ST Trading supplies bolts to DIN and ISO standards – with hexagon, socket cap, countersunk, button and cup heads, in coarse and fine thread. The table helps you specify the right standard in your enquiry. Standards in our range Standard Description DIN 931 Hexagon head bolt, partial thread DIN 933 Hexagon head screw, full thread DIN 960 / DIN 961 Hexagon head bolt, fine thread (partial / full) DIN 6921 Hexagon flange bolt DIN 912 Hexagon socket head cap screw DIN 7984 Hexagon socket thin head cap screw DIN 7991 Hexagon socket countersunk head screw ISO 7380-1 / ISO 7380-2 Hexagon socket button head screw (without / with flange) DIN 603 Cup head square neck bolt (coach bolt) Dimensions and weights for each standard are listed in the PDF catalogue, which also covers hexagon socket set screws (DIN 913–916). Catalogue Download PDF catalogue Need a quote? Send us your list of parts (standard, size, quantity) or a drawing and we will get back to you. Request a quote How to choose a bolt Start with the joint documentation: standard, diameter, thread pitch and length. The thread must match the nut or tapped hole – coarse and fine threads of the same diameter are not interchangeable. Also check whether a full or partial thread is required. Head type depends on the installation space, the available tool and the bearing surface. A hexagon head needs spanner access, a socket head can be tightened along the bolt axis, and a countersunk head needs a properly prepared countersink. Property class (e.g. 8.8, 10.9, 12.9) describes the mechanical properties of a carbon steel bolt, not its corrosion resistance. It should follow the joint design – a higher class is not automatically a better substitute, as it affects nut selection and tightening conditions. Material and coating should suit moisture, temperature, chemical exposure and the materials being joined. Coatings differ in corrosion protection and in their effect on friction during tightening. Stainless steel bolts use a different marking system from carbon steel bolts. Frequently asked questions What information should a bolt enquiry include? Standard, diameter, thread pitch, length, property class, material or coating and quantity. For non-standard parts, describe them in your message – drawings can be sent to the e-mail address on the contact page. Are bolts of the same diameter interchangeable? Not always – thread pitch, length, head geometry and required mechanical properties must also match. A similar appearance does not confirm interchangeability. How is bolt length measured? For most bolts, length is measured from the underside of the head to the end of the shank. For countersunk bolts the length includes the head. Does a higher property class mean a better bolt? No – the class should match the joint design and the mating parts. Changing the class may require re-checking the nut, tightening torque and loads.
