TWI Industrial Member Report Summary 1023/2012
By M Joosten, L Wei and M Gallegillo
The level of welding residual stress is an important consideration in the engineering critical assessment (ECA) of a structure or component such as a pipeline girth weld. A large number of experimental and numerical studies have been undertaken to investigate the through-wall distributions of residual stresses at pipe girth welds, resulting in the generation of residual stress profiles recommended in the fitness-for-purpose procedures such as BS 7910 (BSI, 2007), R6 (EDF, 2011) and API 579-1/ASME FFS-1 (API, 2007). However, as in the findings of the review work on cladding residual stresses (Wei et al, 2010), there are few results for the residual stresses in clad pipes in which the girth weld is typically made using a corrosion resistant (CRA) consumable (similarly to the cladding material), leading to a dissimilar metal joint. The majority of the work (numerically and experimentally) on cladding residual stresses were carried out on weld-clad specimens related to reactor pressure vessel (RPV) applications and very few were found on real structures, such as girth welds in a clad pipeline where the cladding is normally fabricated through a hot-rolling process rather than an overlay welding process. Indeed none of the residual stress profiles given in the assessment procedures was developed for clad pipes. Hence there is the need to carry out an investigation into the welding residual stresses in clad pipe girth welds in order to provide information for the ECA of clad pipe girth welds.
- Measurement of welding residual stresses in clad pipe girth welds using various measurement techniques.
- Development and validation of FEA models with ABAQUS and SYSWELD for simulation of welding residual stresses in clad pipe girth welds.
- Assessment of the effects of heat input, material hardening models, yield strength, weld start/stop on welding residual stresses.
- Provision of a recommendation for the consideration of residual stresses in engineering critical assessment of clad pipe girth welds.