Stainless steel is more noble than carbon steel, but not all grades of stainless are the same. Galvanic corosion requires that the liquid is an electrolite.

     I can't give You specifics, but if You give more details, carbon steel alloy, stainless alloy, and what liquid, maybee someone else can.

Hi Heritage06!
Btw, "Weldcome" to this forum!!! :) :) :)

Check out this website"

http://www.corrosion-doctors.org/

Here's another good source, and you can ask Dr. Kane your question :

http://www.corrosionsource.com/

Both of these sites  should provide the answers you need and yet, Dave pretty much spelled it out for you. :)

Respectfully,
Henry

You  can have problems on the internal side if your fluid is a good electrolyte (water, sea water..) and externally due to moisture condensation (expecially if your plant is offshore / or near the sea). There are many factors that have and influence on galvanic corrosion: area ratio beetwen SS / CS, type of electrolyte..
What kind of fluid do u have ?
S.

http://www.corrosionist.com

Thanks for the replies and the extra corrison websites. Little more information although I think after some study and help from another Weld Engineer I think we may have the situation. The socket weld in question has as the fluid deminiralized water running through it. That makes it about a PH of 7 and since this system is only used in emergency situatuions the water is stagnent for up to 18 months. We think we may have a situation where there cpuld be a combination of first galvanic and then a crevice attack on the stainless. Fortunately if that's what we have the valve was just put in place less than 12 months ago and shoud be acceptable in its present configuration for another 12-18 months. Thanks again.