Product Overview
A 12-point flange screw (also known as a 12-point cap screw or counterbore bolt) is a high-performance threaded fastener featuring a unique head design. Instead of a traditional hexagonal or square shape, it incorporates a 12-sided head with an integrated flange base. This design allows for significantly higher torque transmission and a more secure grip compared to standard hex head bolts.
The integrated flange base acts as a built-in washer, effectively distributing the tightening load over a wider surface area and reducing the risk of indentation or damage to the mating component.
Metric 12-point flange screws are widely used in critical industrial applications where safety, high preload, and space constraints are vital — automotive engines, heavy machinery, aerospace structures, high-vibration systems, and marine engineering.
12 Point Flange Cap Screw
Dimensional Reference Drawing
12 Point Screws Specification
| Standard | DIN 6921, ASME B18.2.7.1M, ISO 14583 |
|---|---|
| Size Range | M6 to M20 (Metric) & 1/4" to 1" (Inch) |
| Thread Type | Metric Coarse, Metric Fine, UNC, UNF |
| Steel Grades | 8.8, 10.9 (High Tensile) | SS 304, SS 316, SS 316L (Stainless Steel) |
| Finish Available | Self, Black, Bright Zinc, Hot Dip Galvanized (HDG) |
| Applications | Automotive engines, Aerospace, Heavy Machinery, High-Vibration Pipelines, Power Plants |
Hexagon Flange Bolts — Metric Size Chart (DIN 6921)
Steel Grades: 8.8, 10.9 | Finish: Self, Black, Bright Zinc, Hot Dip Galvanized | All dimensions in mm
| Nom. Dia. (d) | M6 | M8 | M10 | M12 | M14 | M16 | M20 | |
|---|---|---|---|---|---|---|---|---|
| Thread Pitch | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | |
| Thread Length (b) | L < 125mm | 18 | 22 | 26 | 30 | 34 | 38 | 46 |
| 125–200mm | – | 28 | 32 | 36 | 40 | 44 | 52 | |
| L > 200mm | – | – | 45 | 49 | 53 | 57 | 65 | |
| ds | Min. | 6 | 8 | 10 | 12 | 14 | 16 | 20 |
| Max. | 5.82 | 7.78 | 9.78 | 11.73 | 13.73 | 15.73 | 19.67 | |
| K | Max. | 6.6 | 8.1 | 9.2 | 11.5 | 12.8 | 14.4 | 17.1 |
| Flange Diameter | 14.2 | 18 | 22.3 | 26.6 | 30.5 | 35 | 43 | |
| e | Min. | 10.95 | 14.26 | 16.5 | 17.62 | 19.86 | 23.15 | 29.87 |
| s | Min. | 9.78 | 12.73 | 14.73 | 15.73 | 17.73 | 20.67 | 26.67 |
| Max. | 10 | 13 | 15 | 16 | 18 | 21 | 27 | |
Dimensions For 12-Point Flange Bolts (Inch Sizes)
| Nominal Size | Head Width | Flange Diameter | Head Height | ||
|---|---|---|---|---|---|
| Across Flats | Across Corners | ||||
| Fraction | Decimal | Max | Min | Max | Max |
| 1/4 | 0.2500 | 1/4 | 9/32 | 3/8 | 17/64 |
| 5/16 | 0.3125 | 5/16 | 11/32 | 15/32 | 5/16 |
| 3/8 | 0.3750 | 3/8 | 27/64 | 9/16 | 3/8 |
| 7/16 | 0.4375 | 7/16 | 31/64 | 21/32 | 7/16 |
| 1/2 | 0.5000 | 1/2 | 9/16 | 3/4 | 1/2 |
| 9/16 | 0.5625 | 9/16 | 41/64 | 27/32 | 9/16 |
| 5/8 | 0.6250 | 5/8 | 45/64 | 15/16 | 5/8 |
| 3/4 | 0.7500 | 3/4 | 27/32 | 1 1/8 | 3/4 |
| 7/8 | 0.8750 | 7/8 | 63/64 | 15/16 | 7/8 |
| 1 | 1.0000 | 1 | 1 1/8 | 1 1/2 | 1 |
Metric 12 Point Screws Stockists
As a leading stockist & supplier in Mumbai, we stock 12-point screws across all grades and finishes for immediate dispatch.
AISI 302, 304, 304L, 316, 316L, 310, 317, 317L, 321, 347, 410, 420, 904L etc.
ASTM / ASME A815 UNS No. S31803, UNS No. S32205, UNS No. S31254, UNS No. S31550, UNS No. S32750, and UNS No. S 32760
ASTM A307, A193
ASTM / ASME A/SA193 / 194 B 6, B 7 / B 7M, B 16, 2, 2HM, 2H, GR 8, B 7, B 7M
ASTM / ASME SB 160 / 164 / 425 / 166 / 446 / 574 / 472 UNS 2200 (NICKEL 200) / UNS 2201 (NICKEL 201), UNS 4400 (MONEL 400), UNS 8825 (INCONEL 825), UNS 6600 (INCONEL 600) / UNS 6601 (INCONEL 601), UNS 6625 (INCONEL 625), UNS 10276 (HASTELLOY C 276), UNS 8020 (ALLOY 20 / 20 CB 3)
