This International Standard is applicable to seamless steel and seamless aluminium-alloy transportable gas cylinders (single or those that comprise a bundle) intended for compressed and liquefied gases under pressure, of water capacity from 0,5 l up to 150 l and to seamless steel and seamless aluminium-alloy transportable gas tubes (single or those that comprise a bundle) intended for compressed and liquefied gases under pressure, of water capacity greater than 150 l. It also applies, as far as practical, to cylinders of less than 0,5 l water capacity. This International Standard specifies the requirements for periodic inspection and testing to verify the integrity of such gas cylinders and tubes to be re-introduced into service for a further period of time. This International Standard does not apply to periodic inspection and maintenance of acetylene cylinders or to the periodic inspection and testing of composite cylinders. Unless noted by exception, the use of "cylinder" in this International Standard refers to both cylinders and tubes.