Geometry & drainage
Rolling offset using two 45° bends
- where
- true offset (mm)
- vertical offset, rise (mm)
- horizontal offset, sideways (mm)
- travel (mm)
Explain this equation
Works out the true offset and travel when a pipe moves both up and sideways using two 45° bends. Use it to set out offsets that go round corners.
R is the vertical rise and S is the sideways shift. O is the true offset, the straight-line distance between the two pipe centrelines. T is the travel along the diagonal between the bends.
Rise and sideways shift are at right angles, so Pythagoras gives the true offset. With 45° bends, travel is the offset times √2, about 1.414.
Sense check: 300 mm up and 400 mm across gives a true offset of 500 mm and travel of about 707 mm.
Watch out: these are centreline figures. Deduct fitting take-outs and allow for clearances.
Enter your values to see the result.
Good to know
Centreline geometry only; include actual fitting take-outs and installation clearances.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.