Hot-melt fittings are specialized connectors for plastic piping systems. They are created by heating the pipe and fitting surfaces together to melt them before inserting them into a socket. Similar to plastic welding, when heated to approximately 260°C, polyethylene undergoes molecular-level fusion, resulting in a more reliable seal upon cooling than a physical connection.
The working principle of hot-melt connection:
Heating stage: A specialized hot-melt die simultaneously heats both the pipe end and the fitting socket.
Socketing stage: The softened areas are quickly joined and pressure is maintained.
Cooling and shaping: The molecular chains re-interweave to form a unified structure.
Precautions in practical applications:
Heating time needs to be extended when the ambient temperature is below 5°C.
Fittings made of different materials (e.g., PPR and PE) cannot be mixed.
After fusion, the pipe should be allowed to cool completely to prevent movement that could cause a weak weld.
