ISO 15500-16:2020

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 16: Rigid fuel line in stainless steel

This document specifies tests and requirements for the rigid fuel line in stainless steel, a compressed natural gas (CNG) fuel system component in accordance with ISO 1127 intended for use on the types of motor vehicles defined in ISO 3833. This document is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using natural gas in accordance with the ISO 15403 series. It is not applicable to the following: a) liquefied natural gas (LNG) fuel system components located upstream of, and including, the vaporizer; b) fuel containers; c) stationary gas engines; d) container-mounting hardware; e) electronic fuel management; f) refuelling receptacles.

Véhicules routiers — Composants des systèmes de combustible gaz naturel comprimé (GNC) — Partie 16: Tuyauterie rigide pour combustible en acier inoxydable

General Information

• Status: Published
• Publication Date: 02-Aug-2020
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22/SC 41 - Specific aspects for gaseous fuels
• Drafting Committee: ISO/TC 22/SC 41/WG 3 - Fuel system components and refuelling connector for vehicles propelled by gaseous fuel
• Current Stage: 9092 - International Standard to be revised
• Start Date: 14-Feb-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 15500-16:2012/Amd 1:2016 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 16: Rigid fuel line in stainless steel - Amendment 1
• Effective Date: 09-Jun-2018
• Revises: ISO 15500-16:2012 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 16: Rigid fuel line in stainless steel
• Effective Date: 09-Jun-2018

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-16
Third edition
2020-08
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 16:
Rigid fuel line in stainless steel
Véhicules routiers — Composants des systèmes de combustible gaz
naturel comprimé (GNC) —
Partie 16: Tuyauterie rigide pour combustible en acier inoxydable
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Marking . 2
5 Construction and assembly . 2
6 Tests . 2
6.1 Applicability . 2
6.2 Hydrostatic strength . 3
6.3 Continued operation . 3
6.4 Bending . 3
Bibliography . 4
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 41,
Specific aspects for gaseous fuels.
This third edition cancels and replaces the second edition (ISO 15500-16:2012), which has been
technically revised. It also incorporates the Amendment ISO 15500-16:2012/Amd.1:2016. The main
changes compared to the previous edition are as follows:
— serial number or data code became mandatory in marking.
A list of all parts in the ISO 15500 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/
...