This International Standard deals with seamless steel 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; 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 to be re-introduced into service for a further period of time. This International Standard does not apply to periodic inspection and testing of acetylene cylinders or composite cylinders with steel liners