Defect Separation for Full-Scale Burst and Fatigue Testing

Abstract The LTS (Local Transmission System) Futures Project is conducting full-scale burst and fatigue testing in hydrogen and in water as part of an investigation into repurposing the gas transmission system. The length of the available pipe was limited, so it needed to be used efficiently, by minimising the length of each test vessel. Finite element analysis (FEA) was used to determine the minimum separation distances between the end of the part-through-wall defect or dent, and the end of the test vessel in the burst and fatigue tests, and the minimum separation distances between the individual dents in the fatigue tests. The stress distributions along the pipe axis were calculated and compared with those for a large separation to determine whether the reduced separation was predicted to have a significant effect on the results of the burst or fatigue tests. The methodology used for the analysis, the resulting stress distributions, and the conclusions drawn about minimum separation distances are presented and discussed. The findings show that FEA is useful for designing full-scale burst or fatigue tests when the available material is limited.