Wednesday, May 20, 2020

PHMSA Withdraws Vapor Pressure Rule

The DOT’s Pipeline and Hazardous Material Safety Administration (PHMSA) published a notice in today’s Federal Register (85 FR 30673-30680) withdrawing their advanced notice of proposed rulemaking (ANPRM) on “Vapor Pressure of Unrefined Petroleum Products and Class 3 Materials”. That rulemaking was published in January of 2017.

According to the notice summary, based upon test results obtained by Sandia Laboratories:

“PHMSA is providing notice of its determination that the establishment of vapor pressure limits would not improve the safety of rail transportation of crude oil. Therefore, PHMSA is no longer considering vapor pressure limits for the transportation of crude oil by rail or any other mode. Furthermore, PHMSA is also providing notice that, after considering comments received to the ANPRM, it is no longer considering imposing vapor pressure standards for other unrefined petroleum-based products and Class 3 flammable liquid hazardous materials by any mode.”

Federal Preemption

The notice also includes a discussion of PHMSA’s observations about how this withdrawal would affect State and local attempts to regulate the transportation of crude oil based upon the vapor pressure of that material. The notice begins that discussion by stating:

“PHMSA, in issuing this withdrawal, has affirmatively determined that a national vapor pressure limit for unrefined petroleum-based products is not necessary or appropriate. As explained further below, PHMSA believes that Federal law likely preempts any non-Federal law that attempts to set a vapor pressure limit for these materials.”

PHMSA concludes that discussion by stating:

“A person directly affected by a non-Federal requirement may apply to PHMSA for a determination that the requirement is preempted by 49 U.S.C. 5125. See 49 U.S.C. 5125(d); 49 CFR 107.203-107.213. PHMSA is currently considering a preemption application filed by North Dakota and Montana with respect to Washington's vapor pressure limit, and will consider any application filed with respect to other non-Federal vapor pressure limits.”

In fact, PHMSA has already published their response to the North Dakota and Montana preemption application in last Friday’s Federal Register (85 FR 29511-29528). Unsurprisingly, PHMSA determined that the Washington State rules were preempted by the existing lack of vapor pressure standards in the Hazardous Materials Regulations. Both notices were signed on May 11th, 2019, but the publication review process apparently took longer on this notice.


I think that PHMSA erred in the way they looked at the Sandia Labs test results. As I mentioned in my earlier post on those test results, those tests just looked at the comparative effects of a fire resulting from releases of crude oil with various vapor pressures. Any chemist or fire scientist could have easily predicted the results of those tests, a similar mass of linear hydrocarbons will generate the same amount of heat energy when burned. The fireball tests were equally uninformative because of the extremely high pressure the material was subjected to before the gases were released to the atmosphere.

The testing methodology did nothing to evaluate the effect of vapor pressure on the likelihood of a vapor release during a derailment. Determining the temperature at which a crude oil sample reached a vapor pressure of 32 psig (the pressure relief setting for railcars carrying flammable materials) would provide some measure of predictive value of a vapor release (and probable fireball result) for a given material. In a complex mixture of hydrocarbons like crude oil, that might provide important hazard classification information for regulators. Whether or not that was regulatorily feasible would depend on what transportation safety mitigation factors could be applied to materials with a relatively low temperature to achieve 32 psig.

If President Trump loses the election this November, I would suspect that a Biden controlled PHMSA might revisit this rulemaking.

No comments:

/* Use this with templates/template-twocol.html */