Dimensional and assembly data for M20 Tab Lock Washer for Round Nut to GB/T 858. Includes head size and width across flats, clearance-hole and tapping-drill diameters, tightening torque per property class, and the sizes to step up or down to when the joint requires it.
M20 Dimensional Row (GB/T 858)
| For shaft / nut size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Tab length (mm) | Reference standard |
|---|---|---|---|---|---|
| M20 | 20.5 | 38 | 1.5 | 12 | GB/T 858 |
Spanner & Drive for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 089)
Drive geometry for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 089) is given by the row above; match the tool to the listed values.
Common Applications for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 089)
M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 089) are commonly specified for high-load load-spreading on structural joints.
Installation Tips for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 089)
- At M20 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
When to Step Up or Down from M20
When the joint preload approaches the proof load of M20 class 8.8, step up to M24 class 8.8 (or move to M20 class 10.9). When the joint is over-specified, M16 often saves weight and cost without losing the safety margin.