ISO 11120:2015

Overview

ISO 11120:2015 - "Gas cylinders - Refillable seamless steel tubes of water capacity between 150 l and 3000 l - Design, construction and testing" sets minimum international requirements for the material, design, manufacture and testing of refillable, quenched-and-tempered seamless steel tubes used as large gas cylinders. It applies to tubes with water capacities exceeding 150 l up to and including 3 000 l, with a maximum tensile strength below 1 100 MPa, intended for compressed and liquefied gases in extreme ambient temperatures (normally between -50 °C and +65 °C). Tubes covered by this standard have an opening at each end and can be used singly or in batteries (trailers, ISO modules or skids).

Key topics and technical requirements

• Materials and chemistry: Controls on chemical composition and heat treatment for quenched and tempered steels; Annex A provides typical chemistry groupings.
• Mechanical properties: Tensile, impact and hardness requirements plus provisions when tests are not met.
• Design: Calculation of cylindrical shell thickness, design of tube ends and drawings to ensure safe pressure containment.
• Manufacturing and workmanship: Surface quality, dimensional tolerances (diameter, length, out-of-roundness, straightness, eccentricity), and ultrasonic examination of walls and imperfections.
• Testing and inspection:
  • Type approval including prototype tests and certification.
  • Batch tests and mechanical tests (tensile, impact).
  • Every-tube tests: hydraulic proof pressure, volumetric expansion, hardness, visual inspection, dimensional checks, and ultrasonic non-destructive testing.
• Special provisions for tubes intended for embrittling gases (materials, design and testing).
• Traceability and documentation: Inspection certificates, marking and acceptance certificates (Annexes D–E).

Applications and users

ISO 11120:2015 is intended for organizations involved with large refillable gas cylinders, including:

• Cylinder manufacturers and steel tube mills
• Pressure-vessel and gas system designers
• Transport and distribution companies using trailers, modules or skids
• Conformity assessment bodies, inspection and testing laboratories
• Regulatory authorities and safety engineers managing compressed or liquefied gas systems

Practical applications include transportation and storage of industrial gases, staging of gas trailers, and multi-element gas containers used in medical, industrial and specialty gas supply chains.

Related standards

ISO 11120 is developed by ISO/TC 58 (Gas cylinders) and is intended to work with UN Model Regulations on the Transport of Dangerous Goods and other ISO standards covering cylinder fittings, periodic inspection and testing, and pressure receptacle conformity assessment.

Keywords: ISO 11120:2015, gas cylinders, refillable seamless steel tubes, design, construction, testing, compressed gases, liquefied gases, ultrasonic examination, hydraulic test, type approval.