Corrosion of copper water line?
Corrosion of copper water line?
(OP)
A village water department suffered a failure of a water service line installed under one of our highway projects roughly 8 years ago. It's a 1" lateral that serves a local diner.
The copper line was heavily pitted and perforated from the inside out. The copper on the inside looks almost silver, as if it was plated with some other metal.
It was backfilled with course sand meeting (or supposedly meeting) NYSDOT specs for select granular fill.
Based on this article, I suppose the first steps might be to test for sulfates, chlorides, stray electric currents, etc.
If anyone has any additional suggestions, I'd really appreciate it. This is, as you might expect from my handle, a bit out of my area of expertise.
The copper line was heavily pitted and perforated from the inside out. The copper on the inside looks almost silver, as if it was plated with some other metal.
It was backfilled with course sand meeting (or supposedly meeting) NYSDOT specs for select granular fill.
Based on this article, I suppose the first steps might be to test for sulfates, chlorides, stray electric currents, etc.
If anyone has any additional suggestions, I'd really appreciate it. This is, as you might expect from my handle, a bit out of my area of expertise.
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/





RE: Corrosion of copper water line?
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Corrosion of copper water line?
A couple of observations:
The 1-Inch pipe size is too small for a restaurant. Would expect that a high water velocity would be contributing to the corrosion problem.
The location of the tubing under the road would indicate that the tubing is exposed to road salt. Is the pitting on the exterior or interior? Other metallic piping systems that are located near roads have also experience corrosion due to road salts.
Have other water services experienced corrosion? If not, there is lttle reason to expect that the water quality is the problem.
RE: Corrosion of copper water line?
Looking at the pipe again, it could well be erosion from velocity and turbulence, not corrosion:
I've attached a photo. For scale, that's 1/4 graph paper.[li] I was wrong - the pipe i.d. is ~0.7, not 1". Even though it's a tiny diner, but they'd still use a lot more water than a residence.
[li] the inlet end was cut square, with a burr on the inside, not smoothed or reamed in any way.
[li] The pitting is from the inside out, with only a bit of oxidation on the copper.
We'll have to check the plans, and see if it was a mistake by the designer or the contractor.
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Corrosion of copper water line?
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Corrosion of copper water line?
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Corrosion of copper water line?
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RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Corrosion of copper water line?
Minimum size for just one flush-o-matic is 1.25". Add in a commercial 90 second cycle time dishwasher and you have some very high velocities.
If you replaced the line like for like, then require the restaurant to install a large hydro pneumatic tank to reduce the surge velocities or replace the flush-o-matics with tank type toilets.
Hydrae
RE: Corrosion of copper water line?
rmw
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
If one location has a bad ground with a damaged element in the electric hot water heater, it will corrode service lines for hundreds of feet in the area.
You may have to wait until the hot water heater cycles on to see the stray current.
Other cases show up as the electric service uses the water line as the neutral due to bad earth ground and lacking an adequate service line neutral. The current will follow the water line to the neighbors earth grounds and neutrals to close the circuit.
Hydrae
RE: Corrosion of copper water line?
The electrical code has required for some time that if the electrical service is grounded to a water pipe, an additional earth ground is required. In addition, metallic hot water pipes and cold water pipes are required to be bonded together at the water heater.
Your picture shows corrosion on the interior of the tubing. Note that stray current corrosion will occur on the outside of the tubing, not the inside. That is because the current actually travels on the outer surface of the wire (or tube) not on the inside of the wire.
Here is an additional reference for erosion corrosion:
"As has been emphasized, copper water tube is highly dependent upon the formation and maintenance of a protective film on the inside to provide a long trouble free service life. The film is not hard and abrasion resistant, but rather soft and easily damaged."
"An even more conservative recommendation limiting water velocity to a maximum of 4 fps has been published by the National Association of Corrosion Engineers (NACE)."
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RE: Corrosion of copper water line?
I once read that some Roman copper water pipe was found intact after 5,000 years of burial -- while I agree it is hard to tell much just from the picture, it would certainly appear however you had at least something going on here the Romans didn't have!
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
I would start with a water test. Many overlook the LSI, langlier saturation index.
High chlorides can also cause pitting. High chlorides even will pit 316 stainless steel pipe.
Basically even if your pH is very close to neutral, such as 6.8 if you have low alkalinity and low hardness that can be very corrosive. High velocities can make things worse.
Even high pH and low alkalinity can be a problem.
Take a look at this EPA reference
http://w
Dan Saltsburg
Big Brand Water Filter
RE: Corrosion of copper water line?
RE: Corrosion of copper water line?
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Some plumbing codes prohibit compression fittings under concrete. However, in general, if the manufacturer of the device approves the installation, it is is an accepted practice.
"Flared joints and compression fittings shall not be installed underground except for water services, water meter yokes and stop box connections."
h
RE: Corrosion of copper water line?
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Corrosion of copper water line?