ISO 15500-17:2021

Overview

ISO 15500-17:2021 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 17: Flexible fuel line - defines construction, marking and test requirements for flexible CNG fuel lines (hose or hose assemblies) intended for use on motor vehicles (mono‑fuel, bi‑fuel, dual‑fuel) using natural gas per ISO 15403‑1. It applies to hoses built to SAE J517 (100R8) or JIS B 8362 characteristics and intended for vehicle classes in ISO 3833. The standard excludes LNG components upstream of the vaporizer, fuel containers, stationary engines, container hardware, electronic fuel management and refuelling receptacles.

Key topics and technical requirements

• Marking and traceability: Manufacturer name/trademark, part number, working pressure or pressure/temperature range and mandatory serial number or date code; recommended additional markings (flow direction, fuel type, certification symbol).
• Construction and assembly: Inner plies and braids must resist automotive fluids; optional outer cover must minimize fluid ingress; fittings shall comply with ISO 15500‑19 and be permanently attached.
• Dimensional tolerances: Nominal internal diameter tolerances and measurement methods (tapered plug gauge) are specified.
• Mechanical and durability tests (Clause 6):
  • Hydrostatic strength: tested at 4 × specified working pressure.
  • Continued operation (pressure cycling): 20 000 cycles for high‑pressure lines, 100 000 cycles for low‑pressure lines, followed by leak and hydrostatic testing.
  • Bending: no kinking; ball equal to half nominal ID must pass through.
  • Pull‑off: hose must withstand a calculated tensile force based on inside diameter and working pressure (see standard).
  • Vibration resistance, bending moment, corrosion, ageing (oxygen/ozone/heat) and permeability tests are defined.
• Permeation and electrical requirements: Permeation monitored over extended exposure; electrical resistance between couplings must be low enough to dissipate static (specified in the standard).
• Resistance to automotive fluids: Specific exposure and inspection procedures verify material compatibility.

Applications and users

ISO 15500-17 is used by:

• CNG hose and assembly manufacturers for design, production and quality control
• Automotive OEMs specifying fuel system components for CNG vehicles
• Test laboratories and certification bodies performing conformity and type‑approval testing
• Fleet integrators, system installers and maintenance teams ensuring safe CNG fuel line selection and installation

Practical benefits include improved safety, traceability, standardized testing for durability, permeability and electrical behavior - critical for reliable CNG vehicle fuel systems.

Related standards

• ISO 15500‑1 (general requirements)
• ISO 15500‑2 (test methods and performance)
• ISO 15500‑19 (fittings)
• ISO 15403‑1 (natural gas fuel quality)
• SAE J517 (100R8 hose) and JIS B 8362 (hose specifications)
• ISO 3833 (vehicle classification)

Keywords: ISO 15500-17:2021, CNG flexible fuel line, compressed natural gas, fuel system components, hydrostatic strength, permeability, electrical conductivity, automotive fluids, vibration resistance.