# flux corrosion on copper



## dielectricunion (Feb 27, 2013)

I've heard of copper with pinhole leaks blamed on flux left on joints. Is this something that all flux can cause or just older non water solubles? Most corrosion I see has been obviously because some fool strapped it with EMT hangers or strapped it tight to steel with drywall screws.


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## tjbnwi (Feb 24, 2009)

I've seen more pinholes at the joint because the inside was not reamed to remove the edge created by the cutter wheel.

Tom


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## brunothedog (Sep 8, 2013)

nobody uses flux for copper anymore, they say because the copper expands and contracts much more than the flux.
All joints are siliconed


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## tyb525 (Feb 26, 2013)

tjbnwi said:


> I've seen more pinholes at the joint because the inside was not reamed to remove the edge created by the cutter wheel.
> 
> Tom


How does the inside of the pipe affect the outside?


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## dielectricunion (Feb 27, 2013)

You're telling me you join copper water lines with silicone?


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## tyb525 (Feb 26, 2013)

dielectricunion said:


> You're telling me you join copper water lines with silicone?


I hope he is talking about copper flashing and metalwork.


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## dielectricunion (Feb 27, 2013)

Expect some call backs


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## tjbnwi (Feb 24, 2009)

tyb525 said:


> How does the inside of the pipe affect the outside?


The turbulence inside the pipe caused by the ledge will erode the inside of the pipe. When the pipe is cut for repair you can see/feel the inside pitted and worn away. 

I have not used an acidic flux or paste on water system piping in at least 30 years. 

Tom


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## dielectricunion (Feb 27, 2013)

tjbnwi said:


> The turbulence inside the pipe caused by the ledge will erode the inside of the pipe. When the pipe is cut for repair you can see/feel the inside pitted and worn away.
> 
> Tom


Wow, that's pretty intense. Its hard to believe a tiny lip could cause that much turbulence at standard water pressure.


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## tjbnwi (Feb 24, 2009)

dielectricunion said:


> You're telling me you join copper water lines with silicone?


I think (hope) he was kidding. 

Unless he was refereeing to;

http://www.supergluecorp.com/super-glue/epoxies/copper-bond

Tom


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## tjbnwi (Feb 24, 2009)

Happens more than most notice. There is a lot of flow through pipes. 

Hard to believe that a small river created the Grand Canyon.

Tom


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## GO Remodeling (Apr 5, 2005)

Deburring is in the plumbing code. Commercial plumbers say the higher usage or velocity of the water (think hot water recirc) will erode the pipe quicker if not deburred. 

You learn something new every day here


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## The Coastal Craftsman (Jun 29, 2009)

Hey still do make flux that contains acid. They def work better but you have to make sure you clean every joint. I was always taught to polish the joint with wire wool right after its wiped of also. Not sure this dies anything more than make the joints looks nice. 

There was a write up in a plumbing mag in the UK I read about 10 years ago on the affects of deburring or not. After numerous tests a pipe sliced cut with no deburring created no more turbulence than with it deburred. They said the gap and ledge between the endfeed fittings and the pipe was the main factor in turbulence. They concluded that at standard pressures and flow rates of residential it would never be an issue. Even on hydronic heating systems and recirculating systems.


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## Oconomowoc (Oct 13, 2011)

In the Wisconsin code book it's called "erosion corrosion".

The flow and sizing tables are assuming pipe is deburred. Flow rates have s standard otherwise how could you establish a formula.

The ridge itself causes a interruption in flow pressure and violates state code. The result is turbulence and "erosion corrosion".

About 15 years ago I cut out a 2" copper 90 that was spraying from a pin hole. After repairing the leak I looked inside the elbow and it was crazy. It looked like claw marks in the elbow, water had actually chewed through it.

I was puzzled by this so I decided to do a water calculation on just that line which was serving a bunch of fixtures in a clinic.

It was undersized. This compounded the situation and made it worse. 

I looked at the other fittings and they seemed fine from the outside. We made a recommendation that it should all be tore out and reinstalled correctly. They did nothing.

About 2 years later we had to go back and replace all of it, pinholes everywhere!

This was the result of two problems.
1.) Undersized water distribution 
2.) No reaming whatsoever throughout the system.

Always ream! Formulas used to calculate proper size need inside diameters to remain consistent for the it to work as intended. By not reaming the ridge left by the cutter wheel the inside diameter is reduced, and it is this reduction that causes erosion of the soft copper.


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## hdavis (Feb 14, 2012)

The primary cause of turbulent water flow is under sizing for the flow rate. The further you get from a straight, smooth interior pipe, the earlier it will happen. For an undersized system, burrs make it even more undersized in that location.


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## dielectricunion (Feb 27, 2013)

I replaced a 2" copper drain line for my father in law last year and it had a channel worn so thin where the water slugs. I assumed it corroded because of steel screws used to mount strapping. It was a condensate drain from furnace/ac. Does anyone know if this condensate would be the corrosive culprit?


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## Oconomowoc (Oct 13, 2011)

dielectricunion said:


> I replaced a 2" copper drain line for my father in law last year and it had a channel worn so thin where the water slugs. I assumed it corroded because of steel screws used to mount strapping. It was a condensate drain from furnace/ac. Does anyone know if this condensate would be the corrosive culprit?


Condensate is very corrosive.


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## The Coastal Craftsman (Jun 29, 2009)

Yep condensate is like he says. When I installed furnaces I used to have to install a chamber in the ground that had to be topped up with acid neutralizing crystals so that it could be piped with PVC to that chamber. Its very corrosive.


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