DIN 912 / ISO 4762 socket head, ASME B18.3 inch series, hex (Allen) drive for confined-access bolting
A socket-head cap screw is the right choice when wrench clearance is too tight for an open hex bolt head, when a counterbored seat is required to keep the screw flush with the surface, or when the joint design calls for a hex-drive recess and a cylindrical head profile. Tooling fixtures, hydraulic manifold blocks, valve actuator mounts, instrumentation manifolds, and subsea ROV-friendly fastener assemblies all use SHCS. Ferralium 255 (UNS S32550, EN 1.4507) socket-head cap screws meet DIN 912 / ISO 4762 metric and ASME B18.3 inch dimensional, with hardness ≤ 32 HRC and ferrite content 35 to 55% for NACE MR0175 / ISO 15156-3 Table A.10 sour-service. Per-heat EN 10204 type 3.2 MTC. RFQ: info@torqbolt.com / WhatsApp +91-22-66157017.
| Standard | Region | Size range | Drive |
|---|---|---|---|
| DIN 912 / ISO 4762 | EU, ISO metric | M2 to M64 | Hex socket (Allen) |
| ASME B18.3 SHCS | US, inch | #0 to 4" | Hex socket |
| DIN 7984 (low-head) | EU, low-profile | M3 to M30 | Hex socket, reduced head height |
| DIN 6912 (low-head with key guide) | EU, captive-key | M3 to M24 | Hex socket with internal key recess |
| DIN 7991 / ISO 10642 (countersunk) | EU, flat-head | M2.5 to M30 | Hex socket, 90° countersink |
For ASME flange bolting through stud-bolt holes prefer hex bolts or stud-and-nut assemblies. SHCS is correct for: (a) machined components where the head sits in a counterbored recess flush with the surface, (b) hydraulic and pneumatic manifold blocks where the bolt head must clear a port boss, (c) tooling fixtures and machine-tool bedplate fixings, (d) electrical enclosures where a low-profile fastener is preferred for both aesthetics and tamper resistance, (e) subsea instrumentation pods where hex-bit ROV tools deliver torque from above.
Per-heat EN 10204 type 3.2 MTC: chemistry per ASTM A479 / DIN EN 10088-3, mechanical properties per ASTM E8 / EN ISO 6892, hardness traverse, ferrite-content per ASTM E562, NACE MR0175 conformance with Table A.10 reference. Marking on the screw head: manufacturer ID, ISO grade or A4-80 equivalent strength class, heat number traceability.
