Time before welded pipe is usable?

The water was shut off to my apartment complex, and a few neighbors noticed that some workers had repaired a copper water pipe. Since the workers had left without turning the water back on, someone opened the valve back up.

Did the workers simply forget to turn the water back on, or were they going to return after a certain amount of time? Shouldn’t the pipe be ready to use immediately after they finished fixing it?

Is there any other reason to keep the water off after finishing this type of repair?

Yes. BUT, you have no idea what else may be going on. There may a be a very good reason why they left with the water turned off; or they may have just forgotten.

Yeah, I’d say there’s a good chance that there’s a basement or unattended apartment somewhere that’s currently filling up with water.

Technical nitpick; they soldered the pipe, not welded it. (It is possible to weld copper, but generally unnecessary as copper is rarely used as a structural metal except in alloys).

The pipe should be usable as soon as the solder is cool. I agree with Q.E.D.; it may be that they simply forgot to turn the water back on, but this would be unusual, as you would want to pressurize the joint in order to see whether it leaks. More than likely they had some other reason for not turning it on yet. You should contact the owner or management and ask about it rather than blithely turn the system back on.

Stranger

Could have been brazed, too, although brazing is rarely done with ordinary plumbing; soldering is usually sufficient for the pressures involved.

Thanks for the input. So far, I have not been able to get though to the property manager. I’m not the one who turned the water on, but I’m not going to turn it back off either.

Indoor pool! w00t!