{"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":null,"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}