This document specifies the characteristics of valves made from polyethylene (PE) for piping systems in the field of the supply of gaseous fuels. It is applicable to unidirectional and bi-directional isolating valves with spigot ends or electrofusion sockets intended to be fused with PE pipes or fittings conforming to ISO 4437−2 and ISO 4437‑3 respectively. Valves made from materials other than PE, designed for the supply of gaseous fuels conforming to the relevant standards can be used in PE piping systems according to ISO 4437 series, provided that they have PE connections for butt fusion or electrofusion ends, including integrated material transition joints, conforming to ISO 4437-3. It also specifies the test parameters for the test methods referred to in this document. In conjunction with parts 1, 2, 3 and 5 of the ISO 4437 series, this document 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[1] at a reference temperature of 20 °C for design purposes; NOTE 1 For the purpose of this document and the references to ISO 8233, MOP is considered to be nominal pressure. b) an operating temperature between −20 °C to 40 °C. NOTE 2    For operating temperatures between 20 °C and 40 °C, derating coefficients are defined in ISO 4437‑5. This document covers valve bodies designed for connection with pipes with a nominal outside diameter dn ≤ 400 mm.   [1] 1 bar = 0,1 MPa =105 Pa; 1 MPa = 1 N/mm2.