Strain-Based Design for Materials With HAZ Softening

Pipelines designed using strain-based design principles can place additional demands on the girth weld area to achieve the desired strain capacity. When girth welded, some modern higher-strength pipeline steels can have lower strengths in the heat-affected zone (HAZ) adjacent to the weld. The demands for strain capacity and toughness on these softer regions can be estimated, showing that for reasonable HAZ sizes, the demands are not much greater than without HAZ softening. Effects of internal pressure were explicitly considered. Softening appears to be particularly important for the pipes with the smallest wall thickness.