ISO 15500-20:2015

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 20: Rigid fuel line in material other than stainless steel

ISO 15500-20:2015 provides specific requirements and tests applicable to the rigid fuel line in carbon steel, intended for use on the types of motor vehicles, as defined in ISO 3833, with a service pressure for natural gas as a fuel of 20 MPa (200 bar) settled at 15 °C. ISO 15500 is intended to be applied to vehicles using natural gas which comply with requirements established in ISO 15403‑1 (mono-fuel, bi-fuel, or dual-fuel applications). This part of ISO 15500 does not apply 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. NOTE All references to pressure in this part of ISO 15500 are considered gauge pressures unless otherwise specified.[1] [1] 1 bar = 100 kPa = 0,1 MPa.

Véhicules routiers — Composants des systèmes de remplissage en gaz naturel comprimé — Partie 20: Circuit de combustible rigide en matériaux autres que l'acier inoxydable

General Information

• Status: Published
• Publication Date: 29-Nov-2015
• 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 15500-20:2007 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 20: Rigid fuel line in material other than stainless steel
• Effective Date: 13-Aug-2011

Overview

ISO 15500-20:2015 specifies requirements and test methods for rigid compressed natural gas (CNG) fuel lines made of carbon steel (materials other than stainless steel) for road vehicles. It applies to vehicle types defined in ISO 3833 and is intended for CNG systems with a service pressure of 20 MPa (200 bar) at 15 °C. All pressure references are gauge pressures. ISO 15500-20 is one part of the ISO 15500 series covering CNG fuel system components.

Key topics and technical requirements

• Scope and exclusions
  • Applies to seamless carbon-steel rigid fuel lines for CNG (20 MPa service pressure).
  • Does NOT apply to LNG upstream components, fuel containers, stationary gas engines, container mounting hardware, electronic fuel management, or refuelling receptacles.
• Marking and labelling
  • Components must be traceable: manufacturer name/trademark, model/part number, and working pressure or pressure–temperature range.
  • Marking should be indelible and repeated at intervals ≤ 0.5 m.
• Construction and compatibility
  • Rigid fuel line must be seamless carbon steel and compatible with fittings to prevent electrochemical corrosion.
• Mandatory tests and acceptance criteria
  • Hydrostatic strength: tested per ISO 15500-2, at 4× the working pressure.
  • Continued operation (endurance): 100,000 cycles, followed by the hydrostatic test.
  • Corrosion resistance: 500 hours (tested on the bare rigid fuel line, without protective sleeves).
  • Bending: line is bent over a mandrel (mandrel diameter per RFLE diameter rules) to a U-shape, subjected to corrosion testing, then pressurized to 4× working pressure - no leaks allowed.
  • Additional applicable tests from ISO 15500-2 (leakage, vibration, ageing, fluids compatibility, etc.) are referenced where relevant.

Applications and users

• Who uses it
  • Automotive OEMs and Tier-1 suppliers designing or manufacturing CNG fuel system piping.
  • Component testing laboratories and certification bodies evaluating CNG rigid fuel lines.
  • Fleet integrators, retrofitters, and safety engineers implementing CNG systems in vehicles that comply with ISO 15403-1 fuel quality requirements.
• Practical use cases
  • Designing carbon-steel rigid fuel lines for mono-fuel, bi-fuel, or dual-fuel vehicles.
  • Verifying durability, corrosion resistance and pressure integrity of CNG piping under vehicle operating conditions.
  • Ensuring traceability and compatibility of components for regulatory approval and type-approval processes.

Related standards

• ISO 15500-1 (General requirements and definitions)
• ISO 15500-2 (Performance and general test methods)
• ISO 3833 (Vehicle types - terms and definitions)
• ISO 15403-1 (Natural gas fuel quality for vehicles)

Keywords: ISO 15500-20, CNG fuel line, rigid fuel line, carbon steel, hydrostatic strength, corrosion resistance, bending test, ISO 15500, compressed natural gas standards.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-20
Second edition
2015-12-01
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 20:
Rigid fuel line in material other than
stainless steel
Véhicules routiers — Composants des systèmes de remplissage en gaz
naturel comprimé —
Partie 20: Circuit de combustible rigide en matériaux autres que
l’acier inoxydable
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Marking and labelling . 2
5 Qualifications for construction and assembly . 2
6 Tests . 2
6.1 Applicability . 2
6.2 Hydrostatic strength . 3
6.3 Continued operation . 3
6.4 Corrosion resistance . 3
6.5 Bending . 3
Bibliography . 4
Foreword
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The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 41, Specific
aspects for gaseous fuels.
This second edition cancels and replaces the first edition (ISO 15500-20:2007), which has been
technically revised.
ISO 15500 consists of the following parts, under the general title Road vehicles — Compressed natural
gas (CNG) fuel system components:
— Part 1: General requirements and definitions
— Part 2: Performance and general test methods
— Part 3: Check valve
— Part 4: Manual valve
— Part 5: Manual cylinder valve
— Part 6: Automatic valve
— Part 7: Gas injector
— Part 8: Pressure indicator
— Part 9: Pressure regulator
— Part 10: Gas-flow adjuster
— Part 11: Gas/air mixer
— Part 12: Pressure relief valve (PRV)
— Part 13: Pressure relief device (PRD)
iv © IS
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