Defect and strain tolerance of girth welds in high strength pipelines

Over the last 10 years a number of research programs have been performed to assess the behavior of pipeline girth welds under strain based loading and develop strain based Engineering Critical Analysis/Assessment (ECA) methods. These studies have highlighted that pressureinduced biaxial loading can have a significant influence on the strain capacity of girth welds. The major effect of biaxial loading is an increase in the crack driving force. In comparison, the material’s resistance to fracture appears to be similar under uniaxial and biaxial loading. In North America strain based ECA models have recently been developed by ExxonMobil and Center for Reliable Energy Systems (CRES). This paper presents a comparison of these strain based ECA models and also compares the predictions from these models with the DNV RP 108 ECA procedure developed to assess pipelines installed by reeling. (AU) Copyright © 2013 Companhia Brasileira de Metalurgia e Mineração (CBMM) All Rights Reserved