How are flange bolts classified by grade?

Flange bolts are a class of fasteners consisting of a hexagon and a flange (the gasket under the large-horn head is fixed with the hexagon) and a screw (a rod with an external screw). The national standard is GB5785. / 5789, steam standard Q184, German standard DIN6921, Japanese standard J1SB.1189 and other standard parts, the hexagonal head is divided into two types of flat brain and concave brain, flange type according to the use of different positions, its outer circle The diameters vary, and the bottom has flat surfaces and spurs, and they have a non-slip effect. The rod part is divided into many types according to customer requirements, such as: thick rods, thin rods, reducing diameters, through holes in rods, rod Face-to-face horizontal holes, etc., are classified into 8.8, 10.9, and 12.9 levels, and the surface treatment has ordinary electroplating and environmental protection galvanization according to different positions. Army Green, Dacromet, etc. Alias: flange screw. Flange screws. With pad screws.