pop goes the ball valve

hot_rod

ever hear a ball valve go pop when you solder one?

What can happen is the pressure builds up inside the closed ball and pops the seal out. Often it happens on a valve that has been in service and has water trapped inside the ball, in the off position. The water expands when heated, or steams if excessive heat is used, like un-soldering a stubborn valve :)



This can also happen on solar systems where a shot of high temperature fluid, 300F or more hits that closed ball, like on these purge fill combo valves for example.



I thought this was a clever solution for that potential problem, drill a small hole in the ball so there is no chance for the pressure increase inside the ball.



hr

EricAune

Had this happen once

This actually happened to one of my apprentices about a year ago.  We were making a tie-in on a two inch main.  Had to un-sweat a piece out of a two inch ball valve.  Must have been a low quality valve or something, after reaching high temps it actually exploded sending shrapnel through out the room. 



Amazingly and most of all thankfully he was not hurt.  This changed the way I approach this type of work.  Take the time to drain EVERYTHING down and always crack that valve half way if it has been in service.  Never trust anything!  I know my guy could have been seriously injured.