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Perpendicular pipe saddle coordinates

Calculate a round branch pipe’s outside contact contour on a larger round header.

01Enter your values

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For header radius R, branch radius r and circumferential angle θ, contour drop h=R−sqrt(R²−r² sin²θ). Maximum drop is R−sqrt(R²−r²). Cutback from a square end at the lowest contact plane is maximum drop minus h. Arc distance around the branch is r×θ.

Example
mm
mm

How it works

Calculate a round branch pipe’s outside contact contour on a larger round header.

h(θ) = R − √(R² − r²sin²θ); c(θ) = hmax − h(θ)

Centered perpendicular circular pipes only; branch outside diameter cannot exceed header outside diameter. The table models outside-surface contact, not wall thickness, bevel, weld gap or structural fitness. Cutback and contour drop have opposite references: remove material from the square end by the cutback value. Print scaling is not provided. Works offline after loading. Zero angle lies in the plane containing both pipe axes; the 90° station is transverse to the header axis.

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About this tool

Calculate a round branch pipe’s outside contact contour on a larger round header.

For header radius R, branch radius r and circumferential angle θ, contour drop h=R−sqrt(R²−r² sin²θ). Maximum drop is R−sqrt(R²−r²). Cutback from a square end at the lowest contact plane is maximum drop minus h. Arc distance around the branch is r×θ.

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How to use it

  1. Enter your values

    Header outside diameter · Branch outside diameter · Circumference intervals

  2. Calculate / generate

    Calculate a round branch pipe’s outside contact contour on a larger round header.

  3. Result

    Maximum contour drop: 10 mm Branch circumference: 188.49556 mm

Calculation method

  1. For header radius R, branch radius r and circumferential angle θ, contour drop h=R−sqrt(R²−r² sin²θ).
  2. Maximum drop is R−sqrt(R²−r²).
  3. Cutback from a square end at the lowest contact plane is maximum drop minus h.
  4. Arc distance around the branch is r×θ.
h(θ) = R − √(R² − r²sin²θ); c(θ) = hmax − h(θ)
Example scenario

Perpendicular pipe saddle coordinates

Header outside diameter
100 mm
Branch outside diameter
60 mm
Circumference intervals
12
Result
Maximum contour drop: 10 mm
Branch circumference: 188.49556 mm

Frequently asked questions

What does this result assume?

Centered perpendicular circular pipes only; branch outside diameter cannot exceed header outside diameter. The table models outside-surface contact, not wall thickness, bevel, weld gap or structural fitness. Cutback and contour drop have opposite references: remove material from the square end by the cutback value. Print scaling is not provided. Works offline after loading. Zero angle lies in the plane containing both pipe axes; the 90° station is transverse to the header axis.

Where does my data go?

Calculations run on your device. Form inputs are not sent to a server.

Terms and definitions

Enter your values

Measurement system

The initial choice follows your browser region. Your choice is remembered on this device. Gallons are US gallons. Switching units keeps your numbers unchanged and interprets them in the new unit.

Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.

Header outside diameter

Outside diameter of the main pipe.

Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in

Minimum: 1e-9 · Maximum: 1000000000000 mm

Branch outside diameter

Outside diameter of the perpendicular branch pipe.

Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in

Minimum: 1e-9 · Maximum: 1000000000000 mm

Circumference intervals

Number of equal intervals around the branch; at least four. The closing row repeats the starting position.

Enter a whole number; fractional counts are not valid.

Minimum: 4 · Maximum: 10000

Result

Result

For header radius R, branch radius r and circumferential angle θ, contour drop h=R−sqrt(R²−r² sin²θ). Maximum drop is R−sqrt(R²−r²). Cutback from a square end at the lowest contact plane is maximum drop minus h. Arc distance around the branch is r×θ.

Calculated from your entries using the method below.

Maximum contour drop

Difference between highest and lowest contact planes.

Calculated from your entries using the method below.

Branch circumference

Outside circumference used for the unwrapped coordinate table.

Calculated from your entries using the method below.

Station number

Sequential position around the pipe.

Calculated from your entries using the method below.

Distance around branch · mm

Unwrapped arc distance from the chosen zero-angle generator.

Calculated from your entries using the method below.

Contour drop · mm

Distance below the highest contact plane.

Calculated from your entries using the method below.

Cutback from square end · mm

Material cut back from the lowest-contact square-end reference; not contour drop.

Calculated from your entries using the method below.

Common mistakes and quick fixes

Perpendicular pipe saddle coordinates

Mistake: Cutting by contour drop instead of square-end cutback.

Fix: Use the cutback column for the stated square-end baseline; the two columns use opposite reference planes.

Limits and key assumptions

  • Centered perpendicular circular pipes only; branch outside diameter cannot exceed header outside diameter. The table models outside-surface contact, not wall thickness, bevel, weld gap or structural fitness. Cutback and contour drop have opposite references: remove material from the square end by the cutback value. Print scaling is not provided. Works offline after loading. Zero angle lies in the plane containing both pipe axes; the 90° station is transverse to the header axis.
  • Displayed results may be rounded; rounding does not add measurement precision.