ISO 23551-1:2024

Overview

ISO 23551-1:2024 is the third-edition international standard specifying safety, constructional and performance requirements and type testing for automatic and semi-automatic shut-off valves used with gas burners and gas-burning appliances. It applies to normally closed and general-purpose valves mounted upstream of burners and appliances for fuel gases such as natural gas, manufactured gas and LPG, with declared maximum operating pressures up to and including 500 kPa. The standard excludes corrosive and waste gases and addresses valves actuated electrically, mechanically, hydraulically or pneumatically, including valves with flow controlled by external electrical signals and those fitted with closed-position indicator switches.

Key Topics and Technical Requirements

ISO 23551-1 covers the full lifecycle of valve design verification at the type-test level. Key technical topics include:

• Classification: classes of control, sealing force/pressure surge classifications, groups of controls and control functions.
• Construction requirements: general construction, appearance, moving parts, breather/venting, bypasses, diaphragms, balanced valves and semi-automatic designs.
• Materials and corrosion resistance: housing, springs, seals, surface protection and jointing for safe long-term operation.
• Connections and interfaces: thread types, flanges, compression fittings, GQC connections and provisions for hydraulic/pneumatic actuators.
• Performance testing (type testing only): leak-tightness, pressure surge, torsion/bending, rated flow rate, durability, functional tests (closing/opening functions, sealing and closing forces, delay/opening/closing times), endurance, hydrostatic withstand and resistance to permanent damage at excessive pressure.
• Electrical aspects: requirements for valves employing electrical components or indicators in the gas way.
• Documentation and tolerances: test conditions, tolerances and assembly/disassembly provisions for servicing.

Practical Applications and Who Uses This Standard

ISO 23551-1:2024 is intended for organizations involved in the safety and compliance of gas-burning equipment:

• Valve and component manufacturers - to design, validate and certify automatic and semi-automatic shut-off valves.
• Appliance manufacturers and system integrators - to select compliant upstream shut-off valves for gas burners and domestic/industrial appliances.
• Test laboratories and certification bodies - to perform required type tests and assess conformity with the standard.
• Regulators, safety engineers and procurement specialists - to reference recognized safety/ performance criteria in specifications, approvals and tenders.
• Service and maintenance organizations - for guidance on construction features, marking and expected functional performance.

Related Standards (if applicable)

This document is Part 1 of the ISO 23551 series (Part 1: automatic and semi-automatic shut-off valves). Users should consult other parts of the ISO 23551 series and relevant ISO/IEC standards for broader safety and appliance-specific requirements when designing, testing or certifying gas appliances.