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How to calculate the elbow geometry?

Update:27 Dec 2018

The elbow is a commonly used pipe fitting in the plumbi […]

The elbow is a commonly used pipe fitting in the plumbing device. It is used for the connection of the pipe bend and is used to change the direction of the pipe.

Other titles: 90° elbow, right angle bend, love and bend, stamping elbow, pressing elbow, mechanism elbow, welding elbow, etc.

Elbow manufacturer use: connect two pipes with the same nominal or different diameter, so that the pipeline can be turned 90°, 45°, 180° and various degrees.

The zigzag radius is less than or equal to 1.5 times the diameter of the pipe is attributed to the elbow, and 1.5 times larger than the pipe diameter is attributed to the elbow.

Skills for producing elbows:

It is required to manipulate the radius of curvature. If the radius of the analog is 1.5D, then the radius of curvature needs to be within the required scale of public service. Because most of these pipes are used for welding, in order to improve the quality of the welding, the ends are all turned into bevels, leaving a certain point of view, with a certain side. This requirement is also stricter, how thick the side is, how much the viewpoint is and the scale of error. There are regulations, and there are many more items on the geometric scale than the pipe fittings. The surface quality and mechanical properties of the elbow are basically the same as the tube. For the convenience of welding, the material of the steel of the pipe to be joined is the same.


1.5 times the height of the elbow center A = the diameter *1.524, in fact, the diameter D* multiple, the number of the decimal point after the result is rounded to the whole number, such as the diameter D of 219 is 200, the center height is

200*1.524=304.8, take 305; as for 114, the diameter is 100, and the center height is 100*1.524=15.4, take 152. (The algorithm for radius of curvature of DN100 and above is convenient and quick to calculate).


Poke height = center height + radius of the elbow, such as 1.5 times the diameter of the elbow of the diameter 219 = 305 + 219 / 2 = 305 + 109.5 = 414.5


Outer arc length = (center height + radius) * 3.14 * 2 / 360 * degrees, that is, (poke height) * 3.14 * 2 / 360 * degrees, which can be derived from the outer arc length of the 90 degree elbow = poke height * 3.14/2


Inner arc length = (center height - radius) * 3.14 * 2 / 360 * degrees


The length of the elbow blank = the height of the elbow center * 3.14 / 2 * outer diameter of the elbow / pipe diameter + (pipe wall thickness * 3) + machining allowance, such as the use of 180 * 8 pipe cutting, push 273 The elbow can be calculated by the above formula, and the length of the blank is =381*1.57*273/180+24=931.22mm+ machining allowance.