This Part of EN ISO 15875 specifies the characteristics of fittings for crosslinked polyethylene (PE-X) 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 appropriate to the class of application (see Table 1 of EN ISO 15875-1:2003). This standard covers a range of service conditions (application classes) and design pressure classes. For values of TD, Tmax and Tmal in excess of those in Table 1 of Part 1, this standard 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 test parameters for the test methods referred to in this standard. In conjunction with the other Parts of EN ISO 15875:2003 (see Foreword) it is applicable to fittings made from crosslinked polyethylene (PE-X) and to fittings made from other materials which are intended to be fitted to pipes conforming to EN ISO 15875-2:2003 for hot and cold water installations and whereby the joints conform to the requirements of EN ISO 15875-5. This standard is applicable to fittings of the following types: — mechanical fittings; — electrofusion fittings; — fittings with incorporated inserts.