Conical Tap (Conical Tee) flat pattern
What it is
The nozzle that leaves the pipe flared at the base and tapers to the collar. The ordinary branch handles a cylindrical branch on a pipe and the cone branch handles a cylindrical branch on a cone; what was missing is the CONICAL branch on a pipe — the real nozzle on most vessels, because flaring the base spreads the weld's stress instead of concentrating it in a narrow mouth.
Where it is used
Pressure vessel and tank nozzles, reinforced take-offs on headers, cyclone inlets with a flared base, conical manway necks.
Measurements the calculation needs
- D Diameter of the collar (smaller mouth)
- D1 Diameter of the notional base, on the pipe axis
- D2 Diameter of the pipe
- C Length, from the pipe axis to the collar
- ANG Angle of the nozzle to the pipe axis (90° = upright)
- 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.
Units: mm inches
Worked example
The values the form comes pre-filled with, run through the tool itself:
| Diameter of the collar (smaller mouth) | 7-7/8" (7.874) |
|---|---|
| Diameter of the notional base, on the pipe axis | 15-3/4" (15.748) |
| Diameter of the pipe | 23-5/8" (23.622) |
| Length, from the pipe axis to the collar | 19-11/16" (19.685) |
| Angle of the nozzle to the pipe axis (90° = upright) | 90° |
| Divisions | 32 |
| Plate thickness | 1/4" (0.2362) |
| The flat pattern fits a plate of | 31-13/16" × 12-1/16" |
Result of the example
| Plate | 31-13/16" × 12-1/16" |
|---|---|
| Area and weight | 1.8 ft² · ≈ 17.2 lb in 1/4" steel |
| Arc radii | 19-1/2" |
| Sector angle | 70.6° |
Frequently asked questions
- What does the larger diameter measure, if the big mouth is a saddle?
- It measures the cone's FICTITIOUS base at the pipe's axis — the diameter it would have if it ran down that far. The big mouth is a saddle and has no circle in any plane, so there is nothing to measure on it; the fictitious base is the catalogue convention, and it is the only measurement that closes the part alongside the collar and the length.
- Is the mouth an arc struck with a compass?
- No. The collar is, and it is the sector's constant-radius arc — struck with the compass at the apex. The mouth has a different radius at every station and is marked point by point, like the angle-cut cone's. The difference is that there the polyline was on the inside and here it is on the outside.
- Why does the length have a minimum that depends on the angle?
- Because on a tilted nozzle the mouth is shallower on one side, and if the collar falls short of it the part would have negative length there. The condition falls out of the arithmetic: 2·c·sin(ang) has to exceed d2 + d·cos(ang). At 90 degrees that becomes c greater than half of d2, which is the ordinary branch's guard.
- And if the taper is very small?
- The part is a cylindrical branch, and there is a part for that. Below a millimetre of difference between the two diameters the cone's apex runs too far away and the sector degenerates — the calculation refuses, for the same reason and with the same guard the cone has.
You can work out the figures right here, with no account. PDF, DXF, 3D and history take an account — free, with unlimited calculations.