Electrolysis Revisit

[ptonsparky]

Customer with common complaint of heat pump copper lines failing has stated that he lives within two miles of a gas line that injects dc current to prevent problems on their line. He feels this may be adversely affecting his piping. I had not heard of this yet. Comments?

 

[LEO2854]

Customer with common complaint of heat pump copper lines failing has stated that he lives within two miles of a gas line that injects dc current to prevent problems on their line. He feels this may be adversely affecting his piping. I had not heard of this yet. Comments?

I've never heard of that either.

 

[ptonsparky]

Could not confirm or deny his claim but did find .3 amp of AC on a section of water line. Fixed that by moving the water pipe bonds closer together. Two inches instead of six feet. Also removed some customer added wires that confused the issue.
In short, didnt solve a thing in the two hours I had. Maybe answered some questions the customer had.

 

[cadpoint]

Don't you have something that reads DC ?

I think I'd pull the meter and see if some other metal object had any voltage on it off of the house ground.

 

[ptonsparky]

Yes, I have meters.

Servive is 480 with CTs. Plus a customer owned step down xfmr. He called yesterday morning and two hours was more time than I had to give. I offered to make sure he did not have major ground loop problem. My clamp meters did not find DC current flow on the pipe in question but did find the AC. Plastic waterline coming in that turns to CU.

The pipe in the immediate area is what is failing.

I made drawings and took a few pictures to study in my spare time.

 

[ghostbuster]

Yes,stray DC current will cause electrolysis to occur and speed up the corrosion process.

 

[ptonsparky]

Yes,stray DC current will cause electrolysis to occur and speed up the corrosion process.

No argument there, proving the source is the problem. Esp within time and budget constraints of customer.

View attachment 9360 Like I said. Scratching. I need to check the ht pump closer. Removing the 2 #6 bonds the customer had installed was most likely the source of the AC current.

 

[weressl]

Customer with common complaint of heat pump copper lines failing has stated that he lives within two miles of a gas line that injects dc current to prevent problems on their line. He feels this may be adversely affecting his piping. I had not heard of this yet. Comments?

Active cathodic protection utilizes DC current injection to keep undeground pipes from corroding. Passive utilizes attached electrodes, magnesium or graphite blocks atatched to the pipe, for the same purpose. Both protection methods are quite safe and it would be unlikely to 'complete' their circuit through adjacent equipment, they are targeted to the specific equipment by design. When they malfunction, eg. their connection to the target is severed, all bets are off.

http://www.water.ca.gov/groundwater...ia_well_standards/cpws/cpws_introduction.html

 

[robbietan]

Active cathodic protection utilizes DC current injection to keep undeground pipes from corroding. Passive utilizes attached electrodes, magnesium or graphite blocks atatched to the pipe, for the same purpose. Both protection methods are quite safe and it would be unlikely to 'complete' their circuit through adjacent equipment, they are targeted to the specific equipment by design. When they malfunction, eg. their connection to the target is severed, all bets are off.

http://www.water.ca.gov/groundwater...ia_well_standards/cpws/cpws_introduction.html

and active cathodic protection is also used to prevent corrosion of metal roofs in houses located near the sea.

 

[Open Neutral]

Active cathodic protection utilizes DC current injection to keep undeground pipes from corroding. Passive utilizes attached electrodes, magnesium or graphite blocks atatched to the pipe, for the same purpose. Both protection methods are quite safe and it would be unlikely to 'complete' their circuit through adjacent equipment, they are targeted to the specific equipment by design. When they malfunction, eg. their connection to the target is severed, all bets are off.

But what I recall from working on a pipeline was roughly "Everything you do for yourself hurts others around you.." The corrosion guys went to quarterly meetings with other pipeline cos, AT&T Long Lines [coaxial cables], etc. to hash it out.

 

[rattus]

Copper and Iron

Copper and Iron

The plumbers used to bury brass cutoff valves. They were opened and closed with an iron rod brought to the surface. It was common for galvanic action to eat away at the iron to the point that the rods would twist off rather than actuate the valve. The brass was unaffected though. Maybe you have such a scenario.

 

[kwired]

Customer with common complaint of heat pump copper lines failing has stated that he lives within two miles of a gas line that injects dc current to prevent problems on their line. He feels this may be adversely affecting his piping. I had not heard of this yet. Comments?

What exactly are these "heat pump copper lines"? Refrigerant tubing from an indoor unit to an outdoor unit, heating or cooling coils themselves, part of a ground loop system? are they buried? Are they bonded to the electrical equipment? Does owner have his own DC source somewhere that may be the problem? I kind of have to agree the neighbors cathodic protection is probably not too likely to be a problem here.

What kinds of corrosive materials may be around that create a natural battery and DC current that may be working on this?

 

[rattus]

Weak battery

Weak battery

What exactly are these "heat pump copper lines"? Refrigerant tubing from an indoor unit to an outdoor unit, heating or cooling coils themselves, part of a ground loop system? are they buried? Are they bonded to the electrical equipment? Does owner have his own DC source somewhere that may be the problem? I kind of have to agree the neighbors cathodic protection is probably not too likely to be a problem here.

What kinds of corrosive materials may be around that create a natural battery and DC current that may be working on this?

FWIW, blackland soil is alkaline, at least in my area. Then the copper and the iron would form a weak battery with the moist alkaline soil acting as the electrolyte. In my experience, the iron was touching the brass, but what if the iron were merely in close proximity. I believe plumbers use dielectric unions to join copper and iron pipes.

 

[ptonsparky]

What exactly are these "heat pump copper lines"? Refrigerant tubing from an indoor unit to an outdoor unit, heating or cooling coils themselves, part of a ground loop system? are they buried? Are they bonded to the electrical equipment? Does owner have his own DC source somewhere that may be the problem? I kind of have to agree the neighbors cathodic protection is probably not too likely to be a problem here.

What kinds of corrosive materials may be around that create a natural battery and DC current that may be working on this?

The copper fittings and pipe that is failing is between the incoming pvc water line and the heat pump exchanger. It is a pump & dump.

No other parts of the copper water line are failing. I do not believe it is electrical at all. DC or otherwise. IMO, .3 amps is not enough to cause the apparent damage and it is there, I saw some of the scrap from previous repairs.

I talked to the a lab that does water and soil testing to find out just what tests they could do. The tech said one of the tests checks for Dissolved Contaminates. Brief explanation, you do not need to be pumping sand to cause damage to pipes and pump impellers. My customer said he would share the results of the water tests.