Copper pipe - pinhole leaks and green spots

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dpearson

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My father-in-law discovered a pinhole leak in a 1/2 Copper supply line in the crawlspace underneath his house yesterday. I'm a pretty accomplished DIY'er and in short order we had cut out and replaced a 5' section of pipe using a slip/sweat fitting at each end.

The leak was in the side of the old pipe, not at a fitting. There were no visible dents or scratches, just a green spot with a hole in the middle. About 6 inches down the pipe was another green spot that was just starting to seep water. Most of the piping has green splotches on the outside surface, and the inside of the pipe had lots of blue-green deposits.

I assume the splotches are oxidation of some sort. appears that the oxidation just ate through the wall of the pipe in the 2 problem spots. The area's not prone to freezing.

Has anyone seen this before? What causes this type of damage - and what's the recommended cure?

Thanks in advance!
 

PEW

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Could be defective pipe, abrasives in the water, water PH, or other water related issues. High water pressure will hasten the situation. Sadly, you can most likely expect a recurrence. Just had a duplex where all the pipe had to be replaced, the leaks kept coming.
 

Jadnashua

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I read somewhere that excessive use of acidic flux can cause that problem. It is more likely to happen in the cold lines - in the hot lines, it disolves easier and gets flushed away. It happens more often when the pipes are put in and sit for a while prior to the people moving in, thus preventing the contaminents from being flushed out. Defective pipes can do this, too, regardless. It is more likely to occur downstream of joints.
 

RioHyde

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Here where I am, we see this every now and then due to mineral deposits in the water. Specifically, calcium will cause pitting and eventual pinhole leaks in copper. You see green and/or white deposits on the inside as well as the outside of the copper. Not saying this is definitely the cause of the problem you ran into though. As was stated by others, it could be flux, defective pipe, etc.
 

Ally68

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I have green build up on my copper pipes outside only I have heard it was bad but I can not keep it off of the pipes how bad is it?
 

dpearson

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Thanks everyone for your replies - we'll keep an eye out for more leaks.
 

Gary Slusser

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dpearson said:
Thanks everyone for your replies - we'll keep an eye out for more leaks.

Yuo need to have a water ananlysis done, the usuall causes of pinhole leaks in copper tubing are mostly water quality isssues if not excessive and non-water soluble flux or improper if any reaming of the ends of tubing. Other causes are electrical grounds such as telephone, CATV etc. or use of the plumbing as the building;s ground electrode.

There are many water quality parameters that can cause this; like bacteria, low (acidic) pH, high TDS, DO, CO2 and chloride content, recirculating hot water systems with erosion corrosion etc.. Your describtion suggests water related causes and I would suspect a general overall thining of the wall of the tubing.

Gary
Quality Water Associates
 

Master Plumber Mark

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master plumber mark

listen to this and tell me what you think....

we run into copper pipe like this all the time...

lots of the times it has to do with the way the electrical system is

GROUNDED to the plumbing system....

now stay with me here.........

if your main ground line to the electrical breaker box has come loose, or has a bad dirty connection, the secondary ground to the copper plumbing system
gets all the power surges, ect going through them...

usually we see this secondary ground clamped across the top of the water heater.

now stay with me here................

if the main water supply comming into the house is plastic, or their are any sort of unions in the cold line like at a water softener that would break the proper gounding of this system, everything in the home tries to ground itself into the water heater.

Whenever we find a water heater that only last about 2 years or so, or the customer states that this is the 5th heater that they have had to install...
its usually got something to do with the way the system is gounded.

it eats the water heaters alive and it breaks down the copper pipe

also you have other variables too, like phone lines grounded to your plumbing system, and cable lines too. Door bell transformers ect....---they are all pumping a slight amount of juice into the system.

we have acutally taken out water heaters to see a small spark happen when
we cut the copper pipes apart on them...

this millli-current in time breaks down the elements in the copper.

I tell people to call an electrician and get things better grounded in the home.

now isnt that a wonderful theory??

criticism is more than welcome here.
 

Don Zorn

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Master plumber mark - Interesting. So what did the electrician do to fix the problem? Curious?
 

rrzepka

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You mentioned that the pipe was in a crawl space. Was the pipe in contact with the any stone or gravel, or was the pipe suspended in the floor joists?

The reason I ask is that our HOA just completed a major repiping from the street to one specific building due to over 25 pinhole leaks and green spots. The cause (according to the plumbing contractor) was due to the fill material the original builder used 17 years ago. It had a high concentration of gravel, which was in contact with the pipe and causing an electrolytic reaction within the copper pipe.

By the same token, I do find "master plumber mark"'s comment very interesting.

-Rob
 

Master Plumber Mark

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master plumber mark

you get a different opinion from whoever you ask on this subject.

some electricialn say I am full of baloney and others agree with me ..

generally youi need to install some new ground rods at the breaker box and also sometimes I see a "jumper " across the water meter if it is in the house..

I had a guy actually drill a hole in the garage and drive a new ground rod into the sub gravel then tie a couple of connecters to the water system by the water heater.

that would work ---anything is better than leaving it alone.
 

Gary Slusser

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rrzepka said:
You mentioned that the pipe was in a crawl space. Was the pipe in contact with the any stone or gravel, or was the pipe suspended in the floor joists?

The reason I ask is that our HOA just completed a major repiping from the street to one specific building due to over 25 pinhole leaks and green spots. The cause (according to the plumbing contractor) was due to the fill material the original builder used 17 years ago. It had a high concentration of gravel, which was in contact with the pipe and causing an electrolytic reaction within the copper pipe.

By the same token, I do find "master plumber mark"'s comment very interesting.

-Rob

I suggest you ask the plumbing contractor what in the gravel or copper tubing would cause the pinholes. Personally I suspect electrical currents flowing from the copper to the gravel/soil. Check the ground and grounds on/in that building.

Gary
Quality Water Associates
 

Jimbo

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Copper is somewhat resistant to corrosion. It does have a problem in some environments; it especially does not like to be in contact with cement.

Gravel per se may not be a problem chemically, although it poses a physical challenge. Now, if the gravel is tailings from a cement truck....!


I suggest checking the website of the Copper Development Association. You will find a wealth of info there: www.copper.org
 

Gary Slusser

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I've checked that site numerous times for a page I had saved in my favorites concerning corrosion but since they updated the site a year or so ago, I can't find the page or much at all about corrosion on the site; except now they don't think there is much of a problem with it. But then it is the Copper Development Association's site...

Here's the old link:
http://environment.copper.org/NACE02122/intro.html

Gary
Quality Water Associates
 

Richard S

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similar events

Just a few days ago, I discovered one section of copper pipe covered in green deposits. My entire house is plumbed in copper & this is the only section that this is occuring. It is also the only section that the HVAC guy capped off when they moved my hot water heater about 11 mths ago. I called & they told me that it's due to not cleaning the flux off entirely - from the looks of it, he'd had to not clean it at all. Even though they told me the flux was acidic, they told me that it wouldn't harm the pipe - this, of course, made no sense. I don't see any pinholes yet. Even if I clean off the pipe now, do I need to worry about pinholes developing in the future. Would it be more prudent to replace this section now or would that simply be a waste of my time.

Thanks.
 

Chucknewell

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Electricity and corrosion

Master Plumber Mark- I think your theory is right on, for that particular case of hot water heaters as well as some of the corrosion in copper pipes. Here's a link with a lot of info on corrosion.

http://www.xs4all.nl/~cdewaard/

As you'll see in many chemical corrosion situations the chemical attack itself produces electric currant, much like a battery (lead-acid battery etc.). So by adding more electric currant caused by poor grounding corrosion can become much more rapid.

Coincidently my house had no ground rod installed and the plumbing system was the only electrical ground. Yes, I had a leak too.

There are lots of types and causes for corrosion. I don't think that a missing or poor main ground for the house leaving only the waterline ground is THE cause. But I sure do believe it's an accelerator!

Chuck
 

SRdenny

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In May 2004,, Mr. Scott Denny submitted copper tube/fitting specimen(s) to my office for visual inspection. The specimen(s) were removed from the potable hot water circulating system at a residence in Atherton, CA .
The specimen(s) were:


Here's a rather long winded story of a leak problem I had the pleasure to investigate.




1. A 1-3/4 inch piece of 3/4 inch nominal diameter, Type M, hard drawn copper tube connected by soldering to a 3/4 inch wrot copper 45 elbow connected by soldering to a 1-3/4 inch piece of 3/4 inch nominal diameter, Type M, hard drawn copper tube connected by soldering to a 3/4 inch wrot copper 45 elbow connected by soldering to a 2-1/8 inch piece of 3/4 inch nominal diameter, Type M, hard drawn copper tube.
2. A 2-5/8 inch piece of 3/4 inch nominal diameter, Type M, hard drawn copper tube connected by soldering to a 3/4 inch wrot copper 90 street elbow connected by soldering to a 3/4 inch wrot copper 90 elbow connected by soldering to a 1-1/4 inch piece of 3/4 inch nominal diameter, Type M, hard drawn copper tube.

Information provided with the sample indicated the copper tube system was commissioned in 1992. The leak in question occurred in April 2004. Information was apparently not available regarding the velocity or pressure of the water in the affected section of the system. Information provided indicated the typical water temperature was 130F.

Water distributed at the residence is obtained from the San Francisco Municipal Water Utility. No representative chemical composition data for the water supplied was included with the specimens.




Scott Denny
Frank Denny Plumbing, Inc.
May 12, 2004
Page 2…

Examination of the outside surfaces revealed no significant deterioration by the external environment. Basically, the outside surfaces of the tubes and fitting were covered either with solder or a protective tarnish film of reddish brown material that is probably cuprous oxide (Cu2O). In addition, there were deposits of a greenish material that would probably prove to be the remnants of flux residue that had not been cleaned of the assembly after soldering. Specimen 1 also had greenish white deposits the were formed as a result of water leaking onto the tube surface and evaporating, leaving calcium, carbonate, and malachite materials on the tube surface. Finally, a number of the specimens had solder deposits on the outside tube surface in excess of what would be considered “good workmanship practicesâ€.

Only specimen 1 had a pinhole perforating the tube wall. Examination of the inside surfaces confirmed the belief that the tube failures in this tube had initiated on the waterside surface. The grooved and corrosion-product-free areas of attack were considered to be typical for tubes which had been subjected to conditions causing erosion-corrosion (i.e., accelerated attack related to localized high velocity/turbulent water inside the tube).

In those areas where erosion-corrosion had not taken place, the tube wall was overlaid with a tightly adherent film of brown colored products. Analyses of similar products on other tube specimens in the past suggest that this deposit probably consists primarily of copper oxide (Cu2O). In general, the copper oxide was overlaid with a thin friable layer of loosely adherent brown colored products that were clearly evident to be deposits from the water. The belief that the brown products were deposits from the water was supported by the observation that they could be easily removed by gently wiping them with a wet sponge.

Much of the inside surfaces of both specimens was covered with a black tarnish film that would probably prove upon chemical analysis to be cupric oxide (CuO). The presence of cupric oxide on the waterside surfaces indicated that the water circulated had been heated, at least on occasion, to temperatures in excess of about 160º F (i.e. a condition that typically facilitates erosion-corrosion). Examination of the cut ends of the tubes left no doubt that the ends had not been reamed/deburred prior to assembly.

Based on the visual examination of the specimens submitted for investigation, it can be concluded that the failure reported to me concerning these samples had initiated on and propagated from the waterside surface. The cause of the perforation was erosion-corrosion as a result of localized high water velocity.

Erosion-corrosion on the waterside surface of the tube was at least partially facilitated by (1) water velocity flow rates in excess of recommended values for copper tube systems, and (2) unreamed cut tube ends. In addition, the erosion-corrosion process may have been aided by (1) possible presence of abrasive suspended solids ( hydrated hematite, or silica for instance), (2) water pressures in excess of 80 psig, and (3) heating the water circulated to temperatures in excess of 140 Fahrenheit (F).

Scott Denny
Frank Denny Plumbing, Inc.
May 12, 2004
Page 3…

Basically, the flow rate of the water in the affected section of the system was excessive. The role of velocity, temperature, water chemistry, and other factors in the erosion-corrosion of copper is discussed in the paper “Performance and Selection of Materials for Potable Hot Water Service.†A copy of this paper is included.

Bear in mind that this condition is not peculiar to copper tubing, but can affect other materials as well if water velocities exceed their recommended parameters. However, when erosion-corrosion does occur in copper tube, it is readily identifiable by horseshoe shaped pits throughout the inside of the tube, which is the distinctive signature of damage caused by erosion-corrosion.

Although it is virtually impossible to rehabilitate a piping system that has experienced erosion-corrosion related failures short of replacement of affected areas, a number of recommendations can be made for mitigating the erosion-corrosion of copper tube systems.

The temperature of the hot water circulated should be monitored and, if necessary, adjusted to a safe and energy-efficient 130 F.

The pressure in the system should be measured to insure that it does not routinely exceed approximately 80 psig.

Water flow rates should be measured in the affected section(s) of the system and, if necessary, reduced to insure they do not exceed about 8 feet per second (fps) for cold water. Velocity should not exceed 4 to 5 fps for hot water if the temperature is below 140 F and about 2 to 3 fps if the water temperature is above 140 F.

Equally important, plumbing technicians must use industry standard workmanship when installing copper tube systems. For example, cut tube ends must be properly reamed prior to soldering. Adhering to the general guidelines for tube installation, joint preparation, and soldering presented in the enclosed CDA Copper Tube Handbook and ASTM Standard B828 have been known to eliminate many erosion-corrosion concerns.

Should you require any further information or assistance you can contact me at the phone number or address listed on this letterhead.

Best Regards,

COPPER DEVELOPMENT ASSOCIATION INC.

Jim Weflen

Jim Weflen
CDA Western Region Manager
 

dpearson

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Thanks

Thanks for the detailed reply, Scott. I had no idea such failure analysis was available - I wish we had saved the bad section of pipe!

The inside of the failed section was coated with bright green, loose deposits. It was a seldom-used section (served the cold water side a bar sink), and the leak was ~ 18 inches downstream from the nearest fitting, so my guess is that internal erosion due to particulate or reaming issues isn't the cause.

The pipe was suspended in free air, and the leak wasn't near a hangar so contact with gravel/etc. wasn't a contributing factor.

My guess is that perhaps the installer had flux on his hands when handling or installing the pipe. The spots are right where I would have held onto the pipe as I was hanging it. The house is in the San Mateo, CA hills in an area with abundant ground water seepage so there's always some standing water and high humidity in the crawlspace. Perhaps excess flux combined with the high humidity was enough to corrode the pipe from the outside in after 30+ years.

We'll take another trip under the house and give all the pipes a wipedown with something (suggestions welcome) to try to remove the green spots and any leftover flux.

I'll also double-check the grounding scheme at the panel. I think there's a ground rod and since this was a cold water pipe I don't think electrical current would be the culprit.

Thanks again everyone for the follow ups!
-dave
 
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