## What are miter elbows?

## What are miter elbows?

**Miter elbows** are not standard fittings they are fabricated from pipes. High skill pipe fitter is required to fabricate this type of elbows and Usually, they are preferred for size 10” & above because large size elbow is expensive. Use of miter elbow is restricted to the water line. Miter elbow can be fabricated in 2, 3, & 5 pieces. Generally, fire water line, cooling water in old refinery & petrochemical plant you can see the use miter elbow. Nowadays the use of miter elbow is limited.

**Table of Contents**hide

When setting out, first draw the theoretical cutting line, then determine the position of the cutting line of the highest and lowest point (after beveling) according to the wall thickness, connect the two points, then calculate the length of the prime line of each bisection point, and then cut the line on the coil pipe, and then the required angle can be guaranteed after the assembly. The material is generally carbon steel, stainless steel and alloy steel. In the daily construction, the miter elbow is much less than the elbow welded by the original pipe and the middle plate.

##
**AWWA Recomends:**

- 22.5< to ≤ 45, use 3 pieces
- 45 < to ≤ 67.5, use 4 pieces
- 67.5 < to ≤ 90, use 5 pieces
- A) The larger the O.D. of the fitting, the more competitive a mitered fitting will be. Because of the ultimate use, most fittings 54″ and larger can be fabricated and will provide that competitive edge.
- B) AWWA C208-96 elbows are made from miter cut pieces of pipe. The mitered pieces that make up the elbow are called gores. In a 5-piece elbow, there are two end gores and three middle gores. The dimensions of the end and middle gores are determined based upon formulas provided by AWWA on page 7 of C208-96.
- C) AWWA C208-96 recommends 2 and a half X diameter as an optimum radius, (centerline radius), for mitered elbows with 1 X diameter as the minimum. Due to industry standards for elbows of other specifications, (e.g. A234 WPB), we set the normal radius at 1 and a half X diameter.
- D) However, other standards set the “center-to-face,” or the line originating 90 degrees from the plane of the face of one end of the elbow to the center line of the other end as equal to the center-line radius. AWWA C208-96 DOES NOT FOLLOW THIS PRACTICE! In the AWWA spec, the “radius” is a calculation based upon the formulas mentioned above. The AWWA spec states the radius of a 60″ elbow is 90″. The “center-to-face” is 92.065″.

## Miter Elbow Weight

- Weight = 2*R*n*tan(alfa/(2*n))*W, where
- R = bend radius at end (=circumscribed)
- n = number of miter joints
- alfa = bend angle (total)
- W = Unit weight of pipe (kg/m or lb/ft)

### Steps to calculate miter elbow weight

- Calculate the total length of the bend using the formula, l=r x theta, where r=radius of the center line of the bend and theta = bend angle in radians.
- Unit weight of the pipe/ metre can be obtained from the pipe manufacturer end or from the relevant codes and standard governing the material and process of manufature of the pipe piece used for fabricating the pipe bend. for example: in case the pipe piece grade is API 5L, then refer API 5L for unit weight per meter, or you can refer ASTM A53 code for ASTM pipes and so on.
- And then multiply the unit weight per meter calculated in step 2 to the length of the pipe piece calculated in step 1.

## Formula of Miter Elbow

In above pic, dotted lines shows where the pipe should be cut. Each dotted cut line has a vertical reference line marked at following distances from pipe end.

- L2 : Distance of first and last reference line from pipe ends.
- L1 : Distance between reference lines.
- Cut Back : Offset distance of cut lines from reference lines at the top and bottom of pipe.

Given a formula to make 90 degree elbow of 10″ size with elbow center radius same as standard elbow i.e. 381 mm.

### Miter Elbow Input values:

- D = 90 mm : Required Miter Elbow Degree
- N = 4 : Number of cuts
- E = 381 mm : Standard Miter Elbow Radius
- POD = 273 mm : Pipe Outside Diameter

## Mitered Elbow Dimensions

### 90 Degree Mitered Elbow Dimensions

FOUR WELD 90° LONG RADIUS MITER ELBOW

NOM. DIA |
A Min. |
R Radius |
S Inches |
M |
---|---|---|---|---|

30 | 42w” | 45″ | 17p” | |

32 | 44s” | 48″ | 18s” | |

34 | 47r” | 51″ | 19f” | |

36 | 49f” | 54″ | 21w” | |

38 | 52i” | 57″ | 22r” | |

40 | 55w” | 60″ | 23i” | |

42 | 57s” | 63″ | 24p” | 8r” |

44 | 60r” | 66″ | 25s” | |

46 | 62f” | 69″ | 27″ | |

48 | 65i” | 72″ | 28i” | 9p” |

50 | 68w” | 75″ | 29r” | |

52 | 70s” | 78″ | 30i” | |

54 | 73r” | 81″ | 31p” | 10f” |

56 | 75f” | 84″ | 32f” | |

58 | 78i” | 87″ | 34″ | |

60 | 81w” | 90″ | 35w” | |

62 | 83s” | 93″ | 36y” | |

64 | 86y” | 96″ | 37i” | |

66 | 88f” | 99″ | 38p” | |

68 | 91i” | 102″ | 39f” | |

70 | 94w” | 105″ | 41″ | |

72 | 96s” | 108″ | 42r” | |

78 | 104i” | 117″ | 45s” | 15r” |

84 | 112y” | 126″ | 49i” | |

86 | 115″ | 129″ | 50y” |

**Notes:**

- All Miter Pipe Bend dimensions are given in Inches.
- Welding shall be in accordance with the job specifications.
- These Miter Elbow Pipe are to be used when authorized by the piping spec’s.
- Use “A” dimension only where necessary to meet close clearance requirements or when connecting to flange or fitting.
- Miter Pipe Elbow Material shall be as specified in the job piping materials specification class.
- “M” dimension does not include taper bore length.
- The “M” dimension must be calculated for Miter elbows other than 78″, 54″, 48″ and 42″.

### 45 Degree Mitered Elbow Dimensions

TWO WELD 45° LONG RADIUS MITER ELBOW

DIA NOM |
A | B |
C (1) |
D (1) |
M | |
---|---|---|---|---|---|---|

Min (3) | LR Ell Dim | |||||

3 | 2 | 2 | 1s | 1w | t | |

4 | 2i | 2i | 2y | 1t | u | |

6 | 3s | 3s | 3i | 2 | p | |

8 | 5 | 5 | 4s | 2p | d | |

10 | 6r | 6r | 5f | 3t | 1q | |

12 | 7i | 7i | 7w | 3g | 1r | |

14 | 8s | 8s | 8r | 4p | 1y | |

16 | 10 | 10 | 9i | 5r | 1o | |

18 | 11r | 11r | 10s | 5f | 1s | |

20 | 11i | 1 – 0i | 11f | 6o | 2 | |

22 | 1 – 0r | 1 – 1i | 1 – 1w | 6g | 2e | |

24 | 1 – 1r | 1 – 3 | 1 – 2r | 7f | 2y | |

26 | 1 – 1s | 1 – 4 | 1 – 3i | 8r | 2o | |

28 | 1 – 2s | 1 – 5y | 1 – 4q | 9q | 2s | |

30 | 1 – 3i | 1 – 6i | 1 – 5f | 9o | 2g | |

32 | 1 – 4i | 1 – 7f | 1 – 7 | 10y | 3e | |

34 | 1 – 5i | 1 – 9w | 1 – 8r | 11 | 3y | |

36 | 1 – 6r | 1 – 10r | 1 – 9i | 11i | 3o | |

38 | 1 – 7 | 1 – 11i | 1 – 10p | 1 – 0e | 3s | |

40 | 1 – 7s | 2 – 0s | 1 – 11f | 1 – 0d | 3g | |

42 | 1 – 8i | 2 – 2 | 2 – 1 | 1 – 1i | 4w | 8y |

44 | 1 – 9i | 2 – 3r | 2 – 2r | 1 – 2w | 4y | |

46 | 1 – 10i | 2 – 4i | 2 – 3y | 1 – 2d | 4o | |

48 | 1 – 11r | 2 – 5s | 2 – 4p | 1 – 3u | 4s | 9p |

50 | 2 – 0r | 2 – 7 | 2 – 5s | 1 – 4w | 4g | |

52 | 2 – 1 | 2 – 8r | 2 – 7 | 1 – 4s | 5w | |

54 | 2 – 1s | 2 – 9i | 2 – 8r | 1 – 5y | 5y | 10f |

56 | 2 – 2s | 2 – 10s | 2 – 9y | 1 – 6q | 5o | |

58 | 2 – 3i | 3 – 0 | 2 – 10i | 1 – 6s | 5s | |

60 | 2 – 4r | 3 – 1r | 2 – 11s | 1 – 7y | 5g | |

62 | 2 – 5r | 3 – 2i | 3 – 1 | 1 – 8 | 6w | |

64 | 2 – 6 | 3 – 3s | 3 – 2w | 1 – 8o | 6t | |

66 | 2 – 7 | 3 – 5 | 3 – 3y | 1 – 9t | 6o | |

68 | 2 – 7s | 3 – 6r | 3 – 4i | 1 – 10 | 6s | |

70 | 2 – 8i | 3 – 7i | 3 – 5s | 1 – 10p | 6g | |

72 | 2 – 9i | 3 – 8s | 3 – 6f | 1 – 11t | 7w | |

74 | 2 – 10r | 3 – 10 | 3 – 8e | 1 – 11f | 7y | |

76 | 2 – 11 | 3 – 11r | 3 – 9y | 2 – 0o | 7o | |

78 | 3 – 0 | 4 – 0u | 3 – 10i | 2 – 1e | 7s | 150 |

80 | 3 – 0s | 4 – 1q | 3 – 11s | 2 – 1d | 7g | |

82 | 3 – 1s | 4 – 2g | 9 – 0t | 2 – 2i | 8e | |

84 | 3 – 2i | 4 – 4e | 4 – 2w | 2 – 3w | 8y | |

86 | 3 – 3r | 4 – 5u | 4 – 3t | 2 – 3s | 8o | |

88 | 3 – 4r | 4 – 6g | 4 – 4i | 2 – 4u | 8s | |

90 | 3 – 5 | 4 – 7f | 4 – 5o | 2 – 5q | 8g | |

92 | 3 – 6 | 4 – 9e | 4 – 6f | 2 – 5o | 9w | |

94 | 3 – 7 | 4 – 10y | 4 – 8w | 2 – 5y | 9y | |

96 | 3 – 4i | 4 – 11p | 4 – 9r | 2 – 7 | 9o | |

98 | 3 – 8i | 5 – 0f | 4 – 10i | 2 – 7p | 9s | |

100 | 3 – 9 | 5 – 2w | 4 – 11q | 2 – 8t | 9g | |

102 | 3 – 10 | 5 – 3f | 5 – 0f | 2 – 8q | 10w | |

104 | 3 – 11 | 5 – 4p | 5 – 2q | 2 – 9o | 10t | |

106 | 3 – 11s | 5 – 5f | 5 – 3r | 2 – 10r | 10o | |

108 | 4 – 0i | 5 – 7w | 5 – 4u | 2 – 10f | 10s | |

110 | 4 – 1i | 5 – 8t | 5 – 5o | 2 – 11i | 10g | |

112 | 4 – 2r | 5 – 9o | 5 – 6d | 3 – 0e | 11w | |

114 | 4 – 3 | 5 – 10d | 5 – 8 | 3 – 0d | 11t | |

116 | 4 – 4 | 6 – 0q | 5 – 9e | 3 – 1u | 11i | |

118 | 4 – 5 | 6 – 1t | 5 – 10y | 3 – 2w | 11s | |

120 | 4 – 5s | 6 – 2o | 5 – 11p | 3 – 2s | 11g | |

122 | 4 – 6i | 6 – 3d | 6 – 0d | 3 – 3t | 12w | |

124 | 4 – 7y | 6 – 5q | 6 – 2 | 3 – 4 | 12y | |

126 | 4 – 8r | 6 – 6r | 6 – 3e | 3 – 4q | 12o | |

128 | 4 – 9 | 6 – 7i | 6 – 4y | 3 – 5r | 12s | |

130 | 4 – 10 | 6 – 8s | 6 – 5o | 3 – 6 | 12g | |

132 | 4 – 10s | 6 – 10 | 6 – 6s | 3 – 6o | 13w | |

134 | 4 – 11i | 6 – 11r | 6 – 8 | 3 – 7r | 13t | |

136 | 5 – 0i | 7 – 0i | 6 – 9w | 3 – 7q | 13i | |

138 | 5 – 1r | 7 – 1s | 6 – 10y | 3 – 8o | 13s | |

140 | 5 – 2r | 7 – 3 | 6 – 11i | 3 – 9r | 13g |

**Notes:**

- All Pipe Miter elbow dimensions are given in Inches.
- “C” and “D” dimensions are approximate. Do not use for fabrication.
- These Miter elbows are to be used when authorized by the piping spec’s.
- Use “A” minimum dimension only where necessary to meet close clearance requirements.
- Use butt-weld “A” only where necessary to connect to flange or fitting. Use Miter weld for pipe connection.
- Miter elbow Material shall be as specified in the job piping materials specification class.
- Welding shall be in accordance with the job specifications.
- “M” dimension does not include taper bore length.
- The “M” dimension must be calculated for Miter elbows other than 78″, 54″, 48″ and 42″.

### Mitered Elbow Equivalent Length

Miter Fittings |
Steel e = 0.05 mm |
Spiral Weld Steel e = 0.1 mm |
---|---|---|

Threaded Miter elbows | ||

90° elbow, r/d=1 | 30 | 26 |

45° elbow, r/d=1 | 16 | 14 |

Welded Miter elbows | ||

90° elbow, sharp bend | 55 | 49 |

90° elbow, r/d=1 | 19 | 16 |

90° elbow, r/d=1.5 | 13 | 12 |

90° elbow, r/d=2 | 11 | 10 |

45° elbow, sharp bend | 18 | 16 |

45° elbow, r/d=1 | 14 | 12 |

45° elbow, r/d=1.5 | 9.4 | 8.3 |

**Source**: China **Steel Elbows**** Manufacturer** – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at [email protected]

Please notice that you might be interested in the other technical articles we’ve published:

- Difference Between A Pipe Elbow And A Pipe Bend
- What is a pipe elbow
- How to get high quality pipe elbow
- Use and maintenance of stainless steel elbows
- Seamless Steel Elbow VS Welded Steel Elbow
- Knowledge of Long Radius Elbow
- What are Stamping Elbows

## What is a Mitre angle?

A mitre cut refers to an angled cut on the face of two structures that will be joined to create a corner, which would then be called a mitre joint. A true mitre joint requires two pieces to be cut at 45 degree angles, so when they are joined the corner created will be 90 degrees.

## What is the standard of mitered elbow?

ASME B31.3 – Process Piping

Process Piping is the piping that convey fluids under pressure or vacuum within the limits of a Petroleum refinery, Chemical plant, Gas Processing plant, Pharmaceutical, Textile, Paper, Semiconductor and Cryogenic plants and related processing plants and terminals.

This standard contains rules for piping typically found in the above-mentioned plants and it prescribes requirements for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping.

## What is angle of miter elbow?

Miter pipe elbows bending angle (θ):

15°, 30°, 45°, 60°, 90°, 135°, 180°

## What is Miter bend in piping?

Another type of bend is a Miter bend. A Miter bend is a bend which is made by cutting pipe ends at an angle and joining the pipe ends. A true miter bend is a 90 degree bend made by cutting two pipes at 45 degrees and joining them by welding.