Geometry & drainage
Two-bend pipe offset
- where
- travel (mm)
- perpendicular centreline offset (mm)
- bend angle (°)
- advance (mm)
Explain this equation
Works out the travel and advance for a pipe offset made with two equal bends. Use it to mark out offsets around obstructions.
O is the perpendicular offset between the two pipe centrelines. θ is the bend angle. T is the travel, the diagonal centreline length between the bends. A is the advance, how far along the run the offset takes.
The offset, travel and advance form a right-angled triangle. The offset is the side opposite the angle, so T = O / sin θ and A = O / tan θ.
Sense check: a 300 mm offset with 45° bends needs about 424 mm travel and 300 mm advance. Travel is about 1.414 × offset at 45° and 2 × offset at 30°.
Watch out: these are centreline figures. Deduct fitting take-outs to get cut lengths.
Enter your values to see the result.
Good to know
Centreline geometry only. Deduct fitting take-outs from manufacturer dimensions; these are not finished cutting lengths.
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.