A proposed rule requiring unprotected external piping on cargo tanks to be emptied prior to transport was sent to the Office of Management and Budget in December 2000, but it was withdrawn from review in February 2001. Reportedly, the proposal will remain at the Department of Transportation’s Research and Special Programs Administration (RSPA) until an internal review can be completed by a Bush Administration appointee.
RSPA officials contend that product-laden loading lines, also called wetlines, are vulnerable to impact caused by collisions. The tank truck industry has argued that accidents involving wetlines are infrequent and that eliminating wetlines will be extremely costly.
While the exact provisions of the proposed rule have not been disclosed, comments by RSPA officials suggest that the agency believes technology-based solutions are available. In addition, a retrofit requirement is a virtual certainty.
Discussions about wetlines typically focus on tank trucks and tank trailers used to transport gasoline and other refined petroleum. Semi-trailers have up to five compartments, each with its own loading/unloading line, and the lines typicially are clustered on the curb side.
Aluminum cargo tanks predominate in the US petroleum market, and the product piping is aluminum. Depending on length and diameter, each pipe will hold 25 to 50 gallons of product. As much as 250 gallons of product remains in the wetlines of a five-compartment trailer.