# DOT Specifications 4B, 4BA, 4BW, or 4E — How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested

For DOT Specifications 4B, 4BA, 4BW, or 4E, test or inspection is volumetric expansion testing; interval is every 12 years instead of every 5 years; condition or service qualifier is protected externally by a suitable corrosion-resistant coating and used exclusively for non-corrosive gas that is commercially free from corroding components; regulation section is 49 CFR § 180.209, recorded from its source on 2026-08-06.

- **Container specification:** DOT Specifications 4B, 4BA, 4BW, or 4E _(verified: appears in the quote below)_
- **Test or inspection:** volumetric expansion testing _(our reading, not quoted from the source)_
- **Interval:** every 12 years instead of every 5 years _(verified: appears in the quote below)_
- **Condition or service qualifier:** protected externally by a suitable corrosion-resistant coating and used exclusively for non-corrosive gas that is commercially free from corroding components _(verified: appears in the quote below)_
- **Regulation section:** 49 CFR § 180.209 _(verified: appears in the quote below)_

## What the source says

> A cylinder made in conformance with DOT Specifications 4B, 4BA, 4BW, or 4E protected externally by a suitable corrosion-resistant coating and used exclusively for non-corrosive gas that is commercially free from corroding components may be requalified by volumetric expansion testing every 12 years instead of every 5 years.

## 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/).