Pipe Branch (Tee) flat pattern
What it is
A pipe branch is the mouth cut into the end of one pipe so it seats onto another — the tee, the saddle. Only the branch comes out of this sheet: the main pipe already exists, and all it takes is the hole. Rolled flat, the branch is a rectangle with one edge cut to the intersection curve between the two cylinders.
Where it is used
Tees and branches in industrial piping, nozzles on vessels and tanks, headers, exhaust and compressed-air runouts, manifold take-offs.
Measurements the calculation needs
- D Diameter
- D2 Diameter 2
- C Branch length
- ANG Angle
- DV Divisions
- THK Thickness
Worked example
The values the form comes pre-filled with, run through the tool itself:
| Diameter | 200 mm |
|---|---|
| Diameter 2 | 400 mm |
| Branch length | 400 mm |
| Angle | 90° |
| Divisions | 16 |
| Thickness | 6 mm |
| The flat pattern fits a plate of | 609 × 225 mm |
Frequently asked questions
- Where do I measure the branch length from?
- From the AXIS of the main pipe to the end of the branch — the centre-to-face dimension, which is how piping is dimensioned on a drawing. Measuring from the surface of the main pipe would give a different number for every angle, because the mouth is deeper on one side than on the other.
- Why isn't the cut edge a sine wave?
- Because the branch does not meet a plane, it meets another cylinder. On an angled cut every point of the mouth sits at a height that varies as a sine; here the height comes from two curved surfaces intersecting, and the resulting curve only approaches a sine in the limiting case where the main pipe is much larger than the branch.
- Can the branch be larger than the main pipe?
- Not in this calculation. A branch fatter than the main pipe no longer seats onto it but wraps around it, which is a different part: the mouth stops being a closed curve on the branch. Equal diameters do work, and that is the full-bore tee.
- What changes when the angle is not 90 degrees?
- The mouth becomes asymmetric — very deep on the acute side and shallow on the opposite one. That is the 45-degree branch, used where the flow should enter along the main pipe's stream rather than across it.
