PHMSA ASME Section XII Final Rule: What Canadian Tank Manufacturers Need to Know

By Kopfkino Consulting Corp. · Published October 7, 2026 · Updated October 17, 2026 · 7 min read

PHMSA rule HM-241 adds an optional ASME Section XII route for MC 331, MC 338 and DOT 400-series cargo tanks, effective October 28, 2026. CSA B620 and provincial CRN rules still apply in Canada.

A long-running United States rulemaking crossed the finish line last week. On September 28, 2026, the Pipeline and Hazardous Materials Safety Administration published final rule HM-241 in the Federal Register, incorporating the 2015 edition of ASME Boiler and Pressure Vessel Code Section XII and the 2015 edition of the National Board Inspection Code, Parts 2 and 3, into the Hazardous Materials Regulations. Voluntary compliance was available immediately, and the rule takes effect on October 28, 2026. For Canadian tank manufacturers, repair organizations and compliance managers, the practical questions are what the rule covers, what choices it creates, and what it does not change north of the border. Facts are as of October 7, 2026.

Key takeaways

• HM-241 adds an optional ASME Section XII construction route for MC 331 and MC 338 cargo tanks, DOT 406, 407 and 412 cargo tanks, UN T75 cryogenic portable tanks and multi-unit tank car tanks. Section VIII Division 1 remains available.
• The National Board Inspection Code, Parts 2 and 3 (2015 edition, including Supplement 6), is incorporated for continued service and repair of these tanks.
• Nothing changes in Canada: the TDG Regulations and CSA B620 govern dangerous goods tanks here, and CSA B51 plus provincial registration governs fixed pressure equipment. Neither framework substitutes for the other.

The rule

HM-241, published at 91 FR 61144 under docket PHMSA-2010-0019, authorizes Section XII of the ASME Boiler and Pressure Vessel Code, Rules for Construction and Continued Service of Transport Tanks, as a construction standard for certain specification transport tanks, alongside the National Board Inspection Code for their continued service. PHMSA describes the rule as deregulatory: it imposes no new costs and adds regulatory flexibility by offering an alternative construction path. The lineage is long. In 1995, PHMSA's predecessor agency asked ASME to develop standards specifically for transport tanks; ASME published the first edition of Section XII in 2004; and the rulemaking docket that produced this final rule opened in 2010. Sixteen years later, the standard has a regulatory home.

Which tanks are covered

The Section XII or Section VIII Division 1 choice

The rule preserves the existing Section VIII Division 1 construction route and adds Section XII as an option; it does not convert anyone. The choice is made per design, and it should be documented in the design file and reflected consistently through calculations, drawings and data reports. Section XII was written specifically for transport service, which is the argument for adopting it; customer familiarity, existing quality programs and repair-network practice are the arguments for staying put. Both are legitimate, and the rule's voluntary structure means there is no compliance deadline pressure to switch.

Repairs and continued service: NBIC Parts 2 and 3

The rule incorporates the 2015 edition of the National Board Inspection Code, Parts 2 and 3, including Supplement 6, tying the inspection, repair and continued-service framework to the construction route. For repair organizations, the practical reading is that tanks built or continued under Section XII carry an NBIC-based service history expectation, the same discipline Canadian shops already associate with National Board repair programs. Documentation discipline is the deliverable: repair records, examination results and nameplate continuity all have to follow the tank.

Documentation and records

The rule puts as much weight on records as on steel. The construction route chosen for each tank belongs in the design file, and it has to read consistently across calculations, drawings, nameplate data and data reports. Repair records, examination results and continued-service documentation follow the tank for life, which means a shop that cannot produce a tank's history cannot show compliance with the incorporated NBIC provisions. For Canadian shops serving US customers, the added discipline is cross-referencing: the DOT specification marking, the ASME construction standard and any CSA B620 obligations need to coexist on one documentation trail without being conflated. Build that cross-reference into the traveller or quality dossier now, at the template level, rather than reconstructing it per unit.

What this does not change in Canada

HM-241 is a United States rule under the Hazardous Materials Regulations. In Canada, transportable dangerous goods tanks are governed by the Transportation of Dangerous Goods Regulations and standards such as CSA B620, and fixed pressure equipment is governed by CSA B51 and provincial registration. A Section XII nameplate does not register anything with a Canadian province, and a CRN does not substitute for DOT specification compliance. Manufacturers building for both markets run both frameworks in parallel: the US specification for the tank's transport life, and provincial design registration the moment equipment becomes fixed pressure equipment in a Canadian facility. Our guide to importing pressure equipment into Canada covers the border-crossing version of this analysis, and the note on CRN registration before fabrication explains why the Canadian sequence starts earlier than most manufacturers expect.

Frequently asked questions

Does Section XII replace Section VIII Division 1 for cargo tanks?

No. HM-241 adds Section XII as an optional construction route and explicitly preserves the existing Section VIII Division 1 path. The choice belongs to the manufacturer, per design.

We build only for the Canadian market. Does HM-241 affect us?

Not directly. Canadian transportable tanks remain under the TDG Regulations and CSA B620. The rule matters if you build for the US market, if US customers reference Section XII in specifications, or if you follow ASME transport-tank practice for design consistency.

Must existing MC 331 or DOT 407 tanks be recertified?

No. PHMSA characterizes the rule as deregulatory with no new costs; it creates an option, not a retrofit. Continued service follows the incorporated NBIC provisions.

Do transportable tanks need CRNs in Canada?

Transportable dangerous goods tanks fall under the federal TDG framework rather than provincial CRN registration. Provincial registration attaches to fixed pressure equipment installed in the province; where a transportable unit becomes stationary process equipment, the provincial analysis begins.

Sources

• Federal Register: Hazardous Materials: Incorporation of ASME Code Section XII and the National Board Inspection Code (91 FR 61144, September 28, 2026)
• Waste Today: DOT authorizes ASME standard for hazardous material transport tanks
• Tank Transport: PHMSA authorizes optional ASME Section XII cargo tank construction

Building tanks or pressure equipment for both sides of the border? Kopfkino manages Canadian design registration and CRN submissions for domestic and international manufacturers. See our CRN registration services or contact us about your registration scope.

Topics: PHMSA, ASME Section XII, NBIC, Cargo Tanks, Transport Canada