Jergens 215-066104 Keylocking Thread Insert 3/8-24 Unf

Product Description

The JERGENS 215-066104 is a heavy-duty keylocking thread locking insert designed to create strong, permanent internal threads in parent materials that require reliable thread retention under high load or vibration. Manufactured from C1215 carbon steel with a zinc phosphate coating, this insert accepts a 3/8-24 UNF internal thread and installs via a 9/16-12 external thread. At 0.5 inches overall length, it conforms to NAS 1394 standards and is suited for precision applications where thread pullout resistance is critical. Licensed HVAC, plumbing, electrical, and general mechanical tradespeople working on metal assemblies rely on this type of insert for dependable thread repair and reinforcement.

This insert is used in applications requiring a permanent, load-bearing internal thread in steel, aluminum, or other machinable materials. It is a common solution in industrial machinery, equipment frames, and mechanical assemblies where vibration or torque loads would otherwise strip or loosen standard threaded holes. The keylocking design uses keys driven into slots to lock the insert against rotation after installation, making it well-suited for high-stress, high-cycle service environments in both light industrial and heavy-duty mechanical settings.

Key Features

• 3/8-24 UNF internal thread with a 2B class of fit for standard bolt engagement
• 9/16-12 external thread with a 2A class of fit for precise installation into prepared bores
• Heavy-duty keylocking design prevents rotation under vibration and torque
• C1215 carbon steel construction with zinc phosphate coating for corrosion resistance
• Conforms to NAS 1394 standard
• Overall length of 0.5 inches for compact installation in shallow boss applications

Compatibility

Designed as an OEM-style replacement or new-installation keylocking thread insert for applications requiring a 3/8-24 UNF internal thread installed via a 9/16-12 external thread in accordance with NAS 1394.

Installation Notes

Installation is performed by machinists or mechanical tradespeople using a properly sized tap to prepare the external thread bore before driving the insert. Power down and de-energize any equipment before beginning thread repair or insert installation. Keys must be driven fully into the locking slots after the insert is seated to ensure rotation resistance. Follow applicable machine shop safety practices and consult the equipment manufacturer's specifications for bore preparation and torque requirements.