Flexible Metal Hoses for Cryogenic and Low-Temperature Applications
Combining flexibility, strength, and thermal stability for critical applications
Cryogenic and low‑temperature applications demand hose assemblies that can withstand extreme cold, rapid temperature cycling, and pressure fluctuations while maintaining full mechanical integrity. In these environments, flexible metal hoses ensure safe transfer of liquefied gases and cryogenic fluids, from liquid nitrogen and oxygen to argon and helium, without embrittlement or loss of containment.
Flexmetallic engineers and manufactures stainless‑steel cryogenic hose assemblies in the UK, combining corrugated metal hose cores, specialist alloys, and multi‑layer insulation to deliver reliable performance down to around minus 200 °C. These assemblies sit within the broader family of flexible metal hose assemblies, giving specifiers a consistent platform for both ambient and extreme low‑temperature duties.
Role of hoses in cryogenic duty
In cryogenic systems, hoses must carry ultra‑cold media while accommodating movement, vibration, and thermal expansion between rigid pipework and equipment. Typical duties include:
- Transfer of liquefied gases between storage tanks, mobile vessels, and process equipment.
- Filling and decanting operations in laboratories, industrial gas plants, and medical facilities.
- Low‑temperature service in energy, aerospace, and advanced manufacturing, where flexible connections are required alongside rigid lines.
Specialised cryogenic hoses provide a flexible conduit that maintains low thermal conductivity, limits heat ingress, and remains ductile under extreme cold. For systems that also require high‑temperature or mixed‑duty capability, engineers can reference the core flexible metal hose range to build a coherent specification.
Material selection for extreme cold
Materials used in cryogenic flexible metal hoses must retain ductility at very low temperatures while resisting corrosion from both media and the external environment. Flexmetallic cryogenic hoses typically utilise stainless steels such as 304, 316, and 321, which offer low‑temperature toughness, corrosion resistance, and good fatigue performance under flexing.
Low‑temperature ductility and thermal stability are critical, ensuring the hose can flex without cracking despite rapid temperature changes between ambient and cryogenic conditions. For particularly demanding services, nickel‑alloy constructions and heavy‑wall options are available, with full material traceability via 3.1B certification to BS EN 10204. When matching materials across an installation, specifiers can use the tools and guidance associated with flexible metal hose assemblies to align cryogenic and non‑cryogenic duties.
Insulation, sheathing and frost control
Effective insulation is essential to limit boil‑off, prevent frost build‑up, and protect personnel from contact with ultra‑cold surfaces. Flexmetallic cryogenic hoses can be constructed with multiple insulation layers and protective sheathing to minimise heat transfer, reduce ice formation, and maintain flexibility.
Outer pro‑coil wires, spring guards, and additional coverings can be specified to protect hose carcasses from mechanical damage and to manage bending at connection points. This combination of insulated construction with protective hardware helps maintain performance throughout the service life, particularly in high‑cycle decanting and filling applications. Where insulated cryogenic lines interface with ambient services, the same principles can be integrated into flexible metal hose assemblies used on downstream equipment.
Safety, cleanliness and testing
Cryogenic media such as liquid oxygen and nitrogen present specific safety and cleanliness requirements. Flexmetallic cryogenic assemblies are available oxygen‑cleaned, fully degreased, and supplied with ends plugged to preserve cleanliness during transit and storage.
Assemblies are typically hydrostatically tested at 1.5 times working pressure in accordance with BS EN ISO 10380, with additional helium leak testing available where very low leak rates are required. Full traceability, tagging, and certification ensure that each assembly’s materials, welds, and test records can be verified, in line with the controls applied to the wider flexible metal hose assemblies portfolio.
Construction for low-temperature reliability
The internal corrugated core of a cryogenic hose must balance flexibility with resistance to collapse under pressure or vacuum conditions. Flexmetallic designs these cores to maintain profile stability while allowing repeated flexing, then reinforces them with stainless‑steel braid to provide pressure containment and mechanical strength.
Spring guards, outer coil wires, and optional double‑braid constructions increase robustness at bend points and in high‑stress locations. Precision TIG welding to ASME IX and BS EN 9606‑1 connects end fittings to the hose, forming a fully welded pressure envelope tailored for low‑temperature performance. These techniques mirror those applied across high‑pressure flexible metal hose assemblies, ensuring a consistent standard of fabrication and weld quality.
Handling, routing and installation
Correct handling and routing are vital to maintaining cryogenic hose integrity over time. Recommended practices include:
- Avoiding tight bend radii below the hose’s specified minimum, especially at terminations and moving points.
- Supporting hoses to prevent kinking, torsion, or unnecessary external loading.
- Allowing sufficient slack for thermal contraction at low temperatures and expansion back to ambient.
Guidance on live length, movement, and support arrangements for both cryogenic and ambient‑temperature duties can be developed using principles from Flexmetallic’s technical tools and general flexible metal hose assemblies selection guidance.
Integration with wider hose assemblies
Cryogenic transfer lines seldom operate in isolation; they connect into broader systems that may use different hose types for ambient or high‑temperature fluids. Flexmetallic’s approach allows cryogenic hoses to sit alongside standard flexible metal hose, braided flexible metal hose, and high‑pressure assemblies, giving designers a consistent family of metallic solutions across the process.
Bespoke assemblies can combine cryogenic‑rated sections, insulated lengths, and specific end fittings to create integrated solutions for complex plant layouts, including loading arms, mobile equipment, and test rigs. This single‑source approach simplifies specification, documentation, and maintenance compared with mixing unrelated hose types from multiple suppliers.
FAQs
Conclusion and next steps
Cryogenic and low‑temperature applications place exceptional demands on hose assemblies, requiring materials, construction, and testing regimes that deliver safe, predictable performance under extreme cold. Flexmetallic’s stainless‑steel cryogenic hoses combine low‑temperature ductility, engineered insulation, and rigorous cleanliness and testing standards to support reliable handling of liquefied gases across industries.
For detailed pressure, temperature, and movement capabilities, or to align cryogenic duties with ambient and high‑temperature connections on the same site, use the flexible metal hose assemblies pillar page as the central reference point when developing specifications for cryogenic and low‑temperature systems