Compressed Natural Gas Standards Explained

June 19, 2025

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By Chuck Hayes (Swagelok/Advanced Clean Tech News) Global investment in clean-energy-powered vehicles and their supporting infrastructure continues to grow. Specifically, natural gas-powered vehicles have demonstrated major potential, delivering cost-effective operation and reduced environmental impact versus traditional gasoline or diesel vehicles.

For CNG and RNG systems—be they on-vehicle or part of critical refueling infrastructure—to meet their full potential, selecting and specifying high-performance components capable of handling small-molecule gases over extended fluid system lifespans is essential. But for CNG original equipment manufacturers (OEMs), it can be challenging to determine which products and components are approved for critical applications.

Dozens of small-bore fluid system components are essential in production applications, virtual pipelines, refueling stations, and on-vehicle systems. Each of these components—including tube fittings, valves, hoses, and more—should be subject to rigorous testing and have been proven to deliver reliable performance, as the consequences associated with subpar component performance can be significant.

This article will help you more easily navigate the industry’s testing and documentation landscape, ultimately simplifying component selection for your intended applications.

CNG Standards Explained
There is no single global standard for CNG components and vehicles, which is one reason why navigating component selection can be a challenge. However, there are several standards that maintain significant influence in the marketplace and can be used to help guide your choice of componentry.

The most prominent and established of these standards includes:

ECE R110. This standard is a regulation by UN/ECE that sets uniform provisions for the approval of specific components of motor vehicles using CNG. It also covers the installation of these components in vehicles. The regulation is intended to ensure the safety and reliability of CNG-powered vehicles by setting standards for their design, construction, and performance.
NGV 3.1. This standard establishes requirements for fuel system components for CNG-powered vehicles and applies to devices with service pressures of 16 500 kPa, 20 700 kPa, or 24 800 kPa. It addresses the pressure containment, performance, and safety characteristics of these components.
NGV 4.1. This standard establishes requirements for natural gas dispensing systems, including their mechanical and electrical features. It ensures that the dispensing system is intended primarily to dispense methane directly into the fuel storage container of the vehicle.
ISO 15500-1:2015. This standard specifies general requirements and definitions for CNG fuel system components intended for use on motor vehicles, provides general design principles, and specifies requirements for instructions and markings. The standard is applicable to vehicles using natural gas in accordance with ISO 15403-12. It is not applicable to liquified natural gas (LNG) fuel system components, fuel containers, stationary gas engines, container mounting hardware, electronic fuel management, or refueling receptacles.
ASME B31.3. This standard, known as the Process Piping Code, emphasizes safety and reliability in the design and construction of piping systems used in various industries. It covers aspects such as materials, welding, brazing, heat treating, forming, testing, inspection, examination, operation, and maintenance.

Being familiar with these standards can help CNG engineers and system designers make effective component selections and know what component certifications to seek out. It is worth considering, however, that certification by a manufacturer is not necessarily the most important criterion to evaluate when seeking products that will perform well in specific applications. Rather, specifiers should look for products that have been fully tested by an independent laboratory per the standards’ protocols. The results of these tests are reported to the appropriate regulatory body, and any products that fail testing are handled according to disqualification procedures.

Lab testing may evaluate a wide range of performance criteria, including susceptibility to corrosion, burst, vibration, pressure, and more. You can learn more about the most important performance criteria for natural gas systems in this article. Testing confirms the component has demonstrated equal or better performance to those bearing full certification.

The Importance of Documentation
When selecting critical CNG components, engineers and system designers should have access to a range of documentation that confirms the component is fit to perform in the required application. For this reason, components suppliers should provide the following materials upon request:

International certifications and listings documentation. These certifications help organizations transition to renewable energy solutions and set professionals apart in the industry.
Third-party test reports. As noted earlier, third-party testing ensures reliable component performance. Such reports are generated by third-party laboratories recognized by regulatory bodies, such as the U.S. Environmental Protection Agency (EPA), and provide verification testing of products to ensure they meet the required standards.
Letters of attestation. This is a formal document that verifies compliance with certain standards, regulations, or contractual obligations. These letters can cover various scenarios, such as compliance with industry standards, environmental regulations, or contractual obligations. Letters of attestation may include testing to multiple standards.
Declarations/declarations of conformity. Products that maintain letters of attestation or third-party test reports can be expected to perform equally to those that bear official international certification and therefore can be specified for on-vehicle or dispensing applications.
Tech letters. A tech letter describes the supplier’s approach to meeting a specific set of requirements, such as ASME B31.3.

Production applications, virtual pipelines, refueling stations, and on-vehicle systems all require dozens of small-bore fluid system components to operate reliably. Each of these components should be tested and proven to deliver reliable performance. That’s why it’s important to know what standards you need to look for, the right questions to ask to feel confident in the performance of products to those standards and working with providers that have demonstrated experience within your industry/applications. READ MORE