How to Find Elbow Center of Pipe

May. 05, 2022

If the elbows in your pneumatic conveying system need to be replaced due to wear or abrasion or if you’re designing a new layout for your system, correctly measuring your existing elbows to ensure you order the right size is key.

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45-degree elbow center formula 

90-degree elbow cutting formula

Contact the elbow manufacturer for professional answers

For standard degrees of pipe elbows such as 45° pipe elbows and 90° pipe elbows, elbow center to end dimensions are available in standard pipe charts. But many times, custom elbow angles are required at site which should be cut from standard 45° or 90° elbows.

Black Pipe Fittings Elbow Fig.90

90° pipe elbows

The formula for calculating the center to end distance of such elbows is as follows: Elbow length in mm = Tan(Elbow Angle/2)Elbow Radius in mm

For 90° Long Radius elbows, the center to end dimension given in dimension tables of ASME B16.9 is the same as the radius of the elbow. This is because Tan(90/2) i.e. Tan 45 is 1. Normally custom elbow angles from 45 degree to 90 are cut from 90 degrees standard elbow. But for custom elbow angles smaller than 45 degree, the elbow is normally cut from the existing standard 45-degree elbow. Center to end dimension given in dimension tables for 45-degree elbow must be divided by Tan(22.5) to get the elbow radius for a standard 45-degree elbow. Then we can use the above formula to get elbow angle for custom degrees.


Calculate Elbow Center Example :

Calculate elbow center to end dimension for 2 inch nominal pipe diameter elbow at 30 degree angle, cut from 45 degree LR elbow.

From ASME B16.9, the center to elbow dimension for 2 inch 45 degree elbow is 35 mm.

Radius of elbow = 35/Tan(22.5)

Radius of elbow = 35/0.4142 = 84.5 mm

Length = 0.26795 X 84.5= 22.64 i.e. 23 mm Approx.

If you need help measuring the centerline radius of an existing elbow, it's best to talk to an elbow manufacturing specialist to ensure you get the right measurements and the best solution for your needs. 

At JIANZHI, we won't sell you anything you don't need - we'll sell you the elbow that's best for your individual system. Contact us today to find the right solution for you.


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