Gibraltar KN-31SS-G Round Knurled Check Nut 5/16-18 Unc

Product Description

The GIBRALTAR KN-31SS-G is a stainless steel round knurled check nut designed for 5/16-18 UNC threaded applications. Check nuts, also called jam nuts or lock nuts, thread down against a primary nut or fitting to prevent loosening under vibration, thermal cycling, or mechanical load. This unit features a knurled round head for improved grip during hand-tightening and tool-assisted installation. The uncoated stainless steel construction resists corrosion in wet, chemical, or outdoor environments. The overall height is 3/8 inches, with a 1-inch head diameter, a base diameter of 3/4 inches, and a base height of 3/32 inches. The part weighs 0.06 pounds. Licensed trades and mechanical contractors specify stainless fasteners like this one where mild steel hardware would corrode or fail inspection.

This check nut suits residential and light commercial mechanical installations where a 5/16-18 UNC thread is present and a secondary locking fastener is required. Typical applications include HVAC equipment mounting, plumbing fixture hardware, pump assemblies, and general mechanical panel or enclosure work. The knurled head profile makes it practical in confined spaces where a wrench may not seat fully but hand torque plus tool snugging is sufficient. Sold individually, it is suitable for single-point repairs or small-batch installations without requiring a bulk purchase.

Key Features

• 5/16-18 UNC thread for compatibility with standard inch-series fastener systems
• Round knurled head allows hand-tightening and positive grip without a specialty tool
• Uncoated stainless steel construction resists corrosion in wet or chemically active environments
• Low-profile check nut design seats against a primary nut or fitting surface to prevent loosening
• 1-inch head diameter and 3/8-inch overall height suit tight clearance installations

Compatibility

Designed as an OEM-style replacement or service fastener for mechanical assemblies requiring a 5/16-18 UNC threaded check nut in stainless steel.

Installation Notes

Installation is performed by licensed mechanical, HVAC, or plumbing technicians as part of broader equipment service or assembly work. Thread the check nut onto the stud or bolt until it seats firmly against the primary nut or fitting face, then snug with an appropriately sized wrench. De-energize and isolate any equipment before accessing fastener locations inside live panels or pressurized assemblies. Do not overtighten stainless fasteners, as galling can occur on stainless-to-stainless thread contact without anti-seize compound.