This one happened back in the 70's, when I was a green kid out of high school. I worked in a auto body shop. We had a huge compressor with a 120 gallon receiver. It was a 2-stage compressor and so the cutoff pressure was 175 psi.
I needed another air line, and the tank had a 2" galvanized steel plug on one end. I decided to replace the plug with a bushing reducer down to 3/4" pipe and hook my new line in there.
I shut off the compressor and opened the little 1/4" drain valve on the bottom of the tank to relieve the pressure, but it was taking forever.
I loosened up the 2" plug a little, so that some air was leaking past the threads to try and hurry things up. Still slow as molasses.
Finally the pressure was down to around 25 psi. That didn't seem like much at all to me, figured I could just finish unscrewing the plug and catch it as it came off.
Fortunately I was standing to the side, as the plug shot out of the end like a cannonball. It went right through a doorway and into the field next door. We never found it.
I needed another air line, and the tank had a 2" galvanized steel plug on one end. I decided to replace the plug with a bushing reducer down to 3/4" pipe and hook my new line in there.
I shut off the compressor and opened the little 1/4" drain valve on the bottom of the tank to relieve the pressure, but it was taking forever.
I loosened up the 2" plug a little, so that some air was leaking past the threads to try and hurry things up. Still slow as molasses.
Finally the pressure was down to around 25 psi. That didn't seem like much at all to me, figured I could just finish unscrewing the plug and catch it as it came off.
Fortunately I was standing to the side, as the plug shot out of the end like a cannonball. It went right through a doorway and into the field next door. We never found it.