ISO 22434:2006 specifies the requirements for the inspection and maintenance of cylinder valves, including valves with integrated pressure regulators (VIPR) (see ISO 22435). ISO 22434:2006 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.