Class 350 ductile iron pipe is engineered for demanding water and sewage applications, providing a nominal working pressure of 350 psi (with a 100 psi surge allowance) per ANSI/AWWA C150/A21.50-91. Its spheroidal-graphite iron microstructure combined with shop-applied cement-mortar lining delivers an expected service life exceeding 100 years in normal soil conditions. Installation is streamlined by a full suite of joint options—push-on, mechanical, restrained and flanged—backed by elastomeric gaskets and Field-Lok® 350 restraint systems. It meets global standards (ANSI/AWWA C104/A21.4, C105/A21.5, C110/A21.10 and ISO 2531/EN 545/EN 598) for dimensions, lining, encasement and joint performance. Though Class 350 lists at roughly USD 100–110 per m—well below typical Class 52 (USD 450–650/m)and Class 53 (USD 500–560/m) and comparable to K9 (USD 370–430/m)—the combination of low friction losses, minimal maintenance and unparalleled durability yields superior life-cycle value.
Application Scenarios
Municipal Water Distribution: Ideal for high-pressure potable mains in urban networks, where leak-tight mechanical and restrained joints ensure system integrity under dynamic loads.
Wastewater and Sewage Systems: Cement-mortar lining prevents tuberculation in gravity and force mains, reducing cleaning and rehabilitation costs.
Agricultural Irrigation: Low Hazen–Williams friction factor (C ≈ 140) cuts pumping energy by up to 15% over PVC alternatives, per life-cycle cost studies.
Industrial and Process Piping: Flanged Class 350 fittings are standard in power plants and chemical facilities, offering high impact resistance and flexibility for above-ground runs.
Service Life
Modern ductile iron pipe routinely achieves 100 + years of uninterrupted service when installed with proper bedding and protective measures.
Cement-mortar linings virtually eliminate internal corrosion (“tuberculation”), maintaining high flow capacity over decades.
Comparative life-cycle analyses show Class 350 DI outperforms PVC in total cost of ownership over a 100-year design horizon.
Installation and Jointing
Push-On & Mechanical Joints
Push-on joints use a single rubber gasket and minimal bell-hole excavation, enabling rapid, trench-side assembly.
Mechanical joints rated for Class 350 incorporate Field-Lok® 350 restraint gaskets to resist thrust forces without thrust blocks.
Restrained & Flanged Connections
Restrained-joint pipe harnesses integral coupling glands and gaskets to lock spigot and bell under pressure surges, eliminating separation risks.
Flanged ends (4″–12″) bolt directly to valves or equipment via Flex-Ring® gaskets, ensuring leak-free, rigid connections in pump stations.
Corrosion Protection
Internal Lining: Centrifugally applied cement-mortar per ANSI/AWWA C104/A21.4 offers a smooth barrier for potable and nonaggressive wastewater service.
External Coatings: Options include bonded zinc, asphaltic-base or water-borne epoxy coatings to withstand soil acidity and moisture.
Polyethylene Encasement: Loose-sleeve encasement per AWWA C105/A21.5 protects against stray currents and aggressive soils.
International Standards
-
ANSI/AWWA C151/A21.51: DI pipe dimensions and physical requirements.
-
ANSI/AWWA C150/A21.50-91: Pressure-class thickness tables for working and surge allowances.
-
ANSI/AWWA C104/A21.4 & C105/A21.5: Cement-mortar lining and polyethylene encasement specifications.
-
ANSI/AWWA C110/A21.10 & C111/A21.11: Mechanical and push-on joint performance criteria.
-
ISO 2531:2012, EN 545 & EN 598: Global standards for DI pipe and fittings, covering dimensions, linings and jointing.
Price Comparison with Classes 52, 53 & K Series
| Class | Price Range (USD/m) |
|---|---|
| 52 | 450 – 650 |
| 53 | 500 – 560 |
| 350 | 100 – 110 |
| K9 | 370 – 430 |
Note: Prices vary by diameter, coating, region and order volume; life-cycle efficiency often outweighs higher upfront costs.
Advantages
-
Exceptional Durability: 100 + year lifespan reduces replacement cycles.
-
High Strength: Meets AWWA tensile and impact standards for trench loads and surge events.
-
Corrosion Resistance: Internal linings and external coatings virtually eliminate deterioration.
-
Installation Flexibility: Multiple joint types adapt to soil, pressure and alignment conditions.
-
Sustainability: Up to 60 % recycled iron content; fully recyclable at end of service.
Frequently Asked Questions
-
What does “Class 350” mean?
A pressure-class designation indicating a nominal working pressure of 350 psi with surge allowance, per ANSI/AWWA C150 tables. -
How is internal corrosion prevented?
Cement-mortar linings applied per ANSI/AWWA C104/A21.4 form a chemical barrier against tuberculation. -
Can it resist aggressive soils?
Yes—polyethylene encasement (AWWA C105) and external epoxy coatings guard against stray currents and acidic ground. -
Which joint type offers fastest assembly?
Push-on joints with simple gaskets require minimal excavation and no field bolting, speeding installation. -
What diameters are available?
Nominal sizes from 3″ to 64″ per ANSI/AWWA C151.
Case Studies
-
100 Year Charleston Main: First cement-lined iron mains in Charleston, SC (installed 1922) provided uninterrupted service until 2022, demonstrating DI longevity.
-
Michigan Life-Cycle Analysis: A 1 000 ft, 8″ Class 350 mains project in Michigan showed DI’s lower total cost versus PVC over a 100-year design life.
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 | ….. |
