PHMSA rule now in effect lets cargo tank builders use ASME Section XII

A PHMSA final rule that took effect October 28, 2026 lets manufacturers build several common hazmat cargo tank specifications to ASME's Section XII transport tank code, and sets out which edition of the National Board Inspection Code governs their inspection and repair.

The rule was published in the Federal Register on September 28, 2026, under docket PHMSA-2010-0019 (HM-241). Companies could start following it voluntarily on the publication date. It finishes a rulemaking that began more than a decade ago with petitions from industry groups.

The change is optional. Builders can keep using the code they use now.

What the rule does

The Hazardous Materials Regulations already incorporate ASME Boiler and Pressure Vessel Code Section VIII, Division 1. The new rule adds the 2015 edition of ASME Section XII, a code written specifically for transport tanks, as an approved alternative.

Section XII may now be used to build these tanks:

• cargo tank motor vehicles: MC 331, MC 338, DOT 406, DOT 407 and DOT 412
• cryogenic portable tanks: UN T75
• ton tanks: DOT 106A and DOT 110AW

The rule also incorporates the 2015 edition of the National Board Inspection Code, Parts 2 and 3, including Supplement 6, which covers inspection, repair and alteration of transport tanks.

Which inspection code applies

• A cargo tank built to Section XII must be inspected and repaired under the 2015 National Board Inspection Code and Supplement 6.
• A cargo tank built to Section VIII, Division 1 continues under Part 180 of the hazmat regulations, along with either the 2015 code or the 1992 edition that was already in the rules.

The National Propane Gas Association asked PHMSA to let Section XII tanks be qualified under the 1992 code as well. PHMSA said no, citing that the 1992 code is more than a decade older than Section XII and that Section XII and the 2015 inspection code were developed together.

Stamps for repair shops

An earlier proposal would have required repair shops to obtain a new ASME "TR" stamp. The final rule drops that requirement and instead relies on the "R" stamp that shops already need for coded repairs.

Why it matters for carriers

PHMSA estimates net cost savings of about $8.1 million a year and ties the rule to long-pending petitions and NTSB recommendations after an LPG cargo-tank rollover fire. Existing tanks are unchanged unless they are built, repaired or requalified under the new options. Before buying a new Section XII tank, confirm your inspector or repair shop can work to the 2015 inspection code.