Measured residual stresses and integrity of pipeline girth welds

Abstract

Pipeline girth welds were made by manual metal arc and semiautomatic flux cored arc welding processes, both without post-weld heat treatment. The residual stresses in these welds were measured by neutron diffraction on ANSTO’s strain scanner, Kowari. The two welds had similar residual stress values and profiles. An integrity assessment of the welded branch connection was performed with a conservative estimate based on the measured values of residual stress, and values of residual stress predicted by BS 7910. The critical crack size based on the measurements was almost twice as large, showing the value of these measurements.

Keywords:

• Welding
• Residual stress
• Neutron diffraction
• Structural integrity