Cool-down flow-rate limits imposed by thermal stresses in LNG pipelines
Abstract
Warm cryogenic pipelines are usually cooled to operating temperature by a small, steady flow of the liquid cryogen. If this flow rate is too high or too low, undesirable stresses will be produced. Low flow-rate limits based on avoidance of stratified two-phase flow were calculated for pipelines cooled with liquid hydrogen or nitrogen. High flow-rate limits for stainless steel and aluminum pipelines cooled by liquid hydrogen or nitrogen were determined by calculating thermal stress in thick components vs flow rate and then selecting some reasonable stress limits. The present work extends these calculations to pipelines made of AISI 304 stainless steel, 6061 aluminum, or ASTM A420 9% nickel steel cooled by liquid methane or a typical natural gas. Results indicate that aluminum and 9% nickel steel components can tolerate very high cool-down flow rates, based on not exceeding the material yield strength.
- Publication:
-
Presented at the Cryogenic Eng. Conf
- Pub Date:
- 1981
- Bibcode:
- 1981cren.conf...10N
- Keywords:
-
- Cryogenic Cooling;
- Flow Velocity;
- Pipe Flow;
- Pipelines;
- Thermal Stresses;
- Liquefied Natural Gas;
- Liquid Helium;
- Liquid Nitrogen;
- Stratified Flow;
- Two Phase Flow;
- Fluid Mechanics and Heat Transfer