Heli-coil 328-2 Pipe Sti Tap 1/8-27 Npt 4 Flute Hss

Product Description

The HELI-COIL 328-2 is a pipe STI tap designed to cut threads in pre-drilled holes that will accept STI-style thread inserts on 1/8-27 NPT pipe thread applications. Manufactured from high speed steel with a bright, uncoated finish, this tap features a plug chamfer and four flutes for efficient chip evacuation during cutting. The plug chamfer makes it suitable for through-holes and most standard tapping scenarios. With an overall length of 2.4375 inches and a thread length of 1.0625 inches, it fits standard tap handles and machine spindles used in pipe thread repair and insert installation work. Machinists, pipefitters, and maintenance technicians reach for this tap when restoring or creating threaded connections for pipe fittings and inserts.

This tap is used in residential and commercial maintenance, manufacturing, and repair environments where pipe thread inserts must be installed into metal components. It is specifically suited for STI thread insert applications at the 1/8-27 NPT size, which is common in pneumatic fittings, hydraulic connections, and pipe coupling assemblies. The plug chamfer style makes it appropriate for through-hole tapping where full thread engagement along the thread length is required before the tap exits the material.

Key Features

• 1/8-27 NPT thread form for standard pipe thread insert installations
• High speed steel construction provides durability in ferrous and non-ferrous materials
• Plug chamfer design suited for through-hole tapping applications
• Four flutes promote chip clearance and smooth cutting action
• Bright, uncoated finish for easy visual inspection of cutting edges
• Shank diameter of 0.5625 inches fits standard tap handles and chucks

Compatibility

Designed for use in STI thread insert applications requiring a 1/8-27 NPT pipe thread form. Fits standard tap handles and machine spindles accepting a 0.5625-inch shank diameter with a 0.421-inch square drive size.

Installation Notes

This tap should be installed by a qualified machinist, pipefitter, or maintenance technician familiar with thread insert systems. Always secure the workpiece and ensure the correct STI tap drill hole size has been prepared before tapping. Apply cutting fluid appropriate for the workpiece material to extend tap life and improve thread quality. Do not force the tap if resistance increases unexpectedly - back off to clear chips before continuing.