Holo-krome 73140 Hex Socket Cap Screw 1/2-20 Unf Alloy Steel

Product Description

The HOLO-KROME 73140 is a hex socket cap screw threaded to a 1/2-20 UNF specification with a 2.25-inch length under head. It is partially threaded, machined from alloy steel, and finished with a black oxide coating for corrosion resistance in moderate environments. The drive is a 3/8-inch internal hex socket, requiring an Allen or hex key for installation. This fastener meets ASME B18.3 and ASTM A574 standards, making it suitable for high-strength mechanical assemblies. Machinists, millwrights, and maintenance technicians commonly specify this type of cap screw where a flush or recessed head is needed and torque demands are high.

The 73140 is used in industrial machinery, HVAC equipment frames, structural assemblies, and fabricated components that require a fine-thread fastener with reliable clamping force. The 1/2-20 UNF fine thread pitch provides greater tensile strength and improved resistance to loosening under vibration compared to coarse-thread equivalents. It is appropriate for metal-to-metal joints where precise thread engagement is required. This fastener is commonly installed during equipment assembly, field repair, or scheduled maintenance in manufacturing, mechanical contracting, and facilities environments.

Key Features

• 1/2-20 UNF fine thread for high clamping force and vibration resistance
• 2.25-inch length under head with partial threading for shank-bearing applications
• 3/8-inch hex socket drive for secure torque transfer with standard Allen tooling
• Alloy steel construction meets ASTM A574 high-strength fastener requirements
• Black oxide finish provides mild corrosion resistance and reduces light reflection
• Conforms to ASME B18.3 dimensional standards

Compatibility

Designed as a standard ASME B18.3 hex socket cap screw for use in any application calling for a 1/2-20 UNF partially threaded alloy steel socket head cap screw with a 2.25-inch length under head.

Installation Notes

Installation should be performed by a qualified machinist, millwright, or mechanical technician using a calibrated torque wrench and a properly sized 3/8-inch hex key or socket bit. Always de-energize and lock out equipment before servicing fasteners on powered machinery. Do not use impact drivers on socket cap screws unless the tool is set to a controlled torque mode, as over-torquing alloy steel fasteners can cause thread stripping or head failure. Inspect the mating threaded hole for debris or damage before installation.