Class K8 DN700 ductile iron pipe has a nominal wall thickness of 9.6 mm, per ISO 2531’s formula e = K × (0.5 + 0.001 × DN) (K = 8, DN = 700 mm) . Rated PN 12.5 (1.25 MPa), it serves medium-pressure potable water, sewage, irrigation, gas and fire-protection mains . With cement-mortar lining and optional loose polyethylene sleeving (ISO 8180), its design life exceeds 100 years, reaching 110 years in aggressive soils . Installation utilizes push-on “Tyton,” AWWA C111 mechanical and ANSI B16.1 flanged joints for rapid, leak-free connections . Among K-series, wall thickness increases from K7 (8.4 mm) → K8 (9.6 mm) → K9 (10.8 mm) → K12 (14.4 mm), with K8 priced around US $490–500 / ton on global markets.
Applications
Potable Water Distribution
DN700 mains maintain stable hydraulics and minimize leakage in urban water networks .
Sewage & Drainage
Abrasion-resistant core and smooth lining handle grit-laden wastewater in gravity or force sewers .
Irrigation Systems
Uniform flow under variable demands supports large-scale agricultural and landscape irrigation .
Gas Distribution
When produced per EN 969 and externally coated, DN700 K8 pipes safely convey natural gas up to 16 bar .
Fire-Protection Mains
High ductility and surge resilience ensure reliable fire-water delivery in hydrant loops and feeder mains .
Service Life
Modern ductile iron pipe routinely exceeds 100 years in non-corrosive soils .
Loose-fit polyethylene sleeving per ISO 8180 extends life to 110 years in aggressive environments .
A life-cycle cost analysis (24″ Class 200 vs. 24″ PVC DR 18) shows a $47.68/ft net savings with ductile iron over 50 years, driven by lower pumping and maintenance costs .
University of Michigan research confirms 100 years service life consensus for ductile iron, versus 50 years for PVC .
DIPRA data highlight reduced repair frequency and lower GHG emissions in both production and operation phases .
Installation & Connection
-
Push-On (“Tyton”) Joints: Spigot-socket with an elastomeric gasket enables bolt-free, rapid sealing per ISO 2531 dimensions .
-
Mechanical Joints: Gland-and-bolt restraint per AWWA C111 provides both restrained and unrestrained connections for valves and fittings .
-
Flanged Joints: ANSI B16.1 flanges (Class 125) permit easy disassembly, alignment control and high axial-load resistance .
-
Best Practices: Trench bedding (150 mm graded fill), ≤ 3 % deflection, hydrostatic testing and chlorination per ISO 2531/AWWA C600 ensure joint integrity and longevity .
K-Series Comparison & Pricing
| Class | Wall Thickness (mm)<sup>1</sup> | Pressure Rating | Price (USD/ton)<sup>2</sup> |
|---|---|---|---|
| K7 | 8.4 = 7×(0.5+0.001×700) | PN 10 (1.0 MPa) | $400–450 |
| K8 | 9.6 = 8×(0.5+0.001×700) | PN 12.5 (1.25 MPa) | $490–500 |
| K9 | 10.8 = 9×(0.5+0.001×700) | PN 16 (1.6 MPa) | $545–645 |
| K12 | 14.4 =12×(0.5+0.001×700) | PN 25 (2.5 MPa) | $700–900 |
<sup>1</sup>ISO 2531 nominal-thickness formula
<sup>2</sup>Global supplier surveys (Made-in-China, Alibaba)
International Standards
-
ISO 2531:2009 – Pipe dimensions, linings & joint performance
-
GB/T 13295-2019 – Chinese standard for DIP, fittings & joints in water/gas systems
-
ISO 8180:2020 – Polyethylene sleeving for external corrosion protection
-
AWWA C111/A21.11 – Mechanical-joint specifications for DN 80–600 mm
-
ANSI B16.1 – Flanged-joint dimensions & pressure classes
-
EN 969:2009 – Gas-pipeline ductile iron pipe & accessory requirements
-
ISO 1083:1997 – Ductile iron material grades (tensile ≥ 350 MPa)
Advantages
-
Exceptional Durability: 100 + year life reduces replacement frequency .
-
High Strength & Toughness: Tensile ≥ 350 MPa resists surges & external loads .
-
Comprehensive Corrosion Control: Cement-mortar lining, bitumen/zinc coatings and LPS .
-
Jointing Flexibility: Push-on, mechanical, flanged & restrained options .
-
Sustainable: Made from recycled iron, fully recyclable with lower life-cycle energy vs. PVC .
FAQ
Q1: How do K classes differ?
They follow e = K × (0.5 + 0.001 × DN)—for DN 700, K7=8.4 mm, K8=9.6 mm, K9=10.8 mm, K12=14.4 mm, corresponding to PN 10/12.5/16/25.
Q2: Which joint should I choose?
– Push-On for speed and simplicity
– Mechanical for restrained connections
– Flanged for maintenance access and axial-load resistance.
Q3: Is polyethylene sleeving necessary?
Recommended in aggressive soils for up to 110 years of protection; proven by Everglades City tests .
Q4: What sizes & lengths are available?
DN 80–2600 mm, standard 6 m laying lengths (5.7 m for container loads), with custom cuts on demand .
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
-
Huntsville Utilities, AL: AWWA analysis finds ductile iron’s net life-cycle cost at $150.19/ft vs $197.87/ft for PVC, delivering $47.68/ft savings and $1.84 million PV benefit over 50 years .
-
Everglades City, FL: LPS-encased pipes remained in “excellent condition” after 10+ years in corrosive muck (140–240 Ω-cm) at DIPRA test sites .
-
Energy & Cost Savings: American Water Works Journal reports utilities save $666,999 annually in pumping-energy by using ductile iron vs alternatives, reducing consumption by 7.1 million kWh/yr.
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 | ….. |
