Pressure piping test

[Volnei]

I would like to know what is the procedure that you use to do pressure test piping after welding conclusion in a big plant with ammonia.

Do you also do vacuum test?

Best Regards.

Volnei

[C. Noseworthy]

On Large systems, I generally pressurize with perferably dry plant compressed air to the available pressure ( 9 - 10 bar) I then inspect all joints using soapy water to detect leaks (soap bubbles). The pressure should not change more than a few % for 18 -24 hours (overnight) unless there is a large change in ambient temperature.
Any found leaks are repaired and the system is again pressurized to 9 - 10 bar. Test the repairs. If no leaks are now found, use nitrogen to increase pressure to design working pressure. Repeat the soap test.
When no leaks are found, purge the air/nitrogen and evacuate the system. This can take more than 24-36 hours. A vacuum test is useful but due to the typically large size & potential for moisture presence, in the ammonia system, it may prove difficult to attain a deep vacuum. Watch your vacuum pump for signs of moisture in the oil.

[Volnei]

Thanks C. Noseworthy.

Best Regards.