Hi,
We are trying to replace the counter, sink, and faucets in 3 bathrooms, and we would like to do it ourselves.
We shut off the water supply to the sink and started to unscrew one of the nuts on the tubing, and the tubing/pipe were still firmly attached. After doing a lot of research online, we are fairly sure that we have compression fittings on copper tubing. I believe the compression fittings are permanent and we cannot disconnect them by unscrewing the nut, correct?

Anyway, what is the best way for DIY'ers to proceed? Do we need to cut the copper tubing above the shut off valve and install new lines for the faucet? And do we go with more copper tubing or do we choose stainless flex tubing? We definitely want to avoid soldering or anything with a flame. How do we ensure watertight seals - Teflon tape or plumber's putty?

Is this a DIY job, or should we call a plumber?

This is a typical DIYer , no need for a plumber. The ring rarely can be reoved but the ring and nut above it can be reused when you attach a new pipe. I am not clear on what your have. Is the nut and ring attached to the tube coming down from the faucet or are they attached to the supply pipe coming up toward the sink?

I went to look under the sink again. The compression fitting connects one flex copper tube coming from the shutoff valve and one flex copper tube going toward the faucet. So the connection from the valve to the faucet has the compression fitting at the halfway point. As far as which side the nut and ring are on, I don't believe I can tell. It's at the joint, so I'm not sure.

Once the nut is unscrewed it becomes loose and can slide up the tubing, pull on the tubing and it will unplug itself from the rest of the fitting. Once you do this that ring will not be clearing attached to the line from the faucet or the supply line fom the house. If its attached to the facet just through the whole thing out. I always attach new lines to new faucets and frequently replace shut offs with newer 1/4 turn shut offs

How hard should one have to pull to disconnect the two lines? We unscrewed the nut already and it slid up the tubing, and we tried pulling to separate the two tubes, but they did not budge. How hard should one pull?

If this helps, there is some bright blue material smeared around the joint from the previous homeowners. I'm guessing this may be some sort of joint compound, and is making the separation more difficult?

Show us a picture.

How hard should one have to pull to disconnect the two lines? We unscrewed the nut already and it slid up the tubing, and we tried pulling to separate the two tubes, but they did not budge. How hard should one pull?

If this helps, there is some bright blue material smeared around the joint from the previous homeowners. I'm guessing this may be some sort of joint compound, and is making the separation more difficult?

Does your stop look like this? (see image). Let me know. Tom

Ok, thanks everyone for the interest to help. I went to take some pictures.

Here is a picture at the shut-off valves:
http://img200.imageshack.us/img200/5756/picture1tg.jpg

And here is a picture halfway toward the faucets:
http://img63.imageshack.us/img63/7039/picture2fwa.jpg

Uploaded with ImageShack.us (http://imageshack.us)[/IMG]

What I tried is as follows: in the second picture, I gripped the larger nut and unscrewed it upwards and it slid up the tubing. However, the tubes did not disconnect. I tried pulling them apart, not as hard as I could, but reasonably hard. Let me know what to do. Should I unscrew the nut immediately above the shutoff valve?

Yes, unscrew these copper supplies at the angle stops (... valves). You will use s.s. braided connectors to reconnect with new faucet. They sell these s.s. supplies in all kind of lengths at Home Depot.

Judging from the photos, your angle stops look fine to me. No need to replace them...

Why bother with the coupling of the two pieces of tubing? Disconnect at the stop valve and at the faucet and discard. You will be replacing with a flexible line that reaches from the stop valve to the new faucet.

What you see around the fitting is corrosion cause by a leak.

Ok, thanks a lot for your tips. I will try to unscrew the nut immediately above the valve.

When I shut off water to unscrew that valve, all I need to do is close that valve in the picture, correct? I don't need to shut off the main water to the house, right?

Hi Jenn

If angle valve is working correctly, shutting valve will shut water.

Open faucet valves and shut off angle valves. If water stops coming out of faucet valves, angle valve is doing its job.

If water still comes out of faucet after closing angle valve, u will have to shut off main and repair or replace angle valve.

Chuck