Offset Pipe Branch (Tangential Inlet) flat pattern
What it is
The branch whose axis does NOT cross the main pipe's — the tangential inlet. The ordinary branch requires the two axes to intersect, and so cannot do this one: cyclone inlets, tank feeds, any branch set to one side so the flow enters spinning instead of head-on.
Where it is used
Tangential cyclone and hydrocyclone inlets, swirl tank feeds, side take-offs on headers, runouts offset for want of room.
Measurements the calculation needs
- D Diameter of the branch
- D2 Diameter of the main pipe
- C Length of the branch (from the pipe axis)
- V Offset between the axes
- DV Divisions
- THK Plate thickness
Calculate with your own measurements
No account needed: enter the measurements in millimetres or inches and get the figures and the drawing. The scaled PDF template, the DXF for the cutting table and the 3D model take a free account.
Diameters and sides are outside measurements. The flat pattern already allows for the plate thickness, working on the mean line.
Inches or millimetres? mm inches
Worked example
The values the form comes pre-filled with, run through the tool itself:
| Diameter of the branch | 150 mm |
|---|---|
| Diameter of the main pipe | 500 mm |
| Length of the branch (from the pipe axis) | 500 mm |
| Offset between the axes | 160 mm |
| Divisions | 32 |
| Plate thickness | 5 mm |
| The flat pattern fits a plate of | 456 × 408 mm |
Result of the example
| Plate | 456 × 408 mm |
|---|---|
| Area and weight | 0.15 m² · ≈ 5.7 kg in 5 mm steel |
Ordinate table
| # | Position on the plate | Element height |
|---|---|---|
| 1 | 0 mm | 265.8 mm |
| 2 | 14.2 mm | 266.3 mm |
| 3 | 28.5 mm | 267.9 mm |
| 4 | 42.7 mm | 270.7 mm |
| 5 | 56.9 mm | 274.9 mm |
| 6 | 71.2 mm | 280.5 mm |
| 7 | 85.4 mm | 287.8 mm |
| 8 | 99.6 mm | 297 mm |
| 9 | 113.9 mm | 307.9 mm |
| 10 | 128.1 mm | 320.6 mm |
| 11 | 142.4 mm | 334.9 mm |
| 12 | 156.6 mm | 350.4 mm |
| 13 | 170.8 mm | 366.3 mm |
| 14 | 185.1 mm | 381.8 mm |
| 15 | 199.3 mm | 395.2 mm |
| 16 | 213.5 mm | 404.7 mm |
| 17 | 227.8 mm | 408.1 mm |
| 18 | 242 mm | 404.7 mm |
| 19 | 256.2 mm | 395.2 mm |
| 20 | 270.5 mm | 381.8 mm |
| 21 | 284.7 mm | 366.3 mm |
| 22 | 298.9 mm | 350.4 mm |
| 23 | 313.2 mm | 334.9 mm |
| 24 | 327.4 mm | 320.6 mm |
| 25 | 341.6 mm | 307.9 mm |
| 26 | 355.9 mm | 297 mm |
| 27 | 370.1 mm | 287.8 mm |
| 28 | 384.4 mm | 280.5 mm |
| 29 | 398.6 mm | 274.9 mm |
| 30 | 412.8 mm | 270.7 mm |
| 31 | 427.1 mm | 267.9 mm |
| 32 | 441.3 mm | 266.3 mm |
| 33 | 455.5 mm | 265.8 mm |
Guides about this part
- Pipe saddle calculator and development: how to lay out a pipe-to-pipe branch (tee) at 90 and 45 degrees
- Tube notching template generator: a printable coping template for any tube, angle and offset
- Pipe template, printable at full size: tee saddle, 45° lateral and mitre cut for every pipe size from NPS 1/2 to 12
Frequently asked questions
- What changes in the pattern compared with the ordinary branch?
- The symmetry. On a centred branch the mouth has two equal troughs; here it has one deep and one shallow. At the tangential limit the shallow one disappears altogether and the mouth touches the pipe's side line.
- Can the offset reach the side of the pipe?
- It can, and that is exactly the case the part is named for: with the offset plus the branch's radius equal to the pipe's radius, the branch is tangent. The calculation accepts equality. Past it the branch would run off the side and there would be no closed mouth to cut.
- Where do I measure the length from?
- From the AXIS of the main pipe to the end of the branch, as on the ordinary branch — the centre-to-face dimension.
- And at zero offset?
- The part is exactly the ordinary branch at 90 degrees, and both are in this catalogue. I checked station by station: they give the same heights, with no difference at all.
You can work out the figures right here, with no account. PDF, DXF, 3D and history take an account — free, with unlimited calculations.