# DOT 3A, 3AA, or 3AL — How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested

For DOT 3A, 3AA, or 3AL, test or inspection is water-jacket or direct expansion method; interval is 12 years after the original test date and at 12-year intervals thereafter; condition or service qualifier is used as a fire extinguisher; regulation section is 49 CFR § 180.209, recorded from its source on 2026-08-06.

- **Container specification:** DOT 3A, 3AA, or 3AL _(verified: appears in the quote below)_
- **Test or inspection:** water-jacket or direct expansion method _(our reading, not quoted from the source)_
- **Interval:** 12 years after the original test date and at 12-year intervals thereafter _(verified: appears in the quote below)_
- **Condition or service qualifier:** used as a fire extinguisher _(verified: appears in the quote below)_
- **Regulation section:** 49 CFR § 180.209 _(verified: appears in the quote below)_

## What the source says

> A DOT 3A, 3AA, or 3AL cylinder must be requalified by: (i) The water-jacket or direct expansion method. A requalification must be performed 12 years after the original test date and at 12-year intervals thereafter.

## Source

- https://www.law.cornell.edu/cfr/text/49/180.209

Last verified: 2026-08-06. Review by: 2027-08-06.
Part of [How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested](https://referencesource.org/hazmat-container-retest-intervals/).