Bowmalloy 36221 Hex Head Cap Screw 1-8x4 Grade 9

Product Description

The BOWMALLOY 36221 is a Grade 9 alloy steel hex head cap screw sized 1-8 x 4 inches with a zinc-plated clear chromate finish. Grade 9 alloy steel delivers high tensile strength suited for heavy-duty bolted joints in demanding structural, mechanical, and industrial applications. The partially threaded shank provides a smooth bearing surface that helps align mating components and resist shear loads. The clear chromate zinc plating adds corrosion resistance without obscuring the base metal. This fastener is specified in inch measurements and follows standard hex head geometry for use with common wrenches and sockets. Installers across mechanical, structural, and industrial maintenance trades rely on this screw where high-strength fastening is required.

This cap screw is used in heavy mechanical assemblies, structural steel connections, agricultural equipment, and industrial machinery where Grade 9 strength is specified. The 1-8 thread pitch and 4-inch grip length make it appropriate for thick-section joints. It is sold in packages of 10, making it practical for both single-repair jobs and small-volume production work. The inch-series thread pattern is compatible with standard SAE hardware and tooling commonly found in field and shop environments.

Key Features

• Grade 9 alloy steel construction for high tensile strength in structural and mechanical fastening
• Partially threaded shank provides a smooth shank section for shear resistance and component alignment
• Zinc-plated clear chromate finish offers corrosion protection in general service environments
• 1-8 thread size with 4-inch length under head suits thick-section bolted joints
• Standard hex head geometry compatible with common wrenches, sockets, and impact drivers
• Inch-series fastener conforming to UNSPSC code 31161501 for procurement classification

Compatibility

Designed as a standard inch-series hex head cap screw for use in Grade 9 applications requiring a 1-8 thread size and 4-inch under-head length, compatible with SAE-standard hex nuts and hardware of matching thread class.

Installation Notes

Installation should be performed by a qualified mechanic or millwright using a torque wrench calibrated to the joint engineer's specified torque value for Grade 9 hardware. De-energize and lockout all equipment before fastener replacement or tightening in live machinery. Do not mix Grade 9 fasteners with lower-grade nuts or plates where the joint design requires matched hardware grades. Inspect threads for damage and ensure mating surfaces are clean and free of debris before assembly.