Issuing body
API
Latest edition
2nd Edition (2020)
Region
USA, Global
Equipment items
7
Scope
Single-, double- and full-containment refrigerated tank systems for LNG, LPG, ethylene, ammonia, butadiene, etc. Integrates inner tank, outer tank, foundation, insulation, vapor barrier, and ancillaries.
Key requirements (10)
- Tank systems for refrigerated liquefied gases — covers full / double / single containment.
- Inner tank materials: 9 % Ni steel (ASTM A553) for cryo (LNG, ethylene); SS for very low temp; CS for warmer (NH3, LPG).
- Outer tank: prestressed concrete (full containment) or steel (single/double).
- Insulation in annulus: perlite (loose-fill), cellular glass, PIR foam, depending on system.
- Vapor barrier mandatory for refrigerated systems to prevent atmospheric moisture ingress.
- Heated foundation required for cryogenic service to prevent ground frost heave.
- In-tank submerged pumps mandatory — no bottom or side connections below liquid level.
- Boil-Off Gas (BOG) management: vapor return, BOG compressor, recondenser typical.
- Roof: suspended deck (full containment) with insulation above.
- References API 620 Annex Q/R for inner tank design rules.
Note
Primary US/Global standard for cryogenic and refrigerated bulk storage tanks.
Related standards (5)
Applied to 7 equipment items
Storage Tanks