I. Pre-welding Preparation
1. Equipment Inspection
Confirm that the power supply voltage is stable (220V ± 10% or 380V three-phase power). Check that the hydraulic system, heating plate, and control panel are functioning properly.
Preheat the heating plate to the set temperature (210 ± 10°C for PE80, 225 ± 10°C for PE100) and maintain the temperature for 1-2 minutes to allow for uniform temperature.
2. Pipe Preparation
Use a milling cutter to cut the pipe end smoothly, free of burrs and cracks, with a misalignment of ≤ 20% of the wall thickness.
Clean the pipe end and the heating plate surface to avoid oil and dust that may affect weld quality.
II. Welding Operation Procedures
1. Clamping and Milling
Secure the pipe in the machine frame chuck and adjust the concentricity. The misalignment should be ≤ 10% of the wall thickness.
Start the milling cutter to cut the pipe end. After forming a continuous chip, remove the milling cutter and clean the chips. (Do not touch the weld surface with your hands.) 2. Heating and Butt Jointing
Place the heating plate, close the machine frame, and pressurize to the welding pressure (P1 = P drag + P2). Observe the flange height (usually 1.5mm).
The heat absorption time is calculated based on the wall thickness (e.g., wall thickness x 10 seconds). The switching time should be ≤ 10 seconds. Quickly remove the heating plate and close the pipe.
III. Cooling and Inspection
1. Pressure-Maintaining Cooling
The cooling time is set according to the pipe diameter (e.g., 11-35 minutes for 90-315mm pipes). Maintain a stable pressure during this time.
After cooling, reduce the pressure to zero before removing the fixture to avoid scratching the weldment.
2. Quality Inspection
Visually inspect the weld ring: width 0.35-0.45 times the wall thickness, height 0.2-0.25 times the wall thickness, and no bubbles or dents.
If necessary, perform tensile or ultrasonic testing to ensure the absence of internal defects.
IV. Safety Precautions
Protective Equipment: Heat-insulating gloves (temperature resistant ≥ 300°C), safety glasses, and non-slip safety shoes must be worn. Environmental requirements: Avoid strong winds (>5m/s), rain, and low temperatures (<5°C), and be equipped with a fire extinguisher.
