Why four flat patterns?

Each of the four parts of the U — the two bends and the pieces joining them — has its own development. They are calculated together so the cuts meet on assembly.

How do I choose X and Y?

X is the lateral step of the offset and Y the height. Together they set how far the portal displaces the run.

Pipe Offset (Portal) flat pattern

What it is

The portal is the U-shaped part: two elbows joined by a straight run, solved together so the cuts match. The result comes as four flat patterns, one per segment.

Where it is used

Pipe offsets around obstructions, crossings over beams and walkways, ducting that must step aside and return to the same line.

Measurements the calculation needs

D Outside diameter of the tube
X Clear span between the legs
Y Clear height under the crossbar
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:

Outside diameter of the tube	200 mm
Clear span between the legs	300 mm
Clear height under the crossbar	200 mm
Divisions	16
Plate thickness	10 mm
The flat pattern fits a plate of	597 × 395 mm
Flat patterns produced	4

Result of the example

Plate 1	597 × 345 mm
Area and weight	0.15 m² · ≈ 11.7 kg in 10 mm steel
Plate 2	597 × 395 mm
Area and weight	0.18 m² · ≈ 14.1 kg in 10 mm steel
Plate 3	597 × 345 mm
Area and weight	0.15 m² · ≈ 11.7 kg in 10 mm steel
Plate 4	597 × 395 mm
Area and weight	0.18 m² · ≈ 14.1 kg in 10 mm steel

Pipe Offset (Portal) flat pattern: drawing of the template with the worked example dimensions — Cut lines in purple, welds in green and reference lines in orange. Plate 597 × 395 mm.

Ordinate table

#	Position on the plate	Element height
1	0 mm	155 mm
2	37.3 mm	162.2 mm
3	74.6 mm	182.8 mm
4	111.9 mm	213.6 mm
5	149.2 mm	250 mm
6	186.5 mm	286.4 mm
7	223.8 mm	317.2 mm
8	261.1 mm	337.8 mm
9	298.5 mm	345 mm
10	335.8 mm	337.8 mm
11	373.1 mm	317.2 mm
12	410.4 mm	286.4 mm
13	447.7 mm	250 mm
14	485 mm	213.6 mm
15	522.3 mm	182.8 mm
16	559.6 mm	162.2 mm
17	596.9 mm	155 mm

Frequently asked questions

Why four flat patterns?: Each of the four parts of the U — the two bends and the pieces joining them — has its own development. They are calculated together so the cuts meet on assembly.
How do I choose X and Y?: X is the lateral step of the offset and Y the height. Together they set how far the portal displaces the run.

Pipe Offset (Portal) dimension drawing: D (Outside diameter of the tube), X (Clear span between the legs), Y (Clear height under the crossbar), DV (Divisions), THK (Plate thickness), marked on the part

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