This document specifies the mechanical and physical properties of flat washers made of corrosion resistant austenitic, ferritic and duplex stainless steels, designed to be used in bolted joints in combination with bolts, screws, studs and nuts with specified grades and property classes in accordance with ISO 3506-1 and ISO 3506-2.


These types of washers are also used with other stainless steel fasteners such as screws forming their own mating thread (see e.g. ISO 3506-4).


ISO 3506-6 provides general rules and additional technical information on suitable stainless steels and their properties (detailed properties of stainless steel grades, corrosion behaviour with regards to pitting, crevice and intergranular corrosion, magnetic properties, etc.)


WARNING — Washers conforming to the requirements of this document are tested at the ambient temperature range of 10 °C to 35 °C and are used in applications ranging from –20 °C to +150 °C. However, these washers are also used outside this range down to –196 °C and up to +300 °C for specific applications. It is possible that they do not retain the specified mechanical and physical properties at lower and/or elevated temperatures. Therefore, it is the responsibility of the user to determine the appropriate choices based on the service environment conditions of the assembly (see also Clauses 6 and 7).


This document applies to the following flat non-captive and captive washers with thickness 0,2 mm to 6 mm (see 5.1):


—     plain washers and flat washers (with or without knurls, ribs or chamfers),


—     square washers,


—     square hole washers,


—     shaped plates.


The term “washer” is used in the following for all types of washers and plates within the scope of this document.


This document does not specify requirements for functional properties such as weldability.