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Washers · GB/T 858

M20 Tab Lock Washer for Round Nut Dimensions & Specifications

M20 Tab Lock Washer for Round Nut Dimensions & Specifications reference image

M20 is one of the standard coarse-thread sizes for tab lock washer for round nut under GB/T 858. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.

M20 Dimensional Row (GB/T 858)

For shaft / nut sizeInner diameter d1 (mm)Outer diameter d2 (mm)Thickness t (mm)Tab length (mm)Reference standard
M2020.5381.512GB/T 858

Spanner & Drive for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 073)

Drive geometry for M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 073) 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 073)

M20 Tab Lock Washer for Round Nut — GB/T 858 (Series 073) 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 073)

  • 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.

Mating Parts for M20

A M20 flat washer pairs with a M20 bolt/screw and matching M20 nut.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

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Adjust the parameters in the drawing above and click "Request this configuration" to send the exact specification straight to this form.

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Specification
Business Information

Dimensions & Specifications (GB/T 858)

For shaft / nut sizeInner diameter d1 (mm)Outer diameter d2 (mm)Thickness t (mm)Tab length (mm)Reference standard
M1010.5211.08GB/T 858
M1212.5251.09GB/T 858
M1616.5301.010GB/T 858
M2020.5381.512GB/T 858
M2424.5451.514GB/T 858
M3030.5551.516GB/T 858
M3636.5652.018GB/T 858
M4848.5852.020GB/T 858
M6060.51052.524GB/T 858

Frequently Asked Questions

What grip range is typical for M20 structural bolts?

Grip ranges are highly application-dependent at M20. As a guide, choose a length that gives at least 1× the thread diameter engagement in the nut plus 2–3 thread pitches projecting.

Which washer dimensions matter most for M20?

For a flat washer, the outside diameter (the bearing surface) and the thickness control how the load is spread under the head and how much elastic preload is preserved. The inside diameter must clear the bolt body but not be so large that the head bears mostly on the washer's outer rim.

What is the coarse-thread pitch of M20 for Tab Lock Washer for Round Nut — GB/T 858 (Series 073)?

For M20 the standard coarse pitch is 2.5 mm — this is the value used for Tab Lock Washer for Round Nut — GB/T 858 (Series 073).

What clearance and tapping drill suit M20?

Use a 22 mm clearance hole (ISO 273 medium) for through-fixing, or a 17.5 mm tapping drill for a coarse M20 thread.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.