Plastic Liner Between Outdoor Flat Bottom Tank and Concrete Slab

[PW2006]

We are going to install several flat bottom carbon steel tanks (approx. 15 ft diameter) on a big concrete slab at a outdoor environment. The liquid stored in the tanks is not corrosive. The tank bottom (exterior) has been painted already. I wonder:

(1) if there is need to put a layer of plastic liner on the top surface of the concrete slab under the tank bottom. Would this provide extra help on reducing the corrosion? If we do need, what is the material and thickness that are normally used?

(2) if there is need to seal the tank bottom edge on the concrete? This will help to prevent (or at least reducing) rain water from leaking into the space under the tank bottom. If it can help too, what is the sealant that is normally used at this application?

Thanks.

 

[JStephen]

A layer of 1/2 asphalt expansion joint material is commonly used as padding on a foundation- ASTM D1751, if I remember right. Caulking used at the edge can vary- Sikaflex is one brand I've seen.

 

[ornerynorsk]

Ditto to JStephen's reply. Asphalt impregnated material will repel moisture and provide a better cushioning effect for eneven surfaces, plastic will encourage condensation and corrosion.

 

[JStephen]

That should be 1/2" THICK asphalt material, by the way.

 

[PW2006]

Thank you very much for the information. It looks very reasonable to me.

When I looked for the asphalt impregnated expansion joint material, I found many that meet the ASTM D994 standard. Can I use this ASTM D994 material? I don't know the difference between ASTM D994 and ASTM D1751.

Is there any drawback(s) of using this 1/2" thick asphalt impregnated sheet under the tank, except extra cost? Is this a popular way for putting steel tank on the concrete slab?

Thank you.

 

[IceStationZebra]

I would think that the joint compound would tend to extrude under the weight of the tank - of course depending on the mass of the tank, how stiff the tank is, and how long the joint compound is allowed to set before the tank is filled.

ISZ