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Sizing pipe threaded elements

  1. Feb 27, 2011 #1
    Hi to everyone,

    I have a problem with sizing pipe threaded elements. I am looking for guide rules that with a simple external meassurement I'll be able to determine the element size such as safety valves,threaded pipes,pressure gages,caps etc.
    To clarify my question, hereby an example, when I meassure 1/2" safety valve, I can't relate the 1/2" to the actual possible meassurements (ext/int dia) of this valve.
    The same problem, when meassuring a threaded hole in a vessele..
    I hope that I need not to take several meassurements (ext&int dia, thickness, pitch, number of threads per inch...) and than look at the tables to which size it fits.

    Thanks, Guideon
  2. jcsd
  3. Feb 27, 2011 #2
    The threads are probably National Pipe Thread Taper (NPT). You can find dimension charts online.
  4. Feb 27, 2011 #3
    I once made a keyring with a set of threads on it, then I could just line them up with whatever I wanted to check.
  5. Feb 28, 2011 #4
    Thanks, Guideon
  6. Feb 28, 2011 #5
    This sort of thing is done by standard. You can use loads of different thread types. NPT are good for about 10k psi if I remember correctly. Above that you'll need to use something different.

    Look at a catalogue of someone who sells connetors. So Swagelok, Autoclave engineers, etc.
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