Class K8 DN450 ductile iron pipe has a nominal wall thickness of 7.6 mm, calculated per ISO 2531’s formula e = K × (0.5 + 0.001 × DN) (K = 8, DN = 450) . This thickness class delivers robust structural capacity for medium‑pressure potable water, sewage, irrigation, gas and fire‑protection mains, and supports a design life well beyond 100 years when internally cement‑mortar lined and optionally externally sleeved in polyethylene . Field‑proven joint systems—push‑on (“Tyton”), mechanical, and flanged—ensure rapid, leak‑free assembly to ISO 2531, AWWA C111 and ANSI B16.1 standards . In the K‑series, wall thickness rises progressively from K7 (6.65 mm) to K8 (7.6 mm) to K9 (8.55 mm) to K12 (11.4 mm), with global market prices per ton averaging USD 400–720 (K7), USD 482–529 (K8), USD 545–645 (K9) and USD 482–526 (K12).
Applications
Potable Water Distribution
K8 DN450 ensures leak‑tight, large‑diameter mains in municipal water networks, maintaining hydraulic performance under variable demand and minimizing losses .
Sewage & Drainage
Its abrasion‑resistant iron core and smooth cement‑mortar lining convey grit‑laden wastewater reliably in gravity or force mains .
Irrigation Systems
Stable hydraulic characteristics under fluctuating flows make it ideal for agricultural and horticultural distribution lines .
Gas Distribution
When produced per EN 969 and coated externally, DIP safely transports natural gas in medium‑pressure networks .
Fire‑Protection Mains
High ductility and surge resilience support hydrant loops and feeder mains, ensuring ready‑response water delivery under emergency conditions .
Service Life
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Cement‑Mortar Lining (CML): Predicted life > 100 years based on long‑term utility surveys and coupon testing .
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Polyethylene Encasement: Loose‑fit sleeving per ISO 8180 extends life to ~110 years in aggressive soils, proven at Everglades test sites .
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Life‑Cycle Savings: A Black & Veatch study for Huntsville Utilities showed $666,999 annual pumping‑cost savings, totaling a $17 million PV benefit over 50 years compared to PVC mains .
Installation & Connection
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Push‑On (“Tyton”) Joints: Elastomeric gasket in a spigot‑socket for bolt‑free, rapid, leak‑tight assembly per ISO 2531 dimensions .
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Mechanical Joints: Gland‑and‑bolt restraint per AWWA C111, enabling both restrained and unrestrained connections for valves and fittings .
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Flanged Joints: ANSI B16.1 (or EN 1092) flanges permit easy disassembly, alignment control and high axial‑load resistance .
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Best Practices: Trenching with 150 mm graded bedding, deflection ≤ 3 % of DN, hydrostatic testing and chlorination per ISO 2531/AWWA C600 maximize joint performance and longevity .
K‑Series Comparison & Pricing
| Class | Wall Thickness<sup>1</sup> (mm) | Price Range (USD/ton)<sup>2</sup> |
|---|---|---|
| K7 | 6.65 = 7×(0.5+0.001×450) | $400 – 720 |
| K8 | 7.60 = 8×(0.5+0.001×450) | $482 – 529 |
| K9 | 8.55 = 9×(0.5+0.001×450) | $545 – 645 |
| K12 | 11.40 =12×(0.5+0.001×450) | $482 – 526 |
<sup>1</sup>Per ISO 2531 nominal‑thickness formula.
<sup>2</sup>Global online market ranges from Alibaba and Made‑in‑China 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 national standard for DIP, fittings & joints in water/gas applications.
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ISO 8180: Polyethylene sleeving for external corrosion control.
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AWWA C111/A21.11: Mechanical‑joint specifications (DN 80–600 mm).
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ANSI B16.1: Flanged‑joint dimensions & pressure ratings.
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EN 969: Gas‑pipeline ductile‑iron pipe, fittings & accessories (≤ 16 bar).
Advantages
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Outstanding Longevity: 100 + year design life minimizes replacements and downtime .
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High Strength & Toughness: Tensile strength typically ≥ 420 MPa resists surge and external loads .
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Superior Corrosion Control: Internal CML (ANSI/AWWA C104), plus external zinc/bitumen coatings and LPS .
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Joint Versatility: Choice of push‑on, mechanical, flanged or restrained systems for any site condition .
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Sustainable & Recyclable: Made from recycled iron with lower life‑cycle energy compared to thermoplastics .
FAQ
Q1: How do K classes differ?
They follow e = K·(0.5+0.001×DN)—for DN450, K7=6.65 mm, K8=7.6 mm, K9=8.55 mm, K12=11.4 mm—reflecting rising wall‑thickness and structural/reservoir pressure capacity .
Q2: Which joint type should I choose?
– Push‑on for speed & simplicity; Mechanical for restrained connections; Flanged for re‑assemblies or high axial loads .
Q3: Is polyethylene sleeving necessary?
Recommended in aggressive soils: adds ~10 % life extension to > 110 years; proven by DIPRA Everglades tests .
Q4: What sizes & lengths are available?
DN 80–2600 mm in 6 m laying 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 and axial loads for seismic resilience .
Case Studies
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Huntsville Utilities, AL: Journal AWWA life‑cycle analysis found $666,999/year pumping‑cost savings and $17 million PV benefit over 50 years by choosing DIP vs. PVC .
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Everglades City, FL: DIP with LPS 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 | ….. |
