Plumbing question?

I'm doing a little plumbing work on my home. I need to install a shut off valve. The one that I purchased is a sweat type. My concern is how to sweat the joints without doing any damage to the valve. Should it be open or closed? Do I need to take it apart? What is the trick? Sorry that I left this piece of information out. It is a ball valve.

Public Comments

1. if its a gate or ball valve,close valve, if globe valve which has washer in it, also an arrow pointing direction of flow,leave open Make sure absulutly no water in pipe before sweating
2. It is best to close the valve. That way, no flux or solder can get into the "gate", and hinder you when turning the water off. There is no need to take it apart. Just make sure all the joints are clean, and ream every piece of pipe you cut. Good luck!
3. If you are that unsure of your self with a torch, (been there) , spend a little more and buy a thead type, and put in a union. Male fitting, union,brass nipple, valve, male fitting. Someone 20 years from now will thank you. If you are determined to use what you have, put a damp rag on top of the valve to help keep it from over heating. The first two posts gave you quality advice. I am just giving you a different option.
4. The best thing to do is solder it on with the valve open and with no or as little water in the pipe...you first shut off ur water and drain down ur house by opening a tap upstairs and down...it is important that there is no water