I. Calculate the Setting Value Based on "Drag Pressure + Process Pressure"
1. Measure the Drag Pressure (P_drag)
After depressurizing, slowly increase the pressure and record the pressure value when the clamp just begins to move. This reflects the internal frictional resistance of the equipment.
This value is the basis for the pressure setting, usually 0.2–0.5 MPa, depending on the equipment condition.
2. Superimpose the Standard Welding Pressure (P_1)
Obtain the process pressure from a table based on the pipe wall thickness (e.g., approximately 0.15–0.3 MPa/mm wall thickness for PE pipes).
The actual total pressure should be ≥ P_drag + P_1. If it is lower than this value, the pressure is insufficient.
II. Observe Key Phenomena During the Welding Process
1. Uniformity of Flange Formation During Heating
The two ends should form symmetrical, continuous, and rounded flanges, with a height of approximately 1–3 mm.
If the flange is too small, broken, or protrudes on one side, it indicates uneven or insufficient pressure.
2. Butt Joint Fitting Status
After removing the heating plate, the two tube ends should quickly and tightly fit together without springback or gaps.
If the joint cannot be closed properly or requires multiple pressurizations, it indicates that the system pressure is too low.
3. Joint Quality Inspection After Cooling
Cut open the joint and observe: the weld depth should be uniform and penetrating, without any incomplete welds, porosity, uneven melting, or inclusions.
The width of the weld zone should be at least 1.2 times the tube wall thickness; otherwise, it is considered insufficient pressure.
III. Assisted Judgment Using Instruments and Control Systems
1. The pressure gauge reading should be stable within the set range (e.g., 5–6 MPa) without drastic fluctuations.
2. Use a dual-channel timer to record the heat absorption and cooling times to ensure the entire process is completed under constant pressure.
3. Fully automatic models can monitor the pressure curve in real time through the electronic control system and automatically alarm for abnormal fluctuations.
