Class K12 DN300 ductile iron pipe features a 300 mm nominal diameter and 12 bar working pressure, making it ideal for heavy-duty water, wastewater, fire-fighting, and industrial networks. Its cement-mortar internal lining and fusion-bonded epoxy or bitumen external coatings provide best-in-class corrosion resistance and maintain hydraulic capacity over decades. Independent data from DIPRA show modern ductile iron mains routinely exceed a 100-year service life under proper installation and corrosion control practices. Installation is streamlined by multiple joint systems—push-on, mechanical, and self-restraining—ensuring quick, leak-tight assembly in trench and trenchless projects. Full compliance with ISO 2531, EN 545, EN 598, ASTM A 536, and GB 13295 standards guarantees global compatibility and regulatory acceptance.
Application Scenarios
Potable Water Distribution
DN300 K12 pipes are extensively used in municipal drinking-water networks, where their smooth cement-mortar lining minimizes biofilm formation and helps maintain water quality.
Wastewater & Sewer Force Mains
High pressure rating and abrasion-resistant lining reduce friction losses in gravity and pressurized sewer systems, extending maintenance intervals and lowering operational costs.
Fire Protection Systems
12 bar working pressure and heat-resistant coatings make Class K12 DN300 ideal for hydrant feeder loops and sprinkler mains at airports, industrial parks, and high-rise buildings.
Industrial Fluid Conveyance
Chemical plants, refineries, and cooling-water circuits benefit from ductile iron’s impact resistance and dimensional stability under variable temperatures and pressures.
Trenchless & Subaqueous Installations
Flexible self-restraining joints, weight, and robust coatings protect DN300 pipe in trenchless HDD, river crossings, and corrosive-soil environments, preserving alignment and sealing under ground movement.
Service Life
Modern ductile iron pipe is engineered for 100+ years of operation, as recognized by DIPRA’s Longevity program and reinforced by utilities operating cast-iron mains for over a century.
The Cast Iron Pipe Century Club, started in 1947, highlights water systems still in service after 100 years, underscoring ductile iron’s enduring performance.
Installation & Connection
Push-On Joints
Conforming to ANSI/AWWA C111/A21.11, EPDM-rubber gaskets in bell-and-spigot ends allow tool-light, quick assembly and maintain seals up to 12 bar.
Mechanical (K-Type) Joints
McWane’s ISO 2531 K-type couplings provide axial restraint within the joint, eliminating the need for external thrust blocks while supporting pressures above 12 bar.
Self-Restraining Joints
US Pipe’s TR FLEX restrained joints lock within the bell to resist internal thrust, reducing excavation and installation time at bends, tees, and dead ends in DN100–DN300 ranges.
Corrosion Control
Polyethylene encasement per ANSI/AWWA C105/A21.5 shields barrels and joints from stray currents and aggressive soils, ensuring >100 years of service even in corrosive environments.
International Standards
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ISO 2531:2015 – Ductile iron pipes, fittings, linings, and joints for water pipelines.
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EN 545:2010 & EN 598:2007 – European norms for water supply and sewerage ductile iron pipe systems.
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ASTM A 536 – Material specification for ductile iron castings used in pressure pipes.
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ANSI/AWWA C105/A21.5 – Standard for polyethylene encasement of ductile iron pipe.
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GB 13295-2019 – Chinese national standard for ductile cast iron pipes.
Price Comparison
Compared to Class K9 pipes (approx. $400–500/m), Class K12 commands a premium of around 10–15% (approx. $430–550/m). PN10 (C25) pipes are typically 5–10% less expensive ($360–480/m), while PN16 (C30) pipes fall in the $450–600/m range.
Key Advantages
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Exceptional Durability: 100+ years of proven service reduces full-life costs and service disruptions.
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High Pressure Rating: Class K12 supports up to 12 bar without upsizing, ideal for fire-fighting and industrial processes.
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Superior Corrosion Resistance: Cement-mortar lining plus epoxy or bitumen coatings guard internal and external surfaces.
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Installation Flexibility: Multiple joint systems and corrosion controls suit trench, trenchless, seismic, and submarine applications.
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Environmental Sustainability: High recycled-iron content and full recyclability align with circular-economy goals.
Frequently Asked Questions
Q1: What does “DN300” mean?
DN300 denotes a nominal internal diameter of 300 mm as defined in ISO 2531.
Q2: What defines “Class K12”?
“K-class” indicates wall‐thickness categories; K12 corresponds to pipes designed for 12 bar working pressure with thicker walls than K9 or K10.
Q3: Can Class K12 DN300 pipes be installed trenchlessly?
Yes—ductile iron’s flexibility, combined with self-restraining joints and robust coatings, makes DN300 K12 optimal for HDD and microtunnelling applications.
Q4: How is leak-tight performance ensured?
EPDM gaskets in push-on joints, bolted compression in mechanical joints, and integrated restraints in self-restraining couplings maintain leak-proof seals under pressure.
Q5: What is the expected service life?
With proper installation and corrosion control, DN300 K12 pipes typically perform over 100 years, as certified by DIPRA.
Case Studies
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Kobe Earthquake Resilience (Japan): SⅡ-type DN300 ductile iron pipelines installed before the 1995 Great Hanshin Earthquake suffered no damage despite 1.3 m of ground subsidence, demonstrating exceptional seismic and liquefaction performance .
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Windermere Rising Main (UK): A 1970s DN300 ductile iron sewer rising main in the Lake District, renovated after severe wall thinning, highlights the importance of coatings and inspection in extending service life.
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U.S. Municipal Renewals: Multiple U.S. utilities featured in DIPRA case studies report zero failures and a 70% reduction in break rates after upgrading to K-class ductile iron mains over two decades.
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 | ….. |
