Stainless steel hose covers the widest service envelope of any flexible conduit, from cryogenic duty at −196 °C to superheated steam and hot gases at +550 °C and above, with corrosion resistance no elastomer can match. Two facts drive every correct specification: the corrugated core alone holds very little pressure (the braid carries the pressure load), and working pressure falls steeply as bore size rises. This guide is the engineering reference: construction geometry, alloy selection (304 vs 316L vs duplex), pressure and fatigue behaviour per EN ISO 10380, standards and certificates, and total cost of ownership in EUR terms.
For the specification pitfalls and installation checklists, see the companion article stainless steel hose: what engineers need to know before specifying; if you are weighing metal against a PTFE-lined alternative, start with stainless steel hose vs PTFE hose.
What Is Stainless Steel Hose?
Stainless steel hose is a flexible metallic conduit: a thin-walled austenitic stainless tube formed into a corrugated profile for axial flexibility, normally covered by one or two layers of stainless wire braid, and terminated with welded or threaded end fittings. Unlike elastomeric or thermoplastic hose, it transfers no plasticiser or leachable compound into the fluid, tolerates open flame and radiant heat, and is unaffected by UV, ozone, and most weathering.
A complete assembly has three independently specified elements, corrugated core, braid, and end fittings, and mismatching any one of them to the duty is a common source of premature failure. The governing product standard for corrugated metallic hose assemblies is EN ISO 10380.
How Is Stainless Steel Hose Constructed?
Annular vs Helical Corrugation
Annular hose has closed, ring-shaped convolutions. Pressure is distributed uniformly around each ring, giving the best pressure ratings and fatigue life; it is the default for steam, chemical, and high-pressure duties and the geometry most EN/ISO requirements assume. Helical hose uses one continuous spiral convolution, more flexibility per unit length and easier to make in large bores, but better suited to low- and medium-pressure duties such as exhaust and ventilation ducting.
Interlocked (Strip-Wound) Hose
Interlocked hose is profiled steel strip wound and hooked into a flexible conduit. It is not pressure-tight on its own; it serves as mechanical protection for cables and hoses, or as the flexible carcass around a sealing liner. Do not confuse it with corrugated pressure hose, the two look superficially similar in large bores.
Why the Braid Matters Most
The corrugated core provides flexibility and leak-tightness, not pressure capacity. It is the braid that carries the pressure load: an unbraided corrugated hose typically withstands only a small fraction of the braided assembly's rating and will elongate and squirm under pressure. Adding a second braid layer raises the working pressure substantially, and braid parameters (wire diameter, lay angle, coverage) are validated by type testing under EN ISO 10380. Practical consequence: never pressurise an unbraided corrugation, and never assume two visually similar hoses share a rating.
Which Stainless Steel Grade Should You Choose?
Grade selection is the most consequential decision in the specification. The principal alloys:
| Grade | EN / UNS | Key characteristic | Typical service |
|---|---|---|---|
| 304 / 1.4301 | S30400 | General corrosion resistance | Water, air, mild chemicals |
| 304L / 1.4307 | S30403 | Low carbon, weld-sensitisation resistant | Welded assemblies, cryogenics |
| 316 / 1.4401 | S31600 | ~2 % Mo, chloride and pitting resistance | Marine, chemical |
| 316L / 1.4404 | S31603 | Low carbon + Mo | Welded pharma, chloride environments, seawater |
| 321 / 1.4541 | S32100 | Ti-stabilised for high temperature | Steam, exhaust, heat exchangers |
| 316Ti / 1.4571 | S31635 | Ti-stabilised + Mo | High-temperature chemical service |
| Duplex 2205 / 1.4462 | S32205 | High strength, chloride-SCC resistant | Offshore, chloride-saturated media |
| 904L / 1.4539 | N08904 | High Ni + Mo, acid resistance | Sulphuric/phosphoric acid duties |
The rule of thumb: 316L is the correct default for most industrial duties. Its molybdenum addition raises pitting resistance well above 304, decisive wherever chlorides, seawater, or de-icing salts are present; 304 in a coastal or chloride-rich environment can pit within months where 316L survives for years. For hot, chloride-saturated, or sour (H₂S) service, evaluate duplex 2205 against NACE MR0175 / ISO 15156; for concentrated sulphuric or phosphoric acid, 904L or a nickel alloy such as Hastelloy C-276 may be the only metallic option. Stainless steel is not universally resistant: concentrated hydrochloric acid and wet chlorine attack all standard austenitic grades rapidly, consult a chemical compatibility table.
What Pressure Can Stainless Steel Hose Withstand?
Working pressure depends on bore, braid count, corrugation geometry, and temperature. Indicative values for annular 316L hose at +20 °C:
| DN (mm) | NPS (in) | WP single braid (bar) | WP double braid (bar) | Min. bend radius, static (mm) |
|---|---|---|---|---|
| 10 | 3/8 | ~40 | ~64 | ~40 |
| 16 | 5/8 | ~32 | ~52 | ~60 |
| 25 | 1 | ~25 | ~40 | ~90 |
| 40 | 1 1/2 | ~16 | ~28 | ~140 |
| 50 | 2 | ~12 | ~20 | ~175 |
| 80 | 3 | ~8 | ~14 | ~270 |
| 100 | 4 | ~6 | ~10 | ~340 |
Key takeaway: working pressure falls roughly in inverse proportion to bore diameter for the same construction. Never carry a DN 10 rating across to a DN 50 hose with the same part-number prefix, always read the manufacturer's size-by-size table.
Three further rules. Safety factor: EN ISO 10380 requires a minimum burst-to-working-pressure ratio of 4:1, with hydrostatic proof testing at 1.5 × working pressure; gas service and high-cycle duties often warrant a larger margin. Temperature derating: ratings are quoted at +20 °C and must be derated per the manufacturer's curve at elevated temperature, a hose at +400 °C retains only a fraction of its cold rating. Vacuum: braided corrugated hose is inherently full-vacuum capable in standard sizes. Fatigue life in dynamic duty (pump connectors, vibration absorbers) is validated by the cyclic flexure testing of EN ISO 10380, for high-cycle applications, request the type-test report and the manufacturer's fatigue data rather than assuming a figure.
Where Is Stainless Steel Hose Used?
- Oil, gas, and petrochemical: pump connectors, thermal-expansion absorbers, and instrumentation impulse lines; duplex 2205 for sour or subsea service per NACE MR0175 / ISO 15156.
- Food, beverage, and dairy: hygienic assemblies with electropolished bores (Ra 0.8 µm or better per EN 1672-2 / EHEDG guidance) and sanitary ends — DIN 11851, SMS 1145, Tri-Clamp per DIN 32676, or ISO 2853; these are distinct, non-interchangeable coupling systems.
- Pharmaceutical: all-welded 316L assemblies with ASME BPE-class surface finishes and full traceability to EN 10204 3.1 certificates for WFI and pure-steam duty. FDA 21 CFR 177.2600 / USP Class VI apply only to elastomeric seals or liners within the assembly, not to the metal itself.
- Steam and power generation: titanium-stabilised grades (321, 316Ti) above roughly 300 °C to resist sensitisation; a sensitised assembly in chloride-contaminated condensate fails by intergranular stress corrosion cracking with no external warning.
- Cryogenics and LNG: austenitic grades (304L, 316L) retain toughness to −196 °C; LNG transfer hose additionally falls under EN 13766. Ferritic and martensitic steels are excluded by their ductile-to-brittle transition.
How Should Stainless Steel Hose Be Installed?
Four rules prevent the large majority of field failures:
- Eliminate torsion. Metal hose has essentially zero torsional flexibility; twist during make-up is the leading preventable cause of premature fatigue failure. Use a second spanner on the fitting hexagon, support the hose body, and mark a lay line to verify zero twist after installation.
- Respect the minimum bend radius. Bending below the catalogue MBR concentrates strain at the convolution roots and can cut fatigue life by an order of magnitude. Use a pre-formed elbow or an angled fitting where space is tight.
- Manage vibration. Orient the hose perpendicular to the dominant vibration plane, and clamp long assemblies to prevent resonance amplification.
- Pressure-test before commissioning. Hydrostatic test at 1.5 × working pressure per the applicable code. Treat pneumatic testing with extreme caution, stored energy in compressed gas is vastly higher than in liquid at the same pressure.
In service, inspect on a risk-based interval (annual visual inspection is typical for low-consequence duty; quarterly for high-pressure or hazardous media). Replace, never repair, any assembly with cracks in the hose body, broken braid wires, kinks or bend-radius violations, significant pitting, or leakage at the fittings.
Which Standards and Certificates Apply?
- EN ISO 10380, corrugated metallic hoses and hose assemblies: dimensions, pressure ratings, 4:1 burst requirement, fatigue and marking.
- EN 14585-1, corrugated metal hose assemblies for pressure applications.
- PED 2014/68/EU, hose assemblies for dangerous (Group 1) fluids above the directive's DN and pressure, volume thresholds require CE marking; higher categories involve a Notified Body.
- ATEX 2014/34/EU, in explosive atmospheres, verify earthing continuity across the assembly.
- EN 10204 3.1 / 3.2, material certificates; 3.1 is the industrial baseline, 3.2 (independent inspection) for nuclear, subsea, and some pharma duties.
- NACE MR0175 / ISO 15156, material selection for sour hydrocarbon service.
- ASME B31.3, process piping code context for plant installations.
- ASTM A967, post-weld passivation of stainless components.
Procurement insight: always request the EN ISO 10380 type-test report and the EN 10204 3.1 certificate with the quotation. An assembly without traceable documentation is a compliance and liability risk that negates any unit-price saving.
Is Stainless Steel Hose Worth the Premium?
A 316L pump-connector assembly may cost, say, EUR 450–700 installed, against EUR 100 for a reinforced rubber hose on the same duty, but the rubber hose in hot, ozone-exposed, or chemically aggressive service may need replacement every 18–24 months, while the metal assembly runs 7–15 years in appropriate duty. Add the downtime cost of each unplanned change-out (in continuous process plants, thousands of euros per hour), the consequence of releasing a hazardous fluid, and the inventory simplification of one metal specification replacing several elastomer grades, and the total cost of ownership calculation routinely favours stainless steel in corrosive, high-temperature, and safety-critical service.
Key Takeaways
- The braid carries the pressure: an unbraided corrugated core holds only a small fraction of the assembly rating. Specify core, braid, and fittings as one validated system per EN ISO 10380.
- Working pressure falls as DN rises and derates further with temperature, read ratings size by size at the operating temperature, never per family.
- 316L is the default grade; upgrade to duplex 2205 for chloride-saturated or sour service, 321/316Ti above ~300 °C, and 904L or nickel alloys for concentrated acids. 304 pits quickly in chloride environments.
- EN ISO 10380 requires a 4:1 burst-to-WP ratio and 1.5 × proof testing; PED 2014/68/EU applies to assemblies for dangerous fluids above its thresholds.
- Torsion during installation is the leading preventable failure cause, metal hose has zero torsional flexibility.
- Hygienic couplings (DIN 11851, SMS 1145, Tri-Clamp DIN 32676, ISO 2853) are different, non-interchangeable systems; FDA/USP requirements apply to the elastomeric seals, not the steel.
Browse metallic and high-temperature assemblies in our industrial hoses range or search stainless steel hose, with matching flanges, threads, and sanitary ends in industrial fittings; full datasheets are in our catalogues. For chloride, steam, cryogenic, or PED-scope duties, send the service conditions, our engineering team selects the alloy, braid, and fittings, then fabricates and pressure-tests the complete assembly.