Increasing use is being made of floating production systems for the recovery of oil and gas reserves and these depend on the use of dynamic risers for transportation of the products from the subsea wells. In a typically arrangement several risers made from flexible pipe will be suspended in a catenary such that the surface vessel may safely undergo excursions during the course of normal operation or in storm conditions. This dynamic behaviour, coupled with the need to handle high pressures, places heavy demands on the riser pipe and its terminations. As field developments move into ever-deeper waters and involve the handling of high pressure, high temperature and highly corrosive products, there is concern that current flexible pipe technology will be a limiting factor. With these concerns in mind, interest has been focused on the use of titanium alloy pipe as an alternative to flexibles. The desirable properties of high strength, low weight, low elastic modulus and exceptional corrosion resistance make this pipe extremely attractive and recent engineering studies have confirmed the feasibility of configurations suitable for dynamic riser applications. This paper addresses welding, fabrication and installation methods applicable to efficient production of titanium alloy risers.
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