ISO 9938:2022 PDF

Overview

ISO 9938:2022 is the international procurement specification for aerospace PTFE hose assemblies classified for 204 °C / 28 000 kPa (280 bar) service. This third edition (2022) defines requirements for PTFE-lined flexible hose assemblies intended for use in aircraft hydraulic systems at temperatures from −55 °C to +204 °C and nominal pressures up to 28 000 kPa. The standard also permits use in aircraft pneumatic systems within the same temperature/pressure limits where limited gaseous diffusion through the PTFE liner is acceptable.

Key topics and technical requirements

ISO 9938:2022 covers the full lifecycle of PTFE hose assemblies from construction to delivery. Major technical topics include:

• Materials and construction: requirements for PTFE inner tubes, reinforcement layers and metallic fittings; material suitability and compatibility.
• Inner tube properties: density, tensile strength, elongation, tube roll and proof-pressure for the PTFE liner.
• Dimensional and physical requirements: bore, wall thickness, and hose geometry tolerances.
• Fittings and threads: specification of compatible fittings, thread standards and part numbering of interchangeable components.
• Performance and acceptance tests: proof pressure, burst pressure, impulse testing, thermal shock, volumetric expansion, leakage, elongation/contraction, stress degradation, assembly flexibility and pneumatic surge/effusion testing.
• Electrical and fire safety: electrical conductivity checks and fire resistance requirements where applicable.
• Quality assurance and inspection: qualification testing, sampling plans, periodic control tests, and requalification criteria.
• Preparation for delivery: cleaning, marking, packaging, storage and ordering data.
• Documentation: test reports, traceability and purchaser-supplied data for qualification and conformance inspections.
• Annex A provides equivalent components to aid procurement and interchangeability.

Applications and who should use it

ISO 9938:2022 is intended for:

• Aerospace OEMs and tier suppliers specifying PTFE hose assemblies for aircraft hydraulic and pneumatic systems.
• Procurement and supply-chain teams creating purchase specifications and ensuring supplier compliance.
• Quality, testing and certification laboratories performing qualification and acceptance testing.
• Maintenance, repair and overhaul (MRO) organizations verifying replacement hose assemblies meet original procurement criteria. Use this standard when specifying high-temperature, high-pressure PTFE hose assemblies where reliability, traceability and standardized test evidence are required.

Related guidance

ISO 9938:2022 was prepared by ISO/TC 20/SC 10 (Aerospace fluid systems and components). For full implementation, pair this procurement specification with system-level design requirements and manufacturer installation instructions when selecting PTFE hose assemblies for aircraft systems.