Page 116 - Pipeline Rules of Thumb Handbook

Pipe Design 103

PIPE WALL ACTUAL R. O. T.
DIAMETER THICKNESS TONS (METRIC) TONS (METRIC)
10-inch 3 / 16 -inch 31.5 30
12-inch 5 / 16 -inch 62 60
16-inch 7 / 16 -inch 109 112
20-inch 1 / 4 -inch 79 80
20-inch 5 / 16 -inch 99 100
20-inch 7 / 16 -inch 137 140
24-inch 5 / 16 -inch 118 120
24-inch 8 / 16 -inch 189 192
28-inch 5 / 16 -inch 139 140
30-inch 5 / 16 -inch 148 150
32-inch 7 / 16 -inch 221 224
36-inch 4 / 16 -inch 143 144
36-inch 8 / 16 -inch 285 288

How to find pipe weight from outside diameter and wall thickness

2
Weight (pounds per foot) = (Dt - t ¥ 10.68) W = (4 5 ¥ 25 - 25 2 ) ¥ 10 68.
.
.
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= (1 125 - 0625 ) ¥ 10 68.
.
.
.
¥
.
where D = outside diameter, in. = 1 0625 10 68
.
t = wall thickness, in. = 11 35 pounds per foot
The above equation is based on a density of 490 pounds
Example. Outside diameter = 4.500≤, thickness = per cubic foot for the steel. High-yield-point, thin-wall pipe
0.250≤ may run slightly heavier than indicated.
What is the maximum allowable length of unsupported line pipe?
For Schedule 40 pipe, the maximum span between sup- Example. How wide a ditch can be spanned with four-inch
ports is given by line pipe without the use of intermediate supports?

.
.
=
.
.
.
S = 66 45 = 66 ¥ 212 1399 (14 feet)
S = 66 P S = 74 =¥= 14 feet
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2
7
Note. The above rule is approximate, but conservative. It
where S is the span length in feet and P is the actual outside does not assume that the pipe is held fixed at either end; this
diameter of the pipe in inches. For pipe smaller than 12-inch, condition can make longer spans safe. Also, it does not guar-
the nominal size may be used, and antee that the pipe will not be damaged by floating logs or
debris! This hazard must be evaluated from the conditions
S = 7 N encountered.
Identify the schedule number of pipe by direct measurement
Add three inches to the actual inside diameter; divide this Schedule 120 13 to 15
by the wall thickness; the schedule number can then be iden- Schedule 140 11 to 13
tified by the following table: Schedule 160 9 to 11
Example. Pipe measures 12.5 inches inside diameter, wall
Schedule 30 40 to 50 thickness .75 inch; 15.5/.75 = 20.2; pipe is Schedule 80, 14
Schedule 40 29 to 39 inches outside diameter.
Schedule 60 25 to 29 The rule fails on small diameter pipe (under 6 inches), and
Schedule 80 20 to 23 also on schedules 10 and 20, because of the use of “standard”
Schedule 100 16 to 18 thicknesses in this range.