Category
Cryogenic & Refrigerated Storage
Subcategory
LPG
Applicable standards
6
Issuing bodies
5
Description
Atmospheric refrigerated LPG storage (propane ≈ –42 °C / butane ≈ –6 °C) — full or double containment.
Applicable Standards (6)
API — 2 standards
API 625
Tank Systems for Refrigerated Liquefied Gas Storage
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.
API 620
Design and Construction of Large, Welded, Low-Pressure Storage Tanks
Atmospheric and low-pressure (≤15 psig) welded storage tanks. Annex Q covers refrigerated LNG/LPG; Annex R covers low-pressure refrigerated storage.
Key requirements (7)
- Low-pressure tanks: pressures > 2.5 psig up to 15 psig (≈ 1 barg).
- Design temperatures: ambient down to –50 °F (–46 °C) by default; Annex Q to –270 °F (–168 °C); Annex R for refrigerated.
- Annex Q: refrigerated LNG, ethylene with 9 % Ni or stainless inner shell.
- Annex R: low-pressure refrigerated storage of LPG, NH3, etc.
- Stress allowable: ≤ 1/3 UTS or 5/12 yield (lower governs).
- Joint efficiency E: 1.0 with full RT for primary stress areas.
- Hydrotest: pneumatic + hydrostatic combination commonly used.
NFPA — 1 standard
NFPA 58
Liquefied Petroleum Gas Code
LP-Gas storage, handling, transport in the US.
EEMUA — 1 standard
EEMUA Publication 147
Recommendations for the Design and Construction of Refrigerated Liquefied Gas Storage Tanks
Engineering practice for refrigerated ammonia, LPG, and related storage. Widely cited alongside API 625 / EN 14620.
Key requirements (6)
- UK industry recommendations for refrigerated storage tank inspection, maintenance and repair.
- Tank classification: Type A (full), B (double), C (single) — similar to API 625.
- External inspection ≤ 1 year; partial internal at warm-up windows (5–10 yr typical).
- 9 % Ni steel inspection: surface examination + UT thickness; weld NDE on repair welds.
- Cool-down management: gradient ≤ 5 °C/hr typical to prevent thermal shock.
- Boil-off rate (BOR) monitoring as tank integrity indicator.
BSI — 1 standard
BS 7777 (legacy)
Flat-bottomed, vertical, cylindrical storage tanks for low temperature service
British cryogenic tank code; still referenced on legacy LNG/LPG/ammonia projects.
Key requirements (5)
- British 4-part standard for above-ground vertical flat-bottomed cylindrical tanks for low-temp refrigerated service.
- Part 1: Guide; Part 2: Design (metallic); Part 3: Concrete components; Part 4: Insulation.
- Pre-dates EN 14620; still cited for LNG, ethylene, propane storage in UK / Middle East.
- Temperature scope: down to –165 °C (LNG).
- Defines single, double, full containment with similar criteria to API 625 / EN 14620.
BIS — 1 standard
IS 6044 (Parts 1 & 2)
Code of Practice for LPG Storage Installations
Indian LPG storage facilities — pressurized and refrigerated.
Key requirements (4)
- Indian code for LPG storage installations — Part 1 (above-ground pressurized) and Part 2 (refrigerated).
- Covers spacing, fire protection, vent stack height, instrumentation.
- Aligned with NFPA 58 in approach but with Indian PESO statutory framework.
- Mandatory deluge water spray, gas detection, automatic ROV on inlet/outlet lines.