DIN 931Hexagon headExternal hexagon

DIN 931 M22 × 120 Hexagon head

DIN 931 M22 × 120 is a hexagon head bolt with a 120 mm nominal length, on a M22 × 2.5 mm metric thread. Same head as DIN 933 but with an unthreaded shank under the head. The plain shank carries shear load, which is why these are preferred for structural steelwork and machinery frames.

DIN 931 M22 × 120 — Hexagon headNominal dimensions in mm · Not to scale

Diameter22 mm

Length120 mm

Pitch2.5 mm

Socket size s34 mm

Head height k14 mm

HeadHexagon head

DriveExternal hexagon

Dimensions

Standard: DIN 931
Type: Hexagon head bolt
Size: M22 × 120
Thread: M22 × 2.5
Length L: 120 mm
Socket size s: 34 mm
Head height k: 14 mm
Drive: External hexagon
Head: Hexagon head

Nominal values in millimetres as published in DIN 931. Estimated weight 358.085 g per piece in steel (360.366 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.

Thread data

Full M22 thread page

DesignationM22 × 2.5

Pitch2.5 mm

Nominal Ø22 mm

Pitch Ø20.38 mm

Minor Ø ext18.93 mm

Tap drillØ 19.5 mm

Other lengthsDIN 931 M22

All M22 specifications

M22 × 50 M22 × 60 M22 × 70 M22 × 80 M22 × 100 M22 × 120 M22 × 140 M22 × 160 M22 × 180

Interchangeability

DIN 931 is catalogued with ISO 4014 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.

Equivalent standardISO 4014Hexagon Head Bolt — Partial Thread, Product Grade A/B ComparisonDIN 931 vs ISO 4014Field-by-field differences and a substitution verdict

Choosing and fitting this size

DIN 931 M22 × 120 is a hexagon head in M22, 120 mm long under the head, on a 2.5 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, M22 × 2.5 mm takes a 19.5 mm tap drill, and the external thread's minor diameter is 18.93 mm — that is the section carrying the load, not the nominal M22 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.