Germany’s Schoeller Werk makes its own contribution to the necessary quality and planning assurance with its heavy-duty control-line & chemical-injection pipes for the offshore industry. Their technical design is such that they can withstand not only the extreme pressure conditions which prevail in deep seas, but also extremely high temperatures and aggressive liquid media.
Worldwide, there are more than 2,000 offshore drilling rigs and many more individual wells with oil and gas being extracted on a continuous basis. The technical equipment for these installations sets extreme demands on the hand-picked suppliers from the stainless steel industry.
Germany’s Schoeller Werk took up the offshore challenge 35 years ago and for many years has been among the kingpins of the industry. At its base in the Eifel, the company not only manufactures tubes for the automotive, the chemical and the medical industry, as well as being active in power station and heat exchanger construction, it also creates technologically remarkable solutions for use on drilling rigs.
Example: Oil and gas extraction in Norway
For one company alone, TCO Norway, service provider for Norway’s state-owned Statoil enterprise, Schoeller Werk has supplied over 500,000 metres of piping since winning their custom in spring 2014. At the core of this partnership is a plug-drawn annular pipe made of high-quality nickel-based alloys nos. 825 and 625.
In addition there are austenitic pipes made of class 316 Ti stainless steel. The pipes being delivered impressed Statoil that much, they have defined them as standard for their own specifications.
Apart from a variety of materials, it is necessary to manufacture the various diameters and wall thickness – plug-drawn Schoeller pipes cover all the possibilities. The pipe design and the corresponding quality testing make it possible for the finished solution to withstand internal pressure of up to 2,500 bars without difficulty.
Moreover, the high-quality materials, in conjunction with improved surface quality deriving from the drawing process, are able to resist the effects of salt water and other aggressive media.
The plugs make things smooth
Among the features of the plug-drawn pipes are their geometrically precise curvature and high weld quality. In principle, the basic material is not a factor in this and it is possible to manufacture individual pipes of up to 2,000 metres in length. An internal mandrel (plug) acts to smooth the inside of the longitudinal weld.
In conjunction with an external mandrel, the initial cross-section of the tube can thus be reduced by up to 50%. All in all, this is a longitudinally welded solution which gives the impression of being a seamless pipe. A look at the microstructure of the material reveals that the welded seam can hardly even be detected after the pipe has been drawn. Properties such as these have been key plus points for Schoeller Werk’s offshore customers.