GB/T 28799.3 - 2012 is formulated for PE-RT pipe fittings for hot and cold water. It defines the relevant terms of pipe fittings and standardizes their classification and marking. In terms of technical requirements, the appearance and dimensional accuracy of pipe fittings are clearly stipulated, and key indicators such as sealing performance, pressure resistance, and cold and hot cycle performance of the connection with the pipe are considered. The standard details the test methods of each performance, such as the pressure conditions and test time of the sealing test. In addition, the inspection rules of pipe fittings are given. The standard helps manufacturers control the mass, provides the basis for the selection of suitable pipe fittings for construction hot and cold water pipeline projects, and ensures the reliable connection of the pipeline system and the stable delivery of hot and cold water.