- This topic has 6 replies, 5 voices, and was last updated 23 years, 7 months ago by
Mike_Pantone1.
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MasterPlumbers
In a home I built 8 years ago we have now had 3 leaks in the cold water copper water system. There is no sign of electrolisis, nor should there be it is a total copper system from new. The deterioration developes from the inside of the pipe. Any ideas.
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1. Water at high velocity can cause this condition.
High water velocity may be caused by an
undersized piping system, causing erosion that can cause this to take place.The real solution is to lower the water velocity. Like a throttling valve (Globe pattern) by lowering the velocity of the water in the system you save undue wear on the internal tubing walls. You can also opt for a pressure reducing valve BUT they can be a real pain in the neck to service and globe valve keeps it simple to adjust.
The relationship is as follows:
Reduce pipe size, increase velocity; increase pipe size, reduce
velocity. Recommended velocity for hot water in a copper tube system is 4 –
5 feet per second (fps). If systems are designed to respect these velocities
the piping will last a very long time trouble free. Cold water piping could be slightly higher 2. Numerous, abrupt changes in direction in the piping system. Where
structural conditions cause numerous directional changes, long radius (1.5
Diameter) fittings should be used to minimize the interruption of laminar
flow.
3. Lack of reaming the tube ends. Burrs left on the ID of the tube can
cause interruption of laminar flow resulting in localized high water
velocity and cavitation.4. Protrusions into the flow stream caused by excessive lumps of
solder/brazing material, improperly fabricated tees (branch protruding into
the run pipe), etc. These protrusions can also cause the
interruption of laminar flow resulting in localized high water velocity and
cavitation.5. Excessive water temperature. Heating water above 140 degrees Fahrenheit
can accelerate the process of erosion/corrosion. As the temperature
increases, the velocity should be lowered. At 180 degrees Fahrenheit, the
velocity should be down around 2 – 3 feet per second (fps). ( 180 I use on commercial, industrial and institutional and heating jobs)Bear in mind that these conditions are not peculiar to copper tube, but can
affect other materials as well. However, when erosion/corrosion does occur
in copper tube it is readily identifiable by the horseshoe shaped pitting
throughout the inside of the tubes. Identification OD these pits or grooved
corrosion-product-free areas on the inside of the tube can help you
determine that water velocity is too high and that the reduction of velocity
can correct the condition.Sorry if I got carried away with too much technical jargon, but it is the only way to express the proper way to correct this problem and I think if you have a better picture of what’s going on it helps you with options.
You could also consider having your water tested for the pH value as copper cannot take hard water or acidic and water treatment program may have to be set up.
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Steve: Pin hole leaks in copper pipe is more common than you may think. You mention there is no sign of electrolysis ???
Here are some facts that I have come across over the years in dealing with this type of pipe failure.
The process that is responsible for the pin hole phenomenon has a rather
pretentious name: “Electrochemical Decomposition”. It is also referred to as “Electrolysis”. Without using confusing technical terms, I will try to explain very briefly what happens inside your piping system…how it happens…and why it happens. I will also provide you with some answers on what can be done to deal with the results of electrolysis.
There are three things needed to create a pin hole in a pipe………..
1.) A metallic pipe (Copper) with a liquid (Water) flowing through it.2.) An “Electrolyte”, in this case the water is the electrolyte. An electrolyte is simply a liquid that has the ability to conduct an electrical charge.
3.) And a very very small amount of DC electrical voltage. The electrical energy
needed to fuel this pipe destroying process is so small that a very sensitive
meter is required to detect its’ presence. This voltage is typically rated in “Milivolts” or thousandeths of one volt.Where ever there is a disparity in electrical potential within your piping system,
Mother Nature will set about the business of trying bring things into perfect balance and harmony. To accomplish this task, copper electrons are stripped from the copper atoms that make up the walls of the pipe. These ions (positively charged copper partcles) start toward the electrically deficient section of piping in an attempt at bringing electrical equalibrium within the piping system. Unfortunately this plan does not succeed, and the copper that has been leached from the walls of the pipe
form copper compounds with other minerals found in the water. These new copper
compounds generally produce blue/green stains.
When enough ions are removed, a pin hole will appear.
You also mentioned that the leaks seem to be limited to the cold water lines. This is typical of electrolysis failure, the hot water piping has had the benefit of the water traveling through the water heater . Inside ths water heater is an anode that has been placed there by its’ manufacturer to protect against tank failure from pin hole leaks. The water that passes through the heater imparts some of that protection to the hot water piping as it travels through.
As the other respondent mentioned
there is phenomenon known as erosion corrosion. This type of failure is noted mostly in hot water recirculating lines, especially where there are changes in direction of the flow. Next time you have a failure, cut a small section of pipe that had the leak, and send it to our address listed below and I will be happy to identify the cause and in most cases provide a solution for the problem.
Bud
Suncoast Plumbing http://www.copperknight.com -
Or the original installer used shit quality pipe during installation
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Bungie: If you are as old as I am(only a few of us left) there was a copper pipe in the early 70’s that was thinner than “M” and was called “distribution copper” and had a white stripe on it for identification. Now..thats what I call poopy pipe.
Bud…… -
I have asked this before, What are the wall thickness’ of the copper pipe there ??
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The above listed are all valid possibilites for pin hole leaks. Our neighborhood of 400 has had 60+ pin hole failures just this year (2000). The home range from 12-20 years old, and all have failed at the same time! There are also failures in 4 surrounding subdivisions. We strongly believe the problem to be the Water Company. Our best educated guess so far is over chlorination of the water. Halides (chlorine, florine, bromine, etc) are aggressive to yellow metals (brass, copper, bronze). We are going to have several pipes tested by a metallurgical lab to positively identify the corrosion mechanism. Just another possibility….but check other neighbors, you may not be alone, and if so, it’s possible that it’s you water supplier.
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