Lined Pipelines : A Study of Wrinkles

Abstract

A lined pipeline consists of an outer main load-bearing pipe of Carbon-Manganese steel, termed backing steel, and an inner corrosion resistant alloy layer, termed liner. The purpose of the liner is to serve as a membrane; protect the backing steel from the sour contents owing inside and thus prevent internally corrosion. The main challenge of lined pipelines arise because of its low bending capacity due to local buckling of the liner, termed wrinkling. In installation as well as in operation, the pipeline will be exposed to bending and wrinkling of the liner may occur if the imposed curvature is su cient. Based on previous work in a joint industry project[5], nite element basis for mechanical behaviour of lined pipelines in installation and operation have been developed in present the project. Di erent parameters that in uence the wrin- kling phenomena in installation have been studied. The nite element model - established in the present task - is able to predict the post-buckling behaviour of the liner. This open the possibility to determine a limiting bending strain/cur- vature on lined pipelines based on wrinkling height. The wrinkling behaviour during operational phase is brie y discussed. The analyses indicate that both existing wrinkles from installation and new wrinkles in the operation phase, did not grow when subjected to cycles of operational load conditions. wrinkles during cycles of operational load conditions,