Class K9 DN400 ductile iron pipe is engineered for high-pressure water and wastewater systems, offering a nominal wall thickness of 8.1 mm (T = K × (0.5 + 0.001 × 400), K = 9) and tested to 50 bar working pressure. Its lifespan exceeds 100 years, thanks to cement-mortar lining and external zinc-bitumen coating, and it incorporates ≥ 80 % recycled material for sustainability. Installation is simplified by multiple joint options—push-on, mechanical (Tyton®), restrained (Tyton SIT PLUS®) and boltless ball-and-socket—as well as trenchless methods like HDD and microtunneling. Compared to K7 (6.3 mm, 7 bar), K8 (7.2 mm, 8 bar) and K12 (10.8 mm, 12 bar), K9 strikes the ideal balance of strength and cost at roughly $463–482 per ton. Fully compliant with ISO 2531, EN 545, EN 598 and AWWA C151/A21.51 standards, it ensures global interoperability, while delivering tensile strength ≥ 420 MPa and elongation ≥ 10 %.
Application Scenarios
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Potable water distribution: Mains, transmission lines and treatment-plant interconnects.
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Wastewater conveyance: Gravity sewers, force mains and pump station headers.
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Industrial & raw-water systems: Power plants, refineries and irrigation networks.
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Subaqueous & trenchless crossings: HDD, microtunneling and river crossings with ball-and-socket joints.
Service Life
Modern ductile iron pipe endures for over 100 years under typical operating conditions.
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Internal protection: Cement-mortar lining resists corrosion and biofouling.
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External protection: Zinc-bitumen coating per ISO 8179 shields against soil aggression.
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Sustainability: High recycled-content casting and full recyclability reduce environmental impact.
Installation and Jointing
Class K9 DN400 supports:
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Push-on joints for rapid assembly without thrust blocks.
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Mechanical (Tyton®) and restrained (SIT PLUS®) joints to eliminate concrete thrust blocks.
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Boltless ball-and-socket joints for subaqueous applications, permitting up to 15° deflection.
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Trenchless methods (HDD, microtunneling) with tension-locked spigots for minimal surface disruption.
Product Series Comparison and Pricing
| Class | Design Pressure | Wall Thickness (DN 400) | Typical Price/ton (USD) | Key Applications |
|---|---|---|---|---|
| K7 | 7 bar | 6.3 mm | 463–482 | Low-pressure distribution |
| K8 | 8 bar | 7.2 mm | 463–482 | Medium-pressure mains |
| K9 | 9 bar | 8.1 mm | 463–482 | Standard transmission lines |
| K12 | 12 bar | 10.8 mm | 463–482 | High-pressure transmission |
Wall thickness T = K × (0.5 + 0.001 × D) .
International Standards
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ISO 2531:2009 / ISO 8180 for pipe, fittings and accessories.
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EN 545 & EN 598 (BS EN 545:2010, BS EN 598:2007) for water and sewer mains.
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AWWA C151/A21.51 & C110/A21.10 for U.S. potable-water service.
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ISO 4179 & ISO 8179 for cement-mortar lining and external coating.
Advantages
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High strength & ductility: Tensile ≥ 420 MPa, elongation ≥ 10 %.
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Corrosion protection: Dual linings and coatings defend against soil and fluid chemistry.
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Ease of installation: Modular joints and trenchless options cut labor and downtime.
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Longevity & sustainability: 100+-year lifespan, high recycled content.
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Lifecycle cost savings: Reduced maintenance and energy costs translate to millions saved.
FAQ
Q: Can Class K9 handle seismic loads?
A: Seismic-resilient (SrDiP) rubber-ring joints permit ground movement without leakage.
Q: What coatings are available?
A: Standard cement-mortar lining; external zinc-bitumen; optional epoxy or polyurethane.
Q: How is joint leakage prevented?
A: Precision-cast bells, EPDM/SBR gaskets, and restrained-joint systems (Tyton SIT PLUS®) ensure leak-tight seals.
Q: Are fittings and valves standardized?
A: Yes—compatible with ISO 2531, EN 545 dimensions and AWWA C110 flanges.
Case Studies
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Municipal water-main upgrade (Huntsville, AL): Ductile iron mains yielded a present-value energy cost savings of US $17 million over 50 years.
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Saale River HDD crossing (Merseburg, Germany): 1.1 km of DN 400 WKG ductile iron pipeline, with restrained BLS® joints and thermal insulation, installed for ~ €3 million.
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 | ….. |
