This AD 2000-Merkblatt applies to safet accessories guarding against excess pressure for pressure vessels in which an unacceptable wxcess pressure is prevented by the opening of safety valves of closing of safety shut-off valves.
AD 2000-Merkblatt A4-2004 history
2015AD 2000-Merkblatt A4-2015 Equipment, installation and marking of pressure vessels.Accessory housings