Class K9 DN300 ductile iron pipe has a nominal wall thickness of 7.2 mm, calculated per ISO 2531’s formula e = 9 × (0.5 + 0.001 × 300). It is rated PN 16 (1.6 MPa) for medium-pressure water, sewage, irrigation, gas and fire-protection mains. With an internal cement-mortar lining and optional loose-fit polyethylene sleeving, its design life exceeds 100 years, extending to 110 years in aggressive soils. Installation is rapid and leak-free via ISO 2531-compliant push-on (“Tyton”), AWWA C111 mechanical and ANSI B16.1 flanged joints. Compared with K7 (6.0 mm), K8 (6.4 mm), K9 (7.2 mm) and K12 (9.0 mm), K9 balances strength and economy at US $425–485 / ton. It conforms to ISO 2531, EN 545/598, GB/T 13295, AWWA C111 and ANSI B16.1 standards .
Applications
Potable Water Distribution
K9 DN300 pipes ensure leak-tight delivery in large municipal and rural water networks, maintaining stable hydraulics under variable demand .
Sewage & Drainage
Their abrasion-resistant core and smooth cement-mortar lining handle grit-laden wastewater in gravity or force mains without rapid wear .
Irrigation Systems
Uniform flow and high surge capacity support agricultural and landscape irrigation over extended networks.
Gas Distribution
When produced and tested per BS EN 969 with appropriate coatings, DN300 K9 safely conveys natural gas up to 16 bar.
Fire-Protection Mains
High ductility and surge resilience make it ideal for hydrant feeder loops and sprinkler systems, ensuring rapid response in emergencies.
Service Life
Modern ductile iron pipe consistently exceeds 100 years in benign soils, thanks to its tough nodular-graphite matrix.
Cement-mortar lining (ANSI/AWWA C104) provides internal corrosion protection for a century or more .
Loose-fit polyethylene sleeving per ISO 8180 adds roughly 10 years of external corrosion control in aggressive soils; Everglades field tests confirm “excellent” condition after 10+ years.
AWWA life-cycle analysis shows a $47.68/ft net savings versus PVC and a $17 million present-value benefit over 50 years.
Installation & Connection
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Push-On (“Tyton”) Joints: Spigot-socket with elastomeric gasket per ISO 2531 for bolt-free, rapid sealing .
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Mechanical (AWWA C111) Joints: Gland-and-bolt restraint for both restrained and unrestrained connections .
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Flanged (ANSI B16.1) Joints: Class 125 flanges permit disassembly, alignment control and high axial-load resistance .
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Best Practices: 150 mm well-graded trench bedding, deflection ≤ 3 % of DN, hydrostatic testing & chlorination per ISO 2531/AWWA C600 ensure longevity .
K-Series Comparison & Pricing
| Class | Wall Thickness (mm) | PN Rating | Price (USD/ton) |
|---|---|---|---|
| K7 | 6.0 = 7×(0.5+0.001×300) | PN 10 (1.0 MPa) | $400 – 450 |
| K8 | 6.4 = 8×(0.5+0.001×300) | PN 12.5 (1.25 MPa) | $410 – 470 |
| K9 | 7.2 = 9×(0.5+0.001×300) | PN 16 (1.6 MPa) | $425 – 485 |
| K12 | 9.0 = 12×(0.5+0.001×300) | PN 25 (2.5 MPa) | $550 – 650 |
International Standards
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ISO 2531:2009 – Pipe dimensions, linings & joint performance.
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EN 545/EN 598 – Water and gravity sewer ductile iron standards.
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GB/T 13295-2019 – Chinese specification for DI pipes, fittings & joints.
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ANSI/AWWA C104/A21.4 – Cement-mortar lining requirements.
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ANSI/AWWA C111/A21.11 – Mechanical-joint specs (DN 80–600 mm).
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ANSI B16.1 – Flanged-joint dimensions & pressure classes.
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ISO 8180:2020 – Polyethylene sleeving for external corrosion control.
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BS EN 969:2009 – Gas-pipeline DI pipe & accessories (≤ 16 bar).
Advantages
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Century-Scale Longevity: 100 + years design life reduces replacements and downtime .
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High Strength & Toughness: Tensile ≥ 420 MPa resists surge pressures and external loads .
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Multi-Barrier Corrosion Control: Internal CML, zinc/bitumen coatings and LPS .
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Jointing Versatility: Push-on, mechanical, flanged and restrained options suit any field condition.
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Sustainability: Made from recycled iron, fully recyclable, with lower lifecycle energy use vs. thermoplastics.
FAQ
Q1: How do K-series classes differ?
They follow e = K (0.5 + 0.001 × DN)—for DN 300, K7 = 6.0 mm, K8 = 6.4 mm, K9 = 7.2 mm, K12 = 9.0 mm, matching PN 10/12.5/16/25 respectively .
Q2: Which joint type is best?
– Push-On for speed and simplicity.
– Mechanical for axial restraint.
– Flanged for maintenance and disassembly.
Q3: Is polyethylene sleeving necessary?
Recommended in aggressive soils for an additional ~10 years protection; proven by DIPRA field tests.
Q4: What sizes & laying lengths are offered?
DN 80–2600 mm in 6 m laying lengths (5.7 m for container shipping), custom cuts on demand.
Q5: Can DI pipe be used in seismic zones?
Yes—restrained joint variants (tie-rod, ball-and-socket) handle ground movement and axial loads for seismic resilience.
Case Studies
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Huntsville Utilities, AL: AWWA life-cycle analysis documented a net $47.68/ft savings and $17 million present-value benefit over 50 years for 24″ Class 200 DIP vs PVC.
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Everglades City, FL: Polyethylene-encased pipes 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 | ….. |
