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NPT size for 7500 psi??

NPT size for 7500 psi??

NPT size for 7500 psi??

I need a larger NPT hole than 1/2" for a 7500 psi.  We have been testing at 4500 psi with a 2" NPT (fill with water).  But now we are testing at 7500 psi.  I know API says 1/2 NPT for 10,000 psi, but is there any other spec I can use for a larger NPT at 7500 psi???

RE: NPT size for 7500 psi??

Quick question, is the 2" NPT/LP part of the equipment being tested or part of the test equipment? If the working pressure of the 2 NPT is under 5000 you can test to 10000 but if it's part of your testing equipment your working pressure is 7500 and you're above the recommended working pressure.

RE: NPT size for 7500 psi??

No its part of the Test Equipment.  It sees a direct pressure of 7500 psi

RE: NPT size for 7500 psi??

Your test equipment isn't covered by API. If the volume is small enough it isn't covered by ASME either so all you're subjected to is best practise. Do some calcs to see if the configuration can be rated to 7500 with a reasonable safety factor. Of course your biggest problem might be preventing the connection from weeping and messing up your tests.

RE: NPT size for 7500 psi??

Team Members




RE: NPT size for 7500 psi??

Yah I knew about Autoclave, I was trying to stay away from them due to price, this is a cheap fixture, 36" dia flange

RE: NPT size for 7500 psi??

Hi All,

There is a report available on Awhem website for gas testing of 2" LP thread which held up to 12.7 ksi. Awhem had proposed some changes to API 6A which would allow 1/2" - 4" LP connection to 10K WP. I think API had opted for acme thread instead but nevertheless the report is valid. Only thing is that the material need to be min. 60K yield.



RE: NPT size for 7500 psi??

Yes, I also found the AWHEM API 6A proposed spec.  One of our (my company's) engineering managers was actually on the board.  However, we have decided to use the 1/2" NPT and just use an air hose to blow all the remaining testing fluid out through another NPT port.  Thanks for your help.

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