The Rolling Offset calculator 
Rolling Offset of pipes calculates the length of travel (T) and run (R) based on the vertical (U) and horizontal (S) offsets and the angle (fA) of the elbow fitting. Video Instruction
INSTRUCTIONS: Choose the preferred units and enter the following:
- (U) Vertical Offset
- (S) Horizontal Offset
- (fA) Fitting Angle. Commonly 22.5°, 30°, 45o, 60o, 90o.
Rolling Offset: The calculator returns the length of Travel (T) and Run (R) in inches. However, this can be automatically converted into other length units (e.g. centimeters) via the pull-down menu.
General Information
When running pipes or conduit, it is common to have to change the run-line of the pipes or conduit by using two equal angled elbow fittings (see diagram). This calculator will compute either the amount of pipe needed between the fittings is called the travel, T in the diagram or the run R. Both run and travel can be calculated if one knows the vertical (U) and horizontal (S) offsets and the angle of the fitting (fA). Therefore, the inputs for this equation are:
- (U) - Vertical offset
- (S) - Horizontal offset
- (fA) - Fitting angle. This is the angle of the elbow fitting. The most common fitting angles are 45o, 60o, 90o,and 22.5o.
The Math
To compute the Rolling Offset Travel and Run (aka pipe rolling), the relationship between the travel length and the offsets is as follows:
` x = sqrt( U^2 + S^2)`
` T = x / cos (90 - fA)`
`R = sqrt(T^2 - x^2)`
where:
- R - Run
- T - Travel
- U - Vertical offset
- S - Horizontal offset
- fA - Fitting angle
Note: vCalc allows for multiple units for both length (SI and English) and for angles (degrees and radians). The result will be in inches. However, this can automatically be converted to other length units (e.g. centimeters) with the pull-down menu.
Uses
Rolling Offsets are useful in running any kind of ridged piping including water, sewer, gas, and for running conduit often used in electrical and telecommunications (cable) applications.