Class K8 DN900 ductile iron pipe features a nominal wall thickness class defined by ISO 2531 (K-series), offering robust strength for medium-pressure (PN 12.5/1.25 MPa) water, sewage, irrigation, gas and fire-protection mains . Its internal cement-mortar lining and optional loose-fit polyethylene sleeving extend design life beyond 100 years, reaching 110 years in aggressive soils . Installation is rapid and leak-free via push-on “Tyton,” AWWA C111 mechanical and ANSI B16.1 flanged joints . In the K-series, wall thickness steps from K7→K8→K9→K12, balancing cost and performance—K8 DN900 currently trades around US $430–559 / ton depending on volume and coating . Life-cycle analyses report a $47.68/ft cost advantage over PVC and $17 million PV savings over 50 years in Huntsville, AL, while Everglades field trials show “excellent condition” after 10+ years .
Applications
Potable Water Distribution
DN900 K8 mains provide leak-tight delivery for large municipal water networks, maintaining hydraulic stability under variable demand .
Sewage & Drainage
Abrasion-resistant iron core and smooth cement-mortar lining handle grit-laden wastewater in gravity or force mains .
Irrigation Systems
Uniform flow and surge resilience support large-scale agricultural and landscape irrigation applications .
Gas Distribution
When produced and coated per BS EN 969, DN900 K8 pipes safely convey natural gas up to 16 bar .
Fire-Protection Mains
High ductility and surge capacity ensure reliable hydrant loops and feeder mains for fire-water delivery .
Service Life
Modern ductile iron pipe is engineered to last 100 + years in benign soils, thanks to its recycled-iron matrix and proven linings.
Cement-mortar lining (ANSI/AWWA C104) provides internal corrosion protection, while loose polyethylene sleeving per ISO 8180 adds an extra 10 years in aggressive soils.
An AWWA life-cycle study found a net saving of $47.68/ft (24″ Class 200 vs PVC DR 18) and a $17 million present-value benefit over 50 years .
Installation & Connection
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Push-On (“Tyton”) Joints: Elastomeric gasket in a spigot-socket for bolt-free, rapid assembly per ISO 2531 .
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Mechanical Joints: Gland-and-bolt restraint per AWWA C111 for both restrained and unrestrained connections .
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Flanged Joints: ANSI B16.1 or EN 1092 flanges allow easy disassembly and high axial-load resistance .
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Best Practices: Proper trench bedding, ≤ 3 % deflection, hydrostatic testing and chlorination per ISO 2531/AWWA C600 maximize longevity.
Product Series Comparison & Pricing
| Class | Nominal Thickness<sup>1</sup> | PN Rating | Price (USD/ton)<sup>2</sup> |
|---|---|---|---|
| K7 | ~9.8 mm | PN 10 (1.0 MPa) | $430 – 450 |
| K8 | ~11.2 mm | PN 12.5 (1.25 MPa) | $430 – 559 |
| K9 | ~12.6 mm | PN 16 (1.6 MPa) | $460 – 520 |
| K12 | ~16.8 mm | PN 25 (2.5 MPa) | $700 – 900 |
<sup>1</sup>Per ISO 2531 & GB/T 13295 thickness classes.
<sup>2</sup>Based on global supplier listings (Made-in-China, Alibaba, SDBaotai).
International Standards
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ISO 2531 / GB/T 13295-2019: Pipe dimensions, linings & joint performance.
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ISO 8180:2020: Polyethylene sleeving for external corrosion control.
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ANSI/AWWA C111/C110: Mechanical-joint dimensions & requirements (DN 80–600 mm) .
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ANSI B16.1: Flanged joint dimensions & pressure ratings.
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BS EN 969:2009: Gas-pipeline pipe & joint requirements and test methods.
Advantages
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Exceptional Longevity: 100 + year design life reduces replacement costs and disruptions .
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High Strength & Toughness: Tensile strength ≥ 350 MPa (ISO 1083 grade JS/350–22) resists surge and external loads .
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Comprehensive Corrosion Control: CML, zinc/bitumen coatings & LPS ensure internal/external protection .
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Joint Versatility: Push-on, mechanical, flanged & restrained options adapt to any installation requirement .
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Sustainability: Recycled-iron content and recyclability yield lower lifecycle energy use versus thermoplastics .
FAQ
Q1: How do K-series classes differ?
They follow ISO 2531 thickness classes: K7→K12 define nominal wall thickness (K×(0.5+0.001×DN)), increasing strength and pressure rating from PN 10 to PN 25 .
Q2: Which joint type is best for my site?
– Tyton push-on for rapid, bolt-free assembly
– Mechanical for restrained connections
– Flanged for maintenance access and axial-load resistance.
Q3: Is polyethylene sleeving necessary?
Recommended in aggressive soils for up to 110 years of life extension; proven by DIPRA test sites .
Q4: What sizes and laying lengths are offered?
DN 80–2600 mm in 6 m standard lengths (5.7 m for export containers), with custom cuts on request .
Q5: Can DIP be used in seismic zones?
Yes—restrained joints (tie-rod, ball-and-socket) accommodate ground movement for seismic resilience .
Case Studies
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Huntsville Utilities, AL: AWWA study reports ductile iron’s net lifecycle cost of $150.19/ft versus $197.87/ft for PVC, yielding a $47.68/ft advantage and $17 million PV benefit over 50 years .
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Everglades City, FL: DIP with polyethylene encasement remained in “excellent condition” after 10+ years in corrosive muck (140–240 Ω·cm).
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 | ….. |
