PHOTO: BP PLC

A smart pig, which employs magnetic flux leakage and ultrasonic transduction technologies, is used to examine the inside of oil pipelines.

High-Tech Pipes

Smart pigs do have their limitations. They can be as long as a car, and cannot navigate many pipes. To remedy these faults, the industry envisages smaller, svelter robots that move under their own power and go wherever the operator desires, no matter the direction of the flow of oil (or natural gas, in gas pipelines). These robots will require much lighter sensors, and researchers are looking at a number of techniques.

J. Bruce Nestleroth and Richard J. Davis, of Battelle, based in Columbus, Ohio, describe one sensing method in an article published on August 30 in the journal Nondestructive Testing and Evaluation International. They use a device that moves through a pipeline while rotating pairs of permanent magnets around a central axis, stirring up powerful “eddy currents” in the surrounding metal. Variations in these currents can paint a detailed picture of the pipeline’s walls.

Another method, remote field eddy current (RFEC) testing, uses a coil of wire carrying low-frequency alternating current to induce the eddy currents. Such coils can be made quite narrow, and can thus be used to inspect “unpiggable” pipes from inside. The Department of Transportation is funding projects to test this idea in natural gas pipelines.

The best corrosion-detecting technologies can be effective only if they are implemented, and they aren’t cheap. Before the Prudhoe Bay disaster, BP expected to spend US $72 million on corrosion control. Now, it forecasts it will spend $195 million in 2007 on major Prudhoe Bay maintenance.

Add to that cost the ill will generated by the bad press and the embarrassment of having a former BP corrosion manager plead the Fifth Amendment during a U.S. House of Representatives Energy and Commerce subcommittee hearing. As any risk-management expert will tell you, risk mitigation is less expensive than crisis management. That message is certainly resonating loudly through the executive offices of many an energy company these days.