Pick the part and enter the thread size, a designation, a spanner size or a hex key. A width measured across the flats goes in the field below: the finder reads it within 0.4 mm on a hex head or nut and 0.2 mm on a hex socket, and with a thread size it shows whether the part is to ISO or to DIN at M10, M12, M14 and M22, where the two differ. Below, an offered part can be checked against the result.
On the designation alone: the length, property class and coating are checked separately.
Hex head bolts, nuts and socket head cap screws hold pump covers, valve bonnets, engine fittings and deck machinery all over a ship, and older parts to DIN sit next to newer ones to ISO. Enter the thread size with or without the standard (M12, ISO 4017 M12, DIN 934 M10), a spanner size (AF 19, SW 24) or a hex key (hex key 8): the finder gives s to ISO and to DIN, flags where they differ, draws the head to scale, checks an offered part and writes an RFQ line.
The length, property class and coating do not follow from the spanner size: give them in the request. Sizes below M3 and above M36, inch sizes and other standards are not in this finder.
The spanner size s is the distance between two opposite flats of the hex head or nut, measured with a caliper square to the flats. A worn head measures a little under the nominal size, so the finder reads a measured width within 0.4 mm as the nominal one.
ISO 4017, ISO 4014 and ISO 4032 replaced DIN 933, DIN 931 and DIN 934. The thread stayed the same; the width across flats changed at four sizes: M10 16 mm (DIN 17), M12 18 (19), M14 21 (22) and M22 34 (32).
A socket head cap screw to ISO 4762 or DIN 912 takes a hex key in the head. Its s is the width across the flats of the socket; ISO and DIN give the same key for every size both list.
| Thread | Head ISO 4017, 4014 | Head DIN 933, 931 | Nut ISO 4032 | Nut DIN 934 | Hex key ISO 4762 | Hex key DIN 912 |
|---|---|---|---|---|---|---|
| M3 | 5.5 | 5.5 | 5.5 | 5.5 | 2.5 | 2.5 |
| M4 | 7 | 7 | 7 | 7 | 3 | 3 |
| M5 | 8 | 8 | 8 | 8 | 4 | 4 |
| M6 | 10 | 10 | 10 | 10 | 5 | 5 |
| M8 | 13 | 13 | 13 | 13 | 6 | 6 |
| M10 | 16 | 17 | 16 | 17 | 8 | 8 |
| M12 | 18 | 19 | 18 | 19 | 10 | 10 |
| M14 | 21 | 22 | 21 | 22 | 12 | 12 |
| M16 | 24 | 24 | 24 | 24 | 14 | 14 |
| M18 | 27 | 27 | 27 | 27 | — | 14 |
| M20 | 30 | 30 | 30 | 30 | 17 | 17 |
| M22 | 34 | 32 | 34 | 32 | — | 17 |
| M24 | 36 | 36 | 36 | 36 | 19 | 19 |
| M27 | 41 | 41 | 41 | 41 | — | 19 |
| M30 | 46 | 46 | 46 | 46 | 22 | 22 |
| M33 | 50 | 50 | 50 | 50 | — | 24 |
| M36 | 55 | 55 | 55 | 55 | 27 | 27 |
All sizes nominal, in millimetres: s across the flats of the head or nut, and across the flats of the socket for the hex key. Marked: the sizes where ISO and DIN differ. A dash: the standard has no such size (ISO 4762 has no M18, M22, M27 or M33). A value is given only where two independent tables agree; rows that only one source lists are left out, and for the sizes in this finder the sources agreed. Tolerances are not given.
Every value in the table appears in two independent published tables of the standard, and is left out where they differ. The four ISO and DIN differences are also in a note on the change from DIN to ISO published by a distributor.
Because the bolt is to ISO 4017 or ISO 4014, not to the older DIN 933 or DIN 931. At M10, M12, M14 and M22 the ISO standards changed the width across flats: M10 16 mm instead of 17, M12 18 instead of 19, M14 21 instead of 22, and M22 34 instead of 32. The thread is the same; only the spanner changes. Nuts changed in the same way, ISO 4032 against DIN 934. Every other size from M3 to M36 is the same in both.
For the thread, yes: the size and the coarse pitch are the same. At M10, M12, M14 and M22 the head takes a different spanner, so a ring spanner or socket from the engine-room tool kit may no longer fit. DIN 933, DIN 931, DIN 934 and DIN 912 are withdrawn and replaced by ISO 4017, ISO 4014, ISO 4032 and ISO 4762, but parts to DIN are still widely sold. Give the standard in the request, or the measured width across flats.
ISO 4762 and DIN 912 give the same key for every size both list: 2.5 mm for M3, 5 mm for M6, 8 mm for M10, 10 mm for M12, 14 mm for M16, 17 mm for M20, 19 mm for M24, 22 mm for M30 and 27 mm for M36. ISO 4762 has no M18, M22, M27 or M33; DIN 912 gives them keys of 14, 17, 19 and 24 mm. One key can fit two screw sizes, so measure the thread as well.
Enter the spanner size (AF 19, SW 24, or just 19), or measure across two opposite flats of the head or nut with a caliper. The finder reads a measured width within 0.4 mm as the nearest nominal size and lists the bolts and nuts that take it under ISO and under DIN. A 19 mm spanner fits only a DIN size (M12), an 18 mm spanner only an ISO size (M12).
The standard and the size (ISO 4017 M12, DIN 934 M10, ISO 4762 M8), the spanner size at M10, M12, M14 and M22, where ISO and DIN differ, the length of a bolt or screw, the property class (8.8, 10.9, 12.9, A2-70, A4-80), the coating and the quantity, with a photograph of the old part beside a ruler.
A row of the standard is a cross-check of sizes, not a part selection. Attach the photograph and your measurements, and Vessel Core checks them before an offer goes back.
