The U.S. Transportation Department's Research and Special Programs Administration has issued a rule requiring new and replacement pipelines to be built to accommodate the use of smart pigs.
RSPA said the rule, published in the Apr. 12 Federal Register and effective May 12, will improve the safety of gas, hazardous liquids, and carbon dioxide pipelines.
The agency is drafting another rule spelling out the circumstances under which it will require inspections with smart pigs. The 1992 Pipeline Safety Act requires the proposed and final rules.
RSPA said the final rule will not require use of smart pigs in manifolds, station piping, crossovers, and fittings providing branch line junctures such as tees and other lateral connections.
The current rule allows pipeline operators to seek waivers when it is impractical for them to design or build a line to accommodate a smart pig.
RSPA said some operators wanted the rule to exempt lines operating at low pressure because they had low stress on the pipe wall. RSPA disagreed, saying that just like high pressure lines, low pressure lines are susceptible to corrosion and other types of damage that smart pigs could find.
The agency also denied exemptions sought for above ground, short length, and small diameter pipelines. However, it drafted the rule to apply only to pipeline diameters for which there is a commercially available smart pig, currently 4 in. or larger.
Due to operational problems, the rule exempts gas transmission lines operated in conjunction with a distribution system, gas transmission lines in urban areas, pipelines at storage facilities, and offshore pipelines smaller than 10 in.
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