This document specifies the requirements for the inspection and maintenance of valves (including ball valves and valves with integrated pressure regulator (VIPRs)) for: a) refillable transportable gas cylinders; b) cylinder bundles; c) pressure drums and tubes; which convey compressed, liquefied or dissolved gases. This document does not apply to valves for LPG. NOTE Where there is no risk of ambiguity, gas cylinders, cylinder bundles, pressure drums and tubes are addressed with the collective term gas cylinders within this document. This document applies to valves reused at the time of the periodic inspection of gas cylinders, cylinder bundles, pressure drums and tubes, and may be applied at any other time, e.g. at change of gas service (see ISO 11621). This document does not apply to routine inspection of valves e.g. carried out at the time of gas cylinder filling.