# -21 Test of pressure relief valves.

**Citation:** 49 CFR 179.400-21  
**Type / status:** regulation / current  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** 2026-08-18  
**Published:** Not stated

Each valve must be tested with air or gas for compliance with § 179.401-1 before being put into service.

## Document text

Each valve must be tested with air or gas for compliance with § 179.401-1 before being put into service.

## Provenance

- Official: Yes
- Source: <https://www.ecfr.gov/on/2026-08-18/title-49/section-179.400-21>
- Source ID: `ecfr`
- SHA-256: `8bc51a975633e2b35e0c4483641b64f62c45497a5a6e5ed41cc11867fb3ebc6f`
- Retrieved: 2026-08-20T05:46:20.606Z
- Exported: 2026-08-24T10:34:22.342Z
- Document slug: `49-cfr-179-400-21`

### Source metadata

```json
{
  "cfrTitle": 49,
  "part": "179",
  "section": "179.400-21",
  "subpart": "Subpart F—Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A)",
  "corpusVersion": "2026-08-18",
  "jurisdiction": "US"
}
```