How to Position a NPT Pressure Gauge

D

Thread Starter

Daniel

For an upcoming project we have to install a lot of 1/2 "MNPT gauges and PT in the corresponding isolation/drain valves. The valves have two 1/2" FNPT ports (for the gauge and Tx) and 1/2"MNPT for the process. Also a 1/4" FNPT port for purge and calibration purposes.

All components are stainless steel, and the pressure is 300 psig or less. We want to use standard PTFE tape as sealing (not another sealing compound)


We need to describe a simple method for the mechanical installers, in order to achieve the optimal viewing and operating angle for the three elements, without overtightening the components, since in NPT the seal is metal-to-metal and the thread could be damaged.

Do you have a proven recommendation? For example "use x turns of PTFE tape, tight by hand, and then ... etc". We want to avoid the elements to be installed at any angle, but also avoid over or under torque.

Thanks in advance
 
Thank you David, your reccomendation was useful. You were the only one with a help! I thought my question was easy to solve, but it seems that not

regards
DM
 
If you are concerned about this, use male and female to 1/2" SS compression fittings. This will permit proper thread tightening and still allow rotating the instruments 360 degrees.

For example, Swagelok SS-6-TA-1-8 (3/8 male tube to 1/2 NPT male) and an SS-600-7-8 (3/8 female tube to 1/2 NPT female).

Given any 3D angle to any 3D angle, use a SS-600-1-8 (3/8 female tube to 1/2 NPT female) instead of the male tube fitting, use tubing long enough to bend for proper 3rd-axis orientation.

FWIW, PTFE tape is meant to be a thread lubricant, not a sealant.
 
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