TooBusy wrote:
People generally don't understand that psi is pounds per square inch.
A little story about an industrial accident from early in my career.
We had these HUGE autoclaves at work. The doors were about 8 feet in diameter, weighed a couple of tons and hung on hinges with pins bigger than my wrist, and closed using multiple bolts like a submarine hatch.
One day a fairly new operator got in a rush to get it unloaded. Valves were opened and it was bleeding down. At about 5 psi he tried spinning the wheel to open the door and it wouldn't budge. He thought it was stuck, so he attached the hook from the gantry crane and hit the up button....
End result the autoclave slid back a few FEET through the wall of the building and the door went flying across the shop with the gantry crane in tow.
Thankfully no one was killed.
To take that one step further, this example equates to the door having 7,234 square inches of surface area, x 5psi=36,172 pound of force available to do what it did!
We have a fab shop, and for years we worked on Fuel Oil and Gasoline delivery trucks. They got steam cleaned professionally, and never tested at over 2psig. We had one incident because of a lack of a secondary safety rupture disk, and the regulator was creeping up. I think it hit 20 psig with water filling about 3/4 of the tank as a hydrotest, when the bulkhead reversed itself and tore off of the bottom of the floor. Needless to say, it was fortunate that is all that happened, but it was one EXPENSIVE screw up! We made sure to use secondary and tertiary safety's after that...