sizing pipe threaded elements

[guideonl]

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

[edgepflow]

The threads are probably National Pipe Thread Taper (NPT). You can find dimension charts online.

[Unrest]

simple external meassurement I'll be able to determine the element size such as safety valves,threaded pipes,pressure gages,caps etc.


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.

[guideonl]

Thanks, Guideon

[xxChrisxx]

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.