Changing Direction – Axial Joint
Deflection Explained
There are three ways to change a gasketed
pipeline's direction:
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Fitting (elbow, bend, etc.)
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Curvature of the pipe barrel
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Axial deflection at pipe joints
This tech brief
focuses on the third method, axial deflection.
Mathematically the idea is simple. For
example, if you want to change direction by 5°
and the allowable change in direction at each
joint is 1°, then you need to deflect 5 joints.
The document explains this concept and the geometry involved.
Click here to read.
Design Aid
There are two links in the tech brief -- the first is to a design aid. The designer initially inputs two variables:
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Total angle to be turned
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Allowable angle per joint (from the manufacturer of the pipe to be used)
The first output is the number of joints necessary. After adjusting the number of joints to a whole number, the designer then inputs a third variable: the distance between joints. Outputs are the offset at the end of the deflected pipe and the radius of curvature of the pipeline.
Offset Tables
The second link is to a series of tables that show the linear offsets from the original undeflected pipeline for different allowable angles.
This information should be helpful to a
designer in deciding which method to use to
curve a pipeline.
Regards,
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John F. Houle, P.E. Senior Technical Consultant, PVC Pipe Industry
201 E. John Carpenter Freeway, Suite 750 | Irving, TX 75062
T. 972.243.3902 | F. 972.243.3907 www.uni-bell.org
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