HDPE pipes (high-density polyethylene pipes) are widely used in agricultural irrigation due to their corrosion resistance, aging resistance, good flexibility, and convenient construction. Reasonable selection of pipe diameter and pressure level can effectively improve irrigation efficiency, reduce costs, and extend service life. This article will systematically introduce the selection method of HDPE pipes in agricultural irrigation from three aspects: selection principle, diameter calculation, and pressure level determination.
1. Meet the irrigation flow demand
The pipe diameter must ensure sufficient flow to avoid excessive hydraulic loss due to too small a diameter, which will affect the irrigation effect.
2. Ensure water delivery pressure
According to the terrain height difference, pipe length, and terminal equipment requirements, reasonably select the pressure level to avoid pipe bursting or insufficient water pressure.
3. Take into account economy
The larger the diameter, the higher the investment. It is necessary to optimize the pipe size and reduce the construction and operation costs on the premise of meeting the use requirements.
1. Basic formula
Common flow-velocity formula for irrigation system to calculate pipe diameter:
Q=A×VQ = A \times VQ=A×V
Where:
Q = flow (m³/s)
A = pipe cross-sectional area (m²), A = π × (D/2)²
V = flow velocity (m/s)
2. Recommended flow velocity
Pipe Diameter Range | Recommended Flow Velocity (m/s) | Remarks |
D < 100mm | 0.6 - 1.5 | Low velocity for small diameters to avoid water hammer |
100mm ≤ D ≤ 300mm | 1.0 - 2.0 | Moderate velocity for medium diameters |
D > 300mm | 1.2 - 2.5 | Higher velocity allowed for large diameters |
3. Diameter calculation example
Assuming the design flow rate is 50m³/h, convert to m³/s:
Q=503600≈0.0139 m3/sQ = \frac{50}{3600} ≈ 0.0139 \, m³/sQ=360050≈0.0139m3/s
Take the design flow rate V = 1.5 m/s, then the pipe cross-sectional area:
A=QV=0.01391.5≈0.00927 m2A = \frac{Q}{V} = \frac{0.0139}{1.5} ≈ 0.00927 \, m²A=VQ=1.50.0139≈0.00927m2
Calculate the inner diameter D:
D=2×Aπ=2×0.009273.1416≈0.1085 m≈110mmD = 2 \times \sqrt{\frac{A}{\pi}} = 2 \times \sqrt{\frac{0.00927}{3.1416}} ≈ 0.1085 \, m ≈ 110mmD=2×πA=2×3.14160.00927≈0.1085m≈110mm
Therefore, DN110 HDPE pipe is recommended.
1. Common nominal pressure (PN) levels
Nominal Pressure (PN) | Maximum Working Pressure (MPa) | Application Scenario |
PN6 | 0.6 MPa | Gravity flow, low-pressure water conveyance |
PN10 | 1.0 MPa | General farmland irrigation |
PN12.5 | 1.25 MPa | Undulating terrain, medium to long-distance water transport |
PN16 | 1.6 MPa | Large elevation differences or sprinkler systems |
PN20 | 2.0 MPa | High-pressure main water supply pipelines |
2. Pressure verification formula (Hagen-William formula)
Hf=10.67×L×Q1.85C1.85×D4.87H_f = 10.67 \times \frac{L \times Q^{1.85}}{C^{1.85} \times D^{4.87}}Hf=10.67×C1.85×D4.87L×Q1.85
H_f = Head loss along the way (m)
L = Pipeline length (m)
Q = Flow rate (L/s)
C = Hagen-William roughness coefficient (HDPE takes 150)
D = Pipeline inner diameter (mm)
According to the water source pressure, head and terminal equipment requirements, after verifying the head loss, select the appropriate pressure level.
Determine the design flow (based on the irrigation area, irrigation method, etc.).
Select a reasonable flow rate (based on pipe diameter and system type).
Calculate the pipe diameter (to ensure sufficient flow and economic rationality).
Calculate the head loss based on the terrain and pipe length.
Determine the pressure level (to meet safety and operation requirements).
Comprehensively consider cost and installation convenience to optimize the selection.
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HDPE pipes (high-density polyethylene pipes) are widely used in the field of gas transportation. Due to their superior performance and high safety, they have gradually replaced traditional metal pipes. The following is a detailed description of the advantages and safety standards.
1. Excellent corrosion resistance
HDPE pipes have strong corrosion resistance to chemicals such as acids, alkalis, and salts. They are particularly suitable for buried gas pipeline systems, avoiding the risk of metal pipelines being easily rusted and leaked, and extending their service life.
2. Good flexibility and seismic resistance
HDPE pipes have good flexibility and impact resistance, can adapt to geological movements such as ground subsidence and earthquakes, reduce the probability of pipeline breakage and loose interfaces, and ensure the continuity and safety of gas transportation.
3. Reliable connection and no leakage
HDPE gas pipes mostly use hot-melt butt or electric fusion connection technology. The welding part is integrated with the parent material, and the connection strength is higher than the pipe body, ensuring that the pipeline system is leak-free and significantly improving the operation safety.
4. Lightweight and easy to construct
Compared with traditional metal pipes, HDPE pipes are lighter, easier to transport and lay, and can be supplied in coil form, which reduces the number of interfaces, shortens the construction period, and reduces engineering costs.
5. Excellent aging resistance and service life
HDPE gas pipes are added with anti-ultraviolet and anti-aging additives, and have a service life of more than 50 years (under normal temperature and pressure conditions), greatly reducing the frequency and cost of subsequent maintenance.
6. Good fluid transportation performance
The inner wall of HDPE pipes is smooth, with low friction resistance and a larger flow rate under the same caliber, saving energy transportation costs and improving gas transportation efficiency.
1. ISO 4437 standard
Internationally, HDPE gas pipelines mainly follow the ISO 4437 standard, which regulates the materials, performance, test methods and use requirements of polyethylene (PE) pipeline systems for gas transportation, ensuring the safety and reliability of the pipelines.
2. China National Standard GB 15558
In China, HDPE gas pipelines implement "GB 15558.1-2015 Buried Polyethylene (PE) Pipeline System for Gas Part 1: Pipes", which strictly stipulates the raw materials (PE80, PE100), pipeline pressure levels, dimensions, tolerances, and physical properties (resistance to hydrostatic pressure, resistance to slow crack growth, resistance to rapid crack expansion, etc.).
3. ASTM D2513 (American standard)
American HDPE pipes for gas follow the ASTM D2513 standard, covering the classification of pipes, material requirements, physical properties, connection methods and pressure testing, ensuring the safe application of pipelines.
4. Safe operation specifications
Construction standards: HDPE gas pipe construction must follow standardized operations, such as the "Gas Pipeline Engineering Construction and Acceptance Specifications" (GB 50251-2015), to ensure welding quality, laying depth, and protective measures are in place.
Inspection and acceptance: including pressure testing, welding quality testing, flaw detection, etc., to ensure that there is no leakage and no defects before it can be put into use.
Regular inspection and maintenance: According to the gas company and industry specifications, regular pipeline inspections, inspections, and preventive maintenance are carried out to ensure long-term safe operation.
HDPE pipe has become the preferred material for gas transportation with its excellent corrosion resistance, flexibility, leak-free connection method and long life. At the same time, perfect international and domestic safety standards provide a strong guarantee for the safe operation of HDPE gas pipelines. With the continuous development of urban gas pipeline networks, HDPE pipes will play a more important role in the field of gas transportation.
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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.
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HDPE (high-density polyethylene) pipes are widely used in water supply and drainage, gas transmission and other fields due to their corrosion resistance, good flexibility and long life. Electrofusion welding is one of the common connection methods for HDPE pipes, but various problems may be encountered in actual construction. This article will introduce the common problems, cause analysis and solutions in electrofusion welding in detail to help improve the construction quality.
Electrofusion connection is to heat the HDPE material through the resistance wire inside the electrofusion sleeve (or electrofusion pipe fitting), and form a high-strength sealed joint after cooling. The key steps include:
Pipe end surface treatment (scraping oxide layer, cleaning)
Centering and fixing (avoid eccentricity)
Electric heating (control time and voltage according to manufacturer parameters)
Cooling and curing (natural cooling to avoid external interference)
1. The electric fusion joint is not firm or leaking
Possible reasons:
The oxide layer on the pipe end surface is not scraped clean, resulting in poor fusion
The electric fusion time is insufficient or the voltage is unstable, and the melting temperature is not reached
External force disturbance during cooling
Electrofusion pipe fittings or pipe materials are unqualified (such as doped recycled materials)
Solution:
Strictly handle the pipe end surface:
Use a special scraper to remove the oxide layer (scraping length ≥ electric fusion sleeve insertion depth)
Wipe with alcohol or a clean cloth to ensure that there is no oil or dust
Control heating parameters:
Set the welding machine according to the voltage and time provided by the manufacturer (different pipe diameters and ambient temperatures need to be adjusted)
Use a stabilized power supply to avoid voltage fluctuations
Ensure sufficient cooling:
Cooling time ≥ specified value (usually 20-30 minutes)
It is forbidden to move the pipe or apply pressure during cooling
Select qualified materials:
Purchase HDPE pipes and electric fusion pipe fittings that meet GB/T 13663 standards
Avoid using inferior or recycled materials
2. Smoke or fire during electric fusion
Possible causes:
Resistance wire short circuit or local overheating
Electrofusion pipes damp or internal contamination
Input voltage too high
Solution:
Check the electric fusion pipes:
Before use, check whether the internal resistance wire is intact, without breakage or deformation
Before construction in a humid environment, use a hot air gun to dry the pipes
Control voltage:
Ensure that the output voltage of the welding machine is consistent with the nominal value of the pipe (usually 39.5±0.5V)
Avoid long-term overload power
Emergency treatment:
Immediately turn off the power, replace the pipes and re-weld them after cooling
3. The observation hole is not ejected or ejected unevenly
Possible causes:
Insufficient heating time, material is not fully melted
Insufficient pipe insertion depth or large deviation in centering
Ambient temperature is too low (such as winter construction)
Solution:
Adjust construction parameters:
Extend heating time in low temperature environment (refer to manufacturer's low temperature welding parameters)
Ensure that the pipe insertion depth is aligned with the electric fusion sleeve mark
Check centering:
Use a clamp to fix the pipe to avoid eccentricity (deviation ≤10% wall thickness)
The ejection height of the observation hole should be uniform (generally protruding 1-3mm)
4. The internal diameter of the joint is reduced or blocked after electric fusion
Possible causes:
Excessive accumulation of molten material inside the joint
The pipe port is not chamfered, and the molten material does not flow smoothly
Solution:
Pre-treat the pipe port:
Use a chamferer to process a 15° groove after cutting
Ensure that there are no burrs on the inner wall of the pipe
Control the amount of fusion:
Avoid overheating (operate according to standard parameters)
Electrofusion connection is a key link in the HDPE pipe system, and quality problems may cause leakage or structural failure. The failure rate can be significantly reduced by standardizing operations (cleaning, alignment, parameter control), selecting qualified materials, and strengthening construction management.
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HDPE (High-Density Polyethylene) pipes are widely used in municipal engineering due to their excellent corrosion resistance, flexibility, and long service life. To ensure project quality and durability, the following key points must be strictly observed during installation:
1. Material Inspection
Check pipe appearance: uniform color, free of bubbles, cracks, dents, or other defects.
Stiffness requirement: Municipal drainage pipes should have a ring stiffness ≥ 4000 N/m² (SN4).
Pipe end flatness: Straightness tolerance should be less than 3‰.
2. Trench Excavation
Width requirement: Pipe outer diameter + 0.3 m (for above-ground connections) or + 0.5 m (for in-trench connections), with a minimum width ≥ 0.7 m.
Base treatment: Avoid disturbing the natural soil; backfill and compact with graded gravel if over-excavated.
Groundwater control: Lower the water table to 0.3–0.5 m below the trench bottom.
1. Connection Methods
Butt Fusion (DN ≥ 75 mm): Temperature 210 ± 10°C, voltage stabilized at 200–220 V.
Electrofusion (for confined spaces): Suitable for pipe wells and restricted areas.
Socket Fusion (DN ≤ 63 mm): Control heating time to avoid excessive melt flow.
2. Special Environmental Considerations
Summer installation (DN ≤ 110 mm): Use a serpentine layout to compensate for thermal expansion.
Outdoor installation: Apply shading measures to prevent UV degradation.
Low-temperature environments (below -10°C): Use special low-temperature-resistant pipes.
3. Pipe Laying
Lowering method: Use non-metallic slings (secured at 1/4 of the pipe length from the end); never use center lifting.
Foundation treatment: Use gravel bedding (50–200 mm thick); avoid concrete foundations.
1. Backfilling Requirements
Layered backfilling: Use medium-coarse sand for pipe sides, compaction ≥ 90%.
Mechanical backfilling restriction: Only allowed above 0.7 m from the pipe crown.
Symmetrical backfilling: Backfill both sides simultaneously to prevent deformation.
2. Quality Inspection Standards
Pressure test: Use water as the medium, maintain pressure for 30 minutes.
Joint inspection: Butt fusion beads should be uniform (height ≥ 2 mm).
Alignment control: Horizontal deviation ≤ 1.5 mm/m, total length ≤ 25 mm.
1. Safety Risk Prevention
Static electricity protection: Anti-static measures required in flammable environments.
Trench safety: Install supports to prevent collapse.
Large-diameter pipes (DN ≥ 400): Require special construction plans to control rebound risks.
2. Connection with Manholes
Flexible connection: Use rubber gaskets to prevent leaks.
Anti-settlement treatment: Enhance compaction within 1 m of the manhole.
Table: Key Control Indicators for HDPE Pipes in Municipal Engineering
Item | Standard Requirement | Test Method |
Ring stiffness | ≥ SN4 (4000 N/m²) | Pressure test |
Fusion temperature | 210 ± 10°C | Infrared thermometer |
Backfill compaction | ≥ 90% (pipe sides) | Sand replacement method |
Leak tightness | 0.8 MPa/30 min, no leakage | Hydrostatic test |
By strictly adhering to these technical requirements, HDPE pipeline systems can achieve optimal performance in municipal engineering. It is recommended to conduct pre-construction technical briefings and establish a complete quality traceability system (e.g., RFID tagging) for full lifecycle quality control. For special geological conditions or large-diameter pipes (e.g., DN ≥ 800 mm steel-reinforced pipes), refer to the manufacturer’s specialized construction guidelines.
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