Why isn't the hole symmetric in the sector?

Because the cone flares. At the top the nozzle meets the wall where it is wider and further from the apex; at the bottom, narrower and nearer. In the sector that becomes a curve pulled outward on one side — nothing like the nearly symmetric hole on a shell.

Which diameter do I enter?

The HOLE, as on the holed shell — for a nozzle set on top of the cone it goes at the nozzle's bore, for one set in, at its outside diameter. The welder decides.

Where does the cone's seam go?

Diametrically opposite the hole. A longitudinal weld does not run through a cut-out, and on a cone it is already the most critical joint in the part.

Does this hole match the cone branch in this catalogue?

It does, and it is its mate. Enter the same cone, the same height and the same diameter in both parts and you have both patterns for the job — the branch and the cone.

Cone with Branch Hole development

What it is

The cone with the nozzle hole already marked — the mate of the cone branch, as the holed shell is the mate of the pipe branch. And here it matters more than on a pipe: marking a hole on a cone by hand is far worse than on a cylinder, because the surface does not open into a rectangle. It opens into a sector, and the hole's curve has to be carried into it.

Where it is used

Conical hoppers and silos with a nozzle, conical vessel bottoms with a take-off, cyclone inlets, bins with a side discharge.

Measurements the calculation needs

D1 Smaller diameter (bottom mouth)
D2 Larger diameter (top mouth)
H Height of the cone
D Diameter of the nozzle hole
Y Height of the hole centre (from the bottom mouth)
DV Divisions
THK Plate thickness

Worked example

The values the form comes pre-filled with, run through the tool itself:

Smaller diameter (bottom mouth)	300 mm
Larger diameter (top mouth)	900 mm
Height of the cone	800 mm
Diameter of the nozzle hole	200 mm
Height of the hole centre (from the bottom mouth)	500 mm
Divisions	32
Plate thickness	6 mm
The flat pattern fits a plate of	2274 × 1085 mm

Result of the example

Plate	2274 × 1085 mm
Arc radii	419.2 mm · 1,273.6 mm
Sector angle	126.4°

Cone with Branch Hole flat pattern: drawing of the template with the worked example dimensions — Cut lines in purple, welds in green and reference lines in orange. Plate 2274 × 1085 mm.

Frequently asked questions

Why isn't the hole symmetric in the sector?: Because the cone flares. At the top the nozzle meets the wall where it is wider and further from the apex; at the bottom, narrower and nearer. In the sector that becomes a curve pulled outward on one side — nothing like the nearly symmetric hole on a shell.
Which diameter do I enter?: The HOLE, as on the holed shell — for a nozzle set on top of the cone it goes at the nozzle's bore, for one set in, at its outside diameter. The welder decides.
Where does the cone's seam go?: Diametrically opposite the hole. A longitudinal weld does not run through a cut-out, and on a cone it is already the most critical joint in the part.
Does this hole match the cone branch in this catalogue?: It does, and it is its mate. Enter the same cone, the same height and the same diameter in both parts and you have both patterns for the job — the branch and the cone.

Cone with Branch Hole dimension drawing: D1 (Smaller diameter (bottom mouth)), D2 (Larger diameter (top mouth)), H (Height of the cone), D (Diameter of the nozzle hole), Y (Height of the hole centre (from the bottom mouth)), DV (Divisions), THK (Plate thickness), marked on the part

Calculate a Cone with Branch Hole

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