Please see photos of the copper water service below. There is a button shaped object on the tubing just below the valve with lots of calcification around it. Looks like a nail head to me though I don’t see any rust. It wasn’t leaking at the time so there was no way I was going to scrape or touch it to try to determine what kind of material it was.
Copper sweated to gate valve, right? Looks like plain ole copper tube, don’t get it. If so, I don’t understand what protrusion is there. Weird. Also, what is the discoloration / small dot at area opposite where gate valve would seat when closed? Almost appears that moisture may have started from there, as it’s the high point. Good news is, a gate valve and section of copper are inexpensive and it looks like it’s worth a look at to repair.
I’d be tempted to scrape it, but would have tried to remember that curiosity killed the cat and may have to pay for the plumber too
Yea, that was my take. Absent the weird appendage on the copper tubing, I would have just attributed the calcium buildup to a bad valve body casting, but I’m kind of baffled.
It did take some willpower not to mess with it.
I punted and described it as below with some detailed photos.