M27 Washer Dimensions & Size

M27 washer dimensions are standardized for extreme-load industrial and structural applications, including heavy bridge construction, power plant foundations, large-scale maritime engineering, and heavy manufacturing equipment. Specifically designed for fasteners with a 27 mm nominal diameter, these components ensure stable load distribution and protect mating surfaces from damage during high-torque tightening. This chart covers Form A plain washers, which feature a flat surface without a chamfer (unlike Form B).

M27 size is commonly available under the Normal Series (DIN 125A / ISO 7089), which is the primary standard for general heavy-duty engineering. Based on these standards, M27 washers typically feature a hardness of 200 HV or 300 HV (Vickers Hardness), providing the structural integrity required to prevent “cupping” or deformation under the massive clamping forces of high-tensile structural bolts.

Note: While these values reflect standard manufacturer datasheets, actual dimensions and tolerances may vary based on material (e.g., Stainless Steel vs. Hot-Dip Galvanized Steel) and manufacturing class. Always verify with the official product datasheet for critical applications.

Washer dimension diagram showing inner diameter, outside diameter, and thickness
M27 Standard Series Washer – DIN 125A/ISO 7089
Dimension Size (mm)
Min Max
Inner Diameter 28 28.33
Outside Diameter 49.38 50
Thickness 3.7 4.3
  • Inner Diameter – The diameter of the hole, designed to clear the bolt/screw thread.
  • Outside Diameter – The total width of the washer, determining the load distribution area.
  • Thickness – The height of the washer, providing the spacing and structural support.
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Frequently Asked Questions

What does the “M27” designation mean on a washer?

The “M” stands for Metric, and the number represents the nominal thread diameter of the screw or bolt. An M27 washer is designed specifically for fasteners with a 27 mm nominal major diameter.

What is the difference between Form A and Form B washers?

The difference lies in the outer edge finish. Form A washers have a square, flat edge and are the most common. Form B washers include a 30° to 40° chamfer (beveled edge) on one side, according to DIN 125B and ISO 7090 standards.

What standard is used for M27 washers?

M27 washers in this technical guide follow the Normal Series (DIN 125A / ISO 7089) standard. This is the most common specification for flat washers used with standard hexagon bolts and nuts in structural steelwork.

What does the HV rating mean on a washer?

HV stands for Vickers Hardness. For M27 fasteners, a rating of 200 HV or 300 HV is typical for steel and stainless steel. This ensures the washer resists the intense indentation forces generated during the high-torque installation of large structural bolts.

In which materials are M27 washers commonly available?

M27 washers are most frequently produced in Hot-Dip Galvanized Steel for outdoor structural applications due to superior corrosion resistance. They are also available in A4 (316) Stainless Steel for marine environments and Plain (Black) Steel for heavy machinery.