ISO 24431:2016 PDF

Overview

ISO 24431:2016 - "Gas cylinders - Seamless, welded and composite cylinders for compressed and liquefied gases (excluding acetylene) - Inspection at time of filling" - defines inspection requirements to be performed at the time of filling transportable gas cylinders. It applies to Type 1 (metal), and composite Types 2–5 cylinders with a water capacity up to 150 L (and may be applied to 150–450 L cylinders if filled individually). The standard excludes acetylene cylinders, cylinder bundles, MEGCs and battery vehicles, and can be applicable to LPG (see ISO 10691 for LPG specifics).

Key topics and technical requirements

ISO 24431:2016 sets out practical, safety-focused inspection steps and verification criteria, including:

• Identification of cylinder owner and authorization requirements before filling.
• Inspection stages: before filling, during filling and immediately after filling.
• Verification of serviceable condition:
  • General acceptance/rejection criteria based on visible defects.
  • Exterior and interior condition checks, including provisions for cylinders with coverings or sleeves.
  • Valve integrity and suitability, plus permanent attachments and protective devices.
• Tare and filling mass: procedures to determine cylinder tare and to calculate/verify correct filling weight and filling pressure.
• Gas tightness testing and checks for correct labelling and valve protection after filling.
• Special provisions for composite cylinders (Types 2–5) and for palletized cylinders.
• Handling of rejected cylinders, and informative annexes (residual pressure check; example tare procedure).

The standard emphasizes that inspections must be carried out by trained, competent fillers and is compatible with UN Model Regulations while noting national regulations take precedence where they differ.

Applications and who uses it

ISO 24431 is used to develop and implement safe, auditable filling operations and inspection procedures. Typical users:

• Cylinder filling facilities and gas suppliers
• Cylinder manufacturers and composite cylinder producers
• Transport and logistics companies handling pressurized gases
• Plant safety and compliance managers
• Regulators and certification bodies writing local filling requirements Practical uses include creating prefill checklists, training filler personnel, establishing acceptance/rejection criteria, and ensuring safe filling practices for compressed and liquefied gases.

Related standards

Standards referenced for complementary requirements:

• ISO 6406, ISO 10460, ISO 10461, ISO 11623 (periodic inspection/testing)
• ISO 13769 (marking)
• ISO 25760 (valve removal procedures)
• For LPG specifics: ISO 10691
• For manifolded bundles: ISO 11755

Keywords: ISO 24431:2016, gas cylinders inspection, filling inspection, seamless welded composite cylinders, compressed gases, liquefied gases, cylinder tare, filling pressure, valve integrity, cylinder labelling.