Pipeline third-party damage subject of 2-year study

June 12, 2000
Effects of third-party damage to pipelines will be the focus of research to be supervised by the Gas Research Institute (GRI), Chicago.

Effects of third-party damage to pipelines will be the focus of research to be supervised by the Gas Research Institute (GRI), Chicago.

The US Department of Transportation's (DOT) Research and Special Programs Administration hired GRI, Chicago, to manage the $2 million research that will be conducted over 2 years by Battelle Institute, Columbus, Ohio, and Southwest Research Institute (SWRI), San Antonio.

DOT and GRI will each provide 50% of the funding.

MFL-based work

Battelle will develop improved smart pigs that use magnetic flux leakage (MFL) to find and evaluate such damage as gouges and dents caused by backhoes. DOT has sponsored Battelle research on the issue since 1996.

GRI said axial-direction MFL systems impose a magnetic field on a pipeline wall to detect irregularities and metal loss due to corrosion but cannot reliably detect mechanical damage.

Battelle will seek to develop an MFL magnetizer orientation in the circumferential direction. SWRI will develop criteria for evaluating the effect of mechanical damage on pipe strength and life.

GRI said data would be used from smart-pig MFL systems to predict remaining pipeline life and establish guidelines for remedial action.

Harvey Haines, GRI manager of nondestructive evaluation research, said, "Today, there is no validated technology for establishing the effect of mechanical damage on the strength and remaining life of a pressurized pipe.

"Gouges or dents parallel to the pipe axis are particularly hard to assess with current systems. Under this integrated research program, Battelle, SWRI, and GRI will be able to coordinate their resources and experience."

GRI said gas pipelines use careful installation procedures, call-before-you-dig programs, periodic right-of-way patrols, and other methods to mitigate mechanical damage.

DOT's Office of Pipeline Safety (OPS), however, reports mechanical damage from excavating equipment still accounted for 348 (32%) of 1,084 reportable incidents involving gas transmission and gathering lines during 1985-97.

GRI said, "Improved in-line inspection will help prevent 'delayed failures,' which can happen months or years after the actual contact that damages the pipeline. Such failures represent only 4% of the reportable incidents but include some of the most noteworthy events in recent pipeline history."