Class K9 DN1200 pipe delivers PN 25 (2.5 MPa) service pressure with a nominal wall thickness of 15.3 mm (e = 4.5 + 0.009 × DN), weighs ≈ 459.8 kg/m, and typically costs USD 477.60–524.36 per m. It offers a 100+ year design life in benign soils and 50–80 years under aggressive conditions. Installation options include push-on (Tyton/T-type), mechanical (K-type), and self-restrained joints, all conforming to ISO 2531, EN 545/598, ISO 4179, and ISO 8179.
Application Scenarios
Class K9 DN1200 ductile iron pipe is ideal for:
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Municipal potable water and raw water transmission, offering low head loss over long runs.
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Gravity and rising sewer mains, plus stormwater drainage, where leak-free joints and robustness are critical.
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Fire-fighting mains (hydrants, sprinklers) requiring surge resistance up to 40 bar with restrained joints.
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Industrial effluent, mining, large-scale irrigation, and hydroelectric conduits, benefiting from high tensile strength and ductility.
Service Life
Protected ductile iron pipes reliably exceed 100 years in service, even in corrosive soils, thanks to modern metallurgical and coating practices. In aggressive environments (acidic or sulfate soils), with zinc + bitumen external coatings and cement-mortar lining (ISO 4179) or LPS sleeving, service life remains 50–80 years. High recycled-iron content and full recyclability further lower total life-cycle cost.
Installation & Connections
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Push-On (Tyton/T-Type) Joints
Quick, gasketed assembly; allows up to 5° deflection per joint; 100% leak-free when installed per ISO 2531. -
Mechanical (K-Type) Restrained Joints
Integral restraints lock socket/spigot against axial thrust, enabling pre-test pressure checks and zero-leak performance under surge/vacuum. -
Self-Restrained Joints
Clamped harnesses provide axial restraint up to PN 16 without separate hardware—ideal for tight trenches.
Flanged ends (EN 1092-2) integrate with valves/pumps for PN 25 service; external zinc + bitumen and internal cement lining ensure corrosion protection.
Series Comparison & Price
K-classes differ by wall thickness (t) = K·(0.5 + 0.001·DN). Approximate weights from DN1200 K9 (15.3 mm wall) are 459.8 kg/m. Typical list prices:
| Class | t (mm) | PN | Weight (kg/m) | Price (USD/m) |
|---|---|---|---|---|
| K7 | 7 × 1.7 = 11.9 | 10 | ~358 kg/m† | 360–450 |
| K8 | 8 × 1.7 = 13.6 | 16 | ~409 kg/m† | 390–500 |
| K9 | 9 × 1.7 = 15.3 | 25 | 459.8 kg/m | 477.6–524.4 |
| K12 | 12 × 1.7 = 20.4 | 40 | ~612 kg/m† | ~25–30% ↑ vs. K9 |
†Approximate, based on cross-sectional area and iron density.
International Standards
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ISO 2531: Ductile iron pipes, fittings, accessories & joints for water.
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EN 545 / EN 598: European standards for drinking-water & sewage pipes.
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ISO 4179: Internal cement-mortar lining requirements.
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ISO 8179: External zinc + bitumen coating specifications.
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ISO 21053: Life-cycle & sustainability assessment (industry guidance).
Advantages
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High Tensile Strength (min 420 MPa) and ductility withstand surge and ground movement.
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Exceptional Corrosion Resistance via multi-layer linings & coatings.
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Fast, Leak-Free Installation reduces labor/time costs.
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Environmentally Sustainable: high recycled content, fully recyclable; low life-cycle impact.
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Proven Global Reliability, used in critical infrastructure for over a century.
FAQ
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What defines Class K9 for DN1200?
K = 9 in t = K·(0.5 + 0.001·DN) yields t = 4.5 + 0.009·1200 = 15.3 mm; PN 25 per ISO 2531. -
How long will DN1200 K9 last?
100 years in benign soils; 50–80 years in aggressive soils with standard coatings/linings.
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What coatings and linings are standard?
Internal cement-mortar (ISO 4179) and external zinc (≥ 130 g/m²) + bitumen (≥ 70 µm) per ISO 8179; epoxy and LPS optional. -
Which joint is best for surge-prone systems?
Mechanical K-type joints provide axial restraint and zero-leak performance under transients. -
Is DN1200 K9 potable-water approved?
Yes—ISO 2531 and EN 545 compliance, cement-lined, zinc-coated, PN 25 rated.
Case Studies
Qatar Mega Reservoir Project (KAHRAMAA, Doha)
T-type DN1200–1600 pipes, cement-lined and zinc/bitumen-coated, were installed to deliver 7 days of potable water storage in a desert environment, demonstrating reliability under high demand.
Greece Water Supply Upgrade
A DN1100–DN1200 ductile iron pipeline replaced aging mains, leveraging ISO 2531 K9 pipes for long-term service; this project showcases modern production capability and historic legacy in Shandong Province.
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 | ….. |
