PE pipe (polyethylene pipe) is widely used in water supply, gas transmission, and agricultural irrigation due to its excellent corrosion resistance, flexibility, and long life. Its construction quality directly impacts the long-term stable operation of the piping system, so strict adherence to scientific construction methods and technical specifications is essential. This article will provide a detailed introduction to the PE pipe construction process, key technologies, and precautions.
I. Construction Preparation
1. Material Inspection
PE pipes and fittings must comply with national or industry standards (such as GB/T 13663). Before delivery, the pipe specifications, wall thickness, and appearance quality must be inspected, and the factory certificate and test report must be verified. The pipe surface should be smooth and free of bubbles and cracks, and fittings should be free of defects such as deformation and shrinkage.
2. Tools and Equipment
Common tools include hot-melt welders, electric-melt welders, pipe cutters, tape measures, and levels. Hot-melt welding equipment must be calibrated regularly to ensure precise temperature control (usually 200-230°C, depending on the pipe type).
3. Site Conditions
Before construction, clear the trench of rocks and sharp objects to ensure a flat and solid base. For buried pipe installation, a fine sand cushion layer (≥100mm thick) should be laid at the bottom of the trench to minimize the impact of uneven settlement on the pipe.
II. Pipe Connection Technology
PE pipe connection methods mainly include hot melt, electric fusion, and mechanical connection, with hot melt and electric fusion being the most commonly used.
1. Hot Melt Connection
Applicable to pipes DN ≤ 110mm. The steps are as follows:
• Cutting the pipe: Use a pipe cutter to cut vertically, ensuring the end faces are flat and free of burrs.
• Heating: Insert the pipe and fitting simultaneously into the heated die of the hot melt welding machine. Set the heating time according to the pipe diameter (e.g., DN50 pipe is typically heated for 5-7 seconds).
• Welding: Quickly insert the heated pipe and fitting into place, maintaining a certain pressure (e.g., DN50 pipe, maintain pressure for 1-2 minutes) until cooled and solidified.
2. Electric Fusion
Suitable for large-diameter pipes or complex working conditions, this method achieves a fusion connection by heating the internal resistance wire in the electric fusion fitting. During operation, ensure that the pipe and fitting are aligned axially, and the power-on time strictly follows the manufacturer's specifications (e.g., approximately 8-12 minutes for a DN160 fitting).
3. Mechanical Connection (Backup Option)
Slip-on flange connections, for example, are often used for temporary projects or transitions between pipes made of other materials, but their long-term reliability is lower than that of fusion.
III. Pipeline Laying
1. Trench Excavation
The trench width should ensure sufficient working space (usually the pipe diameter + 500mm on each side), and the depth must meet design requirements (e.g., soil cover ≥ 0.7m on the top of the water supply pipe). If rock layers are encountered, they must be broken up in advance to avoid stress concentration in the pipe.
2. Pipeline Installation
• Pipeline Lowering: Use manual or lifting equipment, placing gently to avoid collisions.
• Pipeline Adjustment: Use a bracket or hoist for temporary fixation, ensuring that the pipe's concentricity deviation is ≤1% of the pipe diameter.
• Backfill: Tamp layer by layer, first filling with fine sand to 300mm above the top of the pipe, then gradually backfilling with original soil. Direct backfilling with rocks or frozen soil is strictly prohibited.
IV. Pressure Testing and Acceptance
After installation, the pipeline must undergo strength and tightness tests:
• Strength Test: The test pressure is 1.5 times the design pressure (but ≥ 0.8 MPa). A pressure drop and no leakage are present after 30 minutes of steady pressure.
• Tightness Test: This is performed after the strength test passes. The test pressure is the design pressure. A pressure drop of ≤1% after 2 hours of steady pressure is present.
V. Precautions
1. Temperature Effects: When the ambient temperature is below 5°C, insulation measures or adjustment of welding parameters are required.
2. Avoiding Scratches: Use soft slings during lifting and transportation to prevent surface damage to the pipe.
3. Long-Term Maintenance: Regularly inspect the pipeline for potential hazards such as ground subsidence and external damage.
The core of PE pipe construction technology lies in standardized connection techniques and rigorous construction management. Scientific material selection, precise welding control, and a rigorous acceptance process ensure safe, efficient operation and extended service life of the piping system. Engineers should flexibly apply these methods based on actual site conditions to achieve optimal construction results.
