Investigation of residual stress development in spiral welded pipe

The residual stresses in spiral welded pipe (SWP) are generated due to localized plastic deformation in the weld-metal and the heat affected zone (HAZ), which cause detrimental effects on the reliability of the pipes. Therefore, it is necessary to investigate these stresses to ensure safe service and operation of pipes used in oil and gas industry. The most commonly used techniques for the evaluation of residual stresses in industries are the split ring test and the hole drilling method. In the experimental part of this work, the semi-destructive hole drilling experimental technique has been adopted for analyzing the stresses in the pipe. The distribution of residual stresses is calculated through different mathematical procedures, such as uniform method, power series method and integral method. The second part of this work consists of finite element (FE) modeling of the split ring test. It is done by sequentially coupling the thermal and structural analysis of welding to assess the adequacy of the split ring method for the estimation of weld residual stresses. Furthermore, the numerically predicted residual distributions during welding are compared with experimentally calculated values using hole drilling method and it is found in good agreement.