ISO 23555-3:2024

Overview

ISO 23555-3:2024 outlines the essential safety, constructional, performance, testing, and documentation requirements for gas safety shut-off devices (SSDs) in gas transmission, distribution, and industrial installations. This international standard applies to SSDs handling fuel gases-such as natural gas, manufactured gas, biomethane, and liquefied petroleum gas (LPG)-with operating pressures greater than 500 kPa (5 bar) and up to 10 MPa (100 bar), and nominal connection sizes up to DN 400. These SSDs operate within a temperature range of −20 °C to +60 °C. By providing comprehensive requirements, ISO 23555-3:2024 plays a key role in supporting safety and reliability within commercial and industrial gas infrastructures, ensuring effective protection against over-pressure and under-pressure situations.

Key Topics

• Scope and Applicability

  • Applies to SSDs used in industrial and commercial gas pipelines and installations.
  • Covers operating pressures from 500 kPa up to 10 MPa.
  • Covers connection sizes up to DN 400.
  • Suitable for a temperature range of −20 °C to +60 °C.

• Types of Devices

  • Devices using pipeline gas as the control energy source, requiring no external power.
  • SSDs integrated with a gas pressure regulator (referencing ISO 23555-2).
  • SSDs including a creep relief device or vent limiter.

• Excluded Applications

  • Devices for domestic installations installed downstream of domestic meters.
  • SSDs for service lines under 200 m³/h flow rate.
  • Industrial on/off process control valves (covered by IEC 60534 standards).
  • SSDs for sour or corrosive gas environments unless additional information is provided.
  • Devices for environments with unspecified contaminants or liquids.

• Performance and Testing

  • Specifies test methods for product type, routine, and batch surveillance testing.
  • Includes requirements for performance, material checks, strength, tightness, anti-static properties, and corrosion resistance.
  • Emphasizes reliability through response time, trip pressure accuracy, relatching, and endurance.

• Design and Safety Features

  • Addresses direct and indirect acting SSDs.
  • Requirements for main components like closing members, trip mechanisms, actuators, and controllers.
  • Consideration for fail-safe operation and manual reopening functionalities.
  • Marking, documentation, packaging, and transportation requirements ensure traceability and safe handling.

Applications

ISO 23555-3:2024 is utilized by manufacturers, engineers, and operators involved in:

• Gas transmission and distribution systems: Enhancing system safety by automatically shutting off gas flow in abnormal pressure conditions.
• Industrial gas installations: Ensuring protection for facilities using natural gas, LPG, biomethane, or manufactured gases.
• Commercial fuel gas infrastructures: Maintaining compliance and operational reliability in gas networks with pressures up to 10 MPa.
• Product conformity assessment: Guiding type testing, routine inspections, and documentation practices for SSDs.

By implementing the requirements of ISO 23555-3, stakeholders can minimize hazards, comply with international best practices, and assure the safety of gas distribution operations.

Related Standards

• ISO 23555-1: General requirements for gas pressure safety and control devices.
• ISO 23555-2: Requirements for gas pressure regulators.
• IEC 60534-2-3: Flow capacity testing for industrial process control valves.
• IEC 60534-4: Inspection and routine testing of control valves.

These associated standards offer a comprehensive framework for controlling and safeguarding gaseous fuel systems. For additional compliance or device integration, referencing these documents is recommended to support robust safety management and system interoperability.