ISO 21012:2018

Overview

ISO 21012:2018 - Cryogenic vessels - Hoses specifies requirements for the design, construction, testing and marking of non‑insulated flexible hoses used to transfer cryogenic fluids. It applies to hoses with nominal sizes DN 10 to DN 100 and an operating temperature range from −270 °C to +65 °C. The standard is intended to ensure hoses are designed and tested to satisfy a generally accepted rated pressure (PR) - typically PR ≥ 40 - and that selected hoses have PR equal to or greater than the maximum allowable pressure (PS) of the equipment they serve.

Key topics and technical requirements

• Scope and sizing: Covers non‑insulated flexible cryogenic hoses for DN 10–100, −270 °C to +65 °C.
• Design & construction: Corrugated metal, elastomer or plastic inner tubes; braids (usually stainless steel or high‑strength copper alloys); end fittings to provide a tight, robust seal and restraint against elongation. Couplings are outside this standard’s scope.
• Materials & compatibility: Materials must be compatible with conveyed fluids and retain ductility at rated minimum temperatures (see ISO 21028‑1). Special notes:
  • Austenitic stainless steel hoses for hydrogen service shall be annealed after formation.
  • Alloys and solders for acetylene mixtures shall contain less than 65% copper.
• Cleanliness: Internal cleanliness required per ISO 23208 to remove hydrocarbons, moisture and particles before service.
• Pressure & mechanical performance:
  • Test pressure used in type/production tests shall be ≥ the hose PR.
  • Burst pressure ≥ 3 × PR (failure should occur in hose body, not connections).
  • Minimum cyclic life: 10,000 pressure cycles from <1 bar to PR (where applicable).
  • Optional bending/rolling‑bend tests, low‑temperature resistance, leak tightness, electrical property checks and resistance to abuse.
• Marking, documentation & testing: Marking area on fittings, material test certificates, production pressure and leak tests, and test certificates are required. Annexes provide typical assembly details and testing guidance.

Applications and users

ISO 21012:2018 is used by:

• Manufacturers of cryogenic hose assemblies and end fittings
• Engineers and specifiers designing cryogenic piping and transfer systems (liquid oxygen, nitrogen, hydrogen, LNG, etc.)
• Quality and testing laboratories conducting type and production tests
• Plant operators and safety engineers selecting hoses to match equipment PS and service conditions

Practical applications include transfer lines for cryogenic storage and process equipment, vehicle refuelling, and laboratory or industrial cryogenic handling where flexibility and low‑temperature performance are required.

Related standards

• ISO 7369 (vocabulary for metal hoses)
• ISO 10806 (fittings for corrugated metal hoses)
• ISO 21010 (gas/materials compatibility)
• ISO 21028‑1 (toughness at cryogenic temperatures)
• ISO 23208 (cleanliness for cryogenic service)