Socket head screws
Designation for socket head screws
Socket head screws must be marked with the designation for the property class described in the section entitled Designation system.
Marking is mandatory for screws in property classes 8.8 and higher.The designation should ideally be stamped into the side of the screw head with sunken figures, or on the top of the head with sunken or raised figures.See figure.
Marking is required for socket head screws with a nominal diameter > 5 mm if the shape of the product allows this.The marking should ideally be placed on the screw head.Marking according to the clock face system for nuts according to ISO 898-2 may be used as an alternative method for small socket head screws.
Examples of designations specified on socket head screws. Source: ISO 898