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 Cap Screws - Hex, Socket, Button & Flat Head, ASTM F468
Monel® 400 cap screws, also called UNS N04400 cap screws, nickel-copper alloy cap screws, alloy 400 cap screws and 2.4360 cap screws, are externally threaded fasteners with a controlled bearing surface under the head, designed to be torqued against a tapped hole or a mating nut. The product is covered by ASTM F468/F468M across hex cap, socket head cap, button head and flat countersunk head configurations; chemistry comes from ASTM B164 bar; the alloy registers as UNS N04400. Monel is a registered trademark of Special Metals Corporation; TorqBolt is not authorized by, affiliated with or endorsed by Special Metals.
Cap Screw Subtypes Covered
F468 groups every Monel 400 cap screw configuration under one mechanical envelope. The head form determines installation method, the drive determines wrench access, and the marking determines the F468 mechanical row that applies on a mill test certificate. The five subtypes stocked in UNS N04400 are listed below.
| Subtype | Head form standard | Drive | F468 marking row | Tensile floor |
|---|---|---|---|---|
| Hex cap screw | ASME B18.2.1 / ISO 4014 | External hex | F 468U / F 468U4 | Full F468 Table 2 |
| Socket head cap screw | DIN 912 / ISO 4762 | Hex socket (Allen) | F 468U / F 468U4 | Full F468 Table 2 |
| Button head cap screw | ISO 7380-1 | Hex socket (Allen) | F 468U | 80% of F468 Table 2 |
| Flat countersunk cap screw | DIN 7991 / ISO 10642 | Hex socket (Allen) | F 468U | 80% of F468 Table 2 |
| Pan head cap screw | DIN 7985 / ISO 7045 | Phillips / Torx / slotted | F 468V (small-dia) | 80% of F468 Table 2 |
Hex Cap Screw (Most Common Form)
The hex cap screw is the workhorse Monel 400 fastener: external six-point head, washer face under the bearing surface, indented top marking, controlled head height per ASME B18.2.1. The dimensional class is tighter than a commercial hex bolt and the bearing surface is concentric to the thread axis. This makes it the preferred form for HF alkylation flanges, marine bulkhead joints, and any application where the bolt is torqued against a milled bearing surface. Procurement detail and torque reference on the Monel 400 hex bolts page.
Socket Head Cap Screw (Allen Drive)
The socket head cap screw replaces the external hex with an internal hex recess driven by an Allen key. Head outside diameter is smaller than the hex form, allowing close packing on flange bolt circles where wrench clearance is limited. DIN 912 / ISO 4762 governs the head and recess geometry; the same F468 mechanical row (F 468U / F 468U4) applies on certification. Button head (ISO 7380) and flat countersunk (DIN 7991) cap screws share the Allen recess but use a domed or conical head respectively. Full procurement detail is on the Monel 400 socket cap screws page.
Size Range and Threading
Hex cap screws span 0.250 in. through 1.500 in., the full ASTM F468 envelope. Socket head, button head, flat countersunk and pan head configurations start at size 0 (0.060 in.) and run through 1.500 in. on the same F468 chemistry. Threading per ASME B1.1 UNC and UNF on imperial; ISO 261 coarse pitch and ISO 965 fine pitch on metric. Fully threaded form per DIN 933 and partial thread per DIN 931 are both stocked for the hex variant.
| Diameter (in / metric) | Hex cap | Socket head cap | Button head | Flat countersunk |
|---|---|---|---|---|
| #0 to #10 / M2 to M5 | not made | stock | stock | stock |
| 1/4 / M6 | stock | stock | stock | stock |
| 3/8 / M10 | stock | stock | stock | stock |
| 1/2 / M12 | stock | stock | stock | stock |
| 5/8 to 3/4 / M16 to M20 | stock | stock | indent | indent |
| 7/8 to 1 / M22 to M24 | stock | indent | not made | indent |
| 1-1/4 to 1-1/2 / M30 to M40 | stock | indent | not made | not made |
F468 Mechanical Floor for UNS N04400 Cap Screws
F468 sets the mechanical floor for Monel 400 cap screws by nominal thread diameter and head form. Hex cap screws and socket head cap screws are tested to full F468 Table 2 values. Button head and flat countersunk head cap screws meet 80 percent of the listed tensile values on full-size testing per F468 section 6.1. Hardness ceiling is 25 HRC across all Monel 400 cap screw configurations, tighter than the NACE MR0175 35 HRC nickel-copper sour service ceiling. Source: ASTM F468/F468M-2016 Table 2.
| F468 marking | Diameter (in) | Hardness | Tensile (ksi) | Tensile (MPa) | Yield min (ksi) | Yield min (MPa) |
|---|---|---|---|---|---|---|
| F 468U (hex, socket) | 0.250 to 0.750 | 75 HRB to 25 HRC | 80 to 130 | 552 to 896 | 40 | 276 |
| F 468U (hex, socket) | 0.875 to 1.500 | 60 HRB to 25 HRC | 70 to 130 | 483 to 896 | 30 | 207 |
| F 468U4 (hex, socket) | 0.875 to 1.500 | 75 HRB to 25 HRC | 80 to 130 | 552 to 896 | 40 | 276 |
| F 468HF (HF alkylation) | all | 60 to 95 HRB | 70 to 120 | 483 to 827 | 30 | 207 |
| F 468V (Ni 405 free-machining) | all | 60 HRB to 20 HRC | 70 to 125 | 483 to 862 | 30 | 207 |
| Button / flat countersunk | all | per parent row | 80% of parent row | 80% of parent row | per parent row | per parent row |
Applications
Monel 400 cap screws ship into four service environments. HF alkylation refinery units use the F 468HF marking against API RP 751 inspection across the 70 to 95 percent acid concentration band. Marine bulkhead and naval ship-hull joints use socket head cap screws for flush installation; flowing seawater corrosion stays below 0.025 mm/yr at 30 deg C. Sour gas wellhead and Christmas-tree bolting uses the F 468U marking, with the 25 HRC hardness cap satisfying NACE MR0175 / ISO 15156-3 Annex A.4. Non-magnetic naval and electronic enclosures use any F468 cap screw form, with magnetic permeability below 1.05 mu/mu0. Cross-references: HF alkylation, marine applications, HF acid resistance.
Companion Components
Monel 400 nuts to ASTM F467 pair with every cap screw configuration: hex nuts, heavy hex nuts, lock nuts. Washers in DIN 125, DIN 9021, DIN 127 and DIN 6798 forms hold the bearing surface flat under the head. Matching the nut and washer chemistry to UNS N04400 prevents galvanic discontinuity inside the clamped joint. Stud and rod alternatives on the stud bolts and threaded rod pages.
Frequently Asked Questions
What is the difference between a Monel 400 hex bolt and a hex cap screw? Both have a six-sided head. The hex cap screw has a tighter dimensional and finish standard (washer face, controlled bearing surface, indented head marking) and is torqued against a tapped hole or nut. The hex bolt is the looser commercial form. Both are covered by ASTM F468 in UNS N04400.
Does ASTM F468 cover socket head cap screws in Monel 400? Yes. F468/F468M-2016 explicitly covers hex cap screws (0.250 to 1.500 in.) and socket head cap screws including socket head cap, button head and flat countersunk head configurations from size 0 (0.060 in.) through 1.500 in.
Are Monel 400 cap screws NACE MR0175 sour service compliant? Yes. F468 caps hardness at 25 HRC, below the NACE MR0175 / ISO 15156 ceiling of 35 HRC for nickel-copper bolting. Mill test certificate type EN 10204 3.2 plus a written NACE compliance statement ship with sour-service orders.
What drives are available? Hex cap screws use an external hex wrench. Socket head, button head and flat countersunk cap screws use a hex socket (Allen) per DIN 912, ISO 7380 and DIN 7991 respectively. Slotted, Phillips and Torx drives stock only on indent for pan head cap screws below M6.
Related Pages
Related Monel 400 fastener pages: socket cap screws, hex bolts, screws, ASTM F468 specification, bolts overview, stud bolts, heavy hex bolts, fasteners hub. Material reference on the Monel 400 home page and UNS N04400 reference.
Request a Quote
Send diameter, length, thread (UNC / UNF / metric), head form (hex cap / socket / button / flat countersunk / pan), applicable F468 marking row 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. EN 10204 type 3.2 mill test certificate plus NACE MR0175 compliance statement included with every sour-service shipment.
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