ISO 9809-3:2019

Overview

ISO 9809-3:2019 - "Gas cylinders - Design, construction and testing of refillable seamless steel gas cylinders and tubes - Part 3: Normalized steel cylinders and tubes" - specifies minimum requirements for the material, design, construction, workmanship, manufacturing processes, examination and testing at the time of manufacture for refillable seamless steel gas cylinders and tubes. It applies to normalized or normalized and tempered steel cylinders and tubes with water capacities up to and including 450 l, intended for compressed, liquefied and dissolved gases.

Key topics and technical requirements

This standard covers the full manufacturing and quality regime for seamless steel gas cylinders, including:

• Materials and heat treatment: controls on chemical composition and heat treatment requirements for normalized steels.
• Design requirements: shell thickness, convex/concave ends, neck and foot rings, neck threads and design drawings.
• Manufacturing quality and workmanship: wall thickness, surface imperfection criteria, straightness, out-of-roundness and mean diameter.
• Non-destructive testing (NDT): ultrasonic examination procedures and acceptance criteria (see Annex B).
• Prototype and type approval tests: hydraulic burst, pressure cycling, bend/flattening (bend retained for prototype tests), base check and thread tests.
• Batch and per-cylinder tests: tensile, impact, hardness, hydraulic (proof pressure and volumetric expansion), leak testing and capacity checks.
• Certification and marking: type approval and acceptance certificate examples (informative annexes) and stamp marking requirements.
• Annexes: manufacturing imperfections (Annex A), ultrasonic guidance (Annex B), and calculation examples for stresses and threads (Annexes E–F).

Practical applications and who uses it

ISO 9809-3:2019 is essential for stakeholders involved in the lifecycle of refillable steel gas cylinders:

• Cylinder manufacturers - to design and produce cylinders that meet international safety and quality benchmarks.
• Quality control and NDT laboratories - for inspection, ultrasonic testing and batch acceptance testing procedures.
• Certification and approval bodies - to issue type approval and acceptance certificates based on standardized prototype and batch tests.
• Gas suppliers and distributors - to ensure cylinder compatibility, safety and regulatory compliance for compressed, liquefied or dissolved gases.
• Regulators and transport authorities - for referencing in national regulations and the UN Model Regulations on transport of dangerous goods.

Related standards

ISO 9809-3 references and aligns with other key documents, including:

• ISO 9809-1 (quenched & tempered steels)
• ISO 10286 (terminology)
• ISO 11114-1 / ISO 11114-4 (compatibility and hydrogen embrittlement)
• ISO 13341 (valve fitting) and ISO 13769 (stamp marking)
• Test method standards such as ISO 6892-1 (tensile), ISO 148-1 (Charpy impact), ISO 6506 / 6508 (hardness)

Keywords: ISO 9809-3:2019, gas cylinders, normalized steel cylinders, seamless steel tubes, cylinder testing, hydraulic test, ultrasonic examination, type approval, cylinder manufacture.