ISO 5175-1:2017

Overview

ISO 5175-1:2017 - "Gas welding equipment - Safety devices - Part 1: Devices incorporating a flame (flashback) arrestor" specifies general requirements and type tests for safety devices that incorporate a flame (flashback) arrestor used downstream of manifold, cylinder or pipeline regulators and upstream of blowpipes for welding, cutting and allied processes. The standard covers design, materials, gas tightness, pressure resistance and functional performance tests but does not prescribe device location in a gas system. It excludes safety devices that do not incorporate a flame arrestor (see ISO 5175-2) and premixed oxy/fuel or air/fuel systems downstream of gas mixers or electrolysis generators.

Key topics and technical requirements

• Flame arrestor performance: Devices must quench flashbacks when tested according to the standard’s flashback resistance test (Clause 6.7).
• Pressure resistance: Housings must withstand a test pressure equal to ten times the device’s maximum operating pressure and in all cases not less than 6 MPa (60 bar) without permanent deformation.
• Gas tightness:
  • External gas tightness per ISO 9090.
  • Internal leakage limits: maximum 50 cm³/h for connection bores < 11 mm, or 0.41·d cm³/h for larger bores (d = internal bore in mm), where internal tightness is required.
• Multifunctional devices: Combines flame arrestor with functions such as non‑return (check) valves, temperature‑sensitive cut‑off valves, and pressure‑sensitive cut‑off valves. Tests cover reverse flow, cut‑off activation and internal leakage after flashback tests.
• Material and connection standards: Materials per ISO 9539; threaded connections and quick couplings per EN 560 and ISO 7289 respectively.
• Special guidance for hydrogen: Because of hydrogen’s burning characteristics, the standard recommends using flame arrestors with temperature‑sensitive cut‑off valves for hydrogen service.

Practical applications

• Use when specifying, designing, manufacturing or testing safety devices for oxy/fuel and compressed‑air fuel gas systems in welding and cutting applications.
• Applicable to equipment suppliers, component manufacturers (flame arrestors, valves, multifunctional assemblies), test laboratories performing type testing, safety engineers, procurement teams and regulatory bodies creating safety rules for gas welding installations.

Who should use ISO 5175-1:2017

• Manufacturers of gas‑welding safety devices and blowpipe assemblies
• Certification and third‑party testing laboratories
• Plant and safety engineers writing equipment specifications
• Standards committees and regulators addressing welding safety

Related standards

• ISO 5175-2 (safety devices not incorporating flame arrestors)
• ISO 9090 (gas tightness testing)
• ISO 9539 (materials)
• EN 560 / ISO 7289 (connections and couplings)
• ISO 10225 (marking) and ISO 15296 (vocabulary)

Keywords: ISO 5175-1:2017, flame arrestor, flashback arrestor, gas welding equipment, safety devices, flame arrestor testing, welding safety, non‑return valve, temperature‑sensitive cut‑off.