Monday, May 11, 2020

PHMSA Harmonization Rule – SADT-SAPT Provisions

Yesterday I noted that the provisions of the new PHMSA harmonization rule for 49 CFR 173.21(f) would not take effect until January 2, 2023. In a limited sense, this is true, but the reality is much more complicated.


There was no mention of §173.21(f) in the notice of proposed rulemaking (NPRM) for this rule.

The last change to that section was made by the previous harmonization rule that was finalized on March 30th, 2017. That change set the ‘forbidden temperature’ for both self-accelerating decomposition reactions and self-acceleration polymerization reactions at less than, or equal to 50˚ C. Earlier versions had set the ‘forbidden temperature’ for polymerization reactions at less than, or equal to 54˚ C.

That change was made to make the Hazardous Material Regulation (HMR) “consistent with existing requirements for Division 4.1 (self-reactive) and Division 5.2 (Organic peroxide) hazardous materials, as well as the 19th Revised Edition of UN Model Regulations for the transport of polymerizing substances in packages and IBCs, which requires temperature control in transport if the SAPT is 45 °C (113 °F) only for polymerizing substances offered for transport in portable tanks.”

Because PHMSA was continuing to conduct investigations to justify that harmonization change, they included a ‘expiration’ of that change set at January 2nd, 2019. The revision to the pre-2017 language was automatically reflected in the ‘current’ version of 49 CFR.

Extend the Expiration

Today’s final rule actually makes two changes to §173.21(f). First, the rule re-instates the language from the earlier rule that had subsequently expired, again harmonizing the HMR with international standards. But, PHMSA’s research is still on-going, so today’s rule also includes provisions re-instating the ‘old’ (as of today) language on January 2nd, 2023.


If this sounds a tad bit complicated, it is because it is complicated. This is the type of problem that PHMSA frequently runs across in its efforts to keep the HMR harmonized with a variety of different international rules and standards. The international regulatory community makes every effort to keep their rules consistent, but the consensus based regulatory process ensures that a slightly different set of considerations will control the language that is adopted each time a change is made. This means that differences are certain to creep into the regulatory documents of the various entities involved.

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