This part of ISO 22391 gives guidance for the assessment of conformity of materials, products, and assemblies in accordance with the applicable part(s) of ISO 22391 intended to be included in the manufacturer’s quality plan as part of the quality management system and for the establishment of certification procedures. In conjunction with the other parts of ISO 22391 (see Foreword), this Technical Specification is applicable to polyethylene of raised temperature resistance (PE-RT) 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 ISO 22391:2009).