Copper Joints under Slab

I know it's not preferred that you have a joint under a slab. But, if there is no way to avoid it what is the most reliable method. I am considering going with flare joints. It's 1/2 copper lines. Any thoughts?

Silver soldering is a code approved, below slab method of joining copper tube and fittings.

I don't remember what the code is on flared joints under slab. Myself, I wouldn't do it because there will never be access to take it apart even if you wanted to. As for any kind of metal line under slab... my experience says that it needs to be protected from the chemicals of the concrete and should be in a plastic sleeve to protect the metal.

Most codes let you either flare or braze under slabs.

joints

I always perfer flare over brazing, if the fittings are available. Brazing is "destructive" in that it removes the temper from the fittings, making them "flexible" and subject to cracking and breaking.

silver solder.

silver

Silver solder also requires a red hot joint, which also detempers the fitting.

Interesting... if using appropriate materials and properly making the weld and protecting it then it should be a moot argument when the concrete is poured...but at least now I know.

Using the "proper material and method" only means it was done to the least highest standard. The "proper" steel gas line, is a very poor material to bury in the ground, but an inspector will approve the installation. I have had 1/2" lines silver soldered to a 2 x 1/2 tee, and the branch of the tee broke off because the fitting's "hardness"/temper had been destroyed by making the joint.