This Part of prEN 1555 specifies the characteristics of valves, made of polyethylene (PE) for piping systems in the field of the supply of gaseous fuels. NOTE: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 prEN 1555 provided they have relevant PE connection for butt fusion or electrofusion ends (see prEN 1555-3:1999). It also specifies the test parameters for the tests methods referred to in the present standard.