ISO 21003-3:2008 specifies the characteristics of fittings for multilayer piping systems intended to be used for hot and cold water installations inside buildings for the conveyance of water — whether or not the water is intended for human consumption (domestic systems) or for heating systems — under specified design pressures and temperatures appropriate to the class of application It also specifies the test parameters for the test methods referred to in this part of ISO 21003. ISO 21003 is a reference product standard. It is applicable to multilayer pipes, fittings, their joints, and also to joints with components made of other plastics and non-plastics materials intended to be used for hot and cold water installations. ISO 21003-3 is intended for use only in conjunction with all the other parts of ISO 21003.