Learn/Shape Generator/Built-in profiles
Pipe Flange
At a glance
- ASME Class 150, tube, and custom round flanges
- Bolt circle and bore parameters
- Flat-pattern friendly output for plasma and laser
The Pipe Flange shape (Fabrication category) generates round flat flanges — an outside circle, a center bore, and evenly spaced bolt holes on a bolt circle. It's built for plate cutting: weld-on pipe flanges, tube-end flanges, and one-off patterns matched to a gasket or a measured mating flange.
Presets
Preset family offers three starting points:
- ASME Class 150 — practical reference dimensions for NPS 1/2 through NPS 12 (fifteen sizes). Each preset fills bore, OD, bolt circle, bolt hole diameter, and hole count — e.g. NPS 2 loads a 2.375 in bore, 6 in OD, 4.75 in bolt circle, and four 3/4 in holes.
- Tube — fabrication-friendly defaults for common round tube from 1.5 to 4.0 in, with 4, 6, or 8 bolts depending on size. These are editable shop defaults, not a formal tube-flange standard.
- Custom — enter every dimension yourself.
Presets only populate the fields; nothing is locked. Bump a bolt hole for clearance or grow the OD for weld access and the rest of the preset stays put.
Dimensions and validation
Five fields define the flange: Bore diameter, Outside diameter, Bolt circle diameter, Bolt hole diameter, and Number of holes (3–64, always evenly spaced). The generator validates the stack before drawing: the bore must be smaller than the OD, and bolt holes must clear both the bore and the outside edge — you get a plain-language error, not an overlapping cut path.
Under Options, Rotation spins the bolt pattern (for two-holes-up versus one-hole-up
orientation against a mating flange), and holes can be routed to the HOLES layer (default) or
layer 0. Every circle is emitted as true arcs, so plasma and laser toolpaths stay round.
Tips
- Matching an existing flange? Measure the bolt circle across two opposite holes (center to center) and start from Custom — presets are references, and real-world flanges drift.
- For an oval or 2-bolt exhaust pattern, use the Exhaust Flange shape instead — it builds the tangent ear-style outside profile this shape intentionally doesn't.