Does your process have any “underground piping”? We do not see this design in newer process designs, but in years past – putting pipe underground seemed like a good idea. This NTSB report does an excellent job of breaking down the failure modes of underground piping. The National Transportation Safety Board determined that the probable cause of the pipeline rupture was:
- external corrosion of the pipe wall due to deteriorated coating
- ineffective cathodic protection
- the failure to detect the corrosion because the pipeline was not inspected or tested after 1988
On December 11, 2012, at 12:41 p.m. a buried 20-inch-diameter interstate natural gas transmission pipeline ruptured in a sparsely populated area, about 106 feet west of Interstate 77. About 20 feet of pipe was separated and ejected from the underground pipeline and landed more than 40 feet from its original location. The escaping high-pressure natural gas ignited immediately. An area of fire damage about 820 feet wide extended nearly 1,100 feet along the pipeline right-of-way. Three houses were destroyed by the fire, and several other houses were damaged. There were no fatalities or serious injuries. About 76 million standard cubic feet of natural gas was released and burned. The owner of the pipeline reported the cost of pipeline repair was $2.9 million, the cost of system upgrades to accommodate in-line inspection was $5.5 million, and the cost of gas loss was $285,000.
The National Transportation Safety Board determined that the probable cause of the pipeline rupture was
1) external corrosion of the pipe wall due to deteriorated coating
2) ineffective cathodic protection
3) the failure to detect the corrosion because the pipeline was not inspected or tested after 1988.
Contributing to the poor condition of the corrosion protection systems was the rocky backfill used around the buried pipe. Contributing to the delay in the controller’s recognition of the rupture was management’s inadequate configuration of the alerts in the supervisory control and data acquisition system. Contributing to the delay in isolating the rupture was the lack of automatic shutoff or remote control valves.
CLICK HERE to download the entire report.