Overview - ISO 7628:2010 (Thermoplastics tubing for air braking systems)
ISO 7628:2010 sets minimum requirements and test methods for thermoplastics tubing (mono‑wall and multilayer) used in road‑vehicle air braking systems. The standard covers materials, construction, dimensions, marking, installation guidance and extensive performance testing. Conformity of production is the responsibility of the tubing manufacturer, and tube marking alone does not guarantee that a tube assembly (tube + end fittings) is suitable for vehicle use - tube assemblies must be tested (Annex B).
Key topics and technical requirements
- Scope & categories: Tubing is classified into four categories with specified maximum working pressures and temperature ranges (e.g., categories for 1 000 kPa and 1 250 kPa with temperature limits up to 125 °C for engine‑compartment use).
- Dimensions and sizes: The standard defines nominal sizes and minimum wall thicknesses for common tubing diameters (examples: 4×1 mm through 19×2 mm).
- Materials & manufacture: Tubing shall be extruded from 100% virgin material (own reworked material allowed up to 20% of new feedstock); reinforcement is permitted when suitable for the application.
- Marking requirements: Tubing must be indelibly marked along a generating line (minimum 2 mm letter height), repeated at least every 350 mm, with seven items separated by slashes (ISO 7628, tubing category, outside diameter × wall thickness, material symbol per ISO 1043‑1, manufacturer designation, date code, etc.).
- Performance testing: A comprehensive test matrix includes:
- Burst tests (at ambient and specified elevated temperatures)
- Deformation under pressure
- Cold impact and impact after ageing
- Layer adhesion (for multilayer tubing)
- Chemical resistance tests (ethanol, battery acid, oil, urea)
- Stress cracking, moisture absorption, low‑temperature flex, heat ageing, artificial weathering and ozone exposure
- Tube‑assembly tests (pull‑out strength, leak testing, pulsating pressure fatigue, vibration, salt spray)
- Acceptance criteria: The standard specifies pass/fail thresholds (e.g., minimum burst factors at ambient and elevated temperatures) and sample sizes for each test.
Practical applications and users
- Who uses ISO 7628: tubing manufacturers, automotive OEMs, tube assemblers, quality and testing laboratories, component suppliers, aftermarket manufacturers and compliance engineers.
- Practical value:
- Ensures tubing safety and reliability in pneumatic braking systems
- Provides harmonized dimensions and marking for traceability
- Defines repeatable test methods for chemical, thermal and mechanical durability
- Helps OEMs and suppliers select compatible tubing and fittings and validate tube assemblies for vehicle integration
- Installation guidance: routing, support and storage recommendations to avoid chafing, kinking, excessive sag and fatigue.
Related standards
Keywords: ISO 7628:2010, thermoplastics tubing, air braking systems, road vehicles, tube assemblies, burst test, tubing categories, multilayer tubing, marking, automotive standards.
