Parameters affecting the weld defect acceptance criteria of clad submarine pipelines installed by S-lay or reel-lay

•Finite element analyses of clad pipeline girth welds•Case studies with S-lay and Reel-lay installation•Different load cases during operation including global buckling, VIV, low cycle fatigue and overtrawling•Sensitivity studies with variation of the most essential input parameters

This case study presents a methodology to determine the criticality of defects in submarine pipeline girth welds made of clad carbon steel and to establish weld defect acceptance criteria. The maximum target acceptance criteria are usually given by the applied design code often with additional requirements set by the client. ECA calculations are carried out in order to demonstrate that the target criteria can be met using the relevant material data, geometry and load input. The ECA methodology must follow the defect development from welding fabrication through pipeline installation from the lay barge, as well as consider loads in the as-laid condition during pre-operational and operational phases until the end of design life and verify that leakage or failure will not occur.