Longitudinal

Northwest Pipeline said longitudinal stress-corrosion cracking caused a pipeline rupture on its 26-inch diameter line near Lake Tapps, WA, on May 1. A report by a metallurgical firm from Texas determined the cause. It is the first time that stress-corrosion cracking, the Canadian pipeline industry’s nemesis, has caused a failure on the Northwest system, the company said. Landslides are usually the cause of pipeline ruptures on Northwest.