![]() NPT fittings are sub-divided into female fittings: FPT, FNPT, NPT(F) and male fittings: MPT, MNPT, NPT(M) Some sources refer to NPT as IPT (Iron Pipe Thread). However because of allowances and variations in the precise thread cuts it's necessary to use a sealant such as teflon tape or pipe thread sealant to assure a leak-free connection. ![]() NPT threads are cut at cut at an angle of about 60° along the length of the fitting, and the actual individual threads are cut at an angle of about 1° 47’ from the centerline of the fitting.Īs a male and female NPT fitting are tightened against this taper the connection is increasingly tight. NPT - National Pipe Thread / NPT (Taper) is the American standard thread pattern for pipe connections and has been in use in the U.S.Take a close look and on these short fittings you can see that the thread cut is tapered. Summary of Plumbing Fitting Thread TypesĪbove: NPT threaded brass pipe nipples. Those fittings, used with flare and compression tubing, depend not on the pipe wall thickness but on a mechanical seal between a flared tubing end against a tapered flare fitting surface, or a compressed brass ring that is squeezed against the tubing exterior wall and also seals against a tapered surface inside of a compression fitting. On the other hand compression fittings and flare fittings use threads that are cut in parallel, without taper. That's true even when the male or female fitting is comprised of the threaded end of a pipe. That taper and wedging combined with proper use of a pipe thread sealant gives a leak-free joint. NPT (National Pipe Threads) also abbreviated as IPT (Iron Pipe Threads) are tapered so that as you tighten NPT male and femal fittings the threads wedge themselves ever more-tightly together. Thanks to Industrial Specialties for permission to adapt this image. Our illustration, adapted from Industrial Specialties Mfg., shows the key difference between tapered threads cut onto standard pipe fittings (NPT or IPT) and parallel-threads cut onto flare or compression fittings (IPT). NPT or IPT pipe threads are tapered, Compression Fitting Threads are Parallel Page top photo: a Rheem brand electric water heater installed in a Christchurch New Zealand home. We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. We give contact information for Rheem brand water heaters, geysers, cylinders, calorifiers and for Rheem water heater installation, operation, & troubleshooting manuals. We have no relationship with advertisers, products, or services discussed at this website.ĭetermine the age of a Rheem water heater based on decoding the serial number. InspectAPedia tolerates no conflicts of interest.
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