A325 & A490 Type 3 Bolts - Galvanic Corrosion

[Scotta27]

Is there concern for galvanic corrosion when using A325 Type 3 or A490 Type 3 (weathering steel structural bolts) with carbon steel plates? The intent would be to take advantage of the corrosion resistence of the Type 3 bolt. Or should Type 1 bolts be used on carbon steel and Type 3 used on weathering steel A588 only? The typical approach usually involves galvanizing A325 Type 1 bolts where applicable. For A490 that can't be galvanized, is Type 3 a better option than coating with ASTM F1136 Grade 3 coating? - I don't have any experience with this. Thanks!

 

[HgTX]

Considering that weathering steel is permitted to be freely substituted for non-weathering steel, there shouldn't be any galvanic corrosion between the two.

I assume the plates are painted?

Hg

Eng-Tips policies: faq731-376

 

[strider6]

i would say no, there will be no galvanic corrosion, however you should also consider the type of exposure. Is it a marine atmosphere or seawater immersed?

Regarding the coupling of galvanized and weathering steel i've found an article from NACE, here below is the main conclusion:

"Overall, the above results indicate there are few, if any, adverse effects resulting from use of galvanized fasteners
with weathering steel."

http://www.onepetro.org/mslib/servl...NACE-98344&soc=NACE&speAppNameCookie=ONEPETRO

S

Corrosion Control

 

[rmw]

One of the components necessary for galvanic corrosion is the presence of an electrolyte. Is thw wetting agent here electrolytic?

rmw