OK yoy experts (especially Bob W. if he's still alive),
My foreman griped today about copper lines touching metal studs and cast iron drains. He said it'd cause electrolysis.
While I think it's a matter of good workmanship (not to mention noise issues), I disagree that this causes electrolysis. My understanding is that fresh water must actually flow between the dissimilar metals. Am I wrong or right?
Sorry Mike, but all it has to do is touch. It's the physical contact and the flow of electrons passing from one metal (or liquid) to another. Each metal comes differently charged with electrons and protons. The act of touching allows the metal with a deficiency of electrons to strip away the metal that has more. Voila! The battle is on.....:>)
Bob Wheatley
Bob,
You say; I believe. That's been the basis of our relationship.
But clear this up, if you don't mind. If it's just contact, then why is it OK to screw copper DWV into cast iron tapped tees, and why is to OK to screw copper into steel pipes on hydronic heating systems?
Mike
Being a former boat owner (and someone who wishes he could afford a nice sport fisherman now) this topic interested me and I did some searching.
I came across a few articles that I thought might be of interest to plumbers.
Chris
Bob, Can we ask questions? or do we just guess away. If we can ask what you observed on your visit... Was there an outward sign of something dumb, like water hooked to the gas line? or did the installation look ok on the surface? Did the restaurant have gas heat and if so did it work? or was it full of water too? If the whole gas system was full of water and someone had not changed something in the system then I would think that the gas control on the HWH had Failed in some bizarre way. Dale
Yes, of course you can ask questions. I re-read my story above and one thing that I didn't make clear was that the store was functioning normal the previous business day. There was no apparent cross connections which was why I asked if there had been any repairmen from any craft in the store in the previous couple of weeks. The only gas was to the water heater and the cooking line. The water heater was of course completely shut down as was the fryers. The mechanical valves on the burners allowed water to stream out when they were opened which to this day was one of the strangest things I've ever seen. The obvious first step is to confirm no mechanical cross connections existed. They didn't. Now what?
Bob Wheatley
"Bob Wheatley" wrote in news: snipped-for-privacy@corp.supernews.com:
. The obvious first step is to confirm no
Now I would call for a exorcism :-P OK, no mechanical cross connections INSIDE the establishment, but what about OUTSIDE? Maybe some dumbass neighbor connected the water main to the gas line?
Eric
After being there for about half an hour and seeing it with my own eyes I was seriously considering calling a priest.:>) I checked the gas meter and water meter for anything that appeared as recent excavations. There were none. But you're getting warmer......
A hint: This story is directly related to Mike's original question in this thread.
Bob Wheatley
"Bob Wheatley" wrote in news: snipped-for-privacy@corp.supernews.com:
OK, so the water main and gas main were buried touching each other? I am having a hard time seeing how the water pressure would have made it into the gas line, but I guess I've see stranger things happen.
Eric
"Eric G." wrote in message news:Xns98B9A8EA4944AXz124HiiUdfEEE6@140.99.99.130...
You're so close now that I'm gonna' go ahead tell the whole story because someone guessing what actually happened is very unlikely.
After eliminating any mechanical cross connections by physically observing every inch of the gas line above grade I had to turn my attention to the service line. There was a catch basin (storm sewer) in the back by the drive through lane. I noticed a small trail of water on the expansion joint at the basin and after dragging my finger across it I was able to determine that the flow was coming out from the outside of the box and then immediately draining right back into the box. Had the storm system not been draining the original leak they might have seen the water leak before the next part of this weird story could have taken place. I then shut of the main water entry and looked at the water meter and the 1/10 dial was spinning like crazy, telling me that there was an apparent leak in the water service between the meter and the building. I then ordered an air hammer rig and some extra help and we shut down the drive through and began breaking concrete. Using the same finger dragging trick I determined the direction from where the water was coming from and followed it back to the leak. Once it was obvious where the leak was at we turned the water off and began digging down and was amazed at what I discovered. There was a point where the gas line and the water line had to cross to get to their ultimate destinations. The gas service was schedule 40 wrapped steel and the water service line was type "K" soft copper. The water line was about 6" deeper than the gas line and exactly at the point where they crossed someone had allowed a 16 penny nail to be backfilled touching the copper water service line. The ensuing electrolysis ate a hole in the copper and it began spraying and that water spray CUT A SLOT in the STEEL gas service line and the weight and forced pressure ultimately was able to push water up the gas line and out the gas stove burners a good 3 or 4 feet higher than the point of rupture. I still have that 16 penny nail to this day as a reminder on one of the strangest calls I ever had to go on.
Bob Wheatley
You win Bob, It might have taken me a Day to figure it was outside that far. Where it cut thru the Gas line, was it on the building side of the meter? or the city side? If it was on the city side, what did it do to the gas meter? Dale
"Dale Wilcox" wrote
Both meters were at the street and both service lines were on the owner or private side of the meters so there was no culpability on the part of the city. Both lines were installed by the plumbing contractor that did the original project. That said, I wouldn't say that I blame the plumber for not noticing a nail during a backfill operation but I do blame the plumber for not wrapping or isolating the copper and protecting it from contact by dissimilar metals.
Bob Wheatley
"Bob Wheatley" wrote in news: snipped-for-privacy@corp.supernews.com:
Simply amazing!! I didn't live through that like you did, but I will remember it forever. Thanks for sharing.
Eric
I did a little further research. What do you think of this article?
Hi Mike, I have read their propaganda before. You have to consider the source. They are "copper.org" and their mission is to positively represent copper as the "ultimate" material for any and everything.
The CDA Mission "The Copper Development Association Inc., CDA, is the market development, engineering and information services arm of the copper industry, chartered to enhance and expand markets for copper and its alloys in North America."
The first paragraph is a freakin' joke: "Electrolysis is an overused and misused term when applied to copper tube. True electrolysis, or electrolytic corrosion, as it is more properly designated with regard to piping, is caused by an imposed (external) stray DC current and virtually ceased to occur with the disappearance of the trolley-car that was powered by high amperage DC current."
They have _zero_ credibility. Try this one instead: (It is simple and easy to understand)
Bob Wheatley
Bob, can you give me a citation for what you just wrote?
My understanding has always been that there needs to be an electrolyte present for galvanic corrosion take place, and that metals with dissimilar galvanic potentials can safely be placed in contact with each other in a dry environment, or even one where the liquid present is non coductive, like for example lubricating oil.
I see too many examples of things like steel pins in brass hinges lasting for decades to believe that very much damage occurs, and what about steel shafts in bronze bearings?
Jeff
I should have been more clear. Water is all that is necessary and that automatically comes with all plumbing systems from condensation. Both hot and cold supply systems will have condensation because of temperature variation between the internal and external enviroments. So, the "act of touching" applies in all copper domestic water supply situations that are relevant to this discussion. But I suppose you could create some non-world reality condition for the purposes of an experiment.
There are several important factors to consider when it comes to galvanic corrosion. The metals of course are obvious, but we have to consider the environment and the relative mass of each metal and the relative size of contact and the relative position each holds in the galvanic series. Even the building's electrical system is a factor.
There was some of this info on my previous posting with this web site:
Bob Wheatley
Oo Oo the 3 stooges plumming right ?
Now you have me worried ( Love the rest of the Thread, BTW)
So on my hot water heater It has Brass fittings, we have the copper lines going up close to the heater, then have the braded stainless hose with the 2 female fittings. One end goes to the heater the other to the plumbing.
The braided sta>>
All of them I have used are stainless and I do not use them on water heaters. If you are going to use a flex then use a standard 3/4x18 waterflex. It's made of brass/copper and it is dielectric.
Bob Wheatley
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