

Kersten Group is leading in bending technology and an expert supplier of curved components and constructions in steel and aluminium. Kersten has an extensive experience in the manufacturing of curved components and constructions for offshore projects worldwide.
www.kerstengroup.com