This part of EN 1555 specifies the characteristics of valves made from polyethylene (PE) for piping systems in the field of the supply of gaseous fuels. NOTE 1 Valves made from other material than polyethylene designed for the supply of gaseous fuels conforming to the relevant standards are permitted to be used in PE piping system according to EN 1555 provided they have relevant PE connection for butt fusion or electrofusion ends (see EN 1555-3). It also specifies the test parameters for the test methods referred to in this standard. In conjunction with Parts 1, 2, 3 and 5 of EN 1555, it is applicable to PE valves, their joints and to joints with components of PE and other materials intended to be used under the following conditions: a) a maximum operating pressure, MOP, up to and including 10 bar; b) an operating temperature of 20 °C as reference temperature; NOTE 2 For other operating temperatures, derating coefficients should be used, see prEN 1555-5:2010. c) an operating temperature between -20 °C and +40 °C. EN 1555 covers a range of maximum operating pressures and gives requirements concerning colours and additives. NOTE 3 It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects, taking into account their particular requirements and any relevant national regulations and installation practices or codes. It is applicable to bi-directional valves with spigot end or electrofusion socket intended to be fused with PE pipes conforming to prEN 1555-2:2008 without any fittings or with PE fittings conforming to prEN 1555-3:2010. This part of prEN 1555 covers valves for pipes with a nominal outside diameter dn 315 mm.