What is Electrolysis and How Can You Eliminate It when Using Stainless Steel Fasteners
March 9th, 2022
Also known as galvanic corrosion, electrolysis happens when two dissimilar metals are directly connected causing the lesser of the two metals to corrode. For the process to occur, the two metals have to also come into contact with a conductive electrolyte. In other words, for galvanic corrosion to start, three things have to meet: an anode (one of the metals), a cathode (the second metal) and an electrolyte. Unfortunately, the meeting of those three things occurs far more frequently than you might expect since water, including groundwater and rainwater, acts as an electrolyte.
That’s why when aluminum and steel come together in seawater, the aluminum begins to corrode and weaken. The good news is that we not only know which metals react, there are easy ways to prevent electrolysis to save yourself costly repairs.
The Galvanic Series
The simplest way to determine whether two metals play well together or have the potential to experience galvanic corrosion is by looking at the Galvanic Series of Metals. If two metals on the list touch in the presence of an electrolytic, the metal with the lower number in the series will be eaten away. And the further apart on the list the two metals are, the more galvanic action occurs.
Metals that make up the Galvanic Series are:
1. Aluminum
2. Zinc
3. Steel
4. Iron
5. Nickel
6. Stainless Steel (400 Series)
7. Tin
8. Lead
9. Brass
10. Copper
11. Bronze
12. Stainless Steel (300 Series)
So for example, you wouldn’t want to use a rivet made of 300 series stainless steel in a copper plate or attach aluminum gutters to a copper roof.
Preventing galvanic corrosion
Once you understand electrolysis, the most important thing to know is how to prevent it:
1. Choosing the right fasteners
Choosing the wrong material for fasteners can not only result in costly repairs, it can be dangerous. That’s why it’s important to always choose fasteners with a higher number on the Galvanic Series than the metal they’ll be used to fasten. This makes going with 300 series stainless steel an obvious choice, since it won’t be corroded by any of the other metals on the list.
2. Insulating and isolating the metals
In addition to choosing the metals for your materials wisely, it’s also possible to insulate one metal from the other to prevent corrosion of the weaker metal. This can be done by using non-conductive materials like paints, coatings, greases or oils or by physically separating reactive metals from each other. For example if your wood roof deck is fastened with steel nails, putting a copper roof directly on top would result in corrosion of the copper. However, if you use an asphaltic felt to separate the roof deck from the nails
, your corrosion worries are over.
3. Adding inhibitors
The final option for prevent electrolysis is the use of inhibitors to make the metal passive. Inhibitors work by removing oxygen from the electrolytic that kickstarts the process, thereby stopping galvanic corrosion before it starts.
Source:
https://www.brikksen.com/home/page/...inate-it-when-using-stainless-steel-fasteners
, and now a days, you can request different levels of media for a smoother or rougher finish. They can can even paint match, although in my experience it may not match 100% unless it’s a common color. For example, they can do blue, but IG Shale blue might not come out as a 100% match…YMMV
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