Copper pipe, brass valve, corrosion

[rileyj]

Hi all,

Some years ago I installed a brass valve on a hot water pipe just after the heater. It's developed a lot of corrosion - see pic. Almost certain I was told by the vendor that brass to copper was ok.

Anyway, I'll replace the valve. Should I install a dielectric union to prevent this?

Thanks,

Riley

 

[Diehard]

You were told correctly. Brass to copper is fine. In fact, all the original fittings were cast brass.
The powdery residue may be from flux being left on the joint and/or a bit of water drip.

 

[Geofd]

i ran across the same thing.....IF it is corrosion....the valves that were installed were a home depot/lowes brand...along with hard water..that didn't help I installed Apollo ball valves they are in great shape...the only thing.....you could wet a rag wipe them down and see whats going on but install new valves any way for piece of mind....

 

[Diehard]

Yes those cast brass devices have been known to occasionally have a pin hole develop that can seep out water.

 

[frodo]

that is a very small seeper leak

 

[Diehard]

Now you know definitely what it is.

 

[frodo]

i know what a leak looks like
it is kinda a plumber thang

The green/blue stuff is cupric chloride, a byproduct of corrosion of the valve body or possible copper leachate in the water. Either way, it's typical of water leakage where the water is of low pH.

The white stuff (sometimes feels fibrous like cotton candy) is just efflorescence. This is from dissolved minerals in the water precipitating out as the leak drips, then dries and deposits miniscule quantities of calcium, sodium, etc on the valve body. You often see this where residual flux was left on a pipe and over time, condensation or outright leakage causes these buildups. It's always more pronounced at joints between dissimilar metals (due to galvanism).

Wearing gloves, as copper chlorides are toxic, you can remove them with full strength vinegar or dilute muriatic acid, lemon juice or even more flux and a bristle brush. Once it's cleaned up, just liberally apply a paste of baking soda and water. It will neutralize the flux and retard further reaction (if it's condensation related). It would be wise to have your water tested for acidity. If you have highly acidic water, it can cause the same problem or just dissolve pipes outright.

 

[rileyj]

Thanks for all the info. The pH has been around 7.5 tho I haven't tested for some time. I'm a homebrewer, but have been brewing at another location the last couple years. That's going to change soon, hopefully. Putting in a utility sink. I'm in Los Angeles which gets water from all over.

I tested TDS a few months ago. It's around 500 ppm, which hasn't changed much from a analysis I had done years ago:

(Ward Labs) pH 7.7 Total Dissolved Solids (TDS) Est, ppm 489 Electrical Conductivity, mmho/cm 0.81 Cations / Anions, me/L 7.5 / 8.0

Think the TDS must makeup for the higher pH?

One more thing. Should I just drain the line and resweat the valve?
[edit: Geofd said to just replace the valve...this one came from Home Depot.]

Again, the advice is really appreciated!

Thanks,

Riley

 

[frodo]

re-sweating is a 50/50 gamble
to fix it correctly
pull the joint apart, while hot, use a clean cotton rag to wipe the excess solder off the pipe
then install a copper fitting brush in your drill
clean the fitting, re- flux, re-solder


I dabble a little in making spirits
and use only bottled water

 

[Diehard]

So I understand it, it has been determined/concluded that it is a seep leak in the soldered joint?

And that's what is meant by the term, "a very small seeper leak".

I was entertaining the possibility of a pin hole in the casting that can seep out water, which has been known to happen, in addition to the possibility of the joint seeping.

Personally, not knowing for sure, I would clean it up and find the source of the seep before reusing the same valve. Or alternately, not go through all that trouble of cleaning and reusing an existing valve and just spend the $6 to $7 for a new one. I would sleep better.

But I'm not a plumber and may be all wet.

 

[frodo]

I agree that it would be better to replace the valve, but not because of a concern of a pinhole
look at the blown up image, you can see the wetness where the pipe enters the cuff of the fitting
if there ws a pin hole in the brass at this location. it would be filled in with solder.

if the wetness was visible in another area besides where the cuff is, i would agree it is a pin hole

 

[rileyj]

Thank all. I'll install a new valve. Don't use Home Depot valves?

Frodo, bottled water gets expensive @ 15 Gals/brew. I put together a portable RO filter. Dilute with filtered tap to target for the style and adjust.

 

[Geofd]

Thank all. I'll install a new valve. Don't use Home Depot valves?

Frodo, bottled water gets expensive @ 15 Gals/brew. I put together a portable RO filter. Dilute with filtered tap to target for the style and adjust.

get your valves at a plumbing supply house or a reputable hardware store