Offset Pipe Branch (Tangential Inlet) development

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

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

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.