Angle stop valve for a 3/8 copper pipe?

[sandywjo]

In one of our bathrooms, at some point a plumber installed smaller 3/8 O.D. copper pipe that come off of the 1/2 copper pipe from wall. Im guessing he added this to make a new connection that compression angle stops could screw onto in the future ( instead of having to have them soldered on.)
Anyway we want to replace these in the bathroom, but something about the size we need for just this bathroom is confusing to me, and here is why.
All other angle stop valves in our house are the standard 1/2 in NOM Compression Inlet x 3/8 O.D. outlet.
But when I measure the actual copper inlet pipe for the 1/2 size valve for all of those it actually measures 5/8 O.D. SO why we needed 1/2 for all the others was odd to me. That just makes understanding what size we need for the one bath with smaller pipe more confusing.
Now that this one bathroom has a even smaller than normal copper pipe 3/8 O.D. connected to our angle stop, a lady from Brasscraft told us we need a 3/8 Nom compression inlet x 3/8 outlet. why is the inlet size she said we needed the exact same as the O.D. of the copper pipe I measured for this one, when all the (1/2 inch inle)t for a pipe that really measured 5/8.
I also enclosed a photo.
SO do we need 3/8 x3/8 like she said
Or does that 3/8 O.D really mean it is a 1/4 size fitting.

 

[havasu]

Seems silly to me. Maybe a built in water restrictor?

 

[jeffmattero76]

Why not remove the 3/8" pipe and the 1/2" x3/8" adapter and solder in a new piece of 1/2" pipe. You could also remove the 90 and get an angle valve, or solder on an adapter and transition to pex.

 

[TomFOhio]

Or you could cut the 3/8 copper just below the green under the nut and go to the plumbing supply and tell them you need a 3/8x3/8 compression straight valve. Install one side on the copper and take the nut and ferrule off the other end and hook your supply line back up to the other side of the valve.

 

[breplum]

I agree with jeffmattero76.
Desolder the elbow, add an escutcheon, extend the pipe and add an angle stop.

 

[TomFOhio]

It sounds to me like this person is not an experienced plumber to be torching and trying to solder under his sink. He should either call a plumber or put in the new valve like mentioned above. If it was sticking out from the wall where he could cut it and then put a 5/8 x 3/8 comp valve in but it doesn't look like it could be done from here.

 

[Geofd]

I know it's strange like some said a bit of inexperience
like Jeff said that's an option are you asking because of
esthetics or function.....if it has worked I wouldn't
touch it until you have to replace the vanity that way
you have more room to work just one opinion....

 

[Mr_David]

I think the OP was asking about the size difference.
Typically when most are talking/referring to 1/2" copper pipe they are actually talking about 5/8 copper tube
They do make a 1/2" OD copper tube but is rarely used.
Pipe is the term used for thicker pipe generally used for threaded pipe and called Iron pipe size (IPS)

You got to HD and ask for 1/2 copper pipe your gonna be taken to the rack of 5/8 copper tubing.
For example you ask for 1/2-in-Coppe x-FPT-Adapter
is actually 5/8 OD solder to 1/2" IPS.

You can get a stop valve that has a 1/2" NOM inlet, which is the same as a 5/8 compression. with a 7/16 and 1/2' SLIP joint outlet.
The outlet size can be confusing.

Common modern day practice is to just screw a hose onto the valve. They used to use 7/16" OD tubing with a slip joint washer.

Got to go. The Op just needs to get a 3/8" compression inlet valve with the outlet to match what ever new hose he decides to install.