Defines the characteristics of fittings for piping systems made from polyethylene of raised temperature resistance (PE-RT), intended to be used for hot and cold water installations within buildings for the conveyance of water whether or not the water is intended for human consumption (domestic systems) or heating systems under the design pressures and temperatures appropriate to the class of application according to ISO 22391-1. It also covers a range of service conditions (classes of application), design pressures and pipe dimension classes, and specifies test parameters and test methods.