GrillGrates causing grates beneath to rust away

[jpwkeeper]

I'm a huge fan of GrillGrates. I generally buy cheap grills and use the GrillGrates to turn them into premium grills.
However, I've had one very odd thing happen, and it's happened on three different grills. Using the Grill Grates on top of the normal grates has caused the grates underneath to rust away to nothing in a fairly short time, like a year.
My latest grill has a grate on it that literally only has metal left around the edges, just enough to hold the GrillGrates up, in 2 years. But the heat deflectors and burners are still in very good shape with barely any rust on them at all, so I'm fairly sure it isn't happening because of not covering the grill enough (and it's very humid here in the summer). The grates on this grill I'm fairly sure were cast iron.
I'm assuming this is the case of galvanic corrosion.
Has anyone else had this happen?
Is there any way I can prevent this from happening? Something I could maybe use as a spacer? Or would removing the GGs between cooks be enough to at least slow it down (or does it happen predominantly when it's hot, so that wouldn't help)? Would keeping the cast iron grates oiled help?
I don't want to spend the money to get the fully fitted GrillGrates (150 dollars later and they'll only work for this grill). My new grill also has cast-iron grates, and replacements aren't exactly dirt cheap, but I need something to hold the Grill Grates up.

Any advice would be appreciated.

 

[mcokevin]

What is the metal composition of the factory grates and the GrillGrates? Sounds like it could be dissimilar metal corrosion, especially if you are in a humid and/or saline environment (e.g. Florida, next to the pool, etc..).

EDIT: Sorry, I didn't read thoroughly. I think you're on the right track with galvanic corrosion (dissimilar metals). Cast iron has a relatively low galvanic rating and will corrode preferentially against a more passive metal. Do you know what the GrillGrates are made out of?

The galvanic table in milspec 889C is a good reference:

https://www.corrdesa.com/wp-content/uploads/2018/08/MIL-STD-889C.pdf

 

[jpwkeeper]

What is the metal composition of the factory grates and the GrillGrates? Sounds like it could be dissimilar metal corrosion, especially if you are in a humid and/or saline environment (e.g. Florida, next to the pool, etc..).

EDIT: Sorry, I didn't read thoroughly. I think you're on the right track with galvanic corrosion (dissimilar metals). Cast iron has a relatively low galvanic rating and will corrode preferentially against a more passive metal. Do you know what the GrillGrates are made out of?

The galvanic table in milspec 889C is a good reference:

https://www.corrdesa.com/wp-content/uploads/2018/08/MIL-STD-889C.pdf

Anodized Aircraft-grade Aluminum.

And I live in Southern Maryland, where people in Florida go when they want to live somewhere else but don't want to miss the humidity.

 

[mcokevin]

Anodized Aircraft-grade Aluminum.

Hmm, I am not exactly an expert in this, but --

The anodized coating should break the electrical circuit between metals.

Also, if the factory grates are cast iron and the GrillGrates are AL2024 that is interesting. They are close on the galvanic scale (i.e. less likely to react with each other), and the AL2024 is more active. So, in theory at least, if this was galvanic corrosion the GrillGrates should corrode in favor of the iron. Between the anodized aluminum and composition of the metals, I would think this is not galvanic corrosion.

Maybe someone smarter than me can weigh in.

 

[tallbm]

I'm a huge fan of GrillGrates. I generally buy cheap grills and use the GrillGrates to turn them into premium grills.
However, I've had one very odd thing happen, and it's happened on three different grills. Using the Grill Grates on top of the normal grates has caused the grates underneath to rust away to nothing in a fairly short time, like a year.
My latest grill has a grate on it that literally only has metal left around the edges, just enough to hold the GrillGrates up, in 2 years. But the heat deflectors and burners are still in very good shape with barely any rust on them at all, so I'm fairly sure it isn't happening because of not covering the grill enough (and it's very humid here in the summer). The grates on this grill I'm fairly sure were cast iron.
I'm assuming this is the case of galvanic corrosion.
Has anyone else had this happen?
Is there any way I can prevent this from happening? Something I could maybe use as a spacer? Or would removing the GGs between cooks be enough to at least slow it down (or does it happen predominantly when it's hot, so that wouldn't help)? Would keeping the cast iron grates oiled help?
I don't want to spend the money to get the fully fitted GrillGrates (150 dollars later and they'll only work for this grill). My new grill also has cast-iron grates, and replacements aren't exactly dirt cheap, but I need something to hold the Grill Grates up.

Any advice would be appreciated.

Hi there and welcome!!!

I ran into a rust issue that I wanted to resolve after I left my propane grill open and uncovered and a rain shower came through. Then a week later I go out and see and OMG the rust. I replaced the grill grates but the underlying burners and metal were all rusted and I needed a solution.

I did some research and stopped the rust in it's tracks in the areas that DO NOT contact the food while cooking. I used VHF Rust Converter to chemically convert the existing rust (iron oxide) into a different iron tannate which is a dark colored and stable material.

Again, this is a solution for metal that does not directly contact the food.

After I applied the converter I did a burn out for 30 min to ensure the converter liquid/chemicals (Tannic acid) was burned away and only the stable iron tannate was left behind.

This worked like a freakin charm and saved the guts of my grill.. and i got to upgrade to heavier duty grill grates. No complaints here.

I hope this info helps and below is the post to the thread where I started my journey and I finally came to my solution and posted about it.

Rust Help, Rain in Open Propane Grill

Well last week I managed to leave my wonderful propane grill lid open and in the rain. After I grill I leave the lid open and eat dinner so it can cool off and I can close the lid and then cover without burning up my grill cover. I forgot to go back outside and close and cover it and yep we had...

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