oxidation

[don m]

the skin on the under side of my trailer has oxidized around the rivets and has fallen over the rivets. I have been using stainless steel fender washers with 1 inch screws of the same material to correct the proplem--but now am having doubts. has any one else had experence with this kind of problem?

[53flyingcloud]

Don,
Sounds to me like your doing the best you can to correct a problem..If It were me, I think I'd go a step futher by putting some kind of heavy duty grease on the stainless steel screws before I installed them. The logic for that: You're 'screwin into' steel frame underneath(most likely) and, by doing this you might stop any rust from spreading. Sort silly perhaps but...Couldn't hurt.
Question; Did this come about because of SALT on the road during the winter months?
If it's possible, could you take some pictures of your unit and, share with us what you're doing to correct it..??
ciao

[thenewkid64]

The biggest problem that you may have is an electrolytic reaction between the Stainless steel and the aluminum.

This is off of the Reynolds Aluminum foil site

1. When aluminum and a dissimilar metal are in contact in the presence of moisture, an electrolytic reaction may occur causing a breakdown of the aluminum. To avoid this use aluminum, glass, ceramic, plastic or paper containers. Do not cover sterling silver, silverplate, stainless steel or iron utensils with aluminum foil.

2. A similar reaction may occur when salt, vinegar, highly acidic foods or highly spiced foods come in contact with aluminum foil. The result of these reactions is a harmless aluminum salt. Some aluminum salts are used in medicines to treat stomach disorders. The food can be safely eaten; however, the aluminum salt particles can be removed from the food to improve the appearance of the food.

Now I will be the firstto admit our rigs skin is thicker than foil, but the process will still occur when moisture is present.

If the holes are normal rivet sized you can get pop rivet backer plates that are alumimum and use them as a washer. Use a longer than before rivet, alumimum as well, and then this cannot happen.

I belive this is why there are regular steel screws where ther are screws in the skin.

Let us know what you decide.

[JW84345]

Hi Don,

I've reattached the belly skin using aluminum rivets reinforced through a small piece of aluminum sheet. I use large rivets (don't know the size off hand). I have a larger sheet of aluminum obtained from the local hardware store, drill the holes needed to put the rivets through and cut out the pieces I need (about an inch square). I am not talking a lot here, less then a dozen over several years. I have not had to redo any of them.

Jim

[otha1]

The rivets holding the aluminum skin must be punched into steel in the chassis in order for them to exhibit the sort of oxidation we experience. Any little bit of salt in the water that collects around them will set up an electrical current. The current is formed by the movement of electrons from one material to the other. Aluminum loses electrons to steel, and just about everything else metallic. If you are using steel screws and washers to secure the skin to the chassis, you will help the situation by cutting out plastic washers from something like a plastic gallon jug and inserting them between the steel washer and the skin. The other suggestion to grease the screws is also a good one. I would use a synthetic grease...