plumbing: torque without bending pipes

[PoorOwner]

OK, I am trying to wrench off this nut that is holding the shower valve's cartridge. The piping is copper and just stands inside the shower.

I have way to hold the valve (visegrip) while I use an adjustable wrench. Though I am afraid I may break the solder joints or copper pipe if I am really going to wrench on it. Just sitting back for now, and trying to do some penetrating oil, descaling. etc

I heard lightly tapping the wrench with hammer might be better than applying huge torque with a wrench.

The nut has 2 flats only.

at this point is it corrosion holding the threads tight? Would CLR free the threads better than vinegar (valve is brass, not sure if CLR will harm it)

If I call a plumber it would be because I am replacing the valve or bath tub all together.

 

[sublimate]

Can you put some heat on it?
That usually frees it up.

 

[stokefire7]

Pic straight on would help.

 

[bbrz]

By any chance you can get to it from behind? Even if you have to cut out drywall. Replace with a modern pressure balance valve. Long term fix.
Other wise, you are just putting off the inevitable. And no, copper does not take much force.

 

[cwlo]

A better picture would be helpful, but are you sure you need to remove that? Looks like the cartridge is already out.

Chris

 

[zkling]

Can you get a basin wrench back there to hold the reaction force from turning the front ******?

 

[Cyberbear]

If you have the experience, you can possibly use pool acid to dissolve the oxidation that may be holding it from loosening up, but be careful, as always. I've had lots of experience dissolving oxidation this way, which is much less harmful than going the brute force pathway.

 

[FullRaceMerc]

Is the valve body not screwed to lumber inside the wall? Usually they are, so pipe alone doesn't have to hold the valve. A lot of times you can see the screws by shining a light thru the opening around the valve.