Ductile Iron Pipe Dimensions

Ductile iron pipes are are mode of ductile cast iron and hence the name. They find extensive application for potable water transmission and distribution. Ductile iron pipes are produced by centrifugal casting method. Internal linings and external coatings are applied to prevent corrosion of ductile iron pipes.

Nominal Diameter or DN, a dimensionless term is used to specify ductile iron pipe dimensions. Similar to steel pipes, the outside diameter of ductile iron pipes is kept constant, and depending on the pipe thickness the inner diameter varies. Ductile iron pipe dimensions vary from region to region. The dimension also varies according to the design code used. In the following paragraphs, the dimensions of ductile iron pipes are provided according to the design codes and regions.

Ductile Iron Pipe Dimensions in North America

AWWA C-151 governs the dimensions of ductile iron pipes in North America. Typical dimensions of centrifugally cast ductile-iron pipes according to AWWA C151/A.21.51 is provided below in a chart format:

Nominal Size Outside Diameter Pressure Class Outside Diameter Pressure Class
(inches) (inches) 150 200 250 300 350 (mm) 150 200 250 300 350
    Wall Thickness (inches)   Wall Thickness (mm) 
3 3.96 0.25 0.25 0.25 0.25 0.25 101 6.35 6.35 6.35 6.35 6.35
4 4.8 0.26 0.26 0.26 0.26 0.26 122 6.6 6.6 6.6 6.6 6.6
6 6.9 0.25 0.25 0.25 0.25 0.25 175 6.35 6.35 6.35 6.35 6.35
8 9.05 0.27 0.27 0.27 0.27 0.27 230 6.86 6.86 6.86 6.86 6.86
10 11.1 0.29 0.29 0.29 0.29 0.29 282 7.37 7.37 7.37 7.37 7.37
12 13.2 0.31 0.31 0.31 0.31 0.31 335 7.87 7.87 7.87 7.87 7.87
14 15.3 0.33 0.33 0.33 0.33 0.33 389 8.38 8.38 8.38 8.38 8.38
16 17.4 0.34 0.34 0.34 0.34 0.34 442 8.64 8.64 8.64 8.64 8.64
18 19.5 0.35 0.35 0.35 0.35 0.35 495 8.89 8.89 8.89 8.89 8.89
20 21.6 0.36 0.36 0.36 0.36 0.39 549 9.14 9.14 9.14 9.14 9.14
24 25.8 0.38 0.38 0.38 0.41 0.44 655 9.65 9.65 9.65 10.4 11.2
30 32 0.39 0.39 0.43 0.47 0.51 813 9.91 9.91 10.9 11.9 13
36 38.3 0.43 0.43 0.48 0.53 0.58 973 10.9 10.9 12.2 13.5 14.7
42 44.5 0.47 0.47 0.53 0.59 0.65 1130 11.9 11.9 13.5 15 16.5
48 50.8 0.51 0.51 0.58 0.65 0.72 1290 13 13 14.7 16.5 18.3
54 57.56 0.57 0.57 0.65 0.73 0.81 1462 14.5 14.5 16.5 18.5 20.6
60 61.61 0.54 0.61 0.68 0.76 0.83 1565 13.7 15.5 17.3 19.3 21.1
64 65.67 0.56 0.64 0.72 0.80 0.87 1668 14.2 16.3 18.3 20.3 22.1

The pressure class in the above table for ductile iron pipe dimension is the rated water pressure that the pipe can withstand in psi. The thicknesses shown in the above table are adequate for the rated water working pressure plus a surge allowance of 100 psi. Thickness calculations are based on the minimum yield strength of 42,000 psi and a safety factor of 2.0 times the sum of the working pressure and 100 psi surge allowance.

Note that the above ductile iron pipe dimensions chart is based on standard pressure classes as specified in AWWA C151. However, there are special thickness classes as well based on AWWA C150 for which the dimensions for ductile iron pipes are provided in Fig. 1:

Ductile Iron Pipe Dimensions for Special thickness classes per AWWA C 150
Fig. 1: Ductile Iron Pipe Dimensions for Special thickness classes per AWWA C 150

Ductile Iron Pipe Dimensions in Europe

European ductile iron pipe industry follows ISO 2531-Ductile iron pipes, fittings, accessories and their joints for water applications. Accordingly, the dimensions of ductile iron pipes in Europe are governed by ISO 2531. Typical Dimensions are provided below:

Pipe Size (DN) Outside Diameter Wall thickness Outside Diameter Wall thickness
inches inches mm mm
  Class 40 K9 K10   Class 40 K9 K10
40 2.205 0.189 0.236 0.236 56 4.8 6 6
50 2.598 0.189 0.236 0.236 66 4.8 6 6
60 3.031 0.189 0.236 0.236 77 4.8 6 6
65 3.228 0.189 0.236 0.236 82 4.8 6 6
80 3.858 0.189 0.236 0.236 98 4.8 6 6
100 4.646 0.189 0.236 0.236 118 4.8 6 6
125 5.669 0.189 0.236 0.236 144 4.8 6 6
150 6.693 0.197 0.236 0.256 170 5 6 6.5
200 8.74 0.213 0.248 0.276 222 5.4 6.3 7
250 10.787 0.228 0.268 0.295 274 5.8 6.8 7.5
300 12.835 0.244 0.283 0.315 326 6.2 7.2 8
350 14.882 0.276 0.303 0.335 378 7 7.7 8.5
400 16.89 0.307 0.319 0.354 429 7.8 8.1 9
450 18.898 0.339 0.374 480 8.6 9.5
500 20.945 0.354 0.394 532 9 10
600 25 0.39 0.437 635 9.9 11.1
700 29.055 0.429 0.472 738 10.9 12
800 33.15 0.461 0.512 842 11.7 13
900 37.205 0.508 0.555 945 12.9 14.1
1000 41.26 0.531 0.591 1,048 13.5 15
1100 45.354 0.567 0.63 1,152 14.4 16
1200 49.409 0.602 0.669 1,255 15.3 17
1400 57.559 0.673 0.748 1,462 17.1 19
1500 61.614 0.709 0.787 1,565 18 20
1600 65.669 0.744 2.008 1,668 18.9 51
1800 73.819 0.815 0.906 1,875 20.7 23
2000 81.969 0.886 0.984 2,082 22.5 25

There are other European Standards those are dedicated to specific type of ductile iron piping as follows EN 15655, EN 877, EN 598, EN 12842, EN 14628, EN 15189, EN 14901, EN 969, EN 15542, EN 545, EN 14525, etc.

Ductile Iron Pipe Dimensions in Australia and New Zealand

The ductile iron piping industry in Australia and New Zealand follows an independent specification AS/NZS 2280- Ductile iron pipes and fittings. Typical dimensions for ductile iron pipes for Australia and New Zealand are provided below:

Nominal Size (DN) Outside Diameter Nominal Wall Thickness Outside Diameter Nominal Wall Thickness Flange Class
(inches) (inches) (mm) (mm)
  PN 20 PN 35   PN 20 PN 35
100 4.803 0.197 122 5 7
150 6.969 0.197 177 5 8
200 9.134 0.197 232 5 8
225 10.197 0.197 0.205 259 5 5.2 9
250 11.26 0.197 0.22 286 5 5.6 9
300 13.583 0.197 0.248 345 5 6.3 10
375 16.772 0.201 0.287 426 5.1 7.3 10
450 19.961 0.22 0.327 507 5.6 8.3 11
500 22.047 0.236 0.354 560 6 9 12
600 26.26 0.268 0.406 667 6.8 10.3 13
750 32.52 0.311 0.48 826 7.9 12.2 15
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Anup Kumar Dey

I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.

One thought on “Ductile Iron Pipe Dimensions

  1. Thanks by your site, very usefull to clarify our doubts during a work day in the project activities.
    Fast consult and quicly response for our doubts.

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