The Department of Transportation (DOT) on Monday published a final rule requiring new onshore natural gas transmission lines and replacements of existing pipe or components to be designed and constructed to accommodate the passage of instrumented internal devices, better known as “smart pigs.”

As for offshore transmission pipelines, the rule calls for certain new lines (10 3/4 inches or more in outside diameter) that run between platforms or from platforms to the shore to be built to accommodate the use of “smart pigs.” It covers only those offshore transmission lines on which construction will begin after Dec. 28, 2005.

The rule was published in the Federal Register by DOT’s Research and Special Programs Administration, which oversees the Office of Pipeline Safety (OPS), and takes effect July 28.

A number of gas pipelines already have made their systems piggable in compliance with the pipeline integrity management program rule, which was issued by the OPS earlier this year, said Terry Boss, senior vice president of environmental and safety at the Interstate Natural Gas Association of America (INGAA).

The so-called “smart pigs” travel with the flow of the fluid in pipelines. Along the way, they collect data that operators subsequently analyze and investigate to learn the physical conditions of a pipeline. They are considered the best means for pipe operators to assess damage or corrosion to their systems, thus averting a rupture and possible explosion in high-population areas.

However, a number of the gas pipeline systems in the United States are 25 years old or more, and are configured in such a way as to make the use of “smart pigs” virtually impossible without undergoing major re-construction.

The final rule is aimed at making the nation’s gas transmission system gradually adaptable to “smart pigs.”

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