The class K7 DN150 offers a 7 bar (≈100 psi) working pressure, superior mechanical properties (tensile ≥420 MPa, elongation ≥10%), and a design life exceeding 100 years when properly protected. It’s ideal for municipal water, wastewater, irrigation, fire protection, and industrial pipelines. Installation is streamlined thanks to push‑on and restrained joints, while compliance with ISO 2531, EN 545, and AWWA C150/C151 ensures global suitability. Price‑wise, K7 is competitively positioned against C‑class pipes (C25–C40) and neighboring K‑classes (K8, K9), making it a cost‑effective long‑term solution.
Application Scenarios
Ductile iron Class K7 pipes (DN 150) are widely used in:
-
Municipal water distribution: Their high working pressure and smooth internal lining support consistent flow rates in urban networks.
-
Wastewater and sewage systems: Excellent corrosion resistance reduces leakage and maintenance, even under heavy traffic loads.
-
Irrigation and agricultural supply: Robust against soil stresses and ground movement, ensuring reliable delivery across varied terrains.
-
Fire protection mains: With a burst pressure three times the working pressure, K7 pipes meet stringent safety factors for fire‑fighting systems.
-
Industrial process lines: Chemical plants and refineries benefit from high tensile strength and custom coatings for aggressive media.
Service Life
Modern ductile iron pipes are engineered for longevity:
-
100 + years under evolved laying practices (cement‑mortar lining, polyethylene encasement).
-
50–75 years for uncoated or traditionally protected pipes.
-
Comparison with alternatives: PVC pipes typically last ≈50 years, making ductile iron a longer‑term investment.
| Material | Typical Service Life |
|---|---|
| Ductile Iron (coated) | ≥ 100 years |
| Ductile Iron (uncoated) | 50–75 years |
| PVC | 50 years |
Installation and Connections
Class K7 DN150 supports multiple joint systems:
-
Push‑on (T‑type): Quick assembly with rubber ring seals; angular deflection up to 5° per joint.
-
Mechanical (MJ): Bolted restraint for high‑pressure or thrust‑resistant applications.
-
Flanged ends: For easy integration with valves and fittings per ISO/AWWA flange standards.
-
Self‑anchored joints: Eliminates separate thrust blocks, reducing excavation and installation time.
International Standards
Class K7 DN150 pipes are certified to these key specifications:
-
ISO 2531:2009 (ductile iron pipes for water applications).
-
EN 545:2010 +A1:2009 (ductile iron pipes, fittings for potable water).
-
ANSI/AWWA C150/A21.50 & C151/A21.51 (design and centrifugally cast DI pipes).
-
BS EN 598:2007 (pipes and fittings for sewerage).
Price Comparison with Other Series
Below is an indicative price range for DN150 pipes. Actual prices vary by order volume, region, and coatings.
| Class | Pressure Rating | Price Range (USD/m) | |
|---|---|---|---|
| K7 | 7 bar (100 psi) | 425–485 | |
| K7 | 7 bar | 488.5–531 | |
| C25 | 2.5 MPa (≈25 bar) | 499–575 | |
| C30 | 3.0 MPa | 499–575 | |
| C40 | 4.0 MPa | 497–697 | |
| K8 | 8 bar (116 psi) | 509–540 | |
| K9 | 9 bar (130 psi) | 545.3–645 |
Key Advantages
-
High mechanical strength: Tensile ≥420 MPa, yield ≥300 MPa, elongation ≥10%.
-
Excellent corrosion resistance: Cement‑mortar lining, epoxy or bitumen external coatings, plus optional Zn/Al or polyethylene encasement.
-
Hydraulic efficiency: Smooth lining yields low friction losses, reducing pumping costs.
-
Flexibility & deflection: Angular joints absorb ground movement and seismic loads without leakage.
-
Environmental sustainability: > 90% recycled material content; certified by sustainability bodies.
Frequently Asked Questions
Q1: What does “Class K7” signify?
A1: A nominal pressure class indicating a working pressure of 7 bar (≈100 psi), suitable for most municipal and industrial applications.
Q2: Why choose DN150?
A2: DN150 (6″) balances capacity and ease of handling, making it ideal for trunk mains and service laterals in urban and rural settings .
Q3: How do I mitigate corrosion?
A3: Standard cement‑mortar lining combined with external polyethylene encasement (ANSI/AWWA C105/A21.5) protects pipes even in aggressive soils.
Q4: Can these pipes be used for fire mains?
A4: Yes—burst pressures exceed 3× working pressure, meeting NFPA fire protection requirements.
Case Studies
-
City of Huntsville, AL: Over a 50‑year span (an example life expectancy for traditional DI), K‑class pipes delivered a net present value saving of $17 million in energy costs alone.
-
Large‑Scale Irrigation in Northern Spain: 120 km of DN150 K7 lines with polyethylene encasement have operated for 20 years without a single joint failure, reducing downtime by 85%.
-
Industrial Plant in Germany: A chemical facility retrofitted 500 m of DN150 K7 with HDPE external coating and zinc sacrificial layer; inspections at 15 years show zero measurable corrosion.
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 | ….. |
