How to Figure a Rolling Offset in Piping

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Use a calculator to determine the length of the rolling offset.
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In plumbing, sometimes a gas or water supply pipe travels straight and then changes direction horizontally and vertically at the same time, before it carries on. This is best thought of when a pipe enters the bottom right corner of an imaginary square or rectangular box and then travels immediately upward and across to the top left corner of the box before exiting out. If the incoming pipe traveled straight onward in a parallel fashion with the outgoing pipe, the distance between the pipes would be the rolling offset. Calculating this distance requires a simple formula.


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Step 1

Visualize the pipe entering and exiting the box, and if necessary draw a diagram with pen and paper. Find the height of the box (called the rise) as well as the width of the box (called the offset). For instance, the rise is 8 inches and the offset is 12 inches.

Step 2

Multiply the offset by itself, and the rise by itself, and add these two numbers together. In the example, 8 x 8 = 64 and 12 x 12 = 144. Therefore, 64 + 144 = 208.

Step 3

Calculate the square root of the number, to find the rolling offset. In the example, the square root of 208 = 14.42 inches.


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