30/5/2564 Tapered Pipe Threads and Fittings: Making the Connection | ISM 800.781.8487 ISM End your search, simplify your supply chain Industrial Specialties Mfg. & IS MED Specialties ISO 9001:2015 Certied Companies Menu TAPERED PIPE THREADS AND FITTINGS: MAKING THE CONNECTION ENSURING A GAS OR LIQUID-TIGHT CONNECTION MEANS UNDERSTANDING TAPERED PIPE THREADS NPT, National Pipe Taper (American) and BSPT (British standard Pipe Taper) are tapered pipe thread standards. Male and female tapered pipe threads wedge themselves together but need a sealant for a completely leak-free connection. Sealants ll any voids between the threads that could travel along the thread spiral. Tube and pipe are not the same thing Tube and pipe are hollow structures designed to provide a path for the ow of uids or gases. The main difference between tube and pipe is that pipe walls are thicker and stiffer. Tubing is never threaded because its walls are too thin. Pipe walls are strong enough to support cut or molded threads. Threaded pipe can provide gas or liquid-tight connections that are mechanically strong. Pipe threads There are many national and international standards for pipe threads. They vary by intended use such as garden hose threads and re hose threads among others. There are also historical developments behind “standard” pipe sizes and the shapes of threads. Examples of this are the differences between American and British threads. Units of measure play a part too. How to Install The two basic categories of pipe thread Plastic Thread Fittings • Parallel or straight pipe thread • Tapered pipe thread Take a look at a selection of ISM's metal threaded ttings and plastic threaded ttings. These provide examples of the most common pipe thread types in use. Tapered pipe threads Piping and ttings are primarily used to carry liquids and gases. Because of this, they need to have threaded connections that are gas or liquid tight. Tapered threads help make better seals. The male and female threads compress and wedge themselves together. As a result, these connections are stronger and leak resistant. The two most common standards for tapered pipe threads NPT American National Standard Taper Pipe Thread BSPT British Standard Pipe Taper Thread NPT pipe thread is the most common tapered pipe thread used in the United States and Canada and is incompatible with BSPT pipe threads. https://www.industrialspec.com/about-us/blog/detail/tapered-pipe-threads-standards-intro 1/7 30/5/2564 Tapered Pipe Threads and Fittings: Making the Connection | ISM Why NPT and BSPT pipe threads are incompatible Thread angle or included angle NPT threads have a 60-degree angle BSPT threads have a 55-degree angle Thread shape NPT threads have attened peaks and valleys BSPT threads have rounded peaks and valleys Thread pitch (TPI, threads per inch) Each NPT and BSPT pipe thread size has a specic number of threads per inch Some common acronyms for American tapered pipe thread types NPT National Pipe Thread Taper FPT, FNPT, NPT(F)* Female or internal tapered pipe threads MPT, MNPT, NPT(M) Male or external tapered pipe threads *This is not NPTF. NPTF stands for National Pipe Taper Fuel. It is also called Dryseal American National Standard Taper Pipe Thread. The design of NPTF provides leak-free connections without using sealants. There are parallel and tapered pipe threads for all pipe standards. NPS, National Pipe Straight, is the American standard for parallel or straight pipe threads. NPS threaded connections need gaskets or O-rings to seal them. Sealant and tapered pipe threads Tapered pipe threads need a sealant for leak-free connections. It lls any voids between the two threads that could cause a spiral leak. They also function as lubricants between the male and female threads. Assembling parts and pipe made of dissimilar materials need special care. This is because sealants make it easier to over tighten ttings. Over tightening ttings MODULAR CHECK VALVES can lead to damage and leaks. We've taken spring-loaded check Download the ISM Plastic Tapered Thread Fittings Installation Guide valves to a whole new level. Mix >> and match imperial and metric connections. Watch the video. Conclusion Understanding tapered pipe threads makes it easier to choose the best component, especially tapered pipe ttings. Parts with matching threads always perform better because matching threads are mechanically stronger and create better gas-tight and liquid-tight seals. What kinds of problems have you had moving between different tapered pipe thread standards when sourcing components for your application? Help us by telling others what you learned. Have questions about tapered or straight pipe threads used on ow control components? If so, send me an email - [email protected]. You can also ask questions using the comments section below. Some additional reading NPT National Standard Taper Pipe Threads Size Chart from Engineers Edge NPS Nominal Pipe Size (North America) from Wikipedia BSPT British Standard Pipe Taper Thread Sizes and Dimensions from AMES, Advanced Mechanical Engineering Solutions https://www.industrialspec.com/about-us/blog/detail/tapered-pipe-threads-standards-intro 2/7 30/5/2564 Tapered Pipe Threads and Fittings: Making the Connection | ISM p p f , g g BSP British Standard Pipe from Wikipedia About the author Steven C. Williams, BS, is the technical writer and an inbound marketing specialist at Industrial Specialties Manufacturing (ISM), an ISO 9001-2015 supplier of miniature pneumatic, vacuum and uid circuitry components to OEM's and distributors all over the world. He writes on technical topics related to miniature pneumatic and uidic components as well as topics of general interest at ISM. « Go back to the blog homepage ALSO ON ISM BLOG Elastomers and What is Acetal Plastic? The Rubbers - Is There a … — POM Plastics for … Subscribe to our blog Stan 4 years ago • 2 comments 2 years ago • 2 comments 2 years ago • 2 comments 5 yea Rubber and elastomer are Acetal plastic is also called Industrial Specialties Mfg. Post words commonly used to polyacetal or and IS Med Specialties are at IS mean any material with … polyoxymethylene … ISO 9001:2015 … Inac 11 Comments ISM Blog Disqus' Privacy Policy 1 Login Recommend 3 t Tweet f Share Sort by Best Join the discussion… LOG IN WITH OR SIGN UP WITH DISQUS ? Name Garry • 6 months ago Hello, Thank you very much for this useful article. It seems that thread sealant is mandatory to use when sealing is achieved using contact between threads. Correct me i am wrong. Can we use NPT threads for an application having temperature = 350 deg C & pressure 150 bar? IMO, pressure is not the point of concern here. But temperature is certainly a point of concern. The reason is that there are no thread sealants which can operate upto 350 deg C. But thread lubricants are available upto 800 deg C. Could you please take a moment to express your advice. Thank you in advance. △ ▽ • Reply • Share › Steven Williams Mod > Garry • 6 months ago Garry https://www.industrialspec.com/about-us/blog/detail/tapered-pipe-threads-standards-intro 3/7 30/5/2564 Tapered Pipe Threads and Fittings: Making the Connection | ISM Garry, Sealants are necessary for leakproof NPT threaded connections. I would recommend looking further for high temperature pipe thread sealant/lubricant compounds. There are definitely thread sealants available that are rated for temperatures over 350 degrees C (about 662 degrees F). You may have better luck if you search for sealant/lubricant pipe thread compounds. NPT tapered pipe thread is suitable for high temperature/high pressure applications. Simply choose fittings and pipe rated for the operating temperatures and pressures. You may want to consider using NPTF pipe threaded pipe and fittings instead of NPT. For leakproof seals, the mating threads of all the fittings and the pipe will need to be NPTF also. Unfortunately, NPTF threaded parts and pipe cost more than NPT threaded parts. NPTF threaded connections do not require a thread sealant. This is because NPTF threads are designed so that the male thread crests interfere with the female thread roots. The thread is crushed in the installation process providing the mechanical seal. For this reason, NPTF fittings and pipe are also not reusable. Here is a good reference resource that includes basic information about NPTF. It is at The Engineering Toolbox. NSI B1.20.1 - NPT - American National Standard Taper Pipe Threads https://www.engineeringtool... Steven Williams Technical Writer and Inbound Marketing Specialist △ ▽ • Reply • Share › βασίλης βελούδης • a year ago Hello, i wanted to ask i question that i have difficulty resolving. I have a ball valve of 3/4 in size and in the end, it has a 3/4 in NPT female thread. In order to connect this valve to a pipe or a fiting, do the pipe or the fiting need to have 3/4 in male NPT thread ? Thank you very much for your time. △ ▽ • Reply • Share › Steven Williams Mod > βασίλης βελούδης • 6 months ago In general, most thread pipe is used carrying liquids or gases. For these type of applications the connections need to be leak free and gas tight. To achieve this quality of a connection, thread standards need to match. You should also follow recommendations for the use of sealing compounds and/or sealing tape. Tapered pipe threads like NPT require the use of pipe joint compounds or tape. This sealing material seals threaded pipe fittings by blocking the spiral leak paths that runs along the pipe threads. Keep in mind that improper sealing or improper use of a sealant can lead to serious problems, including leaks, pipe system damage, contamination and system downtime. Proper installation includes using same material fittings or materials that are similar enough that there is no risk of stripping threads or splitting fittings.