Osg 1251402 Spiral Flute Pipe Tap 1/4-18 Nptf Hss

Product Description

The OSG 1251402 is a spiral flute pipe tap designed for cutting 1/4-18 NPTF internal pipe threads in metal workpieces. It features four right-hand flutes with a 15-degree helix angle that evacuates chips upward out of the hole, making it well suited for blind-hole tapping applications. The bottoming chamfer allows threading closer to the bottom of a bore. Manufactured from high-speed steel and finished with OSG elektraLUBE coating, this tap provides a built-in lubricity layer that reduces friction and extends tool life in production and job-shop environments. Overall length is 2-7/16 inches with a shank diameter of 0.5625 inches.

This tap is used wherever a leak-free NPTF tapered pipe thread connection is required. Typical applications include tapping ports in hydraulic manifolds, pneumatic fittings, fluid system components, and pipe couplings. It is installed by machinists and pipe fitters working with drill presses, CNC machining centers, or tapping heads. The NPTF thread standard produces a pressure-tight mechanical seal without relying solely on sealant compounds, making it a common specification in fluid power and plumbing assemblies.

Key Features

• 1/4-18 NPTF thread size for tapered pipe thread applications requiring pressure-tight seals
• Four right-hand spiral flutes with 15-degree helix angle for efficient chip evacuation in blind holes
• Bottoming chamfer allows threading to within close proximity of hole bottom
• High-speed steel construction provides toughness across a range of workpiece materials
• elektraLUBE finish reduces friction and cutting forces, extending tap service life
• Series S125 design with 0.3750-inch projection and 0.4210-inch square size for standard tap holders

Compatibility

Designed for use in standard tap holders and tapping heads that accept a 0.5625-inch shank diameter with a 0.4210-inch drive square. Intended for cutting 1/4-18 NPTF tapered pipe threads per the NPTF thread standard.

Installation Notes

Installation should be performed by a qualified machinist or pipe fitter using a properly sized tap holder, tapping head, or machine spindle. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap-drill diameter per NPTF specification before tapping. Apply cutting fluid appropriate for the workpiece material even when using the elektraLUBE-coated tap to further reduce heat and wear. Never force a tap that has stopped turning freely, as breakage may result and the tap may become lodged in the workpiece.