Overview - EN ISO 11120:2015 (Gas cylinders, refillable seamless steel tubes)
EN ISO 11120:2015 specifies minimum requirements for the design, construction and testing of refillable seamless steel tubes (large gas cylinders) with a water capacity >150 l up to 3 000 l. It applies to quenched-and-tempered seamless steel tubes intended for compressed and liquefied gases used in worldwide ambient temperatures normally between −50 °C and +65 °C, and to tubes having an opening at each end. Tubes covered by this standard have a maximum tensile strength (Rma) of less than 1 100 MPa and can be used singly or in batteries for trailers and multiple element gas containers (ISO modules/skids).
Keywords: EN ISO 11120:2015, gas cylinders, refillable seamless steel tubes, design construction testing, compressed gases, liquefied gases.
Key topics and technical requirements
The standard addresses the full manufacturing and conformity chain for large refillable steel tubes, including:
- Materials and heat treatment: minimum material controls, chemical composition verification and required heat-treatment processes (quenched and tempered).
- Mechanical properties: tensile, impact and hardness requirements; limits and interpretation for batch testing.
- Design: calculation of cylindrical shell thickness, design of tube ends and fittings, and preparation of design drawings.
- Construction and workmanship: surface condition, control of imperfections, ultrasonic examination and end closures.
- Dimensional tolerances: requirements for diameter, wall thickness, straightness, out-of-roundness, eccentricity, length, water capacity and mass.
- Testing and inspection:
- Type approval: prototype tests and certification procedures.
- Batch tests: mechanical tests and sampling rules.
- Tests on every tube: hydraulic proof-pressure, volumetric expansion, hardness, visual inspection and ultrasonic NDT.
- Special provisions for tubes intended for embrittling gases.
- Documentation and marking: inspection certificates and marking requirements.
Keywords: hydraulic test, ultrasonic examination, proof pressure, volumetric expansion, type approval.
Applications and practical value
EN ISO 11120:2015 is used to ensure the safety, reliability and interchangeability of large refillable gas cylinders across manufacturing, transport and distribution chains. Typical applications include:
- Transportable gas storage on trailers and skids (ISO modules) for industrial and medical gases.
- Bulk storage for liquefied gases where refillable seamless tubes are preferred.
- Design and manufacturing specifications for cylinder producers, and acceptance criteria for purchasers.
Keywords: transportable gas cylinders, ISO modules, gas distribution, cylinder manufacturing.
Who should use this standard
- Cylinder manufacturers and fabricators
- Testing and certification bodies (type approval)
- Gas suppliers, bulk transport operators and fleet maintainers
- Safety inspectors, regulatory authorities and design engineers
Related standards and context
- Prepared by ISO/TC 58 “Gas cylinders” in collaboration with CEN/TC 23 “Transportable gas cylinders”.
- EN ISO 11120:2015 supersedes EN ISO 11120:1999 (as noted in the standard).
Using EN ISO 11120:2015 helps align large refillable cylinder design, testing and manufacture with international best practice for safety and global interoperability.
