This document gives requirements and guidance for the assessment of conformity of compounds, products, and assemblies in accordance with the applicable part(s) of ISO 21003 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 21003 (see Foreword), this document is applicable to multilayer 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 ISO 21003-1:2008, Table 1).