The U.S. Department of Transportation (DOT) is proposing a change to the Hazardous Materials Regulations to allow the transportation of liquefied natural gas (LNG) on railcars. The overture builds on an executive order by President Donald Trump issued earlier this year.

Currently, LNG can only be transported by rail using a portable tank with prior approval from the Federal Railroad Administration (FRA), although the Hazardous Materials Regulations allow DOT 113 specification tank cars to be used for hauling other flammable liquids. Under a notice of proposed rule- making, DOT’s Pipeline and Hazardous Materials Safety Administration (PHMSA) now seeks comment on changes that would allow LNG to be transported in these cars as well.

Citing LNG’s expanding role as a critical domestic and international energy resource, PHMSA proposes to permit the transport of LNG by rail tank car to meet the demand for greater flexibility in the modes of transportation available to transport LNG. The proposed rule would facilitate harmonization across the North American rail network. In Canada, LNG is already authorized for transport in DOT-113 equivalent specification rail tank cars (TC-113C120W).

“Safety is the number one priority of PHMSA and we understand the importance and will make it a top priority to evaluate all public comments and concerns raised throughout the rule-making process,” said PHMSA administrator Skip Elliott. “This major rule will establish a safe, reliable, and durable mode of transportation for LNG while substantially increasing economic benefits and our nation’s energy competitiveness in the global market.”

“FRA shares regulatory oversight responsibility for the safe transportation of hazardous materials by rail,” said Ronald Batory, Federal Railroad Administration administrator. “This rule-making is consistent with our systemic approach to accident prevention, mitigation, and emergency response preparedness.”

Packaging requirements

In the NPRM, PHMSA proposes the following packaging controls:

  • Authorized transport of LNG by rail in DOT-113C120W tank cars. DOT-113 tank cars are vacuum-insulated and consist of an inner stainless steel tank enclosed with an outer carbon steel jacket shell specifically designed for the transportation of refrigerated liquefied gases.
  • Amend the Pressure Control Valve Setting or Relief Valve Setting Table in 49 Code of Federal Regulations § 173.319(d)(2) by adding a column for methane, thus identifying the pressure relief valve requirements for DOT-113s transporting methane.

Operational controls

PHMSA is not proposing new operational controls for transport of LNG by rail tank car. However, PHMSA notes the operational controls (e.g., speed restrictions) set forth in the Association of American Railroads (AAR) Circular OT-55 would apply to the bulk transport of LNG by rail in a train composed of 20 car loads or intermodal portable tank loads in which LNG is present along with any combination of other hazardous materials. OT-55 is a detailed protocol establishing railroad operating practices for the transport of hazardous materials that has been voluntarily adopted by the industry.

Safety case for LNG-by-rail

DOT-113 specification tank cars, including DOT-113C120W tank cars, include a stainless steel inner vessel and a thick steel outer vessel (or jacket); there is an insulated vacuum space between the two vessels to minimize the rate of heat transfer from the atmosphere to the refrigerated liquid during transport; and the cars include pressure relief devices, vents, and valves to prevent or minimize overpressure releases.

Additional requests for information

In addition to commenting on the specific packaging requirements listed above, the NPRM asks the public to comment on the following topics that are within the scope of the NPRM:

  • Whether the authorized transport of LNG by rail has the potential to reduce regulatory burdens, enhance domestic energy production, and impact safety.
  • Whether there is a reasonable basis for limiting the length of a train transporting LNG tank cars and what length is appropriate.
  • Whether there is a reasonable basis for limiting the train configuration, such as by limiting the number of LNG tank cars in a train consist or by restricting where LNG tank cars may be placed within the train.
  • Whether PHMSA should consider any additional operational controls and whether such controls are justified by data on the safety or economic impacts.

Comments on the LNG-by-rail NPRM are due on or before December 23, 2019.