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Pipe Saddle Cut Calculator

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In the realm of plumbing and piping, making precise connections is paramount for a system’s efficiency and functionality. One such critical connection is the saddle cut—a specialized technique enabling a pipe to seamlessly connect with another by sitting atop or alongside it. The Pipe Saddle Cut Calculator emerges as an indispensable tool in this context, simplifying complex measurements and ensuring accuracy in these connections.

Purpose and Functionality

The primary goal of the Pipe Saddle Cut Calculator is to facilitate the process of measuring and cutting a branch pipe so it perfectly fits the contour of a main pipe. This task, essential in various piping installations, involves meticulous calculations to avoid any disruption in the main pipeline.

The calculator uses specific inputs to determine the necessary cut depth and profile for the branch pipe. These inputs include:

  • Main Pipe Diameter (D_main): The outer diameter of the main pipe.
  • Branch Pipe Diameter (D_branch): The outer diameter of the branch pipe.
  • Intersection Angle (θ): The angle at which the branch pipe will intersect the main pipe.

Using these inputs, the calculator performs calculations to output the exact measurements required for the cut, ensuring a precise and snug fit between the two pipes.

Step-by-Step Example

Consider a scenario where you need to connect a branch pipe of 100mm diameter perpendicular (90 degrees) to a main pipe of 200mm diameter. Here’s how the calculator simplifies this task:

  1. Input the Diameters and Angle:
    • D_main = 200mm
    • D_branch = 100mm
    • θ = 90 degrees
  2. Calculation of Cut Depth (H): The formula applied is H=Dmain/2​​−(2Dmain​​)2−(2Dbranch​​)2​, resulting in:
    • =100−10000−2500=100−7500=100−86.6=13.4
    • H=100−10000−2500​=100−7500​=100−86.6=13.4mm

This result tells us that the cut into the branch pipe should be 13.4mm deep to fit perfectly onto the main pipe.


The Formula for Cut Depth (H):


Breaking It Down:

  • Dmain: This is the outside diameter of the main pipe (the big pipe you’re attaching to).
  • Dbranch: This is the outside diameter of the branch pipe (the smaller pipe you’re cutting to attach to the main pipe).
  • H: This is the depth you need to cut into the branch pipe.

Explained in Simple Words:

  1. Half the Main Pipe’s Diameter: First, find half the diameter of the main pipe. This is like measuring the radius of the main pipe.
  2. Squares and Square Roots:
    • Take the value from step 1, square it (multiply it by itself).
    • Do the same for the branch pipe: find half its diameter and then square that.
    • Subtract the square of the branch pipe’s half-diameter from the square of the main pipe’s half-diameter.
  3. Square Root and Subtraction:
    • Take the square root of the result from step 2. This gives you the distance from the center of the main pipe to the edge of the cut on the branch pipe.
    • Subtract this distance from half the main pipe’s diameter. This tells you how deep into the branch pipe the cut should be to make it fit perfectly on the main pipe.


If your main pipe has a diameter of 200mm, and your branch pipe has a diameter of 100mm, here’s how you’d do it:

  1. Half the Main Pipe’s Diameter: 200mm / 2 = 100mm
  2. Squares and Square Roots:
    • Square of 100mm = 10000mm²
    • Half the Branch Pipe’s Diameter = 100mm / 2 = 50mm
    • Square of 50mm = 2500mm²
    • 10000mm² – 2500mm² = 7500mm²
  3. Square Root and Subtraction:
    • Square root of 7500mm² = 86.6mm (approximately)
    • 100mm – 86.6mm = 13.4mm

So, the cut depth (H) would be 13.4mm. This means you need to cut into the branch pipe 13.4mm deep for it to fit snugly onto the main pipe.

Relevant Information Table

InputDescriptionExample Value
D_mainOuter diameter of the main pipe200mm
D_branchOuter diameter of the branch pipe100mm
θ (Intersection Angle)Angle of intersection between the two pipes90°
H (Cut Depth)Depth of the cut needed on the branch pipe13.4mm


The Pipe Saddle Cut Calculator transcends being merely a tool; it’s a facilitator of precision and efficiency in piping systems. Its utility spans across multiple industries, from plumbing and HVAC to oil and gas, wherever piping systems are critical. By ensuring accurate saddle cuts, it prevents leaks and pressure drops, thereby optimizing the system’s performance.

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