Launchpad, September - October 2007
For a full list of proposed, active and closed projects see here
Flaw tolerance in pipeline girth welds subjected to axial straining and internal pressure
Launched: September 2007
Cost per Sponsor: £50,000 pa, two payments
Project Leader: Henryk Pisarski
Pipelines frequently experience strains greater than yield during pipelay and in service. It is therefore critically important to understand the flaw tolerance associated with girth welds in pipes during plastic straining. A number of factors, in addition to axial strain, will affect flaw tolerance. For example, the driving force on a flaw is known to be substantially greater when the pipeline is under internal pressure when the large strains are applied. Material resistance, however, is thought to be unchanged by internal pressure. This Group Sponsored Project will quantify the main factors that affect flaw tolerance at post yield strain levels so that a rigorous, industry agreed method of flaw assessment can be written and the risk of failure minimised. The Sponsor Group will be able to guide the development of suitable methods for assessment. By agreement with the Sponsor Group, TWI will submit the new methodology to the BS 7910 committee with the intention of producing a strain based design annex for the standard.
