Class K8 DN400 ductile iron pipe has a nominal wall thickness of 7.2 mm, calculated per ISO 2531’s formula e = K·(0.5 + 0.001 × DN) with K = 8 and DN = 400 mm . It is rated PN 12.5 (1.25 MPa) for medium‑pressure water, gas and fire mains . With cement‑mortar lining and optional loose polyethylene sleeving, its design life exceeds 100 years, reaching up to 110 years under optimal corrosion control .
Applications
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Potable Water Distribution: Ensures leak‑tight delivery in large‑diameter municipal mains with proven hydraulic performance.
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Sewage & Drainage: Abrasion‑resistant core and lining withstand grit‑laden wastewater in gravity or force mains .
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Irrigation Systems: Stable flow under variable pressures supports agricultural networks and farm sprinklers .
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Gas Distribution: When manufactured and coated per BS EN 969, it safely conveys combustible gases up to 16 bar .
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Fire‑Protection Mains: High surge resilience and ductility meet the demands of hydrant loops and feeder mains .
Service Life
Modern ductile iron pipe is engineered to last over 100 years in benign soils .
With loose polyethylene encasement per ISO 8180, life expectancy extends to 110 years even in aggressive muck .
A Black & Veatch life‑cycle study for Huntsville Utilities found annual pumping‑cost savings of $666,999, yielding a $17 million present‑value benefit over 50 years versus PVC mains .
At Everglades test sites, encased pipes remained in “excellent condition” after 10+ years in corrosive soils.
Installation & Connection
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Push‑On (“Tyton”) Joints: Rubber‑gasketed spigot‑socket assembly for bolt‑free, rapid sealing per ISO 2531.
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Mechanical Joints: Gland‑and‑bolt restraint per AWWA C111 for fittings, valves and restrained connections.
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Flanged Joints: ANSI B16.1 or EN 1092 flanges enable easy disassembly and high axial‑load resistance.
K‑Series Comparison & Pricing
| Class | Wall Thickness (mm)1 | Pressure Rating | Price (USD/ton)2 |
|---|---|---|---|
| K7 | 6.3 = 7×(0.5+0.001×400) | PN 10 (1.0 MPa) | $400–600 |
| K8 | 7.2 = 8×(0.5+0.001×400) | PN 12.5 (1.25 MPa) | $500–560 |
| K9 | 8.1 = 9×(0.5+0.001×400) | PN 16 (1.6 MPa) | $545–645 |
| K12 | 10.8 =12×(0.5+0.001×400) | PN 25 (2.5 MPa) | $750–900 |
1.Per ISO 2531 nominal‑thickness formula.
2.Based on industry price lists and market surveys.
International Standards
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ISO 2531 / EN 545 / EN 598: Pipe dimensions, linings & joint performance
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GB/T 13295‑2019: Chinese specification for DIP, fittings & joints in water/gas systems
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ISO 8180: Polyethylene sleeving for external corrosion control
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AWWA C111/A21.11: Mechanical‑joint specifications for DN 80–600 mm
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ANSI B16.1: Flanged joint dimensions & ratings
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BS EN 969:2009: Requirements & test methods for gas pipelines (≤ 16 bar)
Advantages
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Exceptional Longevity: 100+ year design life minimizes replacements.
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High Strength & Toughness: Ductile-iron grades (ISO 1083) offer tensile ≈ 500 MPa, resisting surges and external loads.
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Comprehensive Corrosion Control: Cement‑mortar linings, zinc/bitumen coatings and polyethylene encasement combat internal/external corrosion.
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Versatile Jointing: Push‑on, mechanical, flanged and restrained systems suit diverse field conditions.
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Sustainability: Made from recycled iron, fully recyclable with lower life‑cycle energy than thermoplastics.
FAQ
Q1: How do K classes differ?
They follow e = K (0.5+0.001 × DN)—for DN 400, K7=6.3 mm, K8=7.2 mm, K9=8.1 mm, K12=10.8 mm, matching PN 10/12.5/16/25 respectively.
Q2: What lining & coating options exist?
Internal: cement‑mortar (ANSI/AWWA C104), epoxy or ceramic; External: bitumen, zinc, polyethylene sleeving per ISO 8180.
Q3: Is DIP suitable for corrosive soils?
Yes—polyethylene encasement or cathodic protection enable 100+ year life even in aggressive environments.
Q4: What sizes & lengths are offered?
Standard DN 80–2600 mm in 6 m laying lengths (5.7 m for container loads), with custom cuts on request.
Case Studies
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Huntsville Utilities, AL: Black & Veatch recorded $666,999 annual pumping‑cost savings and $17 million PV benefit over 50 years versus PVC mains.
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Everglades Test Site, FL: Polyethylene‑encased DIP 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 | ….. |
