I have a home built in the mid-70's and we are wanting to do some remodeling in the bathrooms. Since I can't turn off those old valves under the sinks, I thought this would be a great time to replace them with new quarter-turn valves.
The problem is, I can't seem to get the old compression fitting off to remove the valve, the nut is frozen to the valve body. One of them has a whole bunch of white corrosion around the threads and I haven't even tried that one yet. They are a brass nuts on brass valve bodies, not chromed, and I think that has facilitated part of the sticking.
I am looking for help in how to un-stick/freeze this valves so I can replace them. I am wary of pure brute force as I don't want to make matters worse, unless that is the only way of removing them. Cutting them off will not work since there will not be enough copper pipe extending out to put the new ones on.
Best Answer
Start with some penetrating oil and time. Then proceed to mild heat from outside. You want to expand the nut, but not the inner parts. If you have room, a plumber's torch (judicially applied) or a basic flame from other sources. Be sure to steer clear of vinyl parts that could be damaged.