FUSION BONDED JOINT: AN INNOVATIVE TECHNOLOGY FOR COST EFFICIENT PLASTIC-LINED PIPE INSTALLATION AND OPERATION – QUALIFICATION CAMPAIGN

摘要

In deepwater, corrosion protection of flowlines is becoming a major issue as fluid (production or injection) aggressiveness, temperature and pressure increase. Conventional corrosion allowance of carbon steel flowlines leads to excessive procurement costs, installation weight and welding thickness resulting in non- economic solutions. Clad flowlines present excellent corrosion protection, but the implementation of this technology results in quite expensive solutions with additional NDT difficulties during installation. An interesting alternative to achieve an acceptable corrosion protection in most conditions is the use of plastic liners. However, plastic lining has been mostly limited up to now to reel lay. Transposing as such this technology to J-lay results in a complex quad joint design inducing more welding and NDT difficulties at every offshore joint. Therefore, the use of this attractive technology in J-lay implies the development of a specific field joint design. FRANK, PF-Schwei?technologie and SAIPEM have developed and patented an innovative and cost effective field-joint system: the Fusion Bonded Joint (FBJ). This system maintains the corrosion barrier across girth weld locations along the flowline. This technology has minimal impact on the offshore laying rate due to performing standard steel to steel welds. In addition, it is based on field proven technologies and methods that are commonly employed in gas transportation networks. This paper presents the characteristics of the FBJ system, a passive corrosion protection system for a water injection lines, and discusses its design, fabrication and the results of the qualification that has been carried out. Performed tests address: electro-fusion welding qualification, NDT of plastic welds, qualification of the carbon steel welds and fatigue testing of both carbon steel and plastic welds. The main challenges and outcomes of performed tests will be presented and discussed. A specific focus on the specificities of the fatigue testing campaign will be presented including specific fatigue string design as well as fatigue performance of plastic electro-fusion weld.