A Department of Transportation (DOT) letter to a Florida carrier notes that MC331 cargo tanks are not authorized for transportation of compressed natural gas under current regulations.
The attorney for the carrier, Marlin Gas Transport Inc of New Port Richey FL, requested the DOT clarification after determining that some natural gas pipeline companies use carriers with MC331 tank trailers rather than the DOT-specified cargo tanks. Marlin uses jumbo tube trailers that meet the DOT regulations for pipeline natural gas transportation, according to the attorney, Norman R Garvin of Copulates, Garvin, Light & Hanson PC of Indianapolis IN.
In addition, the DOT letter says some carriers had been issued exemptions to the rule that allowed transportation of compressed natural gas in MC331 cargo tanks, but those exemptions have expired and no new ones have been issued.
According to Garvin, another activity under scrutiny by DOT involves an unauthorized practice by many pipelines employing small trailers pulled on public roads behind pickups mounted with several tanks commonly used as fuel tanks by natural gas vehicles. These tanks are only authorized as a fuel source for the primary power of the vehicle with regulations specific to where the tank can be mounted in a vehicle.