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NTP pipe ID deformation when threading

NTP pipe ID deformation when threading

NTP pipe ID deformation when threading

(OP)
If I have a male 1/2" NTP pipe fitting (.590" ID), and thread it into a female NTP pipe fitting to the point of achieving a good seal to several thousand psi in a hydraulic system, does the ID of the male NTP pipe fitting decrease ever so slightly by the time it is torqued hard enough to achieve a seal? If so, how many thou or fractions of a thou are we talking? If there is a way to calculate this please let me know.
Thank you.

RE: NTP pipe ID deformation when threading

Do you by any chance mean "NPT" instead of "NTP" (in any case question sounds some loaded, as thi ssound slike potentially a whole lot of pressure for threaded connections with less than extra heavy thickness pipes etc.)?  
I guess the answer to your question is nevertheless "YES", but in order to calculate something like this would take a LOT of assumptions (about the specific fabrication, assembly and installation, meaning you'd have to know a lot about what is/was done if you expect accurate results).  
Let's see what others say.

RE: NTP pipe ID deformation when threading

(OP)
Yes, definitely meant NPT... sorry 'bout that!

RE: NTP pipe ID deformation when threading

Theoretically, does the ID of the pipe compress when the OD is threaded into a NPT connection?   Yes, and I think you could even calculate the compression.

Practically?   No.   

The outside fitting is also expanding as the pipe is threaded on and tightened.  So: how much does the outside expand and the inside pipe compress?
The amount is minute - only a few thousandths of an inch.  Is it even measureable in the real world?   How do you verify your calculated number?  Can't cut the pipe in half and measure -> that would relax the compression and make your measured number meaningless.  
The variation on threaded pipe ID is much greater than the amount of compression.  
The percent flow reduction due to compression is meaningless.    

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