As an important representative of modern engineering plastic pipes, high-density polyethylene (HDPE) pipes have become an ideal substitute for traditional metal pipes with their excellent performance and wide application. 315 HDPE pipe belongs to the category of medium and large diameter pipes, and plays a key role in municipal engineering, industrial pipelines and other fields.
The main advantages of HDPE pipes include:
Strong corrosion resistance: can resist corrosion from most chemicals, with a service life of more than 50 years
Good flexibility: adapt to foundation settlement, excellent seismic resistance
Light weight: density is only 0.95g/cm³, easy to transport and install
Reliable connection: hot-melt connection forms a whole, no risk of leakage
Good flow performance: smooth inner wall, low transportation resistance
315mm (DN315) HDPE pipes belong to medium and large diameter pipes in the pipeline system:
Small diameter pipes: DN20-DN110
Medium diameter pipes: DN125-DN315
Large diameter pipes: DN355-DN1600
Pipes of this specification are mainly used in:
Municipal water supply and drainage trunk network
Industrial fluid transportation system
Large-scale farmland irrigation project
Mine tailings transportation pipeline
The standard size of 315mm HDPE pipe follows the GB/T 13663 standard:
Nominal outer diameter: 315mm (allowable deviation ±1.0%)
Nominal pressure level: PN6-PN16 (0.6-1.6MPa)
SDR series: SDR26, SDR21, SDR17, SDR13.6, SDR11
Wall thickness corresponding to different SDRs:
|
SDR Value |
Pressure Rating (MPa) |
Wall Thickness (mm) |
|
26 |
0.6 |
12.1 |
|
21 |
0.8 |
15.0 |
|
17 |
1.0 |
18.7 |
|
13.6 |
1.25 |
23.2 |
|
11 |
1.6 |
28.6 |
The unit weight of 315 HDPE pipe is an important parameter for engineering design, transportation and installation. The calculation formula is as follows:
Weight (kg/m) = π×(D-t)×t×ρ
Where:
D: pipe outer diameter (m)
t: pipe wall thickness (m)
ρ: HDPE density (950kg/m³)
Taking SDR17 series as an example:
D=0.315m, t=0.0187m
Weight=3.14×(0.315-0.0187)×0.0187×950≈16.5kg/m
Weight comparison table of common SDR specifications:
|
SDR Value |
Wall Thickness (mm) |
Theoretical Weight (kg/m) |
|
26 |
12.1 |
10.8 |
|
21 |
15.0 |
13.4 |
|
17 |
18.7 |
16.5 |
|
13.6 |
23.2 |
20.2 |
|
11 |
28.6 |
24.5 |
315mm HDPE pipes are usually supplied in straight sections:
Standard lengths: 6m, 12m
Special customization: 9m, 10m and other non-standard lengths can be produced on demand
Spool supply:
Generally, DN315 pipes are not coiled
Special flexible formula pipes can be coiled in limited quantities (maximum length ≤50m)
According to the requirements of GB/T 13663 standard, the main mechanical properties of 315mm HDPE pipe should meet the following requirements:
Tensile strength: ≥20MPa (fracture)
Flexural modulus: 800-1000MPa
Impact strength: ≥20kJ/m² (23℃)
Elastic deformation range: ≤4% strain
Chemical resistance
|
Chemical Substance |
Resistance |
Usage Recommendation |
|
Acid (20%) |
Excellent |
Suitable for long-term use |
|
Alkali (30%) |
Excellent |
Suitable for long-term use |
|
Salt Solution |
Excellent |
Suitable for long-term use |
|
Organic Solvent |
Fair |
Short-term contact only |
|
Oxidizing Agent |
Poor |
Avoid use |
Design life: 50 years (at 20°C)
Long-term hydrostatic strength (MRS):
PE80 grade: 8.0MPa
PE100 grade: 10.0MPa
Temperature influence coefficient:
|
Temperature (℃) |
Pressure Reduction Factor |
|
20 |
1.0 |
|
30 |
0.87 |
|
40 |
0.74 |
|
50 |
0.62 |
1. Municipal water supply and drainage system
Typical application of 315mm HDPE pipe in municipal engineering:
Water supply main network: select SDR11 or SDR13.6 series, working pressure 1.0-1.6MPa
Drainage main pipe: select SDR17 or SDR21 series to reduce costs
Recycled water reuse system: blue stripe marked pipes are required
Construction points:
Deep requirement: ≥1.0m under motor vehicle lane, ≥0.8m under non-motor vehicle lane
Foundation treatment: sand cushion thickness ≥100mm
Backfill requirements: compaction in layers, each layer ≤300mm
2. Industrial piping system
Application features in the industrial field:
Chemical pipelines: special formulas that resist chemical corrosion need to be selected
Slurry transportation: wear-resistant reinforced HDPE pipes (wall thickness increased by 20%)
Food industry: use white HDPE pipes that meet FDA standards
Design considerations:
Working pressure should be ≤80% of PN grade
High-temperature media need to calculate pressure reduction
Support density needs to be increased in vibration situations
3. Agricultural irrigation projects
Advantages of using 315mm HDPE pipes in large-scale farmland irrigation projects:
Good weather resistance, adaptable to outdoor environments
Smooth inner wall, reducing head loss
Good flexibility, adaptable to terrain changes
System design parameters:
Flow rate control: 1.0-1.5m/s
Working pressure: 0.4-0.8MPa (usually SDR21)
Branch spacing: 50-80m
315mm HDPE pipe mainly adopts hot melt connection technology:
Butt welding:
Applicable conditions: DN≥90mm
Welding process parameters:
Heating temperature: 200±10℃
Heating pressure: 0.15-0.25MPa
Switching time: pipe diameter (mm)/11(s)
Cooling time: ≥30 minutes
Electric fusion connection:
Applicable conditions: various pipe diameters
Welding parameters:
Voltage: 39.5±0.5V
Time: automatically set according to pipe diameter
Cooling time: ≥2 hours
315mm Technical requirements for underground construction of HDPE pipes:
Trench excavation:
Width: pipe diameter + 500mm
Slope: determined according to soil quality (usually 1:0.5)
Pipeline laying:
Use nylon slings to lower the pipe
Keep the pipe in a natural bending state
Reserve 0.5% thermal expansion margin
Backfill requirements:
Initial backfill: fine sand or original soil (no stones) to 300mm from the top of the pipe
Main backfill layer: compacted in layers (each layer ≤300mm)
Final backfill: restore the original soil
315mm HDPE pipe is suitable for trenchless construction methods:
Directional drilling technology:
Maximum laying length: 300-500m
Guide hole deviation: ≤1% length
Back expansion diameter: 1.2-1.5 times the pipe diameter
Pipe jacking technology:
Applicable pipes: SN8 or above ring stiffness
Jacking speed: ≤50mm/min
Relay room setting: one group every 80-100m
1. Marine engineering applications
Special applications of 315mm HDPE pipes in marine environments:
Seawater transportation: anti-salt spray corrosion design
Submarine pipelines: counterweight concrete coating
Aquaculture system: anti-biological attachment treatment
Technical features:
Use PE100-RC material
Increase carbon black content (≥2.5%)
Special anti-ultraviolet formula
2. Ground source heat pump system
Advantages as buried pipes in ground source heat pumps:
Moderate thermal conductivity (0.42W/mK)
Long-term geothermal stability
Flexibility to adapt to stratum changes
Design parameters:
Usually use SDR11 series
Burial depth 1.5-2.0m
Pipe spacing 4-6m
3. Mine tailings transportation
Wear-resistant design of 315 HDPE pipes for mines:
Inner wall smoothness Ra≤0.2μm
Add wear-resistant fillers (such as wollastonite)
Wall thickness increased by 20-30%
Performance requirements:
Wear resistance index: ≤50mm³ (GB/T 1768)
Working pressure: 1.0-1.6MPa
Impact resistance: ≥30kJ/m²
1. How to quickly estimate the weight of 315mm HDPE pipe?
Simple calculation formula:
Weight (kg/m) ≈ 24×SDR value
For example:
SDR17: 24/17 ≈ 1.41kg/m·mm
Wall thickness 18.7mm: 1.41×18.7 ≈ 26.4kg/m
(Note: This method is an estimate, the actual weight is 16.5kg/m)
More accurate memory data:
SDR17: about 16.5kg/m
SDR11: about 24.5kg/m
2. How to calculate the transportation weight of 315 HDPE pipe?
Calculation of transportation weight of 6-meter straight pipe:
Take SDR17 as an example:
Weight of a single pipe = 16.5kg/m×6m=99kg
Estimation of truck loading capacity:
40-foot container can load:
6-meter pipe: about 150 pipes (14.85 tons)
12-meter pipe: about 75 pipes (14.85 tons)
3. How to choose between 315mm and 355mm HDPE pipes?
Selection comparison:
|
Parameter |
DN315 |
DN355 |
|
Flow Capacity |
Q = 0.25πvD² |
Increased by 25% |
|
Weight (kg/m) |
16.5 (SDR17) |
21.0 (SDR17) |
|
Applicable Pressure |
1.0 MPa |
0.9 MPa |
|
Price Comparison |
Baseline |
15–20% higher |
Selection suggestions:
Large flow demand: Choose DN355
High pressure requirement: Choose DN315
Limited budget: Choose DN315
With technological progress and increased environmental protection requirements, 315mm HDPE pipes will replace traditional pipes in more areas, and the market demand is expected to maintain an annual growth rate of 8-10% in the next five years. Understanding its key technical parameters such as weight characteristics is of great significance for engineering design and construction.
