DIN 6923 M20 Flange
DIN 6923 M20 is a flange nut, on a M20 × 1.5 mm metric thread. German designation for the flange nut, superseded on new drawings by the harmonised EN 1661. Dimensions track ISO 4161 to within a few tenths of a millimetre across M5–M20, so the two are treated as interchangeable in practice — but the flange replaces a washer, so check the bearing surface is wide enough before dropping a plain nut in its place.
Dimensions
- Standard
- DIN 6923
- Type
- Flange nut
- Size
- M20
- Thread
- M20 × 1.5
- Socket size s
- 30 mm
- Height m
- 20 mm
- Flange diameter dc
- 42.8 mm
- Drive
- External hexagon
- Head
- Flange
Nominal values in millimetres as published in DIN 6923. Estimated weight 42.451 g per piece in steel (42.722 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M20 thread pageOther lengthsDIN 6923 M20
All M20 specificationsInterchangeability
DIN 6923 is catalogued with ISO 4161 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
DIN 6923 M20 is a M20 nut, on a 1.5 mm coarse pitch. Mating threads should be a matching class nut in the same property class.
Common stock grades are 8.8, 10.9 and 12.9 in steel, plus A2-70 and A4-80 in stainless. Class 10.9 and 12.9 carry roughly 1.25 and 1.5 times the proof load of 8.8, but they also need a properly rated mating nut — a class 8 nut under a 12.9 bolt simply moves the failure into the thread. Zinc-plated 10.9 and above should be baked to avoid hydrogen embrittlement.
For a tapped hole, M20 × 1.5 mm takes a 18.5 mm tap drill, and the external thread's minor diameter is 18.16 mm — that is the section carrying the load, not the nominal M20 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.