First, you'll want to remove the fitting on the supply pipe, either by cutting just below it or unsoldering it with a torch. Then install a 1/4 turn shut-off valve. Your supply flex line will screw onto it.

This one uses a compression fitting to attach to the supply pipe, you can also get solder fittings and Shark-Bite. I'd avoid using Shark-Bite here. You can check out some YouTube videos to see how easy it can be to damage the seals on older work.

You can install compression fitting valves like: https://www.homedepot.com/p/BrassCraft-1-2-in-Nominal-Compression-Inlet-x-3-8-in-O-D-Compression-Outlet-1-4-Turn-Straight-Valve-G2CR14X-C1/202047046 which attach to a cutoff copper pipe. You would need to buy a pipe cutter like: https://www.homedepot.com/p/RIDGID-3-16-in-to-15-16-in-Model-104-Close-Quarters-Tubing-Cutter-32985/100021967 then your sink connectors attach to the valve. You discard the nuts on the end of the valve.

@HU-178658043: "First, you'll want to remove the fitting on the supply pipe, either by cutting just below it or unsoldering it with a torch."

Why? Why wouldn't he just unscrew the old faucet supply line from the connector that's soldered to the copper pipe, attach a new ball valve to the connector, and then attach his new faucet's supply line to the ball valve? All he'd need was the valve, a wrench, and some teflon tape.

Thank you Guys, this is very helpful. I am ordering all the items right now and want to confirm if this is a correct valve?

Link

You are on the right track. The problem is that it doesn't say what size the copper side is. It simply says 3/8". One would have to assume it's 3/8" on both ends.

I think you have 1/2" copper (common). You can check to be sure by going to a hardware store and buying a 1/2" copper fitting and comparing it to what you have.

Order that same valve, but where it specifically states the size of the copper end.

I agree, it looks like it, but it's odd they don't say specifically that the inlet is 1/2"

Thank you for your help Guys, I called them and they confirmed it is 1/2". Going to pick it up today

BTW, you could avoid the expense of a tubing cutter and use a hacksaw, as long as the cut is reasonably square. That method usually comes with a little swearing and a busted knuckle, though.

Hi Guys,

I bought this valve at Lowes. I was told by rep at the store that this should fit 1/2" copper pipe. Size is 5/8 OD Comp x 3/8 OD Comp.

Please see picture below

I just want to confirm with you if this is the right size?

Please let me know and thank you,

irafikov

A 1/2" copper pipe has an outside diameter (OD) of 5/8".

You got the right valve.

Make sure the pipe is clean where the compression band is placed: no blobs of solder or other grunge. You can sand clean with a little fine sandpaper, then wipe off. Put the nut over the pipe first, then the band, then the valve (keeping the valve handle pointed where you want it. Tighten the nut with a wrench while holding the valve with another wrench. Tighten firmly. When you put the water connector hose on, don't overtighten. Just enough to seat the rubber washer.

Hi Guys,

What do you think about push on valves? Do you think they are better than compression? I would install what's best in a long run.

Push on like this for example

I might not know exactly how much I should tighten compression valve and push on valve can might just eliminate this issue. On the other hand, push on valve may not be that securely attached to the pipe.

Please let me know what you think. Thank you for your help guys, this has been very helpful.

Honestly, if you're going to be getting a different valve anyways, then do what wdccruise said. Don't remove the fitting that's already there. Just unscrew the hose, screw on a valve, screw the hose back on.

That's true too, thank you. I guess I want to have less connection to prevent leaks. I also want to learn how to do it via installing new valve for experience sake

Push on (sharkbite) was one of the first options I mentioned.

Compression was second

Push on is almost foolproof for someone without plumbing experience.

Don't try to add a valve on top of what you have. That will go badly. Those aren't tapered MIP threads on the fitting.

BTW: That was a really pricey shutoff valve. Push on tend to be pricey, but that was stupid expensive.

Well I learn something new every day! Thanks for that explanation, Jake. I googled it and see what you mean about the tapered vs not.

irafikov, it you want to do it for experience sake then I'd suggest trying the compression fitting. It isn't that hard to do. The point of the push-on types is that you are spending more for something that you don't have to learn with or think about. It's almost idiot-proof. Cheaper than hiring a plumber, though.

And since you already have it, just give it a go.

(Actually, maybe that's my pre-COVID advice. If you can't figure out the compression fitting, you could always pop out to the store to buy the other push-on type. In this day and age, if you can't figure out the compression fitting, you'll have to leave the water turned off until you can pre-order and go and pick up the other fitting which can take ages)

If you really want to learn, then I'd suggest trying to solder a new valve on. It'll be more expensive if this is the only plumbing you ever do (because you have to buy all of the initial equipment and materials), but in the long run it'll be cheaper per fitting and the best long term fix IMHO. But this is only if you are typically a 'handy' kind of guy. If you don't do other types of DIY around the house, then I wouldn't suggest sweating copper as the first task that you try to do.

When attempting to solder a joint, you could burn down your house or cause a leak. With a compression fitting, you can only cause a leak. :)

A compression fitting is the easiest to do. You'll have to clean the pipe up whether you do push-on or compression. Push-on fittings rely on a plastic gaskety thing inside. They are relatively new to the marketplace and no one knows how long that plastic is going to last. You don't want your first solder job to be under a sink. For one thing, the water has to be drained out of the pipe before it can be soldered.

Sharkbite is less labor. You will need a tubing cutter. I recommend the round ones that are spring loaded and 'clamp' directly on the pipe. It will cut through the pipe in 5-6 full turns. A hacksaw leaves too many burrs, and sharkbite doesn't like burrs. You may need some sandpaper or steel wool to clean the pipe, make it shiny.

@Jake The Wonderdog: "That was a really pricey shutoff valve. Push on tend to be pricey, but that was stupid expensive."

Yup. SharkBite 1/2-inch x 3/8-inch Compression Chrome Straight Stop CA$9.87