We have placed cold rolled in a gas tank by mistake. they are small clips attached to a zinc nickel coated cup. the clips are in place to hold this cup to the bottom of the tank. they will be sitting in gasoline and possibly water at the bottom of the tank full time. expected life of this tank is 15 years
Even if straight unleaded gasoline is not corrosive, you need to consider the corrosiveness of unleaded with 10% ethanol, at least in the U.S. Especially after some water ingress occurrs.
There is information realted to storage tanks and tank failures. I don't know where to find them.
My guess is that you have a problem since these are in the bottom of the tank.
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Corrosion, every where, all the time.
Manage it or it will manage you.
Then you should scrap the parts and remake them to the proper material spec. That is the ONLY acceptable solution for production automotive parts.
There is some chance that these could be mechanically coated with Zinc Nickel. I'm assuming that they were supposed to be made from electro coated zinc nickel coil steel. What is your steel chemistry (IE 1008/1010 or 1075 etc) and rockwell. As carbon content and hardness increase, resistance to aqueous corrosion decreases.
Are these production PPAP'ed parts? Then you have no choice but to scrap and re-make. I'd then hunt down whoever allowed regular cold roll to be ordered/supplied/run and nail them to the wall. If you have a PO that specifies the proper material and its your suppliers fault then you might get them to pay you back for the steel and some costs, but they wont cover all of them.
I agree with Nick 1000%. Particularly in this situation where failure involves danger to human life. In addition, by putting disimilar metals in contact in the presence of an electrolyte you may have set up a corrosion cell.
