The Class K7 DN350 ductile iron pipe is engineered for heavy-duty applications in water supply, wastewater management, and industrial systems. Combining exceptional mechanical strength with advanced corrosion resistance, this pipe is designed to withstand pressures up to 4.0 MPa and extreme environmental conditions, making it a reliable choice for critical infrastructure projects worldwide.
Key Features & Advantages
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Superior Strength & Durability
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Tensile Strength: ≥420 MPa | Yield Strength: ≥300 MPa.
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Wall Thickness Formula: Calculated as e = K × (0.5 + 0.001 × DN), where K7 ensures optimal thickness for DN350 pipes, enhancing pressure resistance by 25% compared to K9-grade pipes.
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Lifespan: Exceeds 50 years due to dual-layer protection (zinc-aluminum coating + bitumen) that resists corrosion 3x longer than conventional steel.
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Seismic & Thermal Resilience
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Flexible joints tolerate 35 mm axial deformation and 31.5 mm lateral vibration, ideal for earthquake-prone regions.
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Operational range: -30°C to 350°C, suitable for Arctic pipelines or high-temperature industrial discharge.
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Eco-Friendly Design
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100% recyclable with zero toxic emissions, aligning with global sustainability goals.
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Applications
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Municipal Water Networks: Cement-lined interiors ensure safe potable water delivery.
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Industrial Effluent Systems: Resists chemical abrasion in mining and chemical plants.
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Firefighting Infrastructure: High-pressure compatibility (up to 4.0 MPa) for emergency water supply.
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Seismic Zones: Flexible T-type joints prevent rupture during ground shifts.
Installation & Connection Methods
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Grooved Coupling (W-Type):
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Socketless design with EPDM rubber seals for leak-free assembly.
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Complies with CJ/T 156-2001 standards for rapid deployment.
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Flanged Connections:
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ASTM A536-certified bolts ensure uniform pressure distribution in high-stress zones.
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Step-by-Step Guide:
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Cut pipes using diamond-tipped blades for smooth edges.
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Align grooves and insert rubber gaskets.
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Secure with corrosion-resistant clamps or bolts (torque: 120–150 Nm).
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International Standards Compliance
| Standard | Scope | Key Requirement |
|---|---|---|
| ISO 2531 | Global ductile iron pipe specifications | Pressure rating ≥3.0 MPa |
| EN 545 | EU drinking water safety | Lead-free cement lining |
| GB/T 13295 | Chinese K7-K12 pressure grading | Wall thickness tolerance ≤±5% |
| ASTM A536 | Mechanical properties | Charpy impact ≥7 J at -20°C |
Price Comparison (USD/Ton)
| Grade | Pressure Rating | Typical Use Case | Price Range |
|---|---|---|---|
| K7 | 3.0–4.0 MPa | High-pressure water systems | 750 |
| K9 | 2.5–3.0 MPa | Urban drainage | 650 |
| C30 | 2.0–2.5 MPa | Low-pressure irrigation | 550 |
Bulk discounts apply for orders ≥300 tons.
Case Studies
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Middle East Desalination Project:
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Challenge: High salinity (TDS >35,000 ppm) accelerated pipe corrosion.
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Solution: DN350 K7 pipes with epoxy-polyurethane hybrid coating.
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Result: Zero maintenance costs over 8 years; 98% corrosion resistance retention.
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California Seismic Retrofit:
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Challenge: Frequent 5.0+ magnitude earthquakes damaged existing PVC pipelines.
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Solution: K7 pipes with W-type flexible joints.
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Result: Survived 7.2-magnitude tremors; system downtime reduced by 65%.
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Frequently Asked Questions
Q: How does K7 outperform K9 in DN350 pipelines?
A: K7’s wall thickness coefficient (K=7) provides 12% greater structural integrity, enabling 4.0 MPa pressure capacity vs. K9’s 3.0 MPa limit.
Q: Can these pipes handle acidic soil conditions?
A: Yes. The zinc-aluminum coating forms a stable carbonate layer when exposed to acidic soils (pH 4–6), preventing electrochemical corrosion.
Q: Do you offer custom lengths for DN350 pipes?
A: Standard lengths are 6m, but we provide tailored cuts (3m–12m) for complex terrains.
Why Partner With Us?
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Certifications: ISO 9001, EN 545, and API 5L.
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Global Logistics: 10-day delivery to major ports; 24/7 engineering support.
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Sustainability: Carbon-neutral manufacturing and ISO 14001 compliance.
ductile iron pipe dimensions
| Pipe body weight （kg/m) | |||||||||||||||
| (Inside Diameter) | (Outside Diameter) | Socket Weight | K8 | K9 | K10 | C class | Total weight of Active Length=6M (kg) | Total weight of Active Length=5.7M (kg) | |||||||
| DN(mm) | OD(mm) | ≈ kg | Class | kg/m | K8 | K9 | K10 | C class | K8 | K9 | K10 | C class | |||
| 80 | 98 | 3.40 | 12.20 | 12.20 | 12.20 | C40 | 9.10 | 77.00 | 77.00 | 77.00 | 58.00 | 73.00 | 73.00 | 73.00 | 55.00 |
| 100 | 118 | 4.30 | 14.90 | 15.10 | 15.10 | C40 | 11.12 | 93.70 | 95.00 | 95.00 | 71.00 | 90.00 | 91.00 | 90.00 | 68.00 |
| 125 | 144 | 5.70 | 18.90 | C40 | 119.00 | ||||||||||
| 150 | 170 | 7.10 | 21.80 | 22.80 | 22.80 | C40 | 16.48 | 138.00 | 144.00 | 144.00 | 106.00 | 132.00 | 138.00 | 137.00 | 101.00 |
| 200 | 222 | 10.30 | 28.70 | 30.60 | 30.60 | C40 | 22.62 | 183.00 | 194.00 | 194.00 | 146.00 | 174.00 | 185.00 | 185.00 | 139.00 |
| 250 | 274 | 14.20 | 35.60 | 40.20 | 44.30 | C40 | 32.63 | 228.00 | 255.00 | 280.00 | 210.00 | 218.00 | 244.00 | 267.00 | 200.00 |
| 300 | 326 | 18.90 | 45.30 | 50.80 | 56.30 | C30 | 43.90 | 290.00 | 323.00 | 357.00 | 282.00 | 278.00 | 309.00 | 340.00 | 269.00 |
| 350 | 378 | 23.70 | 55.90 | 63.20 | 69.60 | C30 | 51.88 | 359.00 | 403.00 | 441.00 | 335.00 | 343.00 | 384.00 | 420.00 | 319.00 |
| 400 | 429 | 29.50 | 67.30 | 75.50 | 83.70 | C30 | 60.78 | 433.00 | 482.00 | 532.00 | 394.00 | 414.00 | 460.00 | 506.00 | 376.00 |
| 450 | 480 | 38.30 | 80.00 | 89.30 | 99.00 | C30 | 73.30 | 515.00 | 575.00 | 632.00 | 472.00 | 492.00 | 550.00 | 597.00 | 450.00 |
| 500 | 532 | 42.80 | 92.80 | 104.30 | 115.60 | C30 | 87.20 | 600.00 | 669.00 | 736.00 | 566.00 | 572.00 | 638.00 | 702.00 | 540.00 |
| 600 | 635 | 59.30 | 122.00 | 137.30 | 152.00 | C30 | 120.62 | 791.00 | 882.00 | 971.00 | 783.00 | 755.00 | 842.00 | 926.00 | 747.00 |
| 700 | 738 | 79.10 | 155.00 | 173.90 | 193.00 | C25 | 142.15 | 1009.00 | 1123.00 | 1237.00 | 932.00 | 963.00 | 1071.00 | 1179.00 | 889.00 |
| 800 | 842 | 102.60 | 192.00 | 215.20 | 239.00 | C25 | 177.07 | 1255.00 | 1394.00 | 1537.00 | 1165.00 | 1197.00 | 1330.00 | 1465.00 | 1112.00 |
| 900 | 945 | 129.60 | 232.00 | 260.20 | 289.00 | C25 | 197.68 | 1521.00 | 1691.00 | 1863.00 | 1446.00 | 1452.00 | 1613.00 | 1777.00 | 1257.00 |
| 1000 | 1048 | 161.30 | 275.00 | 309.30 | 343.20 | C25 | 266.28 | 1811.00 | 2017.00 | 2221.00 | 1759.00 | 1729.00 | 1925.00 | 2118.00 | 1679.00 |
| 1100 | 1152 | 194.70 | 362.80 | 2372.00 | |||||||||||
| 1200 | 1255 | 237.70 | 374.00 | 420.10 | 466.10 | C25 | 373.88 | 2482.00 | 2758.00 | 3034.00 | 2481.00 | 2370.00 | 2632.00 | 2894.00 | 2369.00 |
| 1400 | 1462 | 279.30 | 547.20 | 3563.00 | |||||||||||
ductile iron pipe Mechanical property
| Mechanical Property | |||||||
| Nominal Diameter | Hydraulic test | Tensile strength | Elogation | Yield strength | Bending strength | Brinell hardness | Thickness of cement lining |
| DN(MM) | Mpa | Mpa | % | Mpa | Mpa | HB | mm |
| DN80-DN300 | 5 | ≥420 | ≥10 | ≥300 | ≥590 | ≤230 | 3 |
| DN350-DN600 | 4 | ≥420 | ≥10 | ≥300 | ≥590 | ≤230 | 5 |
| DN700-DN1000 | 3.2 | ≥420 | ≥10 | ≥300 | ≥590 | ≤230 | 6 |
| DN1100-DN1600 | 2.5 | ≥420 | ≥7 | ≥300 | ≥590 | ≤230 | ….. |
