U.S. PHMSA Updates Hazardous Materials Regulations for Transport of Dangerous Goods

On 10 April 2024, the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) recently updated the Hazardous Materials Regulations (HMR) to align them with international standards, incorporating changes to shipping names, hazard classes, and packaging requirements.

The final rule incorporates updated versions of international hazardous materials regulations and standards by reference, including the 2023–2024 edition of the “International Civil Aviation Organization Technical Instructions” (ICAO Technical Instructions), Amendment 41-22 of the International Maritime Dangerous Goods Code (IMDG Code), and the 22nd revised edition of the United Nations Recommendations on the Transport of Dangerous Goods – Model Regulations (UN Model Regulations).

Among several changes, the final rule amends the Hazardous Materials Table (HMT) in Section 172.101 of the HMR. Changes include the addition, revision, and removal of certain proper shipping names, hazard classes, packing groups, special provisions, packaging authorizations, bulk packaging requirements, and the maximum quantity limits for passenger and cargo-only aircraft. In particular, the new rule focuses on the following changes to some entries:

1.  A new entry has been added to the HMT for cobalt dihydroxide powder in certain conditions. This material will be under “UN3550, Cobalt dihydroxide powder, containing not less than 10% respirable particles,” Division 6.1, PG I, with its corresponding new packaging provisions. Materials to be classified under this entry were classified so far as “UN3077, Environmentally hazardous substance, solid, n.o.s., Class 9.” The new classification follows recent toxicity tests performed to comply with the Regulation on the Registration, Evaluation, Authorization, and Restriction of Chemicals in the European Union, which resulted in a global change that affected the hazard classification criteria of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and all the international regulations on transport of dangerous goods.
2. Several other entries that were inadvertently modified in previous rulemakings are now corrected in the new final rule, impacting all the columns of the HMT.
3. In alignment with the international regulations, the entry “UN1169, Extracts, aromatic, liquid” (PGII and PGIII) was removed, and materials so far classified under this entry will be classified under the amended entry “UN1197, Extracts, liquid, for flavor or aroma” (PGII and PGIII).
4. Also, to align with the international regulations, the new rule changed the main hazard class of “UN1891, Ethyl Bromide” from a toxic liquid of Division 6.1 to a Class 3 flammable liquid. This impacts the classification and labeling of products under this entry, as well as the quantity limitations for transportation.
5. Special provision A4 was assigned to the entry “UN2922, Corrosive liquid, toxic, n.o.s.” and special provision A5 was assigned to the entry “UN2923, Corrosive solid, toxic, n.o.s.” Both special provisions specifically address liquids and solids in Packing Group I that also present an inhalation toxicity risk, either by limiting or prohibiting their transport on aircraft.
6. Following the 2023–2024 ICAO Technical Instructions, entries “UN3548, Articles containing miscellaneous dangerous goods, n.o.s.” and “UN3538, Articles containing non-flammable, non-toxic gas, n.o.s.” are assigned to new special provisions A224 and A225, respectively. This allows for their transport on both passenger aircraft and cargo-only aircraft under certain conditions.
7. New special provision 398 was added to “UN1012 Butylene.” This special provision clarifies that butylene mixtures and certain butylene isomers may be assigned to UN1012, with the exception of the isobutylene isomer, which must be assigned to “UN1055 Isobutylene,” which corresponds to different packaging provisions.

For polymerizing substances, special provision 387 established the sunset date of 2 January 2023 for stabilization provisions for transport. Now, the final rule removes the sunset date, meaning that the transport provisions established in special provision 387 for polymerizing substances will remain.

Regarding lithium batteries, the final rule established that special provision A54 must be indicated in the shipping document. This special provision indicates that, irrespective of the quantity limits in column (9B) of the HMT, a lithium battery, including a lithium battery packed with or contained in equipment that otherwise meets the applicable requirements of Chapter 173.185, may have a mass exceeding 35 kg, if approved by the associate administrator prior to shipment. The new requirement to display the special provision A54 in shipping papers aims to improve the communication of potential hazards by ensuring that a copy of the approval is provided with the shipment.

There are other changes on provisions for the transport of lithium batteries and cells indicated in Chapter 173.185. These include changes in packaging provisions. In particular, there is a new exception for test summary requirements for button cell batteries installed in equipment, which will facilitate the transport of traditionally less regulated products, such as wrist watches and key fobs.

Another amendment on lithium batteries is the addition of a new paragraph (a)(5) to Chapter 173.185 to require marking the outer casing of lithium-ion batteries with the Watt-hour (Wh) rating. This requirement reflects other similar international provisions, like Special Provision 348 of the UN Model Regulations; Special Provision 188 of the IMDG Code, Section IA.2 of Packing Instruction 965 (for UN3480); and Section I.2 of Packing Instruction 966 (for UN3481) and 967 (for UN3481) of the ICAO Technical Instructions. This new requirement will apply to lithium batteries but not to lithium cells.

On substances transported in portable tanks that require temperature control, the final rule changed the temperature threshold from 50°C (122°F) to 45°C (113°F). This provision in Chapter 173.21 of the HMR applies to materials that are likely to decompose with a self-accelerated decomposition temperature (SADT) or polymerize with a self-accelerated polymerization temperature (SAPT). This amendment aligns the HMR with temperature thresholds established by the UN Model Regulations and the IMDG Code for these cases.

In addition, the Self-Reactive Materials Table in Chapter 173.224 and the Organic Peroxide Table in Chapter 173.225 were amended by the final rule. Changes include new entries and corrections aligned with the UN Model Regulations, Revision 22.

Shippers, transporters, and operators will need to adopt the new rule published by PHMSA. These amendments are expected to maintain the high safety standard of the HMR, improve compliance, reduce delays and interruptions during transportation, and potentially lower greenhouse gas emissions and safety risks. They are also expected to facilitate transportation efficiency and keep global supply chains open.

The amendments will be effective on 10 May 2024.

Full details of all the changes are available in the Federal Register notice. 

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About the author: Diego Rufino is a 3E regulatory research analyst based in Buenos Aires, where he covers global news on transport of dangerous goods, and hazard communication of industrial chemicals in Latin America. Diego has been in the logistics industry for seven years, and has been part of the 3E ERC team implementing chemical regulatory requirements for more than a decade.