**In the Piping and Pipeline Engineering field, Miter Bend plays an important role because standard Elbows are not easily available and economical for larger pipe sizes. The site Engineer or the Fabrication supervisor is responsible for the perfect delivery of the joints made for the miter bend.This article will provide detailed calculation procedures for finding out the required dimensions, angles of cut, and weight of the pipe. **

## What is a Miter Bend?

**A Miter Bend or Miter Elbow is prepared by mitering (angle cutting) and welding pipe ends of the cut pieces, usually at 45° and 90° to form a corner.** There are two types of miter bend, one non-perpendicular bend & another is 3-D bend. **Miter Elbow/Bend** is made from miter-cut pieces of pipe. **The Miter pieces also called gores, There are two end gores and two middle gores in a 4-piece Miter bend.**

## Standards Associated with Miter Bend

**AWWS (American Water Work Association):**For sizing and the number of cuts/miter.**ASME B16.9:**For end preparation of the miters

### Note: According to ASME B31.3, the number of miters is restricted to a maximum of 5.

## Important Points about Miter Bend

- Miter bends are not standard pipe fittings.
- It is also called a fabricated bend.
- Highly skilled welders and fitters are required for perfect miter bend preparation.
- Used mainly in general services
**(category “D” fluid).** - If used in process lines then above 14” pipe size.
- Used above 6” for utility lines.
- Miter bend can be fabricated with 2, 3, 4, & 5 miters.
- The number of cuts will be a maximum of 5.

**Note:1. **The number of miters will be decided according to the pressure and temperature of the line.

**2.**Application size range can vary from company to company.

## Limitations of Miter Bend

- Poor strength because of the more number of joints.
- Higher pressure drop.
- Higher turbulence.
- Higher risk of corrosion because of more numbers of weld joints.
- Less strength.
- Not suitable for pigging.
- High-skilled manpower is required.

## Advantages of Miter Bend

- Low cost.
- No thinning required
- It can be made at the site or in the workshop.

## Inputs Required for Calculation

Pipe/Line Size | Schedule Number | Material Type | Bend Angle | Number of Cut | Radius of Bend |
---|---|---|---|---|---|

8″ | SCH 120 | CS (Carbon Steel) | 90 | 3 | 2.5 D |

**Table No. 1**

**Note:**D = Pipe/Line size

## Steps for Calculation

### Step-1: Write down the available data(refer to Table No. 1)

We have,

**D = **8”, **OD (Outer Diameter) of pipe = ** 219 mm**Schedule-** SCH120**Material-** CS (Carbon Steel)**Bend Angle = **90°**No. of cuts = **4

R = 2.5 D = 2.5*8*25.4 = 508 mm

### Step-2: As per the number of cuts, Sketch the drawing as below (refer to Fig. 2)

### Step-3: Find the Angle of the Cut (refer to Fig. 2 for all the steps)

We know,

### Step-4: Find the Center Line Length (CL_{1}) of the First Miter

We know from **Pythagoras,s formula,**

#### Important Note:

- The first and last miter always will be of the same length at each point.
- Except for the last miter, all the miter’s length will be double of the first miter at every point.

Therefore,

**CL _{2} = **

**CL**

_{1 }* 2 =**272 mm**

CL

CL

_{3 }**= CL**

CL

_{1 }* 2 = 272 mmCL

_{4}= CL_{1}= 136 mm### Step-5: Calculate the Inside and Outside Radius (IR & OR) of the bend.

We know from fig. 2,

### Step-6: Calculate the Inside Length (IL_{1}) of the First Miter.

We know from **Pythagoras formula,**

Therefore,

**IL _{2} = **

**IL**

_{1 }* 2 =**214 mm**

IL

IL

_{3 }**= IL**

IL

_{1 }* 2 = 214 mmIL

_{4}= IL_{1}= 107 mm### Step-7: Find out the Outside Length (OL_{1}) of the First Miter

We know from **Pythagoras’s formula,**

Therefore,

**OL _{2} = **

**OL**

_{1 }* 2 =**330 mm**

OL

OL

_{3 }**= OL**

OL

_{1 }* 2 = 330 mmOL

_{4}= OL_{1}= 165 mm### Step-8: Find the “Length of Pipe required” for the Miter Bend.

Length of pipe required = CL_{1 }+ Cutting allowance + CL_{2 }+ Cutting allowance + CL_{3 }+ Cutting allowance + CL_{4}**Note- **Cutting allowance depends upon the cutting method used, we are assuming 5 mm, refer to Fig. 3.

Thus,

L = 136+5+272+5+272+5+136** L = 831 mm**

### Step-9: Calculate the Weight of the Pipe.

Check the Plain End Mass in the code book under the code “**ASME B36.10 **for 8” SCH 120 Pipe (refer to Fig. 4).

**Plain End mass is given 90.44 kg/m** as per ASME B 36.10 M

Now,

find the weight using the following formula-**Weight of the Pipe = Plain End Mass * Length of Pipe ( in meter)****Weight (W) = 90.44 * 0.831 = 75 kg.**

### Step-10: Get the Cut-back (optional).

Cut-back = CL_{1} – IL_{1}

**Cut-back = 136 – 107 = 29 mm**

Few more useful resources for you.

Piping Elbows vs Bends: A useful literature for piping engineers

Piping Elbow or Bend SIF (Stress Intensification Factor)

Tee Connection: A short literature for piping engineers

Technical requirements for Pipes & Fittings for preparation of Purchase Requisition

“Pipe Coupling”-A short Introduction for the piping professionals

Comparison of Pipe and Tube (Pipe Vs Tube)

Details about Spectacle Blind and Spacers

I am Mechanical Piping & Pipeline Supervisor Engineer with more than 13 years experience relevant in Oil & Gas Indusry EPC Projects.

I am also Hydraulic Engineer.

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+213770738270

+213673316910

Hello, i Wanna ask about number of cut and number of cuts what a different ?

if i wanna make Elbow 90deg 1200mm for 5 pcs segmented is meaning how many number of cut and cuts ?

Thanks ,

How to do this calculation below

The length of pipe to be cut of 3/4″ pipe that has a 90 and a 45 at each end is _______.

hello , for a single miter bend, how to understand the IL and R?

Mitre bends are not often seen on commercial small-bore

Please Tell me Minimum & Maximum Alowable Defelection Angle in Steel Pipeline Laying Works.

Thank you for the information. Can you assist with the infor on determining the number of miters based on the pressure and temperature of the line?

hi.i wanted to know how it is possible to make a cut to the desired degree in the pipe and different places in PDMS.

for example, cutting a 1 degree in the head of a plain pipe.

thank you.