Offset Branch Pipe Intersection Template

This develops the theoretical intersection of two cylindrical outside surfaces when the branch axis is shifted sideways from the main pipe centerline. At each branch circumference station, the calculator solves the cylinder-intersection quadratic and unwraps the resulting axial cut position.

A zero offset reduces to the ordinary centered fishmouth. The signed offset makes the two sides asymmetric, so the 90° orientation mark matters when wrapping the template.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Main pipe outside diameter

200 mm

Branch outside diameter

80 mm

Angle between pipe axes

90 deg

Branch-axis offset

25 mm

Primary result: Wrap length: 251.3 mm.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

The MVP produces a complete single-valued wrap curve only when |offset| + branch radius ≤ main radius. It models outside surfaces and intersecting axis directions; it does not compensate for wall thickness, bevel, weld gap, ovality, kerf, branch reinforcement or a non-penetrating lateral.