A Publication of

DUCTILE IRON PIPEAn Ultimate Techical Guide to

PRESSURE CLASSES

AStandard Dimensions & Weights of

“Pressure Class” DI Pipe

* Thicknesses and O.D. tolerances shall be in accordance with AWWA/ANSI C151/A21.51 and C111/A21.11 respectively.** Calculated thicknesses for these sizes and pressure ratings are less than those shown above. Presently these are the lowest nominal thicknesses available in these sizes.† Including bell; calculated weight of pipe rounded off to nearest 5 lbs.

PIPE BARREL PUSH-ON MECHANICAL JOINT

PUSH-ON AND MECHANICAL JOINT

DEFL. ANGLE

LAYING LENGTH

DEFL. ANGLE

LAYING LENGTH

18 FT. 20 FT. 18 FT. 20 FT.

SIZEPRESS. CLASS

THICK.* O.D.*WT. PER LGTH†

MAX. DEFL.

WT. PER LGTH†

MAX. DEFL.

WT. PER LGTH†

MAX. DEFL.

WT. PER LGTH†

MAX. DEFL.

IN. PSI IN. IN. DEG. LBS. IN. LBS. IN. DEG. LBS. IN. LBS. IN.

4" 350 0.25** 4.80 5° 205 19" N/A — 8°-18' 210 21" N/A —

6" 350 0.25** 6.90 5° 300 19" 330 21" 7°-7' 305 27" 340 30"

8" 350 0.25** 9.05 5° 395 19" 440 21" 5°-21' 405 20" 446 22"

10" 350 0.26 11.10 5° 510 19" 565 21" 5°-21' 520 20" 575 22"

12" 350 0.28 13.20 5° 655 19" 725 21" 5°-21' 665 20" 735 22"

14"

250 0.28

15.30 3°

770

11"

855

12" 3°-35'

790

13.5"

870

15"300 0.30 825 910 840 925

350 0.31 850 940 865 955

16"

250 0.30

17.40 3°

940

11"

1040

12" 3°-35'

960

13.5"

1060

15"300 0.32 1000 1105 1020 1125

350 0.34 1060 1170 1080 1190

18"

250 0.31

19.50 3°

1090

11"

1205

12" 3°-0'

1115

11"

1230

12"300 0.34 1185 1310 1210 1335

350 0.36 1250 1385 1275 1410

20"

250 0.33

21.60 3°

1290

11"

1425

12" 3°-0'

1315

11"

1450

12"300 0.36 1395 1545 1420 1570

350 0.38 1470 1625 1495 1650

24"

200 0.33

25.80 3°

1550

11"

1710

12" 2°-23'

1575

9"

1740

10"250 0.37 1725 1905 1750 1935

300 0.40 1855 2050 1880 2075

350 .043 1985 2195 2010 2220

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ATechnical Data for “Pressure Class” Ductile

Iron Pipe

Weights for Pipeline Design Weight of Pressure Class Ductile Iron Pipe and Contained Water

Table No. 1

* Based on Ductile Iron Pipe Pressure Classes nominal thickness for all sizes as specified in AWWA C151, and on standard cement lining minimum thickness specified in AWWA C104. The value of Pi (π) used in calculations = 3.1416.

Table No. 2

These weights are based on minimum class Ductile Iron Pipe with minimum thickness standard cement lining as specified in AWWA C104 and on weight of water of 62.4 pounds per cubic foot. The inside diameters are as given in Table No. 1.Pounds of water per foot = 0.4333 X (I.D. in inches)2

Gallons of water per foot = 0.0519 X (I.D. in inches)2

Ductile Iron/Gray Iron Weights ��ÛiÀÃ���Ê�>VÌ�ÀÃ

Diameters, Circumferences and Areas for Pressure Class �ÕVÌ��iÊ�À��Ê-Ì>�`>À`Êi�i�Ì����i`Ê*�«i

PRESSURE CLASS

(psi)

NOMINAL SIZE

(inches)

OUTSIDE DIAMETER

(inches)

INSIDE DIAMETER*

(inches)

O.D. AREA(sq. in.)

I.D. AREA* (sq. in.)

O.D. CIRCUMFERENCE

(inches)

I.D. CIRCUMFERENCE

(inches)350 3" 3.96 3.34 12.32 8.76 12.44 10.49350 4" 4.80 4.18 18.10 13.72 15.08 13.13350 6" 6.90 6.28 37.39 30.97 21.68 19.73350 8" 9.05 8.43 64.33 55.81 28.43 26.48350 10" 11.10 10.46 96.77 85.93 34.87 32.86350 12" 13.20 12.52 136.85 123.11 41.47 39.33250 14" 15.30 14.55 183.85 166.27 48.07 45.71250 16" 17.40 16.61 237.79 216.69 54.66 52.18250 18" 19.50 18.59 298.65 274.35 61.26 58.72250 20" 21.60 20.75 366.44 338.16 67.86 65.19200 24" 25.80 24.95 522.79 488.91 81.05 78.38150 30" 32.00 31.07 804.25 758.18 100.53 97.61150 36" 38.30 37.29 1152.10 1092.13 120.32 117.15150 42" 44.50 43.43 1555.29 1481.39 139.80 136.44150 48" 50.80 49.63 2026.83 1934.54 159.59 155.92150 54" 57.56 56.29 2602.14 2488.58 180.83 176.84

PRESS. CLASS

NOM. SIZE

(inches)

GALS. HELD

(per foot)

WEIGHT – LBS. PER FOOTPRESS. CLASS

NOM. SIZE

(inches)

GALS. HELD

(per foot)

WEIGHT – LBS. PER FOOT

PIPE WATER TOTAL PIPE WATER TOTAL

350 3" 0.45 9.2 3.8 13.0 250 18" 14.24 60.2 118.4 178.6350 4" 0.71 11.3 5.9 17.2 250 20" 17.55 71.2 146.5 217.7350 6" 1.61 15.5 13.4 28.9 200 24" 25.37 85.6 211.9 297.5350 8" 2.90 22.0 24.2 46.2 150 30" 39.35 110.5 328.5 439.0350 10" 4.46 28.3 37.2 65.5 150 36" 56.68 147.7 473.3 621.0350 12" 6.39 36.3 53.3 89.6 150 42" 76.88 188.3 641.9 830.2250 14" 8.63 42.7 72.1 114.8 150 48" 100.40 240.3 838.3 1078.6250 16" 11.25 52.0 93.9 145.9 150 54" 129.16 301.7 1078.4 1380.1

POUNDS PER CUBIC FOOTDUCTILE IRON GRAY IRON

440.64 449.28

TO CHANGE TO MULTIPLY BYGray Iron Ductile Iron 0.9808

Ductile Iron Gray Iron 1.0196

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ADuctile Iron

Pipe Research Association

7�9Ê�� ��1�Ê*, --1, Ê��--¶In the 1991 revision of the ANSI/AWWA C 150/421.50 designs standard for Ductile iron pipe, Pressure Class des-

ignations were incorporated. This raised questions from some utilities and engineers that traditionally specified Ductile iron pipe based on a Thickness Class designation. Pressure Class designations refer to the pipe's ability to hold pressure, whereas Thickness Class refers only to wall thickness. And, as shown below, the same conservative design approach for determining Ductile iron pipe wall thickness continues without compromise.

Example Design Criteria:Nominal diameter: 6 inchess�Laying condition: Type 5s�Depth of cover: 7 feets�Working pressure: 100 psi.s�Surge allowance: 100 psi.s�

Net Thickness:Designing in accordance with AWWA CI50, using the following conservative design

criteria, a “net thickness” of 0.03 inches results:

Factor of Safety: 2 for internal pressure, including surge s� 2 for ring bending 2 for ring deflectionSoil Density: 120 pcfs�

Minimum Manufacturing Thickness:In accordance with AWWA C150, a service allowance of 0.08-inches is added to the

pipe wall “net thickness.” This results in a “minimum thickness” of 0.1l-inches which has 267% more wall thickness than required for design conditions.

Total Thickness:To assure “minimum thickness,” a diameter-dependant allowance for the casting tol-

erance is added to the “minimum thickness.” In this example an allowance of 0.05-inches is added to the “minimum thickness.” We now have a “total thickness” of 0.l6-inches which has 433% more wall thickness than required for design conditions.

Nominal Thickness:The “total thickness” is often much less than the minimum pressure class “nominal

thickness.” For our example the minimum pressure class “nominal thickness” of 0.25-inches exceeds the “total thickness” by an additional 0.09-inches. Thus, for this example, the minimum pressure class nominal thickness is 733% greater than required for design conditions.

This conservative design approach is unmatched in the pressure pipe industry. Using this approach, Thickness Class 52 Ductile Iron pipe would translate into a Pressure Class 1,000 with 933% more wall thickness than needed for the above design conditions.

Many utilities site corrosion concern as a reason for adding wall thickness. However, in our example, while the extra 0.06- inches found between Thickness Class 52 and Pressure Class 350 provides a tremendous increase in pressure capac-ity, in a corrosive environment it would only extend the life of the pipe marginally. The most economical design calls for minimum Pressure Class selection based on loading requirements and polyethylene encasement (ANSI/AWWA Cl05/A21.5) to combat corrosion.

Net Thickness: 0.03

Minimum Thickness: 0.11

+267%

Total Thickness: 0.016

+ 433%

Nominal Thickness: 0.025

+733%

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