The K7 Class DN80 ductile iron pipe is a robust water-conveyance solution, engineered to withstand pressures of up to 7 bar. With a nominal diameter of 80 mm and a minimum tensile strength of 420 MPa, it offers both structural resilience and flexibility in varying soil conditions.
Application Scenarios
Municipal drinking‑water mains and raw‑water supply lines leverage Class K7 DN80 pipes for reliable pressure management and minimal leakage risks. Industrial facilities—such as power plants and chemical processing units—benefit from their chemical resistance and mechanical strength. In agriculture, they serve as irrigation mains, withstanding soil shifts and seasonal temperature variations without cracking.
Service Life
Modern ductile iron pipes routinely surpass a century of service under typical operating conditions, with documented cases of over 100 years in continuous use. Utilities like Monte Vista Water District report valuing DI mains at 100–125 years of functional life, far outpacing alternative materials and minimizing replacement costs over decades.
Installation and Connection
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Joint Methods: T‑type, mechanical‑joint and self‑anchored couplings accommodate various trench geometries and thrust conditions.
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Polyethylene Encasement:
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Method A (preferred): continuous PE sleeve overlapped at joints.
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Method B: separate PE for barrel and joint areas (requires extra wrap for bolts).
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Method C: similar to A with additional joint coverage.
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Trenching & Bedding: Pipes rest on well‑graded bedding; backfill compaction must meet local standards to prevent settlement.
International Standards
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ISO 2531:2009 — materials, dimensions, tolerances, mechanical properties, coatings.
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EN 545 / EN 598 — European requirements for water pipelines.
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ANSI/AWWA C151 — American standard for ductile‑iron pipes.
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Certifications: ISO 9001, ISO 14001, SGS, NSF, WRAS ensure quality management, environmental compliance, and potability.
Price Comparison with Other Series
| Class | China (USD / m) | India (USD / m) |
|---|---|---|
| K7 | 425 – 500 | 450 – 550 |
| K8 | 480 – 600 | 550 – 600 |
| K9 | 600 – 720 | 600 – 650 |
Advantages
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Superior Corrosion Resistance: Epoxy, bitumen or zinc‑aluminum coatings plus cement mortar lining thwart internal and external corrosion.
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Flexibility & Toughness: Ductility reduces cracking under soil movement and seismic events.
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Low Maintenance: Insusceptible to rot, insects, freeze–thaw cycles; lifecycle costs remain low amid rising energy budgets.
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Recyclability: 100% recyclable iron content aligns with circular‑economy goals.
FAQs
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What does DN80 mean?
Nominal Diameter 80 mm; internal bore ≈ 80 mm under ISO 2531 tolerance. -
What is Class K7?
Pressure class rated for 7 bar working pressure; tensile strength ≥420 MPa. -
How long will the pipe last?
Expectation exceeds 100 years in potable‑water service. -
Can these pipes be installed above ground?
Yes—coatings and lining options support above‑ and below‑ground installations. -
Is ductile iron environmentally friendly?
Fully recyclable and often produced with high recycled‑content scrap.
Case Studies
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Municipal Longevity: Monte Vista Water District credits DI mains with delivering 100–125 years of value, far outlasting PVC and other alternatives.
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Utility Success Stories: DIPRA’s repository showcases projects in diverse climates—demonstrating reduced leak rates, easy maintenance, and cost predictability in cities worldwide.
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Risk Mitigation: Historic cast‑iron failures (e.g., 90‑year CI main break) underscore the need for ductile‑iron upgrades to ensure continuous service under extreme conditions.
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 | ….. |
