Variety of production options pays off

BUTTING is the only pipe manufacturer in the world that produces longitudinally welded stainless steel pipes as well as metallurgically clad and mechanically lined pipes (BuBi® pipes). Our customer TechnipFMC utilised the production of these different pipe types "from a single source" and ordered all three pipe variants for the Duva & P1 project from the main plant in Knesebeck.

The Duva & P1 project includes the current expansion of capacity for the Gjøa Floating Production Unit (FPU). The Gjøa gas field is located in blocks 35/9 and 36/7 of the North Sea and was already identified in 1989. The clad pipes and superduplex pipes required for the current expansion were ordered from BUTTING. The pipes are manufactured in different versions in the same dimensions OD 341.6 x (15.4 + 3.0; superduplex: 18.4) mm.

The superduplex pipes are turned into spools, among other things. The metallurgically clad pipes and the mechanically lined pipes are to be delivered to the Orkanger spool base, which is located 45 kilometres southwest of Trondheim on the west coast of Norway. The clad pipes will be welded together there. The pipe-in-pipe system is then assembled before a reel-lay vessel lays the entire pipeline (carrier pipe including the BUTTING pipes) on the seabed in the northern part of the North Sea.

Christian Bölter, from Clad Pipes Sales, explains: "The challenge for us was that the inner diameters of the mechanically lined and metallurgically clad pipes had to fit together exactly and that the tightest tolerances had to be achieved. This is the only way to optimally weld pipes together. We fulfilled this requirement."

The material UNS S31603 was selected for the liner and the cladding. A full-scale reel-lay test in-house at BUTTING is also planned as part of the qualification process for both clad pipe variants. "The test will be conducted in the presence of inspectors from our customer and the end customer. The subsequent trials will also be carried out at BUTTING in the presence of the inspectors, meaning that the results can be discussed and argued directly on site", said Christian Bölter. "The decisive factor is that both metallurgically clad pipes and mechanically lined pipes from BUTTING are qualified for various installation methods – including reel-lay processes."

BUTTING – Progress by Tradition