Flaw Proximity Rules for Parallel Planar Flaws Under Limit Load Conditions

This paper describes the evaluation of adjacent cracks (including parallel cracks in different planes) from a limit load perspective. The proposed approach complements the current ASME Code rules that are largely based on linear elastic fracture mechanics considerations. The evaluation considers limit load analysis and is validated by comparison with test data. In particular the paper provides criteria to determine load capability of structures with offset cracks in parallel planes. The objective of the work was to provide criteria for the evaluation of reactor internals, but the results can be applied to evaluate cracking in ductile pressure boundary piping also.