ISO 15876-3:2017 specifies the characteristics of fittings for polybutene-1 (PB-1) piping systems intended to be used for hot and cold water installations within buildings for the conveyance of water, whether or not intended for human consumption (domestic systems) and for heating systems under design pressures and temperatures according to the class of application (see ISO 15876-1). The designation polybutene is used together with the abbreviation PB throughout this document. ISO 15876-3:2017 covers a range of service conditions (application classes) and design pressure classes. For values of TD, Tmax and Tmal in excess of those in ISO 15876-1:2016, Table 1, this document does not apply. NOTE 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 also specifies the parameters for the test methods referred to in this document. In conjunction with the other parts of ISO 15876, this document is applicable to fittings made from PB and to fittings made from other materials which are intended to be fitted to pipes conforming to ISO 15876-2 for hot and cold water installations, whereby the joints conform to the requirements of ISO 15876-5. ISO 15876-3:2017 is applicable to fittings of the following types: - socket fusion fittings; - electrofusion fittings; - mechanical fittings; - fittings with incorporated inserts. It is also applicable to fittings made from alternative materials which, when fitted to pipes conforming to ISO 15876-2, conform to the requirements of ISO 15876-5.