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jbherberg
Soldering brass pex fittings

I am attempting to change to pex pipe in a bathroom remodel. When I solder the Brass pex fitting to the copper pipe the joint feels loose. I pulled one apart and the solder had completely filled the joint. If I wait a minute then the joint feels tight but now I am nervous about how solid these joints are. Does the brass cool differently than copper so that you have to wait until the brass cools? I need to solder fittings onto a new brass diverter valve and am having doubts about my ability.

johnjh2o
Re: Soldering brass pex fittings

You have to solder the joint then let it cool before you connect the PEX to the fitting.

John

dj1
Re: Soldering brass pex fittings

Brass is copper and zinc, and when soldered with copper it needs a little more time to cool. Just make sure you use the right amount of solder, too much or too little is no good, then gently wipe off the excess, but don't move the joint.

Pelton
Re: Soldering brass pex fittings

jbherberg:

From your post, it sounds like you're not following proper soldering procedure:

You must first take a piece of emery cloth and completely brush clean both the copper and brass mating surfaces.

You must then take some soldering flux (looks like vaseline) and smear it on both surfaces to be mated; you must then join the surfaces and heat them with the propane torch, first spending a few more seconds on the brass fitting to heat it up (larger volume) then on the copper fitting.

When both are hot, you can touch the solder to the joint, this should immediately turn the solder to a liquid state, flowing into the joint;, & completely filling the joint to make a leak-proof bond.

Let the the joint cool, as John notes, before touching or using.

If you do it properly, there is no way you can pull apart the soldered joint.

For more info, Google "How to solder copper tubing" or "How to solder brass fittings".

JLMCDANIEL
Re: Soldering brass pex fittings
Pelton wrote:

jbherberg:

From your post, it sounds like you're not following proper soldering procedure:

You must first take a piece of emery cloth and completely brush clean both the copper and brass mating surfaces.

You must then take some soldering flux (looks like vaseline) and smear it on both surfaces to be mated; you must then join the surfaces and heat them with the propane torch, first spending a few more seconds on the brass fitting to heat it up (larger volume) then on the copper fitting.

When both are hot, you can touch the solder to the joint, this should immediately turn the solder to a liquid state, flowing into the joint;, & completely filling the joint to make a leak-proof bond.

Let the the joint cool, as John notes, before touching or using.

If you do it properly, there is no way you can pull apart the soldered joint.

For more info, Google "How to solder copper tubing" or "How to solder brass fittings".

Actually any soldered joint can be pulled apart while it is hot.

Jack

Fencepost
Re: Soldering brass pex fittings

JB, it sounds to me like you're doing just fine. The brass fitting has a larger thermal mass, plus slightly lower thermal conductivity* than copper, so it takes a little longer to cool down to the point where the solder solidifies. Once you've applied the solder, let it cool sufficiently before moving the joint. If the visible solder is mirror-shiny, it's still molten. When it turns slightly dull, it's solid. If you move the joint while the solder is still molten you can cause an incomplete seal (and therefore, leaks).

When you are soldering onto valve bodies (shower, faucet, etc.) be sure to remove the cartridge/washers so you don't melt the plastic or rubber.

*I think. I could be wrong.

Fencepost
Re: Soldering brass pex fittings

Before you put water in the system, fill it with air to at least 60 PSI and check for leaks with soapy water or bubble soap. It's also recommended to let it sit for an hour or so and make sure the pressure doesn't drop.

If there's a leak, it's way easier to clean up a puddle of air off the floor than water.

When I was an apprentice plumber, we had a 1/2" IPS nipple that threaded in the shower head; the nipple had a tire valve and pressure gauge. Of course, this required a shower valve that could be opened 1/2 way between hot and cold, and allowed backflow.

If doing it with the shower valve is infeasible, you can hook something up to the hot & cold laundry faucets, such as a Y-hose.

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