This tale is back from my days as a non-union industrial plumber.

I was working on a 2" copper domestic water line in 2007. I was teamed up with one other guy. After we completed a portion of the system we pinched and brazed one end of a piece of tube approx 12" long coming out of a ball valve to effectively cap the line for an air pressure test. This was before lunch.

After lunch we went back to work. The test held and we got the installed portion bought off up to the ball valve. My partner said he already let the test off so I could go ahead and de-solder the blanked end from the ball valve and we could continue running copper from that point.

The end of the line was approximately 12' in the air so I climbed up the ladder with my turbotorch and proceeded to lay fire to it. After a few moments, BLAO!

The line, contrary to the word of my co-worker was in fact still under a 150-175 psi air test.

The tube released from the cup of the ball valve and launched across the room, my eyes tracking it in slow motion as it slowly arced downward. It flew 25' and cleared another co-worker's head by inches before lodging itself halfway through a 5/8" sheetrock wall.

I don't know if it would have killed the fellow or merely mutilated his face for the remainder of his life. He looked at me after it happened with a stern glare as he made a fist with one hand, thumb protruding and slowly dragged it across his neck in a gesture reminiscent of a colombian necktie. I sincerely thought I was going to be murdered in the parking by a 5' tall hispanic individual that afternoon.

cliffs: When it comes to lockout/tagout, trust but verify. Put your own eyes on it. Every time.