This European Standard deals with metal isolating valves used for gas distribution systems with maximum operating pressure up to 16 bar, and which operate with fuel gases of the first and the second family, in accordance with EN 437. It applies to valves DN 25 and larger. The types of isolating valves to be considered are: plug and ball valves, gate valves, globe valves and butterfly valves. This standard does not apply to: - valves for domestic installations ; - safety type pressure relief valves ; - wellhead valves. In the case of power operated valves, the requirements for the power source are not covered by this standard. The valves covered in this standard operate in the temperature range : - 20 °C to + 60 °C. This European Standard gives additional requirements to the relevant product standards. In case of contradictions between the above mentioned standards, this standard will prevail.