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Washers · GB/T 95 / ISO 7091

M30 Flat Plain Washer Dimensions & Specifications

M30 Flat Plain Washer Dimensions & Specifications reference image

M30 Flat Plain Washer (GB/T 95 / ISO 7091) are specified by thread size, length and head dimensions. The M30 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.

M30 Dimensional Row (GB/T 95 / ISO 7091)

For bolt sizeInner diameter d1 (mm)Outer diameter d2 (mm)Thickness t (mm)Reference standard
M3031.056.04.0ISO 7089 / GB/T 97.1

Spanner & Drive for M30 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)

Drive geometry for M30 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079) is given by the row above; match the tool to the listed values.

Common Applications for M30 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)

M30 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079) are commonly specified for high-load load-spreading on structural joints.

Installation Tips for M30 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)

  • At M30 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 M30

A M30 flat washer pairs with a M30 bolt/screw and matching M30 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 95 / ISO 7091)

For bolt sizeInner diameter d1 (mm)Outer diameter d2 (mm)Thickness t (mm)Reference standard
M33.27.00.5ISO 7089 / GB/T 97.1
M44.39.00.8ISO 7089 / GB/T 97.1
M55.310.01.0ISO 7089 / GB/T 97.1
M66.412.01.6ISO 7089 / GB/T 97.1
M88.416.01.6ISO 7089 / GB/T 97.1
M1010.520.02.0ISO 7089 / GB/T 97.1
M1213.024.02.5ISO 7089 / GB/T 97.1
M1415.028.02.5ISO 7089 / GB/T 97.1
M1617.030.03.0ISO 7089 / GB/T 97.1
M1819.034.03.0ISO 7089 / GB/T 97.1
M2021.037.03.0ISO 7089 / GB/T 97.1
M2425.044.04.0ISO 7089 / GB/T 97.1
M3031.056.04.0ISO 7089 / GB/T 97.1
M3637.066.05.0ISO 7089 / GB/T 97.1

Frequently Asked Questions

What grip range is typical for M30 structural bolts?

Grip ranges are highly application-dependent at M30. 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 M30?

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 M30 for Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)?

For M30 the standard coarse pitch is 3.5 mm — this is the value used for Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079).

What clearance and tapping drill suit M30?

Use a 33 mm clearance hole (ISO 273 medium) for through-fixing, or a 26.5 mm tapping drill for a coarse M30 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.