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Sizes and tolerances
Rings to 1,200 mm outside diameter, forgings to 300 kg, and the machining allowance that has to sit on the drawing.
| Form | Maximum size | Tolerance basis | Typical part |
|---|---|---|---|
| Rolled rings | To 1,200 mm OD | Section to drawing | Flanges, bearing races, seal rings |
| Closed-die forgings | To 300 kg | Die-dependent | Valve bodies, fittings, structural parts |
| Open-die forgings | To 300 kg | To drawing | Discs, shafts, blocks, large sections |
| Flange blanks | To 1,200 mm OD | Rough machined | Pipeline and pressure-vessel flanges |
As-forged surfaces need a machining allowance. Send the finished drawing and say which dimensions are critical — the allowance is set from that, not from a default.
Machining allowance
| As-forged | Full allowance, part is rough |
| Rough machined | 2–5 mm per side depending on size, ready for finish machining |
| Finish machined | ±0.01 mm on critical dimensions, other dimensions to drawing |
| Basis | The customer drawing is the acceptance document, not a catalogue size |
What decides whether it can be made
- Ring outside diameter and wall section — a very thin wall on a large ring is harder than a heavy one.
- Die availability for closed-die work; a new die is a tooling item with its own lead time.
- Grade and section together — the same shape in Waspaloy and in 718 do not run on the same schedule.