I've seen a few people post pictures of destroyed S-tubes. Never seen a Rock Valve busted in pieces. Does it happen like the S-tubes, any pics?

Seen one over the years,before digital/camra phones.

beat's me, i wonder why ..lol............................

I'd love to see some pics of the destroyed S-Tubes.  Rock valves will break but not the same way.  Anything under pressure wants to straighten out, so imagine the S-Tube trying to straighten out inside the hopper.  I'd imagine the steel could just get worn down over time and not be able to handle the constant flexing any longer.  Also, I know of a lot of people that want to hardface S-Tubes like they do rock valves.  You cannot do that from what I understand.  You just ruin the integrity of the steel, and it will fail eventually from that.  The rock valve extends too, but not as much since it's pretty much straight to begin with, but this little bit of flexing stresses the hopper.  Since the rock valve has the shaft out the back with a nut on it, over time the hopper will have pressed on the nut enough that it cracks the shaft, and the threaded part of the shaft with the nut on it will just fall off.