Allen Cap Screws
What are Allen Cap Screws?
Allen Cap Screws, also known as socket head cap screws, are high-strength fasteners designed with a cylindrical head and internal hex drive. These screws are tightened using an Allen (hex) key, allowing for a secure and flush fit even in tight or recessed spaces. Their clean, compact design makes them ideal for machinery, automotive, electronics, and structural applications requiring precision and aesthetics.
Allen Cap Screws are widely used in high-torque and high-performance environments due to their superior clamping force and space-efficient profile.
Key Features
High
Grip
Durable
Construction
Easy Installation
& Removal
Wide
Compatibility
Corrosion
Resistant
Specifications
| Specification Category | Parameter / Feature | Details / Options |
|---|---|---|
| Size Range | Nominal Diameter | M3 to M64 (Custom sizes available) |
| Length Range | 6 mm to 500 mm (depending on diameter) | |
| Pressure Ratings | ANSI / ASME Class | Suitable for bolted connections in Class 150, 300, 600, 900, 1500, 2500 piping systems |
| PN Ratings | PN6, PN10, PN16, PN25, PN40, PN64 | |
| Product Types | Head Types | Socket Head Cap Screw, Button Head, Flat Head, Low Head, Countersunk |
| Thread Types | Metric (Coarse & Fine), UNC, UNF, BSW, BSF | |
| Drive Type | Hexagonal Socket (Allen key) | |
| Material Options | Carbon Steel | Grade 8.8, 10.9, 12.9 (Hardened & Tempered) |
| Stainless Steel | A2-70, A4-70, A4-80 | |
| Alloy Steel | Black Oxide, Phosphate Coated | |
| Special Alloys | Brass, Titanium, Inconel, Duplex & Super Duplex | |
| Standards & Certifications | ASTM | ASTM A574 (Alloy Steel), ASTM F835 |
| ISO / DIN | ISO 4762, ISO 7380, DIN 912, DIN 7991 | |
| BS / ANSI | BS 4168, ANSI B18.3 | |
| Certifications | ISO 9001, CE, RoHS, PED 2014/68/EU | |
| Design Features | Head Style | Cylindrical with recessed hex drive |
| Threading | Full Thread / Half Thread (as per requirement) | |
| Tolerance | As per ISO 4759, DIN, ASME standards | |
| Coating & Surface Finish | Standard Coatings | Black Oxide, Zinc Plated, Hot Dip Galvanized |
| Optional Coatings | PTFE, Geomet, DACROMET, Nickel Plating | |
| Surface Finish | Bright, Polished, Plain, Phosphated | |
| Testing & Inspection | Mechanical Testing | Tensile Strength, Hardness, Shear Test |
| Non-Destructive Testing | MPI (Magnetic Particle Inspection), Ultrasonic | |
| Destructive Testing | Wedge Tensile, Head Soundness, Proof Load |
Dimensions
| Nominal Size (d) | Pitch (P) | Head Diameter (dk) | Head Height (k) | Socket Depth (t) | Socket Size (s, Hex Key) | Thread Length (b) | Across Corners (e) |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 – 6.0 | 3.0 | 1.5 – 2.0 | 2.5 | 18 | 6.01 |
| M4 | 0.7 | 7.0 | 4.0 | 2.0 – 2.5 | 3.0 | 20 | 7.66 |
| M5 | 0.8 | 8.5 | 5.0 | 2.5 – 3.0 | 4.0 | 22 | 8.79 |
| M6 | 1.0 | 10.0 | 6.0 | 3.0 – 4.0 | 5.0 | 24 | 11.05 |
| M8 | 1.25 | 13.0 | 8.0 | 4.0 – 5.0 | 6.0 | 28 | 14.38 |
| M10 | 1.5 | 16.0 | 10.0 | 5.0 – 6.0 | 8.0 | 32 | 17.77 |
| M12 | 1.75 | 18.0 | 12.0 | 6.0 – 7.0 | 10.0 | 36 | 20.03 |
| M14 | 2.0 | 21.0 | 14.0 | 7.0 – 8.0 | 12.0 | 40 | 23.35 |
| M16 | 2.0 | 24.0 | 16.0 | 8.0 – 9.0 | 14.0 | 44 | 26.75 |
| M20 | 2.5 | 30.0 | 20.0 | 10.0 – 12.0 | 17.0 | 52 | 32.95 |
| M24 | 3.0 | 36.0 | 24.0 | 12.0 – 14.0 | 19.0 | 60 | 39.55 |
| M27 | 3.0 | 41.0 | 27.0 | 14.0 – 16.0 | 22.0 | 66 | 45.20 |
| M30 | 3.5 | 46.0 | 30.0 | 15.0 – 18.0 | 24.0 | 72 | 50.85 |
| M36 | 4.0 | 55.0 | 36.0 | 18.0 – 20.0 | 27.0 | 84 | 60.79 |
Mechanical Properties
| Property | Value | Unit / Standard |
|---|---|---|
| Tensile Strength | 800 – 1220 | MPa |
| Yield Strength | 640 – 1100 | MPa |
| Hardness | 25 – 39 | HRC |
| Elongation | ≥ 8 – 12 | % |
| Density | 7.85 | g/cm³ |
| Impact Toughness | ≥ 20 – 35 | J |
| Modulus of Elasticity (E) | ~200 | GPa |
| Fatigue Strength | 400 – 600 | MPa |
| Corrosion Resistance | Moderate to Excellent | – |
| Thermal Conductivity | 15 – 50 | W/m·K |
| Coefficient of Thermal Expansion | 11 – 17 ×10⁻⁶ | /°C |
| Yield Ratio (YS/UTS) | 0.70 – 0.90 | – |
| Poisson’s Ratio | 0.27 – 0.30 | – |
| Surface Finish | Black Oxide / Zinc Plated / Hot Dip Galvanized / Polished | – |
| Drive Type | Internal Hexagonal Socket (Allen Key) | – |
| Operating Temperature Range | -50 to 300 | °C |
| Standards Compliance | ISO 898-1, ASTM A574, DIN 912, ISO 4762 | – |
Chemical Composition
| Element | SS 304 (%) | SS 304L (%) | SS 316 (%) | SS 316L (%) |
|---|---|---|---|---|
| Chromium (Cr) | 18.0 – 20.0 | 18.0 – 20.0 | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 8.0 – 10.5 | 8.0 – 12.0 | 10.0 – 14.0 | 10.0 – 14.0 |
| Carbon (C) | ≤ 0.08 | ≤ 0.03 | ≤ 0.08 | ≤ 0.03 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 |
| Iron (Fe) | Balance | Balance | Balance | Balance |
| Molybdenum (Mo) | — | — | 2.0 – 3.0 | 2.0 – 3.0 |
Applications of Allen Cap Screws
Construction &
Infrastructure
Automotive & Heavy
Equipment
Manufacturing &
Fabrication
Medical & Laboratory
Equipment
Electrical &
Electronics Assembly
Oil, Gas & Petrochemical
Installations
Do you have questions?
Why are Allen Cap Screws preferred in machinery?
Are stainless steel Allen Cap Screws rust-resistant?
Can Allen Cap Screws be reused?
Do you offer custom threads or lengths?
