Standards
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 925 12-Point Screws (UNS N09925)
External 12-point flange-head screws ASME B18.2.7M / NAS 1351 — aerospace + tight-access applications
Incoloy 925 12-point screws (UNS N09925) are flange-head fasteners with an external 12-point (double-hex) drive profile under the head, originally developed for aerospace applications where high torque needs to be applied through a tight-access wrench engagement and where the integral flange under the head must distribute clamping load on a thin or fragile mating surface. The 12-point external drive (ASME B18.2.7M / NAS 1351 / IFI 115) gives 50% more wrench-engagement positions than a standard hex (12 vs 6), allowing finer rotational positioning and easier engagement in confined spaces. The integral flange (washer face) eliminates the need for a separate washer. TorqBolt manufactures Incoloy 925 12-point screws in M6 to M30 (1/4" to 1-1/4") sizes ASME B18.2.7M / NAS 1351, in the solution-annealed and aged condition with hardness controlled within the 35 HRC NACE MR0175 sour-service cap.
Need Incoloy 925 12-point screws? Email info@torqbolt.com with diameter × length, thread series, head type, quantity. WhatsApp +91-22-66157017.
12-Point Screw Variants
| Variant | Description | Standard |
|---|---|---|
| 12-point flange-head screw | External double-hex drive + integral washer-face flange | ASME B18.2.7M / IFI 115 |
| NAS 1351 internal 12-point | Aerospace internal 12-point socket-drive (subset variant) | NAS 1351 / NAS 1953 |
| 12-point machine screw (no flange) | External 12-point head without integral flange | Customer drawing |
Standard Size Range
| Diameter | UNC (inch) | Metric Coarse | 12-Pt Wrench Size | Length Range |
|---|---|---|---|---|
| 1/4" / M6 | UNC 20 | M6 × 1.0 | 3/8" / 10 mm | 10 to 80 mm |
| 5/16" / M8 | UNC 18 | M8 × 1.25 | 7/16" / 13 mm | 15 to 100 mm |
| 3/8" / M10 | UNC 16 | M10 × 1.5 | 1/2" / 15 mm | 20 to 120 mm |
| 7/16" / M12 | UNC 14 | M12 × 1.75 | 9/16" / 18 mm | 25 to 150 mm |
| 1/2" / M14 | UNC 13 | M14 × 2.0 | 5/8" / 21 mm | 30 to 180 mm |
| 9/16" / M16 | UNC 12 | M16 × 2.0 | 11/16" / 24 mm | 30 to 200 mm |
| 3/4" / M20 | UNC 10 | M20 × 2.5 | 15/16" / 30 mm | 40 to 250 mm |
| 1" / M24 | UNC 8 | M24 × 3.0 | 1-1/4" / 36 mm | 50 to 300 mm |
| 1-1/4" / M30 | UNC 7 | M30 × 3.5 | 1-9/16" / 46 mm | 60 to 350 mm |
Mechanical Properties (Aged)
Tensile 165 ksi min / Yield 110 ksi min / Elongation 18% min / Hardness 32–35 HRC (NACE cap) / Charpy at -46°C: 40 J min. See full mech properties page.
Applications
- Aerospace structural fasteners (aircraft engine accessory mounting)
- Subsea connector bolting (tight-access deepwater applications)
- Compressor + turbine sour-service casing bolts (tight-access flange + integral washer face)
- High-torque tight-clearance bolted joints where standard hex won't fit
- Wellhead-internal bolting with flange-face load distribution (selective use vs standard hex bolts)
- Heat exchanger flange bolting (where the integral flange replaces a separate washer)
Standards
- ASTM B805, UNS N09925 forging stock
- ASME B18.2.7M, 12-Point Flange Screws (metric series)
- NAS 1351 / NAS 1953, National Aerospace Standard 12-point screws
- IFI 115, Industrial Fasteners Institute 12-point flange screws
- ASME B1.1 / B1.13M, thread series; NACE MR0175 Table A.10; API 6A; EN 10204 3.1 / 3.2
Manufacturing Sequence
- Bar input per ASTM B805 in annealed condition
- Cold / warm upset of 12-point flange head with integral washer-face geometry (specialty die set)
- Shank machining + thread rolling (annealed condition)
- Solution anneal + age cycle per heat-treatment specification
- Final inspection: 12-point head dimensional check, washer-face diameter, thread Go / No-Go, 100% hardness
- Marking: heat number on head face + grade designation + NACE stamp (sour orders)
Frequently Asked Questions
Why 12 points instead of 6? Twelve drive positions allow finer rotational increments and easier wrench engagement in tight spaces, the wrench can be removed and re-engaged at any 30° rotation (vs 60° for a standard hex). Higher peak torque tolerance because the load is distributed across 12 contact surfaces. Originally developed for aerospace where access + torque both matter.
Are 12-point screws interchangeable with hex bolts? No, the wrench engagement is different. A 12-point screw needs a 12-point socket; a standard hex socket will not engage properly. Specify the wrench inventory (12-point vs hex) in the application before substituting.
Lead time? Standard sizes M8 to M16 / 5/16" to 5/8": 6–8 weeks (specialty die setup adds time). Larger / NAS variants: 10–12 weeks.
Documentation Package & Related Products
EN 10204 3.1 MTC (3.2 with TPI on request); chemistry, tensile, 100% hardness, 12-point head dimensional + thread Go/No-Go inspection, NACE MR0175 reference. Related: hex cap screws, socket head cap screws, hex bolts, washers, full datasheet.
Request a Quote
Email info@torqbolt.com · Phone +91-22-66157017 · WhatsApp +91-22-66157017. Specify variant, diameter × length, thread series, quantity, applicable standards (ASME B18.2.7M / NAS 1351), MTC level, coating.
References: ASTM B805; ASME B18.2.7M; NAS 1351 / NAS 1953; IFI 115; ASME B1.1 / B1.13M; NACE MR0175 / ISO 15156-3 Table A.10; EN 10204. INCOLOY® is a registered trademark of Special Metals Corporation.
Satisfaction Survey
