Stress relieving and its effect on life of welded tubular joints

This paper describes investigations into the fabrication and repair of large welded tubular joints and how the processes used affect fatigue life. Research has been conducted to determine the benefit of local post weld heat treatment (PWHT) of the connections in terms of hardness and residual stress. The use of hole drilling and trepanning techniques for residual stresses measurements in the clusters are described. The results are compared with fitness-for-service assessments and considered in relation to the fatigue performance of the welded connections. Very substantial theoretical improvement in fatigue life can be expected after PWHT.