rusbeli,
pneumatic tests are quite dangerous if improperly carried out. That's why Al suggests (he's joking, of course) to have someone else to inspect the test instead of you.
Fact is that if a leak develops during a hydro test, a few drops (or milliliters, at the most) of water will spill out and nothing else will happen. On the contrary, if a leak develops during a pneumatic test, an explosion can occur, with dangerous results.
However, pneumatic tests are usual procedures in industrial plant erection. In these cases, they are conducted following a rigorous procedure that has been specified by the equipment manufacturer, the engineering firm that designed the plant, the consulting engineer that has been appointed to make specialized recommendations, or by whoever has the authority to do that.
Back in my days of erector engineer I conducted several pneumatic test on boilers casings, which were to be airtight. The tests were carried out following the manufacturer's instructions, under the supervision of the manufacturer's field engineer. I also did the pneumatic test on a few refinery piping that was too far from a source of water. With the client's approval, we moved an air compressor close to the piping and the test was carried out following the procedure written by the engineering firm that designed the plant. Many years have passed and I don't remember the details.
You don't say where you want to make the pneumatic test (equipment, piping?) nor why you're using nitrogen instead of air.
Giovanni S. Crisi
Sao Paulo - Brazil
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