NPT—American National Standard Taper Pipe threads are widely used in pipe assembly , it is used in general purpose application. It is used for pressure tight joints  of pipes, it need to use sealing compound to get the purpose of sealing. NPT thread gauges are used to test NPT threads’s basic sizes.

NPT thread: NPT thread is a US standard 60 degree taper pipe thread, which is divided into general sealed cylindrical pipe thread and general sealed conical pipe thread. The matching mode is matched by “cone/cone” and “column/cone”. The applied standard: ANSI-ASMEB1.20.1-1983  Same as Chinese Standard GB/T12716-2011.

We (gaugestools) are a professional supplier and manufacturer of NPT thread gauges in  China.  We have 1/16″-6″ NPT thread gauges in stock. Nowadays, our gauges are exported to many countries, like America, Canada, Mexico, Australia, Germany, UK etc. each gauge 100% calibrated with quality assurance.

How to Use NPT thread ring gauges and Plug gauges

from the pictures, you can see there are three step ends. Basic, Min and Max. NPT plug gauges are also like this, three step ends. First, you should be sure the threads of gauges and mating parts are clean without burr. otherwise, the testing results may be not correct, even the gauges will be damaged by burrs. Second,After turning into the gages to the threads of mating parts. ( Ring gauges should be turned into external threads, plug gauges should be turned into internal threads. If the threads ends stay with the basic ends of gauges, it is perfectly well, the threads are quality-passed,  if the threads ends stay between the Min and Max ends, the threads of mating parts are also quality-passed. But if the thread ends stayed outside of the Min ends or Max ends, then the threads are not quality-enough, they has to be rejected.

NPT VS NPTF

NPT is American National Standard Taper Pipe threads, NPTF is National Pipe Thread Fine. NPT is general-purpose taper pipe thread, NPTF is dry-seal taper pipe threads.  gaugestools has NPT thread gauges and NPTF thread gauges in stock, we can ship these gauges worldwide, clients can receive goods taking 3-5 days by expedited shipping (DHL or Fedex). NPT threads need sealing compound to get the target of sealing. NPTF threads no need lubricant or sealing compound to be sealed. NPTF thread reply itself to form a seal. The design principle is to get the side, the crest, and the bottom of the inner and outer threads into contact at the same time to achieve the purpose of sealing. NPT and NPTF have the same thread angle, taper etc. But the crest and bottom heights are not same.  the design of NPT thread gauges and NPTF thread gauges are far different. NPTF threads have higher class of fit than NPT threads. NPTF threads are high precision threads, only be used in special conditions, which has high strength and excellent sealing. If use NPTF threads on brittle hard material with thin section , it may reduce cracking. The crest and bottom don’t have any space between internal and external NPTF threads. NPTF threads are mainly used in conditions of high-temperature high-pressure high sealing requirements . NPT threads have right hand and left hand,  NPTF just have right hand condition. gaugestools can provide both right hand and left hand NPT thread gauges.

NPTF thread taps can be used on tapping NPT threads, but NPT thread taps can’t be used on NPTF threads.