Residual Curvature Zone As-Laid Roll and Out-of-Straightness

Abstract Residual curvature zones have been formed in selected reel-laid pipelines to trigger lateral buckles and control their formation since 2012. Buckle initiation with residual curvature depends on factors that include the as-laid rotation and horizontal out-of-straightness. In this article, a finite element method to forecast as-laid residual curvature configurations is described. With the method, a catenary is formed from the reel-ship to the touch-down point. The model includes a representative length of laid pipe on the seabed. A single residual curvature zone, or train of such zones, transits from the reel-ship, down the catenary to the touch-down point. Hence, the analysis is a static and stationary simulation of a dynamic and kinematic process. The finite element method is computationally efficient and is flexible enough to cover single and pipe-in-pipe systems and multiple residual curvature zones in shallow, medium and deep water; to incorporate pipeline end termination structures and inline tees; to include residual curvature of notionally straight pipe; to give an indication of highly stressed zones; and to permit application of vessel motions. Examples are given in the article.