Taper Pipe Taps

We carry  a complete line of tapered pipe taps including both NPTF and NPT tapered pipe taps, interrupted thread taper pipes taps, spiral flute taper pipe taps and BSPT (British Standard Pipe Taper – also known as R or Rc) and BSPP (British Standard Parallel Pipe – also known as G or Rp) taps.

Our taps comply with all ANSI and ISO standards and specifications and are produced from high quality steels and carbide to meet the needs of our customers. Our goal is to provide cost effective tooling solutions through improved tool life, geometrical improvements, technological coating advances, technical support and effective inventory.

What is Tapered Pipe Tapping? 

Tapered pipe tapping is a technique of making internal thread surfaces that will not leak after assembly, even under pressure. 

When threading a hole requiring a tapered pipe tap, there are two options for manufacturing: a straight hole or a tapered hole. 

Pipe tapping a straight hole creates a progressive thread engagement over the length of the tap as it enters the hole. There is more total material being removed from the workpiece in this process. Torque initially will be low but will rise as the tap enters the hole and the thread engagement increases. 

Making and tapping a straight hole is a straightforward process. You just drill and tap. 

In comparison, pipe tapping a tapered hole requires an extra step in hole preparation – the hole is reamed with a special reamer designed for that particular size tapered pipe tap. The result is a tapered hole that matches the taper of the tap (3/4” per foot). As the tap enters the tapered hole, there is no thread engagement or cutting action until the entire tap reaches the point where tapers parallel each other and then all cutting teeth on all flutes over the entire length of the tap fully engage with the workpiece. This “instant” engagement creats much higher initial torque and heat through the complete part-to-tool contact. 

This can create two challenges: 

  • High Initial Torque – The complete engagement of a tapered pipe tap in a tapered hole and the resultant high torque may be more than the tap can handle resulting in broken teeth and incomplete thread forms.
  • Part to tool friction. A tapered pipe tap means high flank friction and more machine torque (more friction and heat is produced). 

Interrupted thread tapered pipe taps are designed to combat the previous issues. How? Interrupted threads have the cutting teeth removed alternating on every other land. This results in double the chip load on the remaining cutting teeth but only half of the flank friction. As a result, the tool life may be longer because the tool is generating less heat through friction. 

Types of Tapered Pipe Taps

There are two specifications for tapered pipe thread in the United States:

NPT or "National Pipe Thread" is shorthand for the American National Standard Pipe Thread. These threads are for general use and generally require a sealing agent to ensure non-leakage. 

NPTF is the designation given to the National Pipe Taper Fuel (also called the Dryseal American National Standard Taper Pipe Thread). This thread is self-sealing and provides a leak-free seal without the use of sealant compound. 

NPTF threads have the crest and root heights adjusted for an interference fit. (The crest is the high point of a thread and the root is the valley in between threads). This adjustment causes the crest of one surface to “crush” fit in with the root of the mating part, causing an interference fit and filling any gaps eliminating the need for additional sealants. 

Whatever your taper pipe tap needs, Regal has you covered. Our 24-hour special program includes special pipe tap production of special projections and either right or left hand tapered or straight threads.

NPT (American National Standard Taper) taps for general purpose use in a variety of materials conforming to ANSI standards are available.

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NPTF (American National Taper Pipe Fuel) commonly called Dryseal taps are designed for pressure tight joints and must be assembled wrench tight with metal to metal contact of the entire thread profile to eliminate spiral leakage.

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Interrupted thread taper pipe taps always have an odd number of flutes to insure continuous engagement. Every other tooth is removed on each cutting edge to allow heavier chips to flush without packing while the tap is engaged.

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Spiral flute pipe taps are recommended for use in soft and stringy materials where chips packing in the flutes are an issue. The high hook design coupled with the helical flutes lift long stringy chips out of the tapped hole.

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BSPT (British Standard Pipe Taper) 55 degree thread form taps produce an internal thread which joined with an external BSPT thread needs no sealant to produce a pressure tight joint 

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