Types Of Pipe Threads

Resource Description

JIANZHI contains other products and information you need, so please check it out.

It is significant to determine several specific pipe thread variations you require according to the equipment to operate perfectly. Air cylinders, valves, and air preparation units are pneumatic components that need specific types of pipe threads to be equipped with. For instance, pneumatic stuff is required to be equipped with NPT, PT, or G pipe threads. Selecting the proper pipe thread type will offer you the proper performance of your equipment.

At the first sight, pipe threads may seem to be similar. However, if you look closer, you will notice several differences between them. For instance, several pipe threads may have differences from each other by shape, type of angle, or thread pitches. The article includes several types of most common pipe threads, including NPT/NPTF, BSPP (or G), BSPT, PT, Metric (M), and SAE. You will need only two simple tools: a caliper and a pitch gauge.

Pipe Thread Determining Tools

Caliper

A caliper is a useful tool that determines the outside diameter of the male thread, and the inside diameter of the female thread. Applying the caliper will provide you with the most accurate measurements, however, if you don&#;t have one, you may use a straight steel ruler. Nevertheless, you may use the innovative digital caliper for easier work.

Pitch Gauge

A pitch gauge is a tool that helps to determine the pipe threads per inch. This tool determines the distance between the threads for the metric pipe threads.

Identifying Types Of Threads

Pipe threads can be male or female and this is an easy differentiation to understand. Male means that the thread is on the outside of the fitting, it looks like a bolt. The female thread looks like a nut, and it is on the inside of the fitting.

The other aspect you should know is the pitch. Thread pitch is the space among threads. To determine it, you should use a gauge pitch tool or caliper to identify the distance between the threads according to the length of the fitting. Metric threads are identified by the millimetric distance between them, while the other pitch of the thread is determined by the number of threads per inch. For instance, the distance between threads is 1 millimeter, so the pitch is 1 millimeter.

Parallel threads types:

&#; UN/UNF (SAE)

&#; BSPP

&#; metric parallel

Parallel thread example

Tapered threads types:

&#; NPT/NPTF (American Pipe)

&#; BSPT (British Pipe)

&#; metric tapered

Tapered thread example

Apply the caliper to determine the outside diameter of the male thread and the inside diameter of the female thread. Please note that small differences between measurement and size charts are due to various thread manufacturers.

The design of each thread can be tapered or parallel. There are two major classifications of pipe threads: parallel and tapered. The parallel thread is the type where the diameter has the same length as the thread. The tapered thread has a bigger diameter length than the length of the tool.

A flank angle and tapered angle are the only types of angles, even screws with tapered designs are also created with a taper angle. The flank angle relates to the angle between the flank and the cross-cutting line to the axis of the thread. The tapered angle is the angle between the taper and the center axis of the pipe.

How To Identify The Pipe Thread?

Pick up the information you have found out recently and select the proper pipe thread according to the Nominal Dimensions of Standard Threads chart. For example, according to the chart ½-14 NPT determines the pipe thread with nominal inside the diameter of ½ inch and 14 threads to the inch.

Size Pipe OD Tapered Threads Straight Threads NPT BSPTr NPSH NPSM NST (NH) BSPP TPI TPI TPI ODM (max) IDF (min) TPI ODM (max) IDF (min) TPI ODM (max) IDF (min) TPI ODM (max) IDF (min) 1&#;8" .405 27.0 28       27.0 0.397 0.358         0.383 0.337 1&#;4" .540 18.0 19       18.0 0.526 0.468         0.516 0.450 3&#;8" .675 18.0 19       18.0 0.662 0.603         0.656 0.588 1&#;2" .840 14.0 14 14.0 0. 0. 14.0 0.823 0.747         0.825 0.733 3&#;4" 1.050 14.0 14 14.0 1. 0. 14.0 1.034 0.958         1.041 0.950 1" 1.315 11.5 11 11.5 1. 1. 11.5 1.293 1.201 8.0 1.375 1. 11 1.309 1.193 1 1&#;4" 1.660 11.5 11 11.5 1. 1. 11.5 1.638 1.546       11 1.650 1.534 1 1&#;2" 1.900 11.5 11 11.5 1. 1. 11.5 1.877 1.785 9.0 1.990 1. 11 1.882 1.766 2" 2.375 11.5 11 11.5 2. 2. 11.5 2.351 2.259       11 2.347 2.231 2 1&#;2" 2.875 8.0 11 8.0 2. 2. 8.0 2.841 2.708 7.5 3.068 2. 11 2.960 2.844 3" 3.500 8.0 11       8.0 3.467 3.334 6.0 3.623 3. 11 3.460 3.344 4" 4.500 8.0 11       8.0 4.466 4.333 4.0 5.010 4. 11 4.450 4.334 4 1&#;2"                   4.0 5.760 5.       5" 5.563 8.0 11       8.0 5.528 5.395 4.0 6.260 5. 11 5.450 5.359 6" 6.625 8.0 11       8.0 6.585 6.452 4.0 7.025 6. 11 6.450 6.359 8" 8.625 8.0                           10" 10.750 8.0                           12" 12.750 8.0                          

&#; ODM = Outside Diameter of the male; &#; IDF = Inside Diameter of the female; &#; TPI = Threads Per Inch; &#; GHT (3/4") -- 1. ODM, 11-1/2 TPI; &#; Female NPT (Tapered Pipe) thread is not available on hose swivel nuts.

Identify The Pipe Thread Compatibility

When you find out all the details you need to identify the proper pipe thread you should make sure the fitting provides a compatible connection. The best solution to identify male and female fittings is to use this chart.

Abbreviation System Name Compatibility Seal Method BSPP British Standard Pipe Parallel male BSPP with female BSPP washer female BSPP with male BSPP washer female BSPP with male BSPP washer BSPTr British Standard Pipe Taper male BSPTr with female BSPTr thread male BSPTr with female BSPP washer

female BSPTr with male BSPTr

female BSPTr not compatible with male BSPP

thread CHT American Standard Fire Hose Thread (1" National Hose Thread is Chemical Hose Thread, also known as Booster Hose Thread) 1" male NH (NST) with 1" female NH (NST) washer 1" female NH (NST) with 1" female NH (NST) washer 1" thread is used on both 3/4" hose & 1" hose not compatible GHT Garden Hose Thread male GHT with female GHT washer female GHT with male GHT washer thread is same for all size hose not compatible IPS Iron Pipe Straight Thread

generic name for Straight Pipe Thread

see NPSH for compatibility

washer IPT Iron Pipe Thread generic name for All Pipe Thread more information required JIC Joint Industrial Committee used with other mating JIC threads mechanical NH or NST American Standard Fire Hose Thread Coupling Thread (National Hose thread also known as National Standard Thread) male NH (NST) with female NG (NST) washer

female NH (NST) with male NG (NST)

Contact us to discuss your requirements of Threaded Fitting. Our experienced sales team can help you identify the options that best suit your needs.

thread pitch and diameters of fire threads may vary according to local and municipal regulations

not compatible with other systems

washer NPT American Standard Taper Pipe Thread (National Pipe Tapered) male NPT with female NPT thread male NPT with female NPTF thread male NPT with female NPSM washer male NPT with female NPSH washer female NPT with male NPT thread

female NPT with male NPTF

female NPT not compatible with male NPSM or male NPSH

thread NPTF American Standard Taper Pipe Thread (National Pipe Tapered) male NPTF with female NPTF thread male NPTF with female NPT thread male NPTF with female NPSM washer male NPTF with female NPSH washer female NPTF with male NPTF thread female NPTF with male NPT thread

female NPTF with male NPSM or NPSH

NPTF with NPTF threads do not require sealant for the initial use, after that, sealant is required

not compatible NPSH American Standard Straight Pipe for Hose Couplings (National Pipe Straight Hose) male NPSH with female NPSH washer female NPSH with male NPSH washer female NPSH with male NPT washer female NPSH with male NPTF washer female NPSH with male NPSM washer NPSM American Standard Straight Mechanical Joints (National Pipe Straight Mechanical) male NPSM with female NPSM Seal can be either mechanical or washer. Mating fittings must be of same type. male NPSM with female NPSH female NPSM with male NPSM male NPSM with female NPT male NPSM with female NPTF SIPT Straight Iron Pipe Thread generic name for Straight Pipe Thread washer TIPT Tapered Iron Pipe Thread generic name for Tapered Pipe Thread thread NYFD NYFD Fire Department straight thread used in New York City washer Chicago Chicago Fire Department straight thread used in Chicago washer

Conclusion

Every worker knows it is to understand and be able to determine each type of thread. The most common types of threads are applied in the plumbing industry: UN/UNF.

Parallel Unified Thread Standard (UN) bolts are types of pipe threads applied in the plumbing systems in the US, Canada, and the UK. UN can be graded by the number of pipe threads per inch. For example, the pipe thread determined as UNF has the same length as UNC and the only difference is the higher amount of threads per inch. Moreover, UNEF is similar to UNF, but it also has a higher amount of threads per inch for each fitting size.

There are also 6 types of pipe thread that you should differentiate between them and their functions. When you have determined the type of device you need, you should fix it properly for the correct work.

Pipe threads are screwed connections which are particularly used in gas and water installations. In Europe, British Whitworth pipe threads (BSP and BSPT) are the most common. While in the USA the American NPT and NPTF are more common. Both British and American pipe threads are inch threads. This means that the pitch is given in threads per inch. 1 inch corresponds to 25.4 mm. However, for pipe threads, the inch specifications do not correspond to the inch diameter (e.g.: BSP 1&#; = approx. 33.25 mm). This confusing peculiarity has historical reasons. In the past, the inner diameter was the leading factor for measuring pipe threads and this was 25.4 mm. The outer diameter, however, was approx. 33 mm at that time. But due to improvements in steel production and manufacturing it had become possible to produce thinner pipe walls. In order to avoid having to completely replace existing installations that were produced according to the outside diameter, it was decided to increase the inside diameter.

Before we take a closer look at the individual American and British pipe thread types, we would first like to clarify essential differences and important terms for better understanding.

• Difference between cylindrical and tapered thread
  

The pipe threads differ in their shapes. On the one hand there is the cylindrical or parallel thread form and on the other hand there is the tapered or conical thread. In the course of the text we will work out the meaning of the differences further.

• Difference between self-sealing and non-self-sealing threads

In addition, there are pipe thread connections which are self-sealing, i.e. which function without sealant. And pipe threads that are not self-sealing. These require sealants, such as hemp or Teflon tape, to ensure tightness. We will also go into this in more detail later on, with the individual types of thread.

American pipe threads: NPT and NPTF

For the American pipe threads we would like to go into more detail about the NPT thread (National Taper Pipe) and the NPTF thread (National Taper Pipe Dryseal). The American pipe threads both have a flank angle of 60 degrees. In addition, both the NPT and the NPTF are tapered or conical internal and external threads. The American pipe threads are specified in inches.

1 .  National Taper Pipe (NPT)

The thread type National Taper Pipe (NPT) is a tapered or conical pipe thread which is used for pipe fittings. The internal and external threads of the NPT are conical. The NPT thread is self-sealing only at low pressure and when it is not exposed to strong temperature fluctuations. Therefore it is recommended to use additional sealant. It is defined in ANSI B 1.20.1.

2 .  National Taper Pipe Dryseal (NPTF)

The National Taper Pipe Dryseal (NPTF) is also a tapered or conical pipe thread (internal and external thread), which, unlike the NPT, is self-sealing even under high pressure and changing temperatures. It is defined in ANSI B 1.20.3.

NPT vs. NPTF

The main difference between NPT threads and NPTF threads is that the thread profiles are different. In the case of NPTF threads, internal and external threads overlap and can therefore act without sealant.

British pipe threads: BSP and BSPT

The British Whitworth pipe thread is specified in inches and has a flank angle of 55 degrees. At this point we will concentrate on the two thread types BSP and BSP.

3 .  British Standard Pipe (BSP/ G)

The British Standard Pipe is a Whitworth pipe thread and is marked with the abbreviation G. It is a non self-sealing thread. Both the internal and external threads have a cylindrical or parallel thread form. It is only sealed by the interposition of a sealant. It is standardised according to ISO 228.

4 .  British Standard Pipe Taper (BSPT/ R)

Whereas the British Standard Pipe Taper has a tapered external thread and a cylindrical internal thread. It is often abbreviated as R (tapered male thread) and Rp (cylindrical female thread). Due to this thread connection it is self-sealing. It is standardised according to ISO 7-1.

Connection combinations of G and R thread

Combinations of G- and R-threads are possible. However, only in the connection combination:
Tapered R male thread and cylindrical G female thread.

 

Different pipe threads

Since not all pipe threads are the same, this article contains a comparison table of the pipe thread types NPT and BSP. These are also sometimes confused!

To the article: Pipe thread is not equal to pipe thread!

 

These were the 4 most known pipe threads. Do you have questions about threads? Call us or write us. We will gladly help you.