PRODUCTION • PROCESSING • HANDLING
winning its custom in spring 2014. At the core of this partnership is a plug-drawn annular pipe made of high-quality nickel- based alloys of numbers 825 and 625. In addition there are austenitic pipes made of class 316 Ti stainless steel. T e pipes being delivered impressed Statoil so much that it has defi ned them as standard for its own specifi cations. 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. T e pipe design and the corresponding quality testing make it possible for the fi nished solution to withstand internal pressure of up to 2,500 bars without diffi culty. Moreover, the high-quality materials, in conjunction with improved surface quality deriving from the drawing process, are able to resist the eff ects of salt water and other aggressive media.
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 2,000m 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 that 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 off shore customers.
CAREFUL TESTING OF CONTROL AND INJECTION PIPES T e off shore industry uses such pipes as hydraulic control lines for safety valves as well as for pumping chemicals into an oil reservoir. In this way, they support the entire extraction process.
Cross-section to show TIG orbital weld from inside. To supply customers with required lengths of 15,000m and more, individual pipes are orbitally welded together
Markus Zimmermann is head of Team Energy at Schoeller Werk,
www.schoellerwerk.de
www.engineerlive.com 25
T e injection pipes make it possible for rig operators to use chemicals in targeted fashion to liquefy the oil and thus to improve its fl ow properties. During the complex manufacturing process, the pipes undergo various tests to ensure the special quality of the products before they are installed. Strips of metal are welded with a longitudinal seam using the tungsten inert gas (TIG) welding process and rolled into tubes. Apart from the obligatory eddy- current testing, the tubes subsequently undergo an air under water (AUW or ‘bubble’) test. T e tubes are submerged in water and fi lled with air to a pressure of up to 210 bars. A visual inspection is made along the entire length of the tubes to check that they are airtight. So that Schoeller Werk can supply its customers with the required lengths of 15,000m and more, individual pipes are orbitally welded together and an X-ray is made to check that the orbital weld is airtight and free of any pores. Before delivery to customers, Schoeller Werk also subjects the control and injection pipes to a hydraulic test. T is involves fi lling the fi nished coils with hydraulic fl uid and subjecting them to pressures of up to 2,500 bars to simulate the extreme conditions sometimes experienced in off shore work. Apart from pure manufacture of pipes, Schoeller Werk also off ers its customers from the off shore industry a comprehensive service package, which includes, for example, encapsulation of pipes with plastic sheathing in so-called fl at packs. T is means that bundles of pipes can be attached to the extraction
The operational safety and quality of tubes is of the highest priority for the oil & gas sector. Any defect will lead to a loss in energy and standstills, costly maintenance, and in the worst case, environmental damage
tubes and protected from buckling and squashing. Other services include fl ushing and fi lling of pipes. Here the insides of the pipes are fl ushed with hydraulic fl uid until the fl uid reaches the specifi ed ISO or SAE purity classifi cation. T e fl uid fi ltered in this way can remain in the pipes if the customer so requires, meaning that users obtain a product that is ready to use. Furthermore, it is also possible to equip the pipe bundles with electrical wiring or stainless steel support cables. Also, thanks to the smooth internal surface, plug-drawn pipes are also ideal for use as ducting for optical fi bre cables transmitting signals using light. In its work with the off shore industry,
Schoeller Werk has joined an international market. Apart from Norway and Great Britain around the North Sea in Europe, Russia, Saudi Arabia, UAE, Africa, Asia, Australia and South America all count among the key target regions for use of the Schoeller control-line and chemical- injection pipes. ●
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