# all unlined cargo tanks — How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested

For all unlined cargo tanks, test or inspection is Thickness testing; interval is annually; condition or service qualifier is cargo tanks measuring less than the sum of the minimum prescribed thickness, plus one-fifth of the original corrosion allowance; regulation section is 49 CFR § 180.407, recorded from its source on 2026-08-10.

- **Container specification:** all unlined cargo tanks _(verified: appears in the quote below)_
- **Test or inspection:** Thickness testing _(our reading, not quoted from the source)_
- **Interval:** annually _(verified: appears in the quote below)_
- **Condition or service qualifier:** cargo tanks measuring less than the sum of the minimum prescribed thickness, plus one-fifth of the original corrosion allowance _(verified: appears in the quote below)_
- **Regulation section:** 49 CFR § 180.407 _(verified: appears in the quote below)_

## What the source says

> The shell and head thickness of all unlined cargo tanks used for the transportation of materials corrosive to the tank must be measured at least once every 2 years, except that cargo tanks measuring less than the sum of the minimum prescribed thickness, plus one-fifth of the original corrosion allowance, must be tested annually.

## Source

- https://www.law.cornell.edu/cfr/text/49/180.407

Last verified: 2026-08-10. Review by: 2027-08-10.
Part of [How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested](https://referencesource.org/hazmat-container-retest-intervals/).