Buyers regularly ask whether a DIN 933 bolt can be swapped for a GB/T 5783 or an ISO 4017 part. On paper all three describe the same thing. In practice four things decide it, and one of them is not negotiable.
Same part, three designations
| Designation | System | What it specifies |
|---|---|---|
| DIN 933 | German | Hexagon head bolt, fully threaded. Withdrawn and superseded by DIN EN ISO 4017, but still how the part is ordered in most of Europe and Asia. |
| ISO 4017 | International | Hexagon head screws, threads from M1.6 to M64, product grades A and B. The current global reference. |
| GB/T 5783 | Chinese | Hexagon head bolts, full thread. Aligned with ISO 4017 in dimensions and tolerance classes. |
| GOST 7798-70 / 7805-70 | Russian / EAEU | Hexagon head bolts, normal and high accuracy respectively. Widely used in Russia, Kazakhstan and Belarus. |
All four are hexagon head screws with a thread running the full length of the shank. What differs is the tolerance class, the head geometry in detail, the marking, and the certification that comes with the part.
What to compare, in order
- Thread tolerance. Ordinary commercial stock is 6g for the external thread. A part made 6h will not assemble reliably with a 6H nut; if you are matching threads across systems, check the pair, not just the bolt.
- Property class. Class 8.8 is 800 MPa tensile and 640 MPa proof; class 4.8 is 400/320. The class is a strength claim, and it is the first thing to compare when substituting — a bolt that is dimensionally identical can be half as strong.
- Head geometry. Across-flats and head height are standardised per size, but product grade A (small sizes, tighter tolerances) and grade B (larger sizes) differ, and so do chamfer and under-head fillet details. On automated assembly or where a socket clearance is tight, this matters.
- Marking and certification. A property-class 8.8 bolt must carry the class mark and the manufacturer’s identification. Regulated work — structural steelwork, lifting equipment, pressure equipment, rail — usually names the standard on the drawing, and substituting a different designation is then a deviation that has to be approved, not a purchasing decision.
Where substitution is routine
General engineering, machine guards and covers, brackets, jigs, furniture, enclosures, and any joint that is designed on the bolt’s nominal dimensions with a conventional safety margin. In these cases an ISO 4017 part from a reputable mill serves as a DIN 933 bolt without discussion.
Where it is not
Anything where the drawing or the specification names a standard: structural connections, lifting and rigging, pressure equipment, automotive safety parts, and anything going into an inspection regime that requires traceability to a named standard. There, use the designation on the drawing, and take the mill certificate with the batch.
Fully threaded or partly threaded?
Do not confuse the full-thread family with its partial-thread relatives. DIN 931, ISO 4014 and GB/T 5782 are hexagon head bolts threaded to roughly 2×d plus a few pitches. The partial-thread part puts the unthreaded shank in shear, which is what you want in a bearing-type connection; the fully threaded DIN 933 part is the general-purpose choice and lets you use a shorter bolt for a given grip length.
Buying them
We stock the full-thread hexagon head bolt family in 304 and 316 stainless and in grade 8.8 and 10.9 steel, from M1.6 upwards, sold by the piece. The complete size matrix is on the DIN 933 specification page, and the cross-system equivalents are listed on the equivalents table. If you need a designation we do not list, ask — we produce small batches to drawing.