Measuring Threads
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Posted by: DougP ® 07/31/2003, 10:40:26 Author Profile Mail author Edit

What is the correct way to measure NPT threads using a Ring Gage. Are measurements to be taken 1/2 to 3/4 turn below champfer? Or flush with end?

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NPT ring gauge
Re: Measuring Threads -- DougP	Post Reply	Top of thread	Forum

Posted by: RKimball ® 07/31/2003, 22:01:23 Author Profile Mail author Edit

1st, let me clearify that I was not able to prove my answer, after all these years of doing it as I have, ... lots of years. .. not in any of my books.... I was amazed at this. But, I have always made the ring gauge fit within 1.5 turns of flush to the end of the thread. This insures that the male thread will easily enter the standard female and have enough size left to be able to be tightened securely past the point of the material surface RMS, of a good thread form, ... fitting together tighter than the molecular size of most liquids. ... thus the point of a pipe thread. I know I read it in a MIL SPC somewhere early in my years of memory. Perhaps someone can quote the MIL SPC number. -randy- ** The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, don't fail to listen to suggestions. -randy- Modified by RKimball at Thu, Jul 31, 2003, 22:04:03

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Re: NPT ring gauge
Re: NPT ring gauge -- RKimball	Post Reply	Top of thread	Forum

Posted by: DougP ® 08/01/2003, 11:34:47 Author Profile Mail author Edit

Randy, Thanks for the info. You have helped settle different points of view. I also found a site that stated 1 turn large and 1 turn small are acceptable. I have searched a number of sites and most just want you to buy the information. I just registered with this site and was absolutely amazed at the number of topics covered. Thanks Again, Doug

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