This Part of EN ISO 15875 specifies the general aspects of 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 according to the class of application (see Table 1). This standard covers a range of service conditions (application classes) and design pressure and pipe dimension classes. For values of TD, Tmax and Tmal in excess of those in Table 1, this standard does not apply. NOTE It is in 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 (see Foreword) it is applicable to PE-X pipes, fittings, their joints and to joints with components of other plastics and non-plastics materials intended to be used for hot and cold water installations.