PHMSA proposes allowing liquefied natural gas transport by rail

The PIOGA Press

(by Boyd Stephenson and James Curry)

On October 24, the Pipeline and Hazardous Materials Safety Administration (PHMSA) published a notice of proposed rulemaking (NPRM) amending the Hazardous Materials Regulations (HMR) to allow the bulk transport of liquefied natural gas (LNG) in DOT-113C120W (DOT-113) specification railcars.

PHMSA issued the NPRM in response to a petition for rulemaking filed by the Association of American Railroads (AAR). Also, an April 10 Executive Order directed PHMSA to issue a final rule on bulk transportation of LNG by rail by May 2020. Comments on the NPRM are due by December 23.

Over the last decade, the number of LNG facilities and total storage and vaporization capacities have drastically increased. And, according to PHMSA, total liquefaction capacity increased by 939 percent due to new LNG export terminals. With this growth, PMHSA has recognized there may be a need for greater flexibility in the modes of transporting LNG.

While LNG is already authorized for transportation by highway and in maritime vessels, LNG may be transported by railcar only with a special permit from PHMSA or in smaller, portable tanks loaded onto a railcar. However, other cryogenic liquids that are chemically similar to LNG already are authorized to be transported by rail under the HMR.

Currently, there is a pending special permit renewal application to transport bulk LNG in DOT-113 specification railcars using requirements identical to those proposed in the NPRM. The comment period ended August 7, with PHMSA receiving nearly 3,000 comments. The agency has not yet acted on the application.

Proposed changes

In the NPRM, PHMSA proposes to:

• Amend the LNG entry on the Hazardous Materials Table (UN 1972, Methane, refrigerated liquid (cryogenic liquid), 2.1) to allow transportation of bulk LNG in rail tank cars under the terms of 49 C.F.R. § 173.319
• Amend the railcar provisions in the cryogenic liquid table in 49 C.F.R. § 173.319, to add the following requirements for bulk railcars transporting LNG:

― Using a DOT-113 specification rail tank car.
― A start-to-discharge pressure valve setting of 75 psig.
― A design service temperature of -260˚F.
― Maximum pressure when offered for transportation of 15 psig.
― A filling density of 32.5 percent by weight.

PHMSA did not propose any changes to the DOT-113 tank car design for transporting bulk LNG, or for handling bulk LNG in transit, but the agency solicits comments about:
• Whether there is a reason to set a maximum length PHMSA proposes allowing liquefied natural gas transport by rail  November 2019 | The PIOGA Press 13 of trains transporting LNG and, if so, what that maximum length should be.
• Whether there is a reason to limit the number of LNG railcars that can be in one consist (the lineup or sequence of cars in a unit) or to limit where LNG tank cars may be placed within the train.
• Whether PHMSA should apply its high-hazard flammable train (HHFT) rules to trains transporting bulk LNG, including:
― Speed restrictions and tightened speed restrictions in high-threat urban areas.
― Two-way end-of-train devices for faster air brake deployment in emergency situations.
• Whether PHMSA should adopt the AAR’s Circular
OT-55, “Recommended Railroad Operating Practices for Transportation of Hazardous Materials,” which all Class I and II freight railroads operating in the United States currently observe, into the rules for transporting bulk LNG
• Whether the additional route analysis requirements currently applied to HHFTs and to trains transporting explosives, toxic inhalation hazards or radioactive cargo should also be applied to trains transporting bulk LNG

Questions and commentary

Canada already allows the transport of bulk LNG in DOT-113 railcars, but, according to the NPRM, Mexico “does not provide explicit authorization for bulk transportation of LNG in rail tank cars.” Yet, PHMSA cites increased Mexican demand for LNG as one reason why rail transport demand is rising.

Ethylene is a cryogenic liquid that is already approved to be transported in the same type of DOT-113 specification railcars proposed for LNG. But, according to AAR data, only 356 ethylene tank car movements originated in 2015. PHMSA notes that “the numbers of DOT-113 tank cars in operation under the proposed regulatory change could increase well beyond the numbers of DOT-113 tank cars currently in operation.”

In addition to the DOT-113C120W railcar proposed for transporting bulk LNG, AAR’s petition requested PHMSA also authorize the DOT-113C140W (140W) railcar. The 140W is not widely deployed and PHMSA elected not to include it in the NPRM due to a paucity of safety data. Rather, the agency proposes to further study the 140W tank car’s technical standards and performance. The 140W better insulates the tank car’s inner compartment from thermal creep and is designed to allow the railcar to travel for longer periods before the cryogenic liquid can vaporize into gas. Would also authorizing the 140W expand shippers’ options for exporting LNG directly instead of delivering for transfer to a vessel at a maritime port?

PHMSA states that the NPRM does not impose costs or provide benefits exceeding $100 million annually, but the Office of Management and Budget chose to designate it a significant rulemaking, subject to additional review, anyway. At the same time, an executive order mandates PHMSA take final action considering allowing bulk LNG by rail by May 2020. With such an accelerated timeline, will PHMSA be able to resolve public comments and conduct the necessary economic analysis?

The proposed rulemaking can be found at

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