Irwin 1911zr Pipe Tap 1/8-28 Rp 4 Flute Carbon Steel

Product Description

The IRWIN 1911zr is a straight pipe tap designed for cutting internal pipe threads in a range of materials. It follows the RP thread standard at 1/8 inch-28 and is built from carbon steel with a bright, uncoated finish. The taper chamfer eases thread entry and progressively cuts the full thread form. With four flutes and a right-hand thread direction, this tap is manually driven with a tap wrench, giving the technician direct control over speed and feel — an advantage when working in tight spaces or with materials that require careful chip management.

This tap is suited for general-purpose pipe and conduit threading applications in residential and light commercial work. Plumbers, pipefitters, and conduit installers use it when tapping new threads into fittings, pipe ends, or enclosures. It is manually operated, making it appropriate for field work or bench work where a tapping machine is not available. The H2 thread limit designation indicates a tighter tolerance fit, suitable for standard pipe thread assemblies. A 21/64 inch drill size is recommended for the pilot hole prior to tapping.

Key Features

• 1/8 inch-28 RP thread standard for pipe and conduit applications
• Carbon steel construction for general-purpose tapping in a broad range of materials
• Taper chamfer design for progressive thread engagement and easier starting
• 4-flute configuration supports chip evacuation during manual operation
• H2 thread limit for consistent, standard-tolerance thread fit
• Bright uncoated finish — no coating buildup that could affect thread tolerance
• Meets USCTI standards; manufactured in the USA (subject to change)

Compatibility

Designed for standard pipe and conduit tapping applications using RP straight pipe thread form at 1/8 inch-28. Compatible with manual tap wrenches accepting a 5/16 inch shank diameter.

Installation Notes

This tap is manually operated and should be used with a properly sized tap wrench — do not attempt machine operation. Before tapping, drill a 21/64 inch pilot hole and ensure the workpiece is securely clamped. Apply cutting fluid appropriate to the material being tapped to reduce friction and improve thread quality. Advance the tap slowly with consistent back-off strokes to break chips and prevent tap breakage.

Technical Specifications

• Thread Standard: RP (Straight Pipe)
• Thread Size: 1/8 inch-28
• Thread Direction: Right Hand
• Thread Limit: H2
• Number of Flutes: 4
• Chamfer Type: Taper
• Helix Angle: 0 degrees
• Thread Length: 3/4 inches
• Overall Length: 2-1/8 inches
• Shank Diameter: 5/16 inches
• Recommended Drill Bit Size: 21/64 inches
• Material: Carbon Steel
• Finish: Bright (Uncoated)
• Tap Style: Straight Pipe
• Standards: USCTI
• Country of Origin: USA (subject to change)

Standard Information

• Brand: IRWIN
• Manufacturer Part Number: 1911zr