Compression valve under bathroom sink slips off of supply line...

[Kalissa k]

Hi everyone, I was replacing the bathroom sink shut off valves because they both started to drip. The hot water side I was successful with. But the cold water valve is not going well. The problem is that the nut on the copper supply line doesn't stay on the supply line. I don't know if I sanded the copper pipe down too much or if it was the plumbing grease I added but the whole valve and nut just shoot off the supply line now .. what might I have done wrong to cause this almost comical fail?

 

[Tuttles Revenge]

Did you remove an old compression valve and install a new one with all new parts?

If yes, did you cut off a portion of the copper stub out prior to installation of new valve?
-if so how much did you cut off? Compression connections, do exactly what they're named for, compress a brass ring onto the copper, and if someone like my brother tightened it on, may have compressed the copper signifigantly.

Did you use a tool to remove the old compression nut and ferrule? If so, which tool and did it perhaps deform the end of the copper stub out. If it did.. cut off the deformed portion and start on fresh tube.

 

[Sponsor]

 

[Reach4]

Can you measure the OD of your copper pipe? Common would be 5/8 inch =0.625. A digital caliper is a good tool, and yes, I think a whole lot more people should have one.

A compression valve takes a lot of torque to install, and two not-small wrenches. Do not be afraid you are going to crush the copper pipe. You might need both longer wrenches and a really strong friend. The access to the pipe is often limited, and it is hard to apply a lot of torque at arms length.

You did use the new ferrule that came with the valve, right?

 

[John Gayewski]

I also think your copper has been deformed by the removal of the old valves.

Take a reamer and run it onto the copper pipe that's coming from the wall. That should reform it. https://www.amazon.com/Swaging-Prof...71263911&psc=1&ref_=d6k_applink_bb_dls_failed