Pipe locating sensor could help prevent natural gas leaks

Can locate buried ceramic, plastic and metallic objects

The sensor is a flat plate which, when placed on the ground, uses low-frequency electrical waves to detect buried objects.

Des Plains, IL - Successful early tests of a pipeline sensor that locates plastic, ceramic and metallic underground pipes could help reduce dangerous instances of natural gas pipeline breaks. The U.S. Department of Energy is working with the Gas Technology Institute (GTI), Des Plains, IL, to develop the prototype sensor which, if all goes as planned, should be ready for demonstration by the end of this year.

The sensor is one of 11 gas infrastructure reliability research projects selected last year in a program managed by DOE's National Energy Technology Laboratory.

The gas distribution industry has needed such a tool for decades. While not a common occurrence, so-called "third-party damage" -- typically caused by construction crews or, for example, power companies erecting telephone poles -- is the single main reason for pipeline damage. If unreported or undetected, serious consequences can result years after the initial damage was inflicted.

The changes of pipeline damage will inevitably increase as the nation's gas industry installs more transmission and distribution pipes to meet the Nation's growing demand for clean burning natural gas. Demand for natural gas in the United States is projected to expand faster than any other fuel source during the next two decades, largely because more power companies are using natural gas to generate electricity. According to the Energy Information Administration, the amount of electricity generated from natural gas could triple between 1999 and 2020.

The National Petroleum Council, an advisory committee to the Secretary of Energy, recently forecasted the need for more than 38,000 miles of new gas transmission lines and 263,000 miles of distribution mains by 2015.

Increasingly, plastic and ceramic materials are being used in newer gas distribution pipes. In fact, GTI estimates that 72 percent of all 3-inch-diameter natural gas distribution pipes in the U.S. are plastic.

The sensor resembles a flat plate made of electrodes. When placed on the ground, the sensor uses low-frequency electrical waves to detect buried ceramic, plastic and metallic objects. The GTI sensor would address long-standing problems that have impeded the industry's efforts to detect non-metallic distribution lines, which are buried anywhere from 3 to 10 feet deep. In a recent test, the sensor imaged a four-inch plastic pipe beneath four feet of soil.

Competing sensors that use high-frequency waves are more expensive and not as effective because soil more easily absorbs high-frequency waves. High frequencies formed the backbone of detection systems used by the military and mining industry because they produce clearer images of metal objects. Borrowing components from these existing sensors, GTI's low-frequency technique is enhanced by multiple antennas that sharpen an image's resolution without the high costs associated with electronics that support high-frequency sensors. The low-frequency technique also detects non-metallic objects, a capability that most other sensors don't have.