MILD STEEL

Common standards for mild steel washers include DIN 125 (or the more recent ISO 7089) and BS4320 which specifies the dimensions and tolerances for metric flat washers.

Key Metric Standards

  • DIN 125 (Form A): The most widely used standard for mild steel washers. It defines a circular flat washer with a central hole for distributing loads.
  • ISO 7089: The international replacement for DIN 125 Type A. Mild steel versions are usually 200 HV, suitable for use with bolts up to property class 8.8.
  • BS 4320: A British standard specifically for metric washers.

Forms A, B, C and D are “bright” washers and forms E, F, and G are designated as "black" mild steel washers.

In the UK and Europe, washers are often classified into "Forms" which determine their specific proportions:

Form

Description

Use Case

Form A

Normal diameter, normal thickness

General purpose engineering

Form B

Normal diameter, light thickness

Light-duty applications

Form C

Large diameter, normal thickness

Marine decks and cleats

Form G

Largest diameter and extra thickness

Heavy-duty load spreading

 

MILD STEEL
METRIC

METRIC
IMPERIAL

IMPERIAL