Deck Plate mod on fresh water tank

[Randy J.]

Someone here a while back suggested using a marine deck plate to gain access to an RV fresh water tank. I intend to do so but wonder what sealant to use between the two plastic surfaces. Silicone seems the obvious easy choice but I am concerned about using it around potable water. There is a type that is said to be safe for aquariums but looking more closely, it isn't recommended for around food. Anybody found one?

Another choice would be high temperature glue sticks. These seem totally innocuous from their MSDS's and bond well to polyethylene (the tank, I think) but perhaps not as well to polypropylene (the deck plate). And they do have a waxy surface which one assumes may leech.

Randy

[Jared J]

I used 3m 5200. Even with full tanks, the only time it might touch mine is with sloshing.

[Raz]

Originally Posted by Randy J.

Another choice would be high temperature glue sticks. These seem totally innocuous from their MSDS's and bond well to polyethylene (the tank, I think) but perhaps not as well to polypropylene (the deck plate). And they do have a waxy surface which one assumes may leech.

Randy

Hi Randy, this project is on my list as well. What I found is that not much sticks to polyethylene which is why it is used widely for food products. It occurs to me that a rubber (or similar material) gasket might be a better approach. . McMaster Carr is a great information source for materials. That's where I will look. I'll be interested in your solution. Raz

McMaster-Carr

[Ice-breaker]

Originally Posted by P. Raz

Hi Randy, this project is on my list as well. What I found is that not much sticks to polyethylene which is why it is used widely for food products. It occurs to me that a rubber (or similar material) gasket might be a better approach. . McMaster Carr is a great information source for materials. That's where I will look. I'll be interested in your solution. Raz

McMaster-Carr

I would go with the rubber gasket approach suggested by Raz, as it gives you the flexibility to open and close your tank at will without having to remove and replace caulking or other sealant.

[Jared J]

Originally Posted by Ice-breaker

I would go with the rubber gasket approach suggested by Raz, as it gives you the flexibility to open and close your tank at will without having to remove and replace caulking or other sealant.

That's the whole point of installing the deck plate.





The top of my tank wasn't completely flat. I suppose a soft rubber would have worked. I already had the 3m 5200 because I was installing bulkheads in my kayaks. I put a hose in the filler blocking most of the opening, cracked the deck plates loose until all air was gone and water came out the top, tightened them, then let them sit under pressure from the hose for a few hours. No leaks.

[tractors1]

My late wife was a chemical engineer; I recall her pointing out that an MSDS sheet covers the safety of the material as sold and that for adhesives it's not 100% accurate once the adhesives have cured as the volatiles are gone and the material has changed chemical composition to a stable form.

[Eric Heinz]

I used a butyl tape that I bought from an RV store. I think that it is normally used to seal RV windows and other exterior openings.
I don't have a part number or even the name of the manufacturer.