The Class K9 DN500 ductile iron pipe is engineered for high-pressure water distribution systems, offering more than 100 years of service life and conforming to ISO 2531, EN 545, and AWWA C151 standards. It installs via push-on or mechanical joints, resists corrosion, and provides excellent seismic and fire-resistant performance. Compared to adjacent classes (K7, K8, K12), K9 balances wall thickness, pressure capacity (9 bar), and cost. Its advantages include high tensile strength (≥420 MPa), versatile coatings, and minimal maintenance.
Application Scenarios
Class K9 ductile iron pipes (DN500) are widely used in:
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Municipal water mains and drinking water networks for reliable, long-term service.
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Sewage and wastewater systems, leveraging smooth internal linings to reduce friction and clogging.
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Fire-fighting mains, with high pressure and temperature resilience.
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Industrial process piping, handling corrosive or abrasive fluids when coated appropriately.
Service Life
Modern ductile iron pipes consistently exceed a century of operation:
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Predicted life span: >100 years under normal service conditions.
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Century Club recognition for utilities with cast iron mains still in service since early 1900s.
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Longevity arises from ductile iron’s toughness, corrosion-resistant linings, and periodic maintenance.
Laying & Connection
Installation methods include:
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Push-on (Type T) joints: Rubber ring seals ensure quick, leak-tight assembly
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Mechanical joints: Bolted glands deliver restraint under pressure and axial loading
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Flanged connections: Double-flanged sections for valves and pumps
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Trenchless techniques: Horizontal directional drilling, microtunneling in urban areas
Series Comparison & Price
The “K” number denotes nominal pressure capacity in bars and relates to wall thickness per ISO 2531. Below is a price comparison (median prices in USD/m):
| Class | Pressure Rating | Median Price/m | Key Difference |
|---|---|---|---|
| K7 | 7 bar | 450 | Thinner wall, lowest cost |
| K8 | 8 bar | 560 | Moderate thickness |
| K9 | 9 bar | 510 | Balanced cost/performance |
| K12 | 12 bar | 890 | Thicker wall, highest strength |
See the chart above for a visual comparison.
International Standards
Class K9 DN500 pipes meet major global standards:
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ISO 2531 (Cast iron pipes – requirements)
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EN 545 / EN 598 (Water supply – fittings)
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AWWA C151 (American Water Works Association standards)
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IS 8329 (Indian standard for pressure pipes)
Advantages
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High strength: Tensile ≥420 MPa, elongation ≥10%
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Corrosion control: Cement mortar or epoxy cement lining, zinc/bitumen external coating
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Recyclability: Nearly 100% recycled at end of life
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Energy efficiency: Smooth interior reduces pumping costs
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Resilience: Excellent seismic, fire, and impact resistance
FAQ
Q1: What does “DN500” mean?
A1: “DN500” refers to a nominal diameter of 500 mm per ISO 6708.
Q2: How thick is a K9 pipe wall?
A2: Wall thickness follows e = K(0.5 + 0.001·DN), so for DN500 and K=9, e ≈ 9·(0.5+0.5) = 9 mm (min 7 mm)
Q3: Can K9 handle sewage?
A3: Yes—K9’s internal cement lining resists abrasion; widely used in wastewater conveyance.
Q4: Are fittings standardized?
A4: Yes—sockets, mechanical joints, and flanges conform to ISO 2531/EN 545.
Case Studies
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Monte Vista Water District, CA, USA: Over 125 yrs of ductile mains with minimal rehabilitation—part of DIPRA’s Century Club.
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Urban Trenchless Installation, Europe: 600 mm Class K9 installed via directional drilling under historic streets, no service interruption.
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Fire Main Upgrade, Middle East: 8 km of K12 for 12 bar fire mains, delivered in 30 days, zero leaks after 3 years.
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 | ….. |
