SCC: An SCC cluster is assessed was defined to be “significant” by the Canadian Energy Pipeline Association (CEPA) (3) in 1997 provided that the deepest crack, in a series of interacting cracks, is greater than 10% of the wall thickness and the total interacting length of the cracks is equal to or greater than 75% of the critical length of a 50% through-wall flaw that would fail at a stress level of 110% of SMYS. CEPA also defines the interaction criteria. The presence of extensive and “significant” SCC typically triggers an SCC mitigation program (See discussion under Post-Assessment Step), but a crack that is labeled “significant” is not necessarily an immediate threat to the integrity of the pipeline.