This standard BS EN ISO 21670:2014 Fasteners. Hexagon weld nuts with flange is classified in these ICS categories:
21.060.20 Nuts
This International Standard specifies characteristics for hexagon weld nuts with flange, with sizes M5 to M16 (coarse thread) or D = 8 mm to 16 mm (fine pitch thread), of product grade A.
Weld nuts conforming to this International Standard are suitable for use with bolts of property classes up to 10.9 according to ISO 898-1.