Dis-similar piping materials / galvanic corrosion

[snoop02]

Does anyone have a any experience welding stainless steel piping components to carbon steel pipe in outside industrial applications? I've read that galvanic corrosion can be an issue. Does anyone have any experience with this, and is there a way to stop it?

 

[stanweld]

There are numerous such dissimilar welds in industrial applications. In some atmospheric service exposures, galvanic corrosion has been a problem. Painting has proved an effective remedy.

 

[EdStainless]

What is the environment? If you are handling a fluid that is corrosive then yes, you will have galvanic corrosion issues.
The common approach is to have the stainless lined (such as with epoxy) for a distance from the interface and a little bit of the steel. You will also want to coat the inside of the joint itself.
On the outside of there is a chance for this pipe to get wet and it is near the sea coast then paint all of it.

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Plymouth Tube

 

[snoop02]

The environment could be a roof top in south Florida.
This is piping for a refrigeration system. The fluid is not corrosive, but this section of the pipe may not be insulated and would be subject to condensation and the elements.

 

[EdStainless]

I would suggest that you paint he outside of all of it.
It is even more important to paint if the pipe will be insulated.

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Plymouth Tube

 

[snoop02]

Thanks for the replies guys.

 

[strider6]

as other suggest you've to paint the SS but also the CS 'cause in that atmsphere the CS will corrode also due to atmospheric corrosion.
If it's in florida and exposed to atmosphere with high chloride it could be a concern also SCC of Stailess Steel. I mean if the tube is exposed to the sun (i don't know the operating temp of the tube)can reach high temp and above 60°C there is a risk of SCC. it should something to be evaluated.

Welding stainless steels to other steels

http://www.bssa.org.uk/topics.php?article=101

S

Corrosion Prevention & Corrosion Control

 

[EdStainless]

General corrosion of the CS, SCC risk of the SS. that is why it should all be painted.

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Plymouth Tube

 

[snoop02]

Operating temperatures can be anywhere between -45C & 30C.
The fluid is ammonia.

Gents - thanks for the input and links, they have been most helpful.