# Cooldown.

- **operation:** document
- **citation:** 49 CFR 193.2505
- **title:** Cooldown.
- **source type:** regulation
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** current
- **official:** true
- **published on:** Not available
- **effective on:** 2026-08-18
- **summary:** (a) The cooldown of each system of components that is subjected to cryogenic temperatures must be limited to a rate and distribution pattern that keeps thermal stresses within design limits during the cooldown period, paying particular attention to the performance of expansion and contraction device
- **machine formats:** - **json:** https://regulus.evalyn.ai/document/49-cfr-193-2505.json
- **markdown:** https://regulus.evalyn.ai/document/49-cfr-193-2505.md
- **app url:** https://regulus.evalyn.ai/document/49-cfr-193-2505
- **source url:** https://www.ecfr.gov/on/2026-08-18/title-49/section-193.2505
**body:**

(a) The cooldown of each system of components that is subjected to cryogenic temperatures must be limited to a rate and distribution pattern that keeps thermal stresses within design limits during the cooldown period, paying particular attention to the performance of expansion and contraction devices.

(b) After cooldown stabilization is reached, cryogenic piping systems must be checked for leaks in areas of flanges, valves, and seals.
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- **body characters:** 439