Correct hardness and strength-class matching helps reduce thread damage and preload variation.
Check the matching grades
Match the nut class to the bolt grade according to the applicable standard. For DIN or ISO assemblies, confirm the compatible classes on the drawing or purchase order.
Before ordering
- State the bolt and nut standard and class.
- Confirm coating and thread fit.
- Request material and inspection documents when required.
For stainless or special applications, review corrosion, temperature, and galling requirements separately.
For a practical line-by-line comparison, see the GB/T 5782 hexagon head bolt, DIN 933 fully threaded hex bolt and nylon-insert lock nut pages. Confirm the complete assembly specification with the hardware team before ordering.