Tapping Taper Pipe Threads

Internal pipe threads are almost always tapered and this means the issues are much more severe than straight thread tapping, whether it’s a valve, a fitting or even a large housing.  Tapping tapered pipe threads requires every thread segment to be engaged.  Chipping or galling can occur when the tap reverses because of the engagement of each cutting edge. In straight tapping only, the chamfered section and first full thread are engaged in removing metal so the engagement is less severe.

Because of the taper, the land or thread section increases as the diameter increases causing less room for chips at the large end. Regal’s engineers have taken steps to reduce or eliminate the problems of galling and chip packing by providing constant relief on the major, pitch, and minor diameter of the thread.

Our flute shape, which typically is designed as general purpose, can be modified when we know the material and condition of the material to be tapped.


Regal’s standard styles include:

  • A medium hook for general purpose
  • High hook for softer materials
  • Low angle flute face for cast iron and brass. 

In addition, we also provide 5 flute interrupted thread styles which reduces friction and allows for better chip ejection. The chip load per tooth is heavier but with more cutting faces, it frequently is the best option when chip packing occurs. 

Spiral flute taper pipe taps can be used to lift chips and is practical in softer materials.


Surface treatments, such as nitride and steam oxide, can reduce wear and extend tool life and in higher production tapping. Titanium Nitride and other coatings help to eliminate galling and chipping of the cutting edges.  

Request a quote today and learn how Regal’s unique taper designs go beyond “Cutting edge.”