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wr@insulatedpipeline.com
wyy@insulatedpipeline.com
Published:2024-08-15 | Last Updated: 2025-06-11 Views: 152
i. Polyurethane foam insulated steel pipes: an efficient insulation solution
Polyurethane foam insulated steel pipes are widely used in various industries due to their excellent insulation properties. These pipes are the core components of efficient heat transfer systems.
ii. Core Structure and Materials
Polyurethane foam-insulated steel pipes feature a three-layer composite structure:
Inner pipe (working pipe): Typically a pressure-bearing steel pipe (seamless steel pipe or welded steel pipe) responsible for conveying fluid media.
Middle layer (insulation layer): Made of rigid polyurethane foam.
Outer layer (protective layer): Typically made of high-density polyethylene (HDPE) or other durable materials.
iii. Core Advantages of Polyurethane Foam
Excellent Insulation: As an insulating layer, polyurethane foam reduces heat loss (or cold loss).
Temperature Stability: Ensures that the fluid inside the pipeline (such as hot water, steam, or oil) maintains a stable temperature during long-distance transportation.
Energy Efficiency: Effective insulation directly translates into energy savings and reduced operational costs.
iv. Application Scenarios
District Heating/Cooling Systems: Long-distance transportation of hot water or cold water.
Oil and Gas Transportation: Maintaining the required temperature for crude oil or natural gas pipeline transportation.
Industrial Processes: Various industrial applications requiring strict temperature control.
v. The Key Role of Outer Layer Protection
Physical Protection: Resists soil pressure, impact, and excavation damage.
Waterproof and Moisture-Resistant: Completely isolates moisture, protecting the performance of the polyurethane foam insulation layer from moisture-related degradation.
Corrosion Resistance: Protects the entire pipeline system from chemical corrosion caused by soil and environmental factors.
vi. Advantages
Selecting polyurethane-insulated pipes (i.e., polyurethane foam-insulated steel pipes) offers multiple benefits:
High durability and reliability: The multi-layer structural design ensures long-term stable operation in harsh environments.
Significant energy savings: Excellent insulation performance significantly reduces heat loss.
Cost-effective: Reduces energy expenses and lowers long-term operational costs.
Easy installation: Often采用prefabricated direct burial form, simplifying on-site construction and shortening the construction period.
| Nominal diameter（DN） | Outer diameter of steel pipe（mm） | Insulation layer thickness（mm） | Steel pipe wall thickness（mm） |
|---|---|---|---|
| 15 | 21.3 | 30-60（According to specific needs） | 2.0-3.0 |
| 20 | 26.9 | 2.5-3.5 | |
| 25 | 33.7 | 3.0-4.0 | |
| 32 | 42.4 | 3.0-4.5 | |
| 40 | 48.3 | 3.5-5.0 | |
| 50 | 60.3 | 3.5-5.5 | |
| 65 | 76.1 | 4.0-6.0 | |
| 80 | 88.9 | 4.0-6.5 | |
| 100 | 114.3 | 4.5-7.0 | |
| 125 | 139.7 | 5.0-8.0 | |
| 150 | 168.3 | 5.5-9.0 | |
| 200 | 219.1 | 6.0-10.0 | |
| 250 | 273.0 | 6.5-11.0 | |
| 300 | 323.9 | 7.0-12.0 | |
| 350 | 355.6 | 7.5-13.0 | |
| 400 | 406.4 | 8.0-14.0 | |
| 450 | 457.0 | 8.5-15.0 | |
| 500 | 508.0 | 9.0-16.0 | |
| 550 | 559.0 | - | - |
| 600 | 610.0 | - | - |
| 650 | 660.0 | - | - |
| 700 | 711.0 | - | - |
| 750 | 762.0 | - | - |
| 800 | 813.0 | - | - |
| 850 | 864.0 | - | - |
| 900 | 914.0 | - | - |
| 950 | 965.0 | - | - |
| 1000 | 1016.0 | - | - |
| 1050 | 1067.0 | - | - |
| 1100 | 1118.0 | - | - |
| 1150 | 1168.0 | - | - |
| 1200 | 1219.0 | - | - |
i. Steel pipe prefabrication: Select seamless steel pipes or SSAW steel pipes and process them strictly in accordance with standards.
ii. Surface treatment: Remove rust and grind the outer surface of the steel pipe to ensure that it is clean and dry, thereby enhancing the adhesion of the insulation layer.
iii. Polyurethane foaming: Inject polyurethane raw materials into the layer between the steel pipe and the outer protective pipe, and form it into a high-efficiency insulation layer through foaming.
iv. Outer casing formation: High-density polyethylene (HDPE) pipes are used to tightly wrap the insulation layer, ensuring waterproofing and corrosion resistance.
v. Quality inspection: The finished product undergoes comprehensive testing, including insulation layer density, thermal conductivity, steel pipe wall thickness, and outer casing quality, to ensure compliance with standards.
vi. Packaging and transportation: Qualified products are packaged with moisture-proof materials, sorted by specification for storage, and transported to the construction site or the customer's designated location.
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i. Corrosion resistance: Resists acid, alkali, and corrosive media, extending the service life of the pipeline.
ii. Strong waterproofing: Prevents moisture penetration, protects the insulation layer, and ensures long-lasting insulation performance.
iii. High mechanical strength: Impact-resistant and wear-resistant, protecting the internal structure.
iv. Good flexibility: Does not become brittle at low temperatures, adapting to bending and installation requirements.
v. Easy to install: Easy to process, with excellent heat-sealed welds, reducing costs.
vi. Environmentally friendly and non-toxic: Meets green building requirements and is environmentally friendly.
| Item/Standard | China National Standard GB/T 29047 | European Standard EN 253 | American Standard |
|---|---|---|---|
| Scope of Application | Pre-insulated buried pipes and fittings with high-density polyethylene outer sheath and rigid polyurethane foam | Pre-insulated buried pipes for district heating hot water networks | Mainly used in construction, heating, and chemical industries |
| Working Steel Pipe | Complies with GB/T 8163 or GB/T 9711, etc. | Complies with relevant European steel standards | Complies with ASTM A53, etc. |
| Insulation Layer Density | ≥60 kg/m³ | 60-80 kg/m³ | 60-80 kg/m³ |
| Thermal Conductivity | ≤0.033 W/(m·K) | ≤0.033 W/(m·K) | ≤0.03 W/(m·K) |
| Water Absorption Rate | ≤0.2 kg/m² | ≤0.2 kg/m² | ≤0.2 kg/m² |
| Outer Sheath | High-density polyethylene, density ≥940 kg/m³ | High-density polyethylene, meets relevant performance requirements | High-density polyethylene |
| Environmental Requirements | Complies with Chinese environmental standards, non-toxic and harmless | Complies with EU environmental directives | Complies with US environmental regulations |
| Other Requirements | Corrosion resistance, waterproof, heat resistance, etc. | Corrosion resistance, waterproof, heat resistance, etc. | Corrosion resistance, waterproof, heat resistance, etc. |
i. Outer protective layer performance specifications
Density: ≥940 kg/m³.
Carbon black content: 2.5% ± 0.5%.
Melt flow rate: difference ≤0.5 g/10min.
Tensile yield strength: ≥19 MPa.
Elongation at break: ≥350%.
Longitudinal shrinkage rate: ≤3%.
Heat resistance: Tensile strength (80°C, minimum yield time 1500 hours) ≥ 4 MPa.
ii. Insulation Layer Technical Specifications
Foam closed-cell rate: ≥ 88%.
Foam density: ≥ 60 kg/m³.
Compressive stress: ≥ 0.3 MPa.
Water absorption rate: ≤ 10%.
Thermal conductivity: ≤0.03 W/(m·K) (100°C, 96 hours).
iii. Insulation pipe technical specifications
Outer diameter increase rate of outer protective pipe: ≤2%.
Axial eccentricity rate: ≤6.0 mm.
Shear strength:
At 23±2°C, ≥0.12 MPa.
At 140±2°C, ≥0.08 MPa.
Impact performance: No visible cracks on the outer protective pipe.
iv. Other requirements
Protective layer thickness: Should not be less than 1.2 mm.
End faces of the corrosion-resistant insulation layer: Must be sealed with waterproof caps to prevent water ingress.
Resistance to chemical medium corrosion: Resists 10% HCl, 10% NaOH, and 3% NaCl solutions (80°C, 300 hours) without changes.
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E-mail：wr@insulatedpipeline.com
E-mail：wyy@insulatedpipeline.com
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