Pipe-in-Pipe Walking: Understanding the Mechanism, Evaluating and Mitigating the Phenomenon Available to Purchase

This paper addresses the walking phenomenon of pipe-in-pipe system, which can cause the cumulative axial displacement, leading to the potential failures of tie-ins or risers. The main mechanism that drives the pipe-in-pipe walking is the nonlinear spacer-pipe friction (between the inner pipe and outer pipe) and pipe-soil friction, together with thermal transients along the pipe-in-pipe system during start-up and shutdown. Sensitivity studies are also performed by investigating the effect of variation in spacer-pipe friction coefficient, pipe-soil friction coefficient, transient temperature profile and internal pressure through detailed finite element simulation with Abaqus. The paper also presents some methods to mitigate the pipe-in-pipe walking and some advantages of selecting pipe-in-pipe system in deepwater development.