sweating copper to brass valves ?

[glennster]

helped a buddy with a plumbing project he had. i was sweating in some 1/2 inch brass gate valves. i pulled the stem asem out when i sweated them. he said he never takes them apart, just sweat em in. what do you guys do? i figure with the stem out, you wont damage the packing or gasket from the heat.
 

[bjb in TX from Ne]

I just redid part of the plumbing in my house. The gate valve did not have any warnings; the ball valve for the water heater said "do not use excessive heat". I sweated both as a unit and no leaks wide open. The ball valve was not as tight after soldering and the gate valve is leaking a few drops fully closed but I think I can stop that by tightening the shaft packing.
 

[Dick2]

I open the valves; letting a little heat escape can mean the difference between a good valve and a leaking valve. I only use ball valves; I stopped using gate valves years ago.
 

[jackinok]

you cant really take a ball valve apart for sweating,so i never did. gate valves it depends.small valves i didnt most of the time,but sizes in the 1 1/2 on up range i did simply because they require so much more heat. globe valves most defintly pull them apart. towards the last i never even used gate valves if at all possible. they cause so many problems later on that i tried to stay away from them altogether.
 

[oliver power]

simply open the valve. Never use any more heat than neccessary. Also better off useing a hot flame. Mapp gass would heat the imediate area to be sweated quicker, not allowing the rest of the valve to absorb too much heat. Where as propane might heat the entire mass of the brass valve before solder melts.
 

[Stan in Oly, WA]

I've always taken them apart when that's possible. When it's not, I've sometimes wrapped a wet rag around the center of the fitting before soldering. I have no way of determining whether it helps, but if the rag is still steaming (not completely dried out) when I get a good soldered joint I figure it's probably provided some cooling at that location.

The problem with damaged valves is that they usually work fine in the open position. A valve that is permanently open during normal use---the shut off for the supply side on a water heater, for instance---may not let you know that it's not going to work just when you really need it.

Stan
 

[MarkB_MI]

I only use ball valves now. There's no reason to use gate or globe valves; the cost difference is very small, and ball valves are pretty much maintenance-free. That said, if you have to sweat in a gate or globe valve, you'll save yourself a lot of aggravation by taking it apart first.
 

[Stephen Newell]

There are different kind of valves. Some have plastic and rubber parts inside. I always take these parts out of the valve before I sweat the pipe. I learned this by melting the plastic packing the first time I did one.
 

[El Toro]

I installed those single lever shutoff valves in 2008. I couldn't move the copper pipe so I used a sweat union. I didn't disassemble the valves. I installed 7 valves. They work a lot better than the cheap valves installed when the house was built 44 years ago. I didn't remove the old shutoff valves. Hal
 

[JML755]

I've never taken valves apart. 1/2" isn't a problem at all. On larger stuff, 3/4" & 1", I'll do what Stan does: wrap a wet rag around the valve. Haven't had a problem in 30+ years.