Finite Element Assessment of Difficult Pipelines at Bends

This paper presents numerical assessment of difficult pipelines at bends using the finite element method (FEM). Difficult pipelines are those that are unable to be inspected using a pig inspection tool. These unpiggable pipes, especially at the bend sections, exhibit difficulties to be piggable for several reasons, thus they are exposed to hazards that can neither be inspected nor controlled. The structural response of the bends is then required to be investigated. This paper aims at simulating the structural response of bends caused by internal corrosions using the ANSYS FEM software. Circular pitting corrosion at different depths and diameters were applied to simulate the stress distribution for three pipe models, namely standard 90° pipe bend, miter bend and unbarred full-bore tees pipe bend near dead end. The results of different corrosion equivalent stress distribution were compared and the most reliable type of bend was reported.