# MC 331 — How often hazmat cylinders, cargo tanks, IBCs and portable tanks must be retested

For MC 331, test or inspection is Internal Visual Inspection; interval is 10 years; condition or service qualifier is less than 3,500 gallons water capacity in dedicated propane service constructed of nonquenched and tempered NQT SA-612 steel; regulation section is 49 CFR § 180.407, recorded from its source on 2026-08-10.

- **Container specification:** MC 331 _(verified: appears in the quote below)_
- **Test or inspection:** Internal Visual Inspection _(our reading, not quoted from the source)_
- **Interval:** 10 years. _(verified: appears in the quote below)_
- **Condition or service qualifier:** less than 3,500 gallons water capacity in dedicated propane service constructed of nonquenched and tempered NQT SA-612 steel _(verified: appears in the quote below)_
- **Regulation section:** 49 CFR § 180.407 _(verified: appears in the quote below)_

## What the source says

> MC 331 cargo tanks less than 3,500 gallons water capacity in dedicated propane service constructed of nonquenched and tempered NQT SA-612 steel (see Note 5) | | 10 years.

## 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/).