To understand the basic knowledge of elbow, the determination of an elbow must know the diameter, radius and angle of elbow, and some have straight section. According to the angle, there are 45 °and 90 °180 °, which are the most commonly used, and other abnormal angle bends, such as 60 °, are also included according to the engineering needs. The angle of the elbow needs to be measured with a tool, and only 180 degrees, 90 degrees and 45 degrees can be seen.

Formula for calculating the size of the elbow:

- 1. 5 times the center height of the elbow = path * 1.524, in fact, is the path * multiple, the number after the decimal point of the resulting result is round to the integer, such as the path of 219 is 200. the center height is 200 ≤ 1.524 ≤ 304.8, take 305; if the path of 114 is 100, the center height is 100 ≤ 1.524 ≤ 152.4, take 152.

(suitable for DN100 and above elbow curvature radius algorithm convenient and fast calculation). - Stamp height = center height + radius of elbow, such as 1.5 times diameter 219 elbow height = 305 x 219 ≤ 2 ≤ 305 ≤ 109.5 ≤ 414.5.
- The outer arc length = (center height + radius) * 3.14 ≤ 2 ≤ 360 * degrees, that is, (stamp height) * 3.14 ≤ 2 ≤ 360 * degrees, from which the outer arc length of 90 degree elbow can be calculated = poke height * 3.14 × 2.
- Inner arc length = (center height-radius) * 3.14 ≤ 2 ≤ 360 * degrees.
- The blanking length of the elbow = the height of the center of the elbow * 3.14 ≤ 2 * the outer diameter of the elbow / pipe diameter + (pipe wall thickness * 3) + machining allowance, such as using 180 × 8 pipe blanking, pushing 273 elbow, the above formula can be calculated:

The blanking length is 381 ≤ 1.57 ≤ 273 / 180 / 24 / 931.22 mm + processing allowance.

## Calculation Formula of 45 degree Elbow in Pipeline

- The calculation method of the short pipe in the middle of two 45 degree bends is as follows: short connection length = height difference x 1.4142 ≤ 0.8284R, R = bending radius of elbow (that is, the length of 90 °bending head).
- First of all, calculate the center height, calculate. Then the central length minus the height of the elbow on both sides is the short pipe length in the middle.

The elbow requires the radius of curvature to be controlled. For example, if the radius length is 1.5D, the curvature radius must be within the required tolerance range. Because most of these pipe fittings are used for welding, in order to improve the welding quality, the end of the car into a groove, leaving a certain angle, with a certain edge, this requirement is also relatively strict, how thick the edge, how much angle and deviation range are specified, geometric size is more than the pipe fittings.

## The theoretical weight of the elbow

Weight of elbow = (outer diameter-wall thickness) * wall thickness * 0.02466 * length

1) the outer diameter is not equal to the nominal diameter, equal to the outer diameter at the groove of series 2

2) length = 2 π R * angle / 360, the calculated weight length of elbow is the arc length corresponding to the angle of elbow in the circumference of R as radius.

3) R is the bending radius of the elbow.