THE QUALIFICATION AND CONTINUED EVOLUTION OF REELED STEEL CATENARY RISERS

摘要

Technip began qualification of reeled Steel Catenary Risers (SCR) back in 1997. Industry had raised concerns at that time over the plastic straining cycles that are intrinsic to the reel lay method and the impact these could have upon the service fatigue life of the girth welds. The qualification programme, therefore, included comparison of reeled welds against virgin welds for a suite of fatigue and mechanical testing including full scale fatigue and fatigue crack growth tests. Reeling was shown to have no discernable impact for the fatigue performance level sought when a controlled SCR fabrication process was adhered to. This provided sufficient confidence that the technology was fit for purpose and led to successful fabrication and installation of the first reeled SCR in 2001. Since then more than 25 have been installed in the Gulf of Mexico, with most projects including full scale weld fatigue test qualification following reeling simulations.This paper includes the following: (a) a summary of the philosophy adopted for qualification, fabrication and installation of a reeled SCR, (b) presentation of the reeled SCR track record and evolution of the technology to include mechanized welding processes (c) a look at ongoing developments targeting even higher fatigue performance, and (d) discussion on the development of fracture mechanics techniques that provide further confidence in the concept and can be used to derive appropriate weld acceptance criteria.