Heli-coil R1191-9 Free Running Insert 9/16-18 Unf

Product Description

The HELI-COIL R1191-9 is a free running wire thread insert designed to create durable internal threads in stripped, damaged, or soft-material parent threads. Manufactured from stainless steel with a bright, uncoated finish, this insert provides corrosion-resistant thread repair or reinforcement in a 9/16-18 UNF thread profile. It measures 0.844 inches in overall length at a 1-1/2D length-to-diameter ratio and features 12-1/2 free coils. The tanged design allows for standard installation with a drive mandrel and includes a breakoff tang for post-installation removal. Licensed technicians and machinists in HVAC, plumbing, and general mechanical trades routinely specify this insert for thread restoration in aluminum, cast iron, and steel housings.

This insert is suited for applications requiring reliable thread repair or thread strengthening in ferrous and non-ferrous base materials. Common installation scenarios include restoring threads in compressor housings, valve bodies, pump flanges, and equipment enclosures. The 9/16-18 UNF thread standard is frequently encountered in hydraulic fittings, fastener joints, and precision mechanical assemblies. Each package contains 6 inserts, making it practical for field service kits and shop inventory.

Key Features

• 9/16-18 UNF thread profile for compatibility with unified fine thread fastener systems
• 0.844 inches overall length at a 1-1/2D ratio for standard-depth thread engagement
• 12-1/2 free coils providing full thread-form support across insert length
• Stainless steel construction with bright, uncoated finish for corrosion resistance
• Tanged design compatible with standard HELI-COIL installation tooling
• Packaged in quantities of 6 for shop and field use

Compatibility

Designed for use in any parent material tapped to HELI-COIL STI specifications for a 9/16-18 UNF free running insert installation. Requires the corresponding STI tap and installation mandrel sized for this insert series.

Installation Notes

Installation should be performed by a qualified mechanic or technician using the correct STI tap, installation tool, and tang breakoff tool for the 9/16-18 series. The parent bore must be drilled and tapped to STI oversize dimensions before insert installation. Always de-energize, depressurize, and secure the equipment before performing any thread repair on live systems. Do not reuse a removed insert.