4 inch (about DN100) high-density polyethylene (HDPE) pipe is a plastic pipe widely used in water supply, gas, industrial fluid transportation and drainage systems. HDPE pipe has become an ideal substitute for traditional metal pipes due to its excellent corrosion resistance, high flexibility, long life (more than 50 years) and light weight and easy installation.
Strong corrosion resistance: not affected by acid, alkali, salt and electrochemical corrosion, suitable for harsh environments.
High flexibility: can adapt to foundation settlement and has excellent seismic performance.
Light weight: easy to transport and install, reducing construction costs.
Low fluid resistance: smooth inner wall, low friction coefficient, and improved transportation efficiency.
Environmentally friendly and non-toxic: meets drinking water transportation standards (such as GB/T 17219).
1. Municipal water supply and drainage system
Urban tap water transportation
Rainwater and sewage discharge
2. Gas transportation
Medium and low pressure gas pipeline network (in accordance with GB 15558.1 standard)
3. Industrial pipeline
Chemical fluid transportation
Slurry and mud pipeline
4. Agricultural irrigation
Drip irrigation and sprinkler irrigation system
1. Preparation before construction
Material inspection: Ensure that the pipes and fittings are not damaged and the specifications meet the design requirements.
Trench excavation:
Width: pipe diameter + 300~500mm (for welding and backfilling).
Depth: below the frozen soil layer (≥1.2m in northern areas) to avoid external force damage.
Foundation treatment: lay a 100~150mm sand cushion layer at the bottom of the trench to prevent sharp objects from damaging the pipeline.
2. Pipeline connection method
(1) Hot melt butt welding (applicable to large diameter pipelines)
Use a butt welding machine to fix the pipe and mill the end face to ensure flatness.
Heat the heating plate to 200~220℃, and quickly connect and pressurize the pipe ends after they melt.
After cooling, a high-strength weld is formed. Check whether the weld ring is uniform.
(2) Electric fusion connection (suitable for complex environments or emergency repairs)
Clean the pipe ends and insert the electric fusion sleeve.
Turn on the power to heat and fuse the pipe and the pipe fittings.
Do not move the pipe during cooling.
3. Pipeline laying and backfilling
Use nylon slings when laying pipes to prevent metal ropes from scratching the pipe wall.
Backfilling adopts layered compaction method:
First layer: fine sand or soft soil (≥300mm), manually compacted.
Upper layer: original soil backfill, mechanically compacted to 95% density.
4. Pressure test
Water pressure test: 1.5 times the working pressure, stable pressure for 1 hour without leakage.
Air tightness test: 1.1 times the working pressure, 24-hour pressure drop ≤1%.
1. Avoid high-temperature welding: In summer, it is necessary to prevent the hot melt temperature from being too high, which may cause material degradation.
2. Prevent mechanical damage: It is strictly forbidden to drag or hit the pipe during construction.
3. Bending radius control: The minimum bending radius of 4-inch HDPE pipe is ≥ 20 times the pipe diameter (about 2m).
4. Warning protection: A warning tape is laid above the buried pipe to prevent excavation damage.
|
Characteristic |
HDPE Pipe |
Steel Pipe |
PVC Pipe |
|
Corrosion Resistance |
Excellent (No anti-corrosion needed) |
Requires anti-corrosion treatment |
Good |
|
Service Life |
50+ years |
20-30 years |
20-25 years |
|
Installation Cost |
Low (No welding equipment needed) |
High (Requires welding) |
Medium |
|
Flexibility |
High (Excellent seismic resistance) |
Low (Prone to cracking) |
Brittle |
4 inch HDPE pipe has become the mainstream choice for modern pipeline engineering due to its durability, economy and convenience of construction. Correct selection, standardized installation and strict acceptance are the key to ensure the long-term stable operation of the pipeline network.
