Material Analysis
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Leakage at Welded Joints of High-Density Polyethylene PPR Pipes
Problem Phenomenon
After hot-melt welding of PPR/PP-R pipes, the joints leak in the pressure test, and the weld strength is insufficient.
Leakage at welded joints is a common failure point in pipeline systems and affects the safety of water supply systems.
Cause Analysis
（1）The welding temperature is improper, not reaching the melting temperature of the material or too high, causing degradation
（2）The welding time is insufficient, and the depth of the surface molten layer is not enough
（3）The pipe and the fitting are not concentric during welding
（4）The welding surface is contaminated with oil, water, or dust
（5）The pipe wall thickness is uneven or the fitting diameter does not match
Solution
（1）Control the hot-melt welding temperature at 260-280°C (PPR/PP-R), and strictly calibrate the heating plate temperature
（2）Strictly implement the welding time according to the standard: 5s for DN20 pipe, 7s for DN25 pipe, etc.
（3）Use special clamping tools to ensure the pipe and the fitting are concentrically aligned
（4）Clean the welding surfaces of the pipe and the fitting before welding to remove oil and dust
（5）Use pipes and fittings of the same brand and the same series to ensure dimensional matching
Key Takeaway
Leakage at PPR welded joints is caused by improper welding parameters or contamination of the welding surface, and the welding temperature, time, and cleanliness need to be strictly controlled.
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