In municipal engineering, the installation of HDPE (high-density polyethylene) pipes must follow strict specifications to ensure their durability, sealing and safety. The following are key precautions:
Material acceptance
Check the quality certification documents of pipes and fittings (such as certificates of conformity, test reports) to ensure compliance with national standards such as GB/T 19472.2.
Appearance inspection: no cracks, scratches, depressions or bubbles, and the port is flat and burr-free.
Check whether the specifications (such as SDR value, ring stiffness grade) are consistent with the design requirements.
Trench excavation
Trench bottom width: When the pipe diameter is ≤DN500, the trench width is ≥ the outer diameter of the pipe + 0.5m; when the pipe diameter is larger, sufficient operating space must be reserved.
Slope and base: Slope according to design requirements (such as 1:0.33), the base must be flat and free of gravel and hard objects, and the over-excavated part should be backfilled and compacted with sand and soil.
Groundwater level: If groundwater is encountered, it is necessary to take precipitation measures or replace the gravel layer with anti-floating pipes.
Connection method
Hot-melt butt welding (applicable to large-diameter pipes):
Clean the heating plate, control the temperature (200~220℃), and perform the welding pressure and time according to the manufacturer's parameters.
Check the uniformity of the flange after butt welding to avoid false welding.
Electrofusion connection (with socket pipe fittings):
Ensure that the oxide layer is scraped off the pipe end, the insertion depth is clearly marked, and the power-on time/voltage meets the requirements of the pipe fittings.
Mechanical connection (flange or clamp): Check whether the sealing ring is installed in place and the bolts are tightened symmetrically.
Main points for laying
Flexible foundation: Lay a 10~15cm medium-coarse sand cushion layer, and fully support the 120° range below the pipe.
Bending radius: Cold bending is allowed, but the curvature radius ≥ 25 times the pipe diameter (such as DN400 pipe requires R ≥ 10m).
Snake laying: When the temperature changes greatly, reserve 2%~3% of the expansion and contraction to avoid thermal expansion and deformation of the straight line.
Backfill in layers
Backfill on the pipe side: use sand or fine soil with a particle size of ≤10mm, symmetrically compact in layers (each layer ≤20cm), and the compaction degree ≥90%.
50cm above the top of the pipe: direct mechanical rolling is prohibited, and manual compaction is adopted.
Upper backfill: compact in layers according to the requirements of roads or greening to avoid settlement.
Special area treatment
Add steel casing protection when crossing the road, and seal and prevent seepage at both ends of the casing.
Soft soil foundation needs to be replaced or reinforced with gravel piles to prevent uneven settlement of the pipeline.
Testing items
Pressure test: inject water to stabilize the pressure for 1h, and the pressure drop is ≤0.05MPa to be qualified (refer to GB 50268).
Water-tight test: non-pressure pipelines are tested in sections according to the specifications, and the allowable water seepage is ≤Q=0.0046Di (m³/24h·km).
Electrofusion joint inspection: Detect the fusion quality by X-ray or ultrasonic.
Safety measures
Groove support: set baffles or slopes when the depth is ≥1.2m, and set warning lights at night.
Lifting operation: use nylon slings to avoid scratches on pipes, and keep personnel away from the radius of the boom.
Leakage: strictly check the quality of the interface to avoid socket failure or incorrect welding parameters.
Deformation: control the compaction degree during backfilling to avoid overloaded vehicles rolling over inadequate backfill sections.
Through standardized construction and full-process quality control, HDPE pipes can give full play to their advantages of corrosion resistance, good flexibility, and long life (more than 50 years), and are suitable for municipal scenarios such as water supply and drainage, rainwater and sewage pipe networks.
Official website: www.phtopindustry.com | www.phpipes.com
Contact us: Email:inquiry@phtopindustry.com | Whatsapp:+86 15093100892
Company address: Room 802, 8th Floor, Building 5, Jinyin Modern City, Jinshui District, Zhengzhou City, Henan Province, China
High-density polyethylene (HDPE) pipes have been widely used in the field of municipal engineering due to their excellent corrosion resistance, flexibility, connection reliability and long service life, especially in water supply and drainage, gas, power sheathing and sewage treatment systems. However, HDPE pipes still need to strictly follow the specifications during installation to ensure the quality of the project and the safety and stability of pipeline operation.
1. Material acceptance: Confirm that the HDPE pipes and fittings used meet the design and national standards, and check whether there are cracks, scratches, deformation and other defects on the surface of the pipe.
2. Construction site inspection: Clean the construction site to ensure that the foundation is flat and there are no sharp stones or hard objects to prevent damage during pipeline laying.
3. Equipment preparation: Prepare corresponding Pipe Welding Machine, hot melt sleeve machine, electric melting machine according to the scale of the project.
1. Correct handling and storage:
Handle with care during handling to avoid severe impact and falling.
Place the pipe on a flat surface during storage to avoid long-term direct sunlight and heavy pressure.
2. Selection of pipe connection method:
Butt-melt: Suitable for the connection of large-diameter straight pipes. The welding surface must be kept clean, and the welding temperature and pressure must meet the standards.
Electrofusion connection: Suitable for connection with limited space or special pipe fittings. The welding surface should be cleaned before connection, and the operation should be strictly carried out in accordance with the parameters provided by the electrofusion pipe fitting manufacturer.
Flange connection: Suitable for connection with metal pipes or equipment interfaces. Sealing gaskets should be used to tighten the bolts evenly.
3. Pipeline laying and backfilling:
Pipeline laying should be straight and stable, and the turning point should be constructed according to the minimum bending radius to prevent damage caused by forced bending.
Backfill soil should be compacted in layers. It is forbidden to directly roll the top of the pipe with large machinery to avoid local pressure causing pipe deformation.
1. Temperature influence:
HDPE materials are greatly affected by temperature. During winter construction, the heating and cooling time should be appropriately extended, and in summer, overheating and deformation should be prevented.
2. Welding quality control:
After each welding, the flatness and uniformity of the weld should be checked, and the welding strength test should be performed if necessary to ensure that the welding is firm and reliable.
3. Prevent foreign matter from entering the pipeline:
During the installation process, the pipeline opening should be temporarily blocked to prevent mud and debris from entering and affecting subsequent use.
Pressure test: After the installation is completed, a water pressure or air pressure test should be carried out according to the specifications to check the sealing and pressure bearing capacity of the pipeline system.
Inspection of the interface between the inspection well and the pipeline: Ensure that the interface between the inspection well and the pipeline is tight and there is no leakage.
Completion data is complete: including construction records, welding records, pressure test records, etc., to provide guarantees for subsequent operation and maintenance.
Regularly check the operation of the pipeline, focusing on the ground settlement area and the interface.
For areas with shallow burial depth and large external force influence, protective measures can be added to extend the service life.
The application of HDPE pipes in municipal engineering not only improves the durability and economy of the pipe network, but every detail in the installation process cannot be ignored. Scientific and standardized construction management is the key to ensuring the long-term safe operation of the HDPE pipe system.
Official website: www.phtopindustry.com | www.phpipes.com
Contact us: Email:inquiry@phtopindustry.com | Whatsapp:+86 15093100892
Company address: Room 802, 8th Floor, Building 5, Jinyin Modern City, Jinshui District, Zhengzhou City, Henan Province, China