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Old 08-13-2016, 10:03 AM   #21
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Originally Posted by folivier View Post
Thanks Star. I was looking at the river gage above Covington but good to know that the level is lower closer to the lake.
We're monitoring the situation. It's so bad all around us. My daughter is trapped in her apt in Baton Rouge. Her apt. Is not flooded but the streets all around her are impassable.

I was just reading a fb post from Livingston parish that they are sending a Blackhawk helicopter to help with rescues. People are trapped on their roofs and posting on fb begging to be rescued because they can't get through to 911.

It's a horrible situation.
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Old 08-13-2016, 12:04 PM   #22
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Were water comes out of strainer to pump,make up a hose to barbed to correct size hose ,so you can back flush the strainer to outside thru hull fitting. This will blow away the outside alge. Put a 3"chlorine pool tap into strainer and let it resolve thru the system. This will help kill any alge growth in the lines. When you get to clean water inspect the thru hull for blockage. Each time I clean my a/ c strainer I add a 3" tab to kill the growth within the lines. Living aboard in the keys at this time of year, the tap dissolves quickly and I have found no problems. We also get a lot of bay grass ,so I cut 6" of a 5 gallon bucket drilled many 1/2" holes and attached it to the outside of the thru hull with a wire tie. This keeps most of the grass out of the strainer. Of course I remove it if we go cruising.
Try bromine tabs. Smaller (1"), slower dissolving and less corrosive than chlorine.
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Old 08-13-2016, 12:36 PM   #23
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Try bromine tabs. Smaller (1"), slower dissolving and less corrosive than chlorine.
what is chlorine corrosive to? Does it affect copper?

Reason I ask is, my slip neighbor just tried a couple pieces of copper pipe in his screen, and is going to try the bromine. Surprisingly the (2) 1/4" x 3" copper pipe pieces that he put in his SS screen were actually etched after 1 week of continuous use.

As best I can tell the copper pipe pieces were etched by the salt water alone. And that strikes me as really bad since the A/C's condenser is made from copper tubing.
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Old 08-13-2016, 05:43 PM   #24
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what is chlorine corrosive to? Does it affect copper?

Reason I ask is, my slip neighbor just tried a couple pieces of copper pipe in his screen, and is going to try the bromine. Surprisingly the (2) 1/4" x 3" copper pipe pieces that he put in his SS screen were actually etched after 1 week of continuous use.

As best I can tell the copper pipe pieces were etched by the salt water alone. And that strikes me as really bad since the A/C's condenser is made from copper tubing.
The tubes should be cupronickel.

Metals and Corrosion Resistance
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Old 08-13-2016, 09:50 PM   #25
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About 2-4 times a year I have to flush with acid. My drill is to dump the Groco strainer, fill it with Barnicle Buster. I have my pump with a standard 110 plug on the cord with the AIr Con control. That way I can manually cycle the pump. I pump the Buster into the system by cycling the pump from an onboard source of 110. I usually do this about 3times, then walk away and let it marinate for a few hours. Then fire up the AC and the crud comes blowing out.

I had no luck with copper in the strainer. The Bromide seems to work ok but still the acid treatment is king. Nasty water is a real pain.i am sure the constant circulation is better practice. This way is easy and quick.
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Old 08-14-2016, 08:06 AM   #26
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Interesting paragraph on wikipedia in regards to cupro...

Quote:
In seawater, the alloys have excellent corrosion rates which remain low as long as the maximum design flow velocity is not exceeded. This velocity depends on geometry and pipe diameter. They have high resistance to crevice corrosion, stress corrosion cracking and hydrogen embrittlement that can be troublesome to other alloy systems. Copper-nickels naturally form a thin protective surface layer over the first several weeks of exposure to seawater and this provides its ongoing resistance. Additionally, they have a high inherent biofouling resistance to attachment by macrofoulers (e.g. seagrasses and molluscs) living in the seawater. To use this property to its full potential, the alloy needs to be free of the effects of, or insulated from, any form of cathodic protection.
It seems that you shouldnt use a pump that pushes water real fast through the pipes or the corrosion resistance lowers? How fast is too fast?

And it also seems that you shouldnt bond the pipes to the boats bonding system. I never would have guessed that one.
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Old 08-14-2016, 08:21 AM   #27
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Originally Posted by what_barnacles View Post
Interesting paragraph on wikipedia in regards to cupro...



It seems that you shouldnt use a pump that pushes water real fast through the pipes or the corrosion resistance lowers? How fast is too fast?

And it also seems that you shouldnt bond the pipes to the boats bonding system. I never would have guessed that one.
The a/c system is grounded through the panel and there is (ABYC) an ACground - DCnegative bond at the panel. If you also have underwater metals bonded (ABYC) you cannot isolate the a/c from the cathodic protection system.

With the boat wired to ABYC standards isolation from the cathodic protection system would, I think be impossible. I also don't see how a cathodic bonding system could interfere with the biochemical reaction (anti-fouling properties) of copper and marine growth.

Wikipedia is a great resource but I'm a little skeptical on this one (and a few others on Wikipedia)
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Old 08-14-2016, 07:38 PM   #28
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Galvanic Properties

Copper-nickel alloys lie mid-way in the galvanic series being compatible with other copper alloys but more noble than zinc, aluminium, steel and aluminium bronze and less noble than passivated stainless steels, nickel alloys and titanium. The 70-30 alloy is slightly more noble than the 90-10 alloy. As with all bimetallic couples careful attention should be given to avoiding unfavourable galvanic area ratios.

Galvanic contact with less noble copper-alloys, carbon steel and zinc negates the biofouling resistance of copper-nickel. Therefore, in applications requiring the full biofouling resistance of copper-nickel, such as boat hulls, the use of anodes and impressed current cathodic protection systems should be avoided.


https://www.copper.org/applications/...tifouling.html

Not pretending to know anything about cupro nickel corrosion...
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Old 08-14-2016, 07:49 PM   #29
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Galvanic Properties

Copper-nickel alloys lie mid-way in the galvanic series being compatible with other copper alloys but more noble than zinc, aluminium, steel and aluminium bronze and less noble than passivated stainless steels, nickel alloys and titanium. The 70-30 alloy is slightly more noble than the 90-10 alloy. As with all bimetallic couples careful attention should be given to avoiding unfavourable galvanic area ratios.

Galvanic contact with less noble copper-alloys, carbon steel and zinc negates the biofouling resistance of copper-nickel. Therefore, in applications requiring the full biofouling resistance of copper-nickel, such as boat hulls, the use of anodes and impressed current cathodic protection systems should be avoided.


https://www.copper.org/applications/...tifouling.html

Not pretending to know anything about cupro nickel corrosion...

From the link you provided (seems like a legit site) .....

Galvanic contact with less noble copper-alloys, carbon steel and zinc negates the biofouling resistance of copper-nickel. Therefore, in applications requiring the full biofouling resistance of copper-nickel, such as boat hulls, the use of anodes and impressed current cathodic protection systems should be avoided.

Splash zone sheathing on steel offshore platforms in 90-10 copper-nickel should at least span from below mean tide level to well into the atmospheric zone. Potential galvanic corrosion on the adjacent steel is addressed by coating the top section with paint; the bottom, submerged junction will be protected by the cathodic protection system normally applied to the structure.


I'm confused, this makes little sense to me and seems like multiple contradictions and I am a certified corrosion analyst.
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Old 08-15-2016, 08:12 PM   #30
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I think what they are "trying" to say is, the copper wont get the initial corrosion layer that is the primary protection against slime and stuff if it's electrically connected to a less noble metal, like zinc. The zinc keeps it from corroding and negates the whole purpose of using cupro (biofouling resistance).

Thats why I posted in the first place. I hadnt heard of that before.
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