PHMSA's HM-215S hazmat proposal: what shippers and carriers should know
The latest harmonization rule would update UN, ICAO, IMDG and Canadian TDG references and split the lithium battery CTU entry. Comments are due December 28.
PHMSA has opened its next round of hazmat harmonization. Here is what is in it and what to do now.
What was published
On October 27, 2026, the Pipeline and Hazardous Materials Safety Administration published a notice of proposed rulemaking titled "Hazardous Materials: Harmonization With International Standards." It runs under docket PHMSA-2025-0048 (HM-215S) and would amend 49 CFR parts 171, 172, 173, 175, 176, 178 and 180.
PHMSA does this every two years. Federal hazmat law directs DOT to keep the Hazardous Materials Regulations (HMR) generally consistent with international rules unless they are unnecessary or unsafe.
The standards being adopted
- UN Model Regulations, 24th revised edition
- ICAO Technical Instructions, 2027-28 edition, plus Addendum 1 to the 2026-27 edition
- IMDG Code, Amendment 43-26, mandatory on January 1, 2027
- Transport Canada TDG Regulations, as last amended October 25, 2024
- several new or updated ISO standards referenced in those frameworks
Changes that matter on the road
Battery-powered cargo units. UN3536 today covers lithium batteries installed in a cargo transport unit (CTU) without saying which chemistry. PHMSA proposes three entries:
| UN number | Proper shipping name | |---|---| | UN3536 | Lithium ion batteries installed in cargo transport unit | | UN3563 | Lithium metal batteries installed in cargo transport unit | | UN3564 | Sodium ion batteries installed in cargo transport unit |
Special Provision 389 would be revised so the shipping name reflects the main chemistry, and mixed chemistries must be identified for emergency responders. PHMSA cited a 2024 overturned-truck fire near Baker, California, where responders could not tell what type of batteries were inside.
Canada. The TDG reference used in 18 HMR sections, including 49 CFR 171.12 on North American shipments, would move to the 2024 amendments.
Paperwork and packaging. The rest of the package updates proper shipping names, hazard classes, packing groups, special provisions, packaging authorizations, air quantity limits and vessel stowage rules.
Cost
PHMSA classes the rule as deregulatory. It estimates net annualized cost savings of about $56,000 at a 3% discount rate and $49,000 at 7%.
What to do now
- Nothing changes yet. This is a proposal.
- If you ship or haul battery energy storage systems in containers or trailers, review the proposed UN3536 split and SP 389 wording.
- Comment by December 28, 2026 on regulations.gov. Put "PHMSA-2025-0048 (HM-215S)" or RIN 2137-AF75 at the top of your comment.