A natural gas company based in Western Canada was faced with legal action after a fire involving a natural gas explosion destroyed a home and damaged two others, resulting in one fatality and one injury. A three-quarter inch steel gas pipe that was 50 years old was found corroded and fractured at a kink where it passed through the concrete foundation. Was the fracture the cause or an effect of the explosion? How could one tell?
To perform an analysis, the company hired a forensic engineering firm, which in turn enlisted the Canadian Neutron Beam Centre to provide residual strain measurements. The strains at the point of fracture were found to be ‘compressive’ relative to a comparable pipe, meaning that the pipe would normally resist cracking. Yet a corrosion pit showed evidence of stress corrosion cracking, a type of cracking that is slow growing.
These factors provided strong evidence that the pipe was likely subjected to tension over time while in service, and that the fracture was not due to faulty pipe. When the engineering firm inserted the strain data from the CNBC into computer models of how pipes fracture, this hypothesis was confirmed, thus eliminating one scenario in which the pipe fracture could have caused the fire.
While the parties did not reach a final consensus about the root cause of the accident, the evidence from various sources—including the CNBC data—was valuable in informing them about the likelihood of whether the gas line was the cause or effect. Armed with this knowledge, the parties subsequently reached an out-of-court settlement.