ISO 15500-16:2020

Overview

ISO 15500-16:2020 is an international standard developed by the International Organization for Standardization (ISO) that defines the specifications, tests, and requirements for rigid stainless steel fuel lines used in compressed natural gas (CNG) fuel systems for road vehicles. Serving as Part 16 of the ISO 15500 series, this document applies specifically to fuel lines designed for mono-fuel, bi-fuel, or dual-fuel vehicles operating on natural gas compliant with the ISO 15403 series. The standard excludes components related to liquefied natural gas (LNG) systems, fuel containers, stationary gas engines, certain hardware, electronic fuel management, and refuelling receptacles.

The document aims to ensure safety, durability, and compatibility of stainless steel rigid fuel lines under natural gas fuel conditions, providing test methods such as hydrostatic strength, bending, and continued operation to verify performance.

Key Topics

• Scope and Applicability

  • Focus on rigid stainless steel fuel lines conforming to ISO 1127 dimensions
  • Intended for use in vehicles as defined by ISO 3833 classification
  • Exclusions include LNG fuel system upstream components, fuel containers, and refuelling hardware

• Marking Requirements

  • Essential for traceability with mandatory markings including:
    • Manufacturer’s name, trademark, or symbol
    • Model or part number
    • Working pressure with temperature range
    • Serial number or date code
  • Additional recommended markings cover fuel direction, fuel type, certification symbols, and type approval references

• Construction and Assembly

  • Use of seamless cold-worked austenitic stainless steel tubes compliant with ISO 1127
  • Conformance with general requirements outlined in ISO 15500-1 and ISO 15500-2
  • Manufacturing tolerances based on ISO 15500-2 guidelines

• Testing Procedures

  • Hydrostatic Strength: Tested to at least four times the working pressure (20 MPa standard, adjustable for higher pressures)
  • Continued Operation: Durability tested through 100,000 operational cycles followed by hydrostatic testing
  • Bending Test: Fuel lines bent around a mandrel per defined diameters, then tested for integrity and leakage under pressure
  • Additional tests including leakage, corrosion resistance, ozone aging, heat aging, and resistance to automotive fluids ensure reliability

Applications

ISO 15500-16:2020 plays a critical role in regulating the quality and safety of CNG fuel lines for various types of natural gas vehicles, including:

• Mono-fuel Vehicles: Dedicated natural gas vehicles exclusively fueled by CNG
• Bi-fuel and Dual-fuel Vehicles: Vehicles capable of operating on both natural gas and another fuel source such as gasoline or diesel
• Public and Commercial Transport: Ensuring fuel system integrity under rigorous operating conditions
• OEM Manufacturers and Component Suppliers: Providing standardized requirements to maintain product consistency and safety compliance
• Aftermarket Parts Production: Enabling reliable replacement components that meet international safety and performance standards

By adhering to this standard, manufacturers can assure end-users of high durability, safety, and performance in CNG fuel system applications, enhancing the adoption of clean energy vehicles.

Related Standards

• ISO 1127: Stainless steel tubes-dimensions, tolerances, and masses-forms the basis for tube specifications used in fuel lines
• ISO 15500-1: Defines general requirements and terminology for compressed natural gas fuel system components
• ISO 15500-2: Details performance and test methods for CNG fuel system components referenced throughout ISO 15500-16
• ISO 3833: Classification and definitions of road vehicle types relevant for applicability of the fuel system component
• ISO 15403 Series: Natural gas quality specifications for compressed natural gas used as vehicle fuel

These interconnected standards collectively ensure that all CNG fuel system components meet robust quality and safety criteria throughout design, manufacturing, installation, and service life.

Keywords: ISO 15500-16, CNG fuel system components, compressed natural gas, stainless steel rigid fuel line, road vehicle fuel lines, natural gas vehicles, CNG fuel line tests, hydrostatic strength, bending test, vehicle fuel system standards, ISO compressed natural gas standards.