The main connection methods of polyethylene pipes are hot melt connection, electric fusion connection and flange connection. The precautions for different methods are as follows:
1.Hot melt connection (applicable to pipe diameter ≥63mm)
Pre-welding treatment:
Use special tools to remove the oxide layer on the end face of the pipe, ensure that the interface is clean and dry, and the axis of the two ends of the pipe is aligned (misalignment ≤10% wall thickness).
The temperature of the heating plate is controlled at 210±10℃, and the heating time is determined according to the pipe diameter (such as De110 pipe heating for about 120 seconds) to avoid excessive heating and carbonization of the pipe.
Welding process:
After heating, quickly remove the heating plate, axially pressurize the pipe and the pipe fitting, and the pressure-maintaining cooling time must be sufficient (such as De110 pipe cooling ≥45 minutes). It is strictly forbidden to move the pipeline during cooling.
2.Electric fusion connection (suitable for small pipe diameter or emergency repair)
Interface inspection:
The inner wall of the electric fusion sleeve and the outer wall of the pipe must be wiped clean and must not have oil or water stains; when the pipe is inserted into the electric fusion sleeve, the insertion depth must be marked to ensure that it is in place.
Welding parameters:
Set the welding current and time according to the mark on the electric fusion sleeve to avoid over-welding (such as excessive ejection of the sleeve observation hole) or cold welding (the interface is not completely fused).
3.Flange connection (suitable for connection with metal pipes or equipment)
The hot-melt flange connector between the flange and the PE pipe end must be welded firmly, and the bolts must be symmetrically and evenly stressed when tightening to prevent eccentric leakage of the interface.