# -21 Test of pressure relief valves.

- **operation:** document
- **citation:** 49 CFR 179.400-21
- **title:** -21 Test of pressure relief valves.
- **source type:** regulation
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** current
- **official:** true
- **published on:** Not available
- **effective on:** 2026-08-18
- **summary:** Each valve must be tested with air or gas for compliance with § 179.401-1 before being put into service.
- **machine formats:** - **json:** https://regulus.evalyn.ai/document/49-cfr-179-400-21.json
- **markdown:** https://regulus.evalyn.ai/document/49-cfr-179-400-21.md
- **app url:** https://regulus.evalyn.ai/document/49-cfr-179-400-21
- **source url:** https://www.ecfr.gov/on/2026-08-18/title-49/section-179.400-21
**body:**

Each valve must be tested with air or gas for compliance with § 179.401-1 before being put into service.
- **truncated:** false
- **body characters:** 104