InfrastructureIndustrial stent-like repairs for failing pipelines

Published 14 September 2011

There are thousands of miles of pipe underground in the United States, some more than 100 years old; gas, oil, water, and sewage seep, and sometimes gush, through corroded joints and defective welds every day; new technology uses carbon and glass laminates to repair and replace failing pipelines

There are thousands of miles of pipe underground, some more than 100 years old. Gas, oil, water, and sewage seep, and sometimes gush, through corroded joints and defective welds every day. Pipeline owners often know nothing about the condition of the lines they operate, and even less about where the next gas explosion or contaminated city water supply will occur.

Even when problems with failing infrastructure can be detected, the methods of repair currently available are technologically outdated, logistically complex, and prohibitively expensive. A University of Arizona engineering professor may have a solution to this infrastructure problem that’s growing deadlier each year.

New reports by the National Transportation Safety Board and the Gas Technology Institute could mean fewer gas explosions due to pipeline ruptures, like the one that happened a year ago in San Bruno, California.

On 9 Sept 2010, a 54-year-old gas pipeline ruptured in a residential area of San Bruno. The cause was a defective weld in a 30-inch-diameter pipeline. The gas explosion blasted a crater about 72 feet long and 26 feet wide. The explosion and fire killed eight people and destroyed thirty-eight homes.

The NTSB accident report estimates that almost fifty million cubic feet of natural gas were released during the incident. “The accident pipe would not have met generally accepted industry quality control and welding standards in 1956,” the 30 August report states. “Indicating that those standards were overlooked or ignored.”

A University of Arizona release reports that a month before the NTSB report was released, the Gas Technology Institute published a test report approving a new technology, PipeMedic, that uses carbon and glass laminates to repair and replace failing pipelines. GTI is a nonprofit research and development organization that serves the natural gas industry.

PipeMedic was developed by Mo Ehsani, professor emeritus of civil engineering at the University of Arizona College of Engineering and a pioneer in the structural application of fiber-reinforced polymers, or FRPs.

Ehsani was a faculty member in the UA department of civil engineering and engineering mechanics for almost thirty years before he left in 2009 to focus on his structural engineering repair business, QuakeWrap, which he founded in 1994.

His research at UA focused on the seismic behavior of structures and on innovative approaches to repairing and retrofitting civil structures using FRPs.

Ehsani describes PipeMedic as a “superlaminate” because it uses crisscrossing carbon fibers and layers of glass fabric that are saturated with resin, then pressurized