ISO 4017 M20 × 30 Hexagon head
ISO 4017 M20 × 30 is a hexagon head bolt with a 30 mm nominal length, on a M20 × 1.5 mm metric thread. ISO version of the full thread hexagon head screw. Head dimensions are dimensionally compatible with DIN 933 for the same nominal size.
Dimensions
- Standard
- ISO 4017
- Type
- Hexagon head bolt
- Size
- M20 × 30
- Thread
- M20 × 1.5
- Length L
- 30 mm
- Socket size s
- 30 mm
- Head height k
- 12.5 mm
- Drive
- External hexagon
- Head
- Hexagon head
Nominal values in millimetres as published in ISO 4017. Estimated weight 73.985 g per piece in steel (74.456 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M20 thread pageOther lengthsISO 4017 M20
All M20 specificationsInterchangeability
ISO 4017 is catalogued with DIN 933 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
ISO 4017 M20 × 30 is a hexagon head in M20, 30 mm long under the head, on a 1.5 mm coarse pitch. Mating threads should be a matching class nut or a tapped hole of the same nominal size.
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.