depending on the size of the vessel,
when new construction, pneumatic can be used safely by following contaiment procedures,
a lot of hi-press air, O2, weld gasses cylinders are air tested.
ER
I still am not comfortable with pneumatic test if a hydrotest is a viable option. When we do a pressurization of a vessel or mostly a system with gas we only use it as a opened flange or open valve test and not as proof test of the equipment itself.
As for walking by equipment in operation in my forty plus years concerned with the design and inspection of same I’m always have a little concern that did we do as thorough inspection and or repair as possible at the last outage. This is not for myself but for the operators and maintenance people that have to be around the equipment everyday. This is a real feeling as I can’t recall how many times we would be concluding a job and something would catch my eye and make me look closer and find something that hadn’t been noted previously.
Small air tanks.
Every time I think of pneumatic testing of tanks I think about the Italian Scuba diver who would over pressured his Scuba tanks to 5500 psig so he could dive to 400 ft in search of Fire coral. His method of selecting the tanks was to proof test tanks until he got one to hold, about one in 25, the 5500 psig.
The irony of this gentleman's endeavor was that the air tanks or deep diving didn't kill him his neighbor stabbed him to death over a garden hose.
Though I don’t dive anymore just visiting some of the dive shops scares the hell out of me they way they handle compressed air. When you walk into a shop by the back entrance and right beside the door are a wad of tanks manifold togather being filled you tend to want to make a hasty retreat but your too scared to go back by the tanks.
Never hammer test the welds on a vessel under pneumatic test.
UncleSyd said "Never hammer test the welds on a vessel under pneumatic test." Amen to that. I'm with you - I'd never approve a pneumatic test where hydro is a real option.
Deanc - interesting link.
GenB - containment is a safety measure due to the inherent dangers of pneumatic testing - it does not make pneumatic testing safe.
