PHMSA Pipeline & Hazardous Materials Brief

Headline

PHMSA issues administrative preemption determination voiding California's 2028 reusability mandate for propane cylinders

Executive Summary

PHMSA published a notice of administrative determination of preemption on September 10, 2026, finding that the Federal Hazardous Materials Transportation Act preempts California's reusability mandate for propane cylinders. The mandate would have required all propane cylinders sold in California on or after January 1, 2028 to be reusable or refillable.

PHMSA found the mandate both non-uniform with federal packaging regulations and an obstacle to the federal hazardous materials transportation framework. Both grounds independently support the preemption finding.

Bottom Line

DOT-39 non-reusable propane cylinders retain their status as federally authorized packagings for hazardous materials transport. Cresthaven reading: propane cylinder manufacturers and California-market distributors relying on DOT-39 specifications face the removal of the state reusability requirement as an operative compliance obligation, though the determination's downstream effect on California's broader packaging sustainability program warrants continued review.

Key Regulatory Signals

• California Mandate Preempted Under Federal Transportation Law: PHMSA's determination finds that California Public Resources Code Sections 42395 through 42395.2 impose design and manufacturing requirements on propane cylinders that are not substantively the same as federal Hazardous Materials Regulations governing DOT-39 non-reusable cylinders. The determination applies to cylinders represented, marked, certified, or sold as qualified for hazardous materials transportation.
• DOT-39 Non-Reusable Cylinders Retain Federal Authorization: DOT-39 cylinders, which are non-reusable and non-refillable seamless or welded cylinders made of steel or aluminum, remain federally authorized packagings for transporting propane, classified as a Division 2.1 flammable gas, under the Hazardous Materials Regulations. The California mandate's effective ban on these cylinders in the state is the basis for PHMSA's obstacle-preemption finding.
• Worthington Enterprises Named as Applicant: Worthington Enterprises, Inc. filed the preemption application on August 18, 2025, asserting two grounds: non-uniformity with federal cylinder design and manufacturing standards, and obstruction of the federal hazardous materials transportation regime. PHMSA's determination resolves both grounds in Worthington's favor.
• Mandate Exemptions Do Not Alter the Preemption Finding: The California mandate included exemptions for construction-industry cylinders under 15 ounces, cylinders with a height-to-width ratio of 3.55 to 1 or greater, and cylinders sold to state or local government agencies under a federal disaster purchasing program. PHMSA's preemption determination covers the mandate as a whole. Cresthaven reading: manufacturers and distributors of DOT-39 propane cylinders operating in California markets face a materially changed compliance landscape, as the federal preemption determination removes the January 1, 2028 reusability requirement as a state-law obligation for covered cylinders.

Regulatory Delta

• No prior PHMSA preemption determination on propane cylinder reusability mandates appears in recent agency history.
• The determination applies an obstacle-preemption theory alongside a non-uniformity finding, establishing that state environmental or waste-management policy governing federally specified hazardous materials packaging can be preempted on two independent grounds.
• Other packaging categories within that framework are not addressed by this determination.

Materiality Classification

MEDIUM — PHMSA's preemption determination resolves a specific state-law conflict affecting DOT-39 propane cylinder manufacturers and California-market distributors, and the obstacle-preemption theory applied here is relevant to any manufacturer whose federally specified hazardous materials packaging faces analogous state sustainability mandates.

Intelligence Outlook

Monitor PHMSA's docket and the Federal Register for any challenge, reconsideration petition, or judicial review of this preemption determination, and monitor California legislative activity for amendments to the reusability mandate or related packaging sustainability provisions.