Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Socket Cap Screws - UNS N04400 DIN 912 / ISO 4762
Monel® 400 socket cap screws (also called Monel 400 socket head cap screws, UNS N04400 Allen bolts, hex socket cap screws or Inco 400 SHCS) carry the cylindrical head plus internal hex drive defined by DIN 912 metric and ISO 4762 metric, with mechanicals from ASTM F468 covering socket head cap screw configurations from size 0 (0.060 in.) through 1.500 in. nominal thread diameter. Chemistry follows ASTM B164 bar stock; the alloy registers as UNS N04400. The screw lands on hydraulic manifolds, instrument valve bonnets, subsea junction boxes and pump-end plates where the bolt circle is too tight for a hex wrench. Monel is a registered trademark of Special Metals Corporation; TorqBolt is not authorized by, affiliated with or endorsed by Special Metals.
Scope of DIN 912 / ISO 4762 for Monel 400
DIN 912 and ISO 4762 are functionally equivalent metric specifications for socket head cap screws with cylindrical head and internal hexagon drive. The cylindrical head sits flush within a counterbored pocket, lower profile than a hex head and far smaller flange diameter than an equivalent hex bolt. Thread per ISO 261 coarse pitch is standard; ISO 262 fine pitch is available on indent. ASTM F468 §4.2.4.2 requires sockets up to 1.00 in. nominal with product length up to 6.00 in. to be roll-threaded; larger sizes may be cut or rolled at producer option. Class 3A UNRC / UNRF threads apply to imperial sizes 0 to 1.000 in.; Class 2A above 1.000 in. through 1.500 in. inclusive.
DIN 912 / ISO 4762 Head and Socket Dimensions
Source: DIN 912 / ISO 4762 nominal dimensions. Head diameter is roughly 1.5 times the thread diameter; head height equals nominal thread diameter. Hex socket size is the across-flats (AF) of the internal drive.
| Thread | Head dia (mm) | Head height (mm) | Hex key AF (mm) | Min key engagement (mm) |
|---|---|---|---|---|
| M3 | 5.5 | 3.0 | 2.5 | 1.3 |
| M4 | 7.0 | 4.0 | 3 | 2.0 |
| M5 | 8.5 | 5.0 | 4 | 2.5 |
| M6 | 10.0 | 6.0 | 5 | 3.0 |
| M8 | 13.0 | 8.0 | 6 | 4.0 |
| M10 | 16.0 | 10.0 | 8 | 5.0 |
| M12 | 18.0 | 12.0 | 10 | 6.0 |
| M16 | 24.0 | 16.0 | 14 | 8.0 |
| M20 | 30.0 | 20.0 | 17 | 10.0 |
| M24 | 36.0 | 24.0 | 19 | 12.0 |
| M30 | 45.0 | 30.0 | 22 | 15.5 |
Size Range and Stocked Lengths
Metric M3 through M30 and imperial 1/4 in. through 1-1/2 in. cover the F468 socket head envelope. Lengths from 6 mm (short M3) up to 200 mm in M30. DIN 912 is partial thread (long shanks have an unthreaded grip section); DIN 7984 is the low-head variant; DIN 6912 is the low-head with central pilot hole for shorter key engagement.
| Thread | Stocked length range (mm) | Tensile area (mm²) | Common pitch (mm) |
|---|---|---|---|
| M3 | 6 to 30 | 5.03 | 0.5 |
| M4 | 6 to 40 | 8.78 | 0.7 |
| M5 | 8 to 50 | 14.2 | 0.8 |
| M6 | 10 to 60 | 20.1 | 1.0 |
| M8 | 12 to 80 | 36.6 | 1.25 |
| M10 | 16 to 100 | 58.0 | 1.5 |
| M12 | 20 to 120 | 84.3 | 1.75 |
| M16 | 25 to 160 | 157 | 2.0 |
| M20 | 30 to 180 | 245 | 2.5 |
| M24 | 40 to 200 | 353 | 3.0 |
| M30 | 50 to 200 | 561 | 3.5 |
F468 Mechanical Floor for Monel 400 SHCS
ASTM F468 Table 2 sets the mechanical floor by alloy and nominal thread diameter. Socket head cap screws are explicitly listed in the F468 scope and meet the full Table 2 values (button head and flat countersunk reduce to 80%). Class A (Ni 400) is weldable; Class B (Ni 405) is free-machining for unwelded joints. Hardness max 25 HRC is tighter than the NACE MR0175 35 HRC ceiling for nickel-copper.
| Marking | Diameter (in) | Hardness | Tensile (ksi) | Tensile (MPa) | Yield min (ksi) | Yield min (MPa) | Elong. |
|---|---|---|---|---|---|---|---|
| F 468U | 0.250 to 0.750 | 75 HRB to 25 HRC | 80 to 130 | 552 to 896 | 40 | 276 | 20% |
| F 468U | 0.875 to 1.500 | 60 HRB to 25 HRC | 70 to 130 | 483 to 896 | 30 | 207 | 20% |
| F 468U4 | 0.875 to 1.500 | 75 HRB to 25 HRC | 80 to 130 | 552 to 896 | 40 | 276 | 20% |
| F 468V (R-405) | all | 60 HRB to 20 HRC | 70 to 125 | 483 to 862 | 30 | 207 | 20% |
Hex Key Drive (Internal Hexagon, Allen Type)
The internal hexagon socket per DIN 912 takes a metric Allen key; standard ISO 2936 long-arm hex keys engage the full socket depth. Drive runout is set by the key engagement depth ("min T" column above) plus a 2-degree taper at the bottom for clearance. Power-tool driving needs a hex bit holder rated for the screw torque rather than a hand key. The cylindrical head and recessed drive let the screw sit flush in a counterbore (per ISO 273 / DIN 974), keeping the assembly geometry flat where a hex head would protrude. Manifold and valve-bonnet bolt patterns rely on this property.
Applications
Instrument hardware on flow-meter bonnets and valve actuators where wrench clearance is unavailable. Naval auxiliary plant: seawater pump end plates, condenser tube-sheet retainer rings, bilge valve bonnets. Pump and valve OEM kits: needle valve packing followers, pressure relief valve internal cap, control valve actuator yoke bolts. Subsea junction boxes and electrical penetrator end caps. Hydraulic manifolds in offshore process modules. Acid service: HF alkylation instrument tap-offs at API RP 751 inspection points; refer to HF acid resistance.
Sour Service Note (NACE MR0175)
F468 caps Monel 400 hardness at 25 HRC across all diameters; the NACE MR0175 / ISO 15156-3 ceiling for nickel-copper alloy bolting is 35 HRC. The socket cap screw clears the hardness gate by design. Verify the H2S partial pressure, chloride concentration and operating temperature against ISO 15156-3 Annex A.4 for the full sour qualification. Sour-service shipments leave Mumbai with EN 10204 type 3.2 mill test certificate plus the NACE MR0175 compliance statement. Detail on sour service applications.
Companion Components and Related Pages
Pair the socket cap screw with a Monel 400 nut to ASTM F467 (hex or lock) and a matched washer to avoid galvanic discontinuity in the clamped joint. For low-profile assemblies use DIN 6912 low-head SHCS; for higher tensile demand on the same socket form, see Monel 400 bolts overview, Monel 400 hex bolts, cap screws overview or stud bolts. Bar stock for the screws is ASTM B164; alloy reference is nickel-copper alloy.
FAQ
What hex key fits an M10 socket cap screw? 8 mm AF per DIN 912 / ISO 4762. M6 takes 5 mm, M8 takes 6 mm, M12 takes 10 mm, M16 takes 14 mm, M20 takes 17 mm. Full table above.
Are socket head cap screws weaker than hex cap screws in F468? No. F468 §6.1 reduces tensile by 20% only for button head and flat countersunk head variants. Socket head cap screws meet the full Table 2 mechanicals.
Are threads rolled or cut? F468 §4.2.4.2 requires rolling for sockets up to 1.00 in. nominal with product length up to 6.00 in. Larger sizes may be rolled or cut at producer option. Class 3A threads up to 1.000 in., Class 2A above.
Does the cylindrical head fit a counterbore? Yes. Use ISO 273 medium fit counterbore for clearance; DIN 974 lists matching counterbore diameters for each thread size.
Request for Quote
Send thread size, length, head form (standard DIN 912, low-head DIN 7984 / 6912), thread class and quantity to info@torqbolt.com or WhatsApp +91-22-66157017. Ex-Mumbai price and lead time returned within one working day. Domestic India 3 to 7 working days; export through JNPT with EN 10204 type 3.2 certification and NACE MR0175 compliance statement on request.
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