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Pipe elbows size

pipe elbow size

An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 90° or 45° angle, though 22.5° elbows are also made.

The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.

Pressure: SCH5 to SCH160
Size range: 1/2 to 56 inches (DN 15 to DN 1,400mm), 22.5 Deg, 45 Deg, 90 Deg, 180 Deg
Manufacturing standards: ANSI, ISO, JIS and DIN
Process: butt welding, seamless, threaded , or socketed

Elbows are split into two groups which define the distance over which they change direction; the center line of one end to the opposite face. This is known as the “center to face” distance and is equivalent to the radius through which the elbow is bent.

Here below, for example, you will find the center to face distance of NPS 2 elbows (the A distance on the image)

The center to face distance for a “long” radius elbow, abbreviated LR always is “1½ x Nominal Pipe Size (NPS) (1½D)”, while the center to face distance for a “short” radius elbow, abbreviated SR even is to nominal pipe size.

Pipe elbow size

Nominal pipe sizeOutside Diameter at Bevel Center to EndCenter to CenterBack to Faces
45° Elbows90°Elbows180°Return
H        F       P       K
DNINCHSeries ASeries BLRLRSRLRSRLRSR
1521.3181638-76-48-
2026.9251638-76-51-
25133.73216382576515641
3242.43820483295647052
4048.345245738114768362
50260.35732765115210210681
6576.1(73)76409564191127132100
80388.9894711476229152159121
9031/2101.6-5513389267178184140
1004114.310863152102305203210159
1255139.713379190127381254262197
1506168.315995229152457305313237
2008219.1219126305203610406414313
25010273273158381254762508518391
30012323.9325189457305914610619467
35014355.63772215333561067711711533
40016406.44262536104061219813813610
45018457.24782846864571372914914686
50020508529316762508152410161016762
55022559-347838559
60024610630379914610
65026660-410991660
700287117204421067711
75030762-4731143762
800328138205051219813
85034864-5371295864
900369149205681372914
95038965-6001448965
1000401016102063115241016
1050421067-66316001067
1100441118112069416761118
1150461168-72617531168
1200481220122075818291219

Pipe Elbow Center Calculation

For standard degrees of pipe elbows such as 45° and 90°, 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.

Formula for calculating center to end distance of such elbows is as follows:

Elbow length in mm = Tan(Elbow Angle/2) X Elbow Radius in mm

Where:

For 90° Long Radius elbows, center to end dimension given in dimension tables of ASME B16.9 is same as radius of 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 degree standard elbow. But for custom elbow angles smaller than 45 degree, elbow is normally cut from 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 elbow radius for standard 45 degree elbow. Then we can use above formula to get elbow angle for custom degrees.

Same procedure applies to 3D elbows.

Example 1:

Calculate elbow center to end dimension for 4 inch nominal pipe diameter elbow at 60 degree angle, cut from 90 degree LR elbow.

From ASME B16.9, center to elbow dimension for 4 in elbow is 152 mm.

Length = Tan (60/2) X 152

Length = 0.57735027 X 152

Length = 87.757 i.e. 88 mm Approx.

Example 2:

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, 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

Length = 22.64 i.e. 23 mm Approx.

Wall Thickness of Elbows

The weakest point on an elbow is the inside radius. ASME B16.9 only standardizes the center to face dimensions and some squareness dimensional tolerances. The wall thickness at the weld line location even is standardized, but not through the rest of an elbow. The standard states that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. A maximum tolerance is specified only at the ends of the fitting.

Many providers of buttweld elbows (and tees) provide one schedule greater thickness so that sufficient wall thickness, after forming, remains.

Theoretical weight of elbows

NPSLR 90° ELBOWSELBOWS SR 90°
inchesSch. 5SSch. 10SSch. 40SSch. 80SSch. 5SSch. 10SSch. 40SSch. 80S
1/20.050.060.080.10.030.040.050.07
3/40.060.070.090.110.040.050.060.07
10.090.150.180.20.060.10.120.13
1.250.130.20.250.350.090.130.170.12
1.50.180.30.40.50.120.20.270.33
20.30.50.70.90.20.330.470.6
2.50.60.851.351.80.40.60.91.2
30.91.322.90.60.91.351.9
41.4245.90.91.352.653.9
52.93.66.59.71.952.44.356.5
64510.5162.73.35710.5
87.41021.533.54.96.714.522.5
1013.616.838.552.59.111.225.635
1223.427597915.61839.553
142935709419.323.54763
1641.3479512527.531.563.584
1851.85912015834.539.580105
207385146194495798129
241221402102828294140188

Angularity tolerances of pipe elbow

NDMax off angleMax off plane
QP
1/2 a 412
5 a 824
10 a 1235
14 a 1637
18 a 24410
26 a 30510
32 a 42513
44 a 48520
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