In tube fittings, there are several pipe thread types. Understanding the type of thread tailored to specific tasks can make the process even more approachable and less daunting. So, in this article, we will explore the two types of pipe threads.
What are the types of pipe thread?
Generally, we divide pipe threads into two types:
v The parallel
v Tapered threads
Parallel threads
Parallel threads typically include the BSPP, metal parallel, and UN/UNFF types of threading and connection.
Conversely, the tapered threads include the metal tapered, BSPT, and NPT/NPTF connections.
What do both types look like?
To know if your tube has a parallel or tailored thread, the thread diameter should tell the whole story. If you notice a thinner diameter as it approaches the end, then you have a tapered thread in your hands. On the other hand, if you notice a constant diameter from the top to the bottom, then what you have is a parallel thread. You can check out visual references to get a clearer picture of what these entails. Usually, you can find if your fitting is tapered by comparing it with an already known parallel. Something like calipers can help a great deal in this regard. If you notice that the threads of the tube touch the caliper as it courses its entire length, then you have a parallel thread. On the other hand, if you notice that the thread rocks at some point, then you're looking at a tapered thread.
Now, on identifying which is parallel and which is tapered, the question is how do you know whether it is BSPP or metal parrel, or the specific type? This is where pitch determination comes into play.
With a pitch gauge tool, you can identify the thread’s specific sizes. Each specific type of thread has a different pitch size. So, once you find out this size using your pitch gauge tool, you can then compare them with the standards table to p know the exact connection it has.
You can as well factor the thread size in. Before using this method, you want to be sure that the thread is a pipe thread. As you probably know, not all tapered threads are pipe threads.
So, if you’ve confirmed that you have a pipe thread in your hands, you can then go on to find out the relevant nominal size profile and compare the thread size accordingly. You can measure the thread’s outside diameter with a caliper to get this value.
Conclusion
In this thread identification article, we highlighted three different steps, starting from the right way to identify parallel and tapered threads, to getting the specific thread type via thread size and pitch sizes. When measuring these, you should be extremely cautious because using the wrong thread for any purpose will result in leaks, and property damages, among others.
So, always ask questions if you’re not sure. If you are perhaps confused about the options available for you or you’re looking to take the first step and request a quote, be sure to contact us and we are always here to help.
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