Failure analysis and fitness-for-service assessment for a pipeline

Failures during hydrotest have been analyzed for a new crude oil pipeline, indicating that the main cause of failures is severe lack of fusion defects formed by inadequate welding heat input in electric resistance welded (ERW ) pipe welds. The fitness-for-service (FFS) assessment has been carried out for the pipeline by use of the fracture mechanics approach, which shows th at the pipeline may leak before break under designed operating pressure, an d the lack of fusion defects in the welds may propagate under the condition of fluctuating pressure. The prediction of remaining life for the pipeline is given in this paper. (C) 2001 Elsevier Science Ltd. All rights reserved .