Actuallly, at the location where the Bellingham pipeline failed a smart pig had earlier detected a discontinuity in the pipeline. If one assumed that the abnormality was caused by corrosion, the depth did not require repair under the ASME code. If it was a gouge (with stress concentration) then it required immediate repair.
The pipeline operator fought with one of its employees over the catorization of the discontinuity. The operator determined that it was a corrosion. It was also at a real low point in the line and no nearby pressure releif. It wasn't corrosion, there was a waterhammer and two boys and a young man died.
I liked your description of Diablo Canyon. When I was at Bechel Power SF Power Div Headquarters we kept hearing stories about how PG&E was having price contolled plate steel welded into I beams, because there was a shortage of I-Beams. Some things associated with the long errection of that plant were crazy.
Gas ruling clouded by safety issues
Federal safety officials are raising doubts about a judge's ruling that El Paso Corp. should have run its natural gas pipeline at peak pressure during the California energy crisis. The questions--echoed by industry safety experts--could bolster the Houston energy company's claim that it did not illegally squeeze gas supplies to drive up prices in California.