This International Standard specifies minimum requirements for the material, design, construction, workmanship, examination and testing at manufacture of refillable welded steel cylinders for the sub-atmospheric pressure storage of liquefied and compressed gases. It only applies to the cylinders themselves, irrespective of the materials contained therein (e.g. adsorbents, media, materials and/or gases) and other related applications. The cylinders have a test pressure not greater than 42 bar and a water capacity from 0,5 l up to and including 12 l exposed to ambient temperatures for the purpose of facilitating the sub-atmospheric pressure storage of liquefied and compressed gases. Inspection at the time of fill is specified in Annex A and periodic inspection and testing is specified in Annex B. High-pressure and low-pressure liquefied gases as specified in Annex C can be suitably filled into these cylinders. The filling pressure will be less than one bar gauge at 21 °C.