This European Standard specifies requirements for using a combination of appropriate in situ (without dismantling), non-destructive examination (NDE) techniques, for example visual examination, acoustic emission testing [AT] and ultrasonic testing [UT] when periodically inspecting and testing seamless steel pressure vessels (tubes) with a water capacity between 150 l and 3 000 l, used for compressed and liquefied gases for a further period of service. This European Standard is applicable only to pressure vessels (tubes) installed in locations where attempting any removal from their containing superstructure would be hazardous, or where the downtime required to remove them would hinder a continuous operation of a plant or service. This European Standard does not apply to pressure receptacles used for the transport of gases as described under the TPED. This European Standard only applies to pressure vessel (tube) assemblies where the designs permit all necessary inspections stipulated.