WASHINGTON – As tanker carriers feared, the Obama administration has proposed a ban on flammable liquids in wetline pipes on the underside of tanker trailers.

The Pipeline and Hazardous Materials Safety Administration's so called "wetlines" rule would cover tank trailers carrying Class 3 flammable liquids, which includes gasoline.

Most straight trucks are exempted, however.

Any trailer built two years after the rule takes effect will not be able to carry more than 0.26 gallons in its wetlines – basically trace amounts -- or must have structural protection.

Existing trailers would have 12 years to come into compliance.

The rule will effectively require expensive protection systems or purging systems to air out the wetlines.

Ironically, wetlines were created when the industry switched from top to bottom liquid bulk loading in order to enhance government fall protection standards as well as government air quality rules.

As Today's Trucking reported last year, industry insiders insist the proposed rule is a solution in search of a problem.

Despite claims by the administration that the rule will save lives by eliminating the risk of wetlines being ruptured in crashes, there's reportedly been only one documented case in the U.S. of a death resulting from a wetlines­incident since 2000 – and even in that instance, there's little evidence a broken wetlline was to blame.

John Conley, National Tank Truck Carriers president, says the rule isn't necessary when you consider all the costs involved.

He adds that the US DOT completed two cost-benefit reports which previously overruled the proposal.