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3/8 NPT Internal Thread Tolerance

3/8 NPT Internal Thread Tolerance

3/8 NPT Internal Thread Tolerance

(OP)
Does anyone know the formula to calculate the acceptable min/max diameter for an internal 3/8" NPT?
Thank You!

RE: 3/8 NPT Internal Thread Tolerance

The thread is usually already provided by the part or assembly (as a screw in fitting or valve for example) or is very simply - almost automatically - done by a commercial tap purchased already cut.

Don't get me wrong, there are tolerances in the threads, taps, dies, and parts involved, but unless you are somehow needing to write a CAD/CAM program to actually drive the machine - just specify the thing.

Put the pipe dope or Teflon (properly wrapped) on the threads and go.  

RE: 3/8 NPT Internal Thread Tolerance

(OP)
Thanks racookpe1978 but I am in need of the formula.

RE: 3/8 NPT Internal Thread Tolerance

With a taper thread you can easily tap too deep or not deep enough and get the diameters wrong. I would look in the Mahinery Handbook if I could find mine right now. I'm sure you could find the specs with Google as well.

RE: 3/8 NPT Internal Thread Tolerance

(OP)
Thank You Compositepro but I could not find the formula information in the Machinery Handbook or on Google.  I am beginning to think this formula is a well kept secret!!

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