The Union Butterfield 1545A(NPT) high-speed steel pipe tap has straight flutes with high hook, a black oxide surface finish, and a round shank with a square end, and is used to create NPT (National Pipe Taper) right-hand threads in a range of materials, with strength in carbon steel and alloy steel. NPT thread is an ANSI-standard thread configuration designed to be used with a sealant to create a leak-free tapered pipe joint. Black oxide improves lubricity, resists corrosion, and will not chip or flake off. Black oxide also helps to prevent buildup and welding of material on the tap’s cutting edge when working with iron and steel. The straight flutes are suitable for threading through holes (extending through the workpiece) and blind or bottoming holes (with only one opening). This tool has deep flutes with high hook to manage long curly chips.
Right-hand threads are designed to tighten when a head or nut is rotated clockwise (the most common threading direction). High-speed steel (HSS) is a common general-purpose steel for cutting tools and is compatible with a variety of materials. The round shank with square end helps to minimize rotation in the tool holder. This tool can be used in machines, such as drill presses or lathes, or with hand tools such as tap wrenches.
In the Union Butterfield 1545A(NPT) series, taps with nominal diameters of 1/16” to 1/2” have four flutes and taps with a nominal diameter of 3/4” have five flutes. In this series all taps have semi-bottoming chamfers. This tap conforms to ANSI standards and is suitable for normal pipe thread tolerance.
Taps produce internal threads in previously formed holes and can be used in machines (such as drill presses) or with hand tools. Common types of taps include hand taps, spiral point taps, spiral flute taps, thread forming taps, and pipe taps. Hand taps (straight-flute taps) collect chips in the straight flutes of the tool; spiral point taps push chips through holes ahead of the tool; and spiral flute taps pull chips back from the tip of the tool, up and out the hole. Thread forming taps, also known as cold forming taps, press rather than cut to create threads in a drilled hole, and no chips are created. Pipe taps create threads in pipes and pipe fittings. Each thread type designates a thread profile and each type is identified with an abbreviation. In the U.S. and Canada, the Unified Thread Standard is the dominant thread type, including UNC (Unified Coarse), UNF (Unified Fine), and NPT (National Pipe Taper) threads, among others.