Assessment of flaws in pipe girth welds

This paper is a review of recent work aimed at assessing the significance of circumferential flaws in pipeline girth welds with respect to avoiding failure due to fracture, including excessive ductile crack extension, and local plastic collapse. One of the objectives of such assessments is to define maximum tolerable flaw sizes and so avoid unnecessary weld repair without compromising the integrity of the pipe. The review focuses on installation and operational conditions that give rise to axial plastic straining in the pipe. It is shown that stress-based assessment methods can be modified to obtain acceptably safe outcomes, but it is also shown that they do have limitations. Strain-based assessment methods are introduced which appear to provide a more robust approach. However, these will require experimental validation before a codified procedure is developed and generally accepted by the industry. (AU) Copyright © 2013 Companhia Brasileira de Metalurgia e Mineração (CBMM) All Rights Reserved