Low-cycle fatigue design of welded offshore pipe components: A modern view on ASME B31 code

•The low-cycle fatigue (LCF) design rule of pipelines in ASME B31 code is studied.•The structural strain method generalizes ASME B31 design rule for welded pipelines.•The structural strain method can analyze LCF behavior of irregular pipe tee joint.•Different aspects of the structural strain method are discussed in detail. The welded pipe components are prone to low-cycle fatigue (LCF) at welds, especially under extreme loadings. ASME B31.8 specifies the fatigue design rules of the welded pipelines. In this work, the LCF fatigue analysis approach stipulated in the ASME B31 code is revisited to figure out its underlying mechanism, limitations, and scope, by analyzing two sets of LCF fatigue data of piping structures using different strain information. A structural strain method is proposed to generalize the pseudo-stress idea implied in the ASME code, which correlates large amounts of high- and low-cycle fatigue data of weldments into the master E-N curve.