DANSK DS/EN 3016 PDF

This standard specifies the characteristics of heat resisting steel, countersunk, load spreading washers for use in aerospace applications at temperatures not exceeding 650 °C.
They are intended primarily for use under the head of bolts with strength classification up to 1 250 MPa. They are used to provide sufficient bearing area to prevent indentation of parent metals with low compressive strength at operating temperatures, thus ensuring no relaxation in the bolt load occurs.