Corrosion

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Old 11-14-06, 12:38 PM
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Corrosion

I have an older home and still have some galvanized water pipes but some have been replaced with copper. I have connected copper directly to galvanized and got severe corrosion both outside and inside the pipes in just a few years. I also have used dielectric unions and some of them show some corrosion outside, but I haven't taken any apart to see what is inside.

Now I have been told that a brass nipple is the best way to transition from galvanized to copper because it provides more separation between the dissimilar metals.

Are brass nipples the best way to make this transition and avoid the corrosion problem?
 
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Old 11-14-06, 11:38 PM
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Anytime you connect two dissimilar metals, it is a ticket to galvanic corrosion. The best defense is a dielectric union...............
 
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Old 11-14-06, 11:40 PM
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Anytime you connect two dissimilar metals, it is a ticket to galvanic corrosion. The best defense is a dielectric union............... Stay with the dielectric unions!
 
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Old 11-15-06, 08:32 AM
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Well, I already installed a 3" brass nipple. Now I understand that it should be a minimum of 6".

Is this a matter of 3" is good but 6" is better, or do I need to redo the job?
 
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Old 11-17-06, 09:52 PM
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It should be 6", but if you've already done the work, and it's accessible, you can just keep an eye on it. It it's going to get buried in a wall, replace w/ 6". I personally prefer brass nipples for dielectric over the unions.
 
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