I. Process Parameter Control: Ensuring the "Internal Quality" of the Weld
The heating plate temperature must be accurately set: 210±10℃ for PE80 pipes, and 225±10℃ for PE100 pipes. Too low a temperature will result in insufficient melting, while too high a temperature will cause material degradation, affecting the weld strength.
The heat absorption time should be calculated reasonably based on the pipe diameter and wall thickness, usually estimated as "pipe diameter ÷ SDR × 10" (unit: seconds), ensuring a uniform molten layer of 1~2mm is formed on the end face.
The switching time (from removing the heating plate to completing the butt joint) must be controlled within 10 seconds to prevent the molten surface from cooling or becoming contaminated, causing a weak weld.
The cooling process must be carried out under pressure and allowed to cool naturally. Forced water cooling or moving the pipe is strictly prohibited. The cooling time is determined by touching the rolled edge until it feels warm and hardens; generally, approximately 1 minute corresponds to 1mm of wall thickness.
Fully automatic welding machines should record complete data on temperature, pressure, and time for each weld joint to ensure quality traceability.
II. Post-Weld Appearance Inspection: Visually assess whether the "external appearance" meets standards.
Edge Shape: A qualified weld should have a full, uniform, semi-circular edge with a height between 1 and 2 mm. Too low an edge indicates insufficient heating; too high an edge may indicate excessive pressure; asymmetry indicates poor alignment.
Joint Alignment: The axes of the two pipes should be aligned, and the misalignment should not exceed 10% of the wall thickness. For example, for a 6mm thick pipe, the misalignment should not exceed 0.6mm.
Edge Cutting Inspection (Sampling): Cut the edge every 50mm and perform a 180° back bend inspection. There should be no cracks, fissures, or lack of fusion at the center line. If delamination or exposed fusion lines are found, it indicates incomplete welding.
