Overview
ISO 7314:2002 - "Aerospace - Fluid systems - Metal hose assemblies" defines requirements for medium‑pressure, high‑temperature flexible metal hose assemblies used in aerospace fluid systems. It covers hoses for conveying air and other gases in pneumatic, bleed‑air, heating/ventilating and instrument‑air systems for continuous service from −55 °C to +400 °C with short excursions up to +650 °C. The standard limits flow velocity to 54 m/s (higher velocities require special damping) and specifies two construction types: Type 1 (welded convoluted inner tube - moderate mass/flexibility) and Type 2 (seamless or butt‑welded/redrawn convoluted inner tube - low mass/high flexibility).
Key topics and technical requirements
- Materials and construction: Inner tube, braid and end fittings are made from stabilized austenitic stainless steel; materials must be defect‑free and suitable for the specified temperature range.
- Hose types: Type 1 (welded inner tube) and Type 2 (seamless or redrawn/butt‑welded inner tube). Type 2 assemblies may substitute for Type 1 without further approval; the reverse requires customer consent.
- End fittings and joints: End‑fittings are welded to the hose; welds must be fusion welds compatible with the base material. Fitting masses and configuration are controlled.
- Heat treatment: Where stress relief is required, weld joints shall be stress‑relieved at 895 °C ±15 °C for 2 h ±15 min to ensure corrosion and embrittlement resistance.
- Dimensions, pressure and bend radius: Tables in the standard (Tables 2–4) define nominal diameters, operating/proof/burst pressure ratings (with temperature correction factors), and minimum static/dynamic bend radii.
- Performance & qualification tests: Mandatory qualification and production tests include:
- Visual/examination and dimensional checks
- Proof pressure and burst tests
- Corrosion (salt‑spray/immersion) tests
- Vibration and braid integrity tests
- Flexure/pressure cycling (50,000 cycles)
- Repeated torque (fitment) tests
- Cold and thermal‑shock tests
- Stress‑corrosion (Strauss) tests
- Quality assurance: Supplier and user responsibilities, inspection classification, test methods and preparation for delivery (closures, packaging, marking).
Applications
ISO 7314 is intended for aerospace applications requiring reliable metal flexible hoses where high temperature, medium pressure and long life under vibration/flexure are critical. Typical uses:
- Pneumatic and instrument air systems
- Bleed air ducting
- Environmental control/heating and ventilation lines
- Any gas‑conveying service in aircraft/space vehicles within the stated limits
- Aerospace hose manufacturers and fabricators
- Design and systems engineers specifying fluid/system components
- Procurement teams and suppliers verifying compliance
- Quality, test and certification engineers responsible for qualification and acceptance testing
Related standards
- Normative reference: ISO 8625‑1 (Aerospace fluid systems vocabulary - general terms and definitions). Consult product drawings and applicable contractual documents for interfacing requirements.
Keywords: ISO 7314, metal hose assemblies, aerospace fluid systems, flexible metal hose, high temperature hose, hose qualification, braid reinforcement, proof pressure, burst test, bend radius.