The Union Butterfield 1541(NPT) uncoated, high-speed steel pipe tap has straight flutes with medium hook 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. The straight flutes are suitable for threading through holes (extending through the workpiece) and blind or bottoming holes (with only one opening). Designed for average conditions, this tap has a medium hook, or rake angle, that is suitable for general-purpose pipe tapping.
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. With no coating or surface treatment, this uncoated tool can be used on a broad range of materials and provides an economical alternative to coated tools. 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 1541(NPT) series, taps with nominal diameters of 1/16” to 1/2” have four flutes, taps with nominal diameters of 3/4” to 1 1/4” have five flutes, and taps with nominal diameters of 1 1/2” and 2” have seven 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.
Precision Dormer manufactures cutting tools under the following brands: Precision Twist, Dormer, and Union Butterfield. The company has locations around the world, and provides tools adhering to ANSI, NAS, and DIN standards.