This International Standard specifies the requirements for the inspection and maintenance of cylinder valves, including valves with integrated pressure regulators (VIPR) (see ISO 22435). This International Standard may be applied to cylinder valves at the time of the periodic inspection of gas cylinders, bundles, drums and trailers, and at any other time, e.g. at change of gas service (see ISO 11621). It does not apply to routine inspection of cylinder valves carried out at the time of cylinder filling. NOTE National standards and regulations may apply to maintenance of cylinder valves.