How to connect fittings to a fiberglass tank.

[Joelk]

I am going to try to modify an old pressure tank to work as a "Sediment Bowl Type Tank"(think OLD tractor/lawn mower).

I got a bladder tank that appears to be made of fiberglass and have removed the bladder from it. I will be able to use the existing fitting on the bottom of the tank for the "flush valve", but need to plumb two fittings into the top for the water supply to enter and exit the tank. The tag on the tank says it is rated for 125 PSI.

I need to connect lines (probably 1") to the tank where there currently are no fittings/holes.

What would be the best type/material fittings to use?

How should I attach them to the tank?

Will Auto Body Fiberglass/Resin work with the material the tank is made of?

I need to put the fittings near the top of the tank, but it would be easier to plumb if I put them in the sides near the top, instead of on the top.

Any reason to think one or the other(the side or the top) would be a stronger/better place to put the fittings?

Thanks, Joel

 

[phishfood]

The best place to add fitting to a pressure tank is in the curved top of the tank. I wouldn't use fiberglass for this, but it might be possible to make it work.

Personally, I would look for either a dented/damaged clearance water heater, or a galvanized non bladder tank for this. The water heater already has two top fittings, the galvanized would be relatively easy to add fittings to, as long as you can weld.

 

[Joelk]

Thanks for the reply.

I already have this tank, it will never rust out, and it fits the available space very well, so I think I will try to use it.

I looked up the info on the tank, a Well Mate WM6 and I see that it is actually made of High Density Polyethelene with fiberglass wrapped around it. As such, I don't think trying to fiberglass something to it is the way to go.

I could feel inside the tank and it seems really thick. Feels like 1/2" perhaps even thicker.

My prefered fitting would be made like a sink drain fitting where it would have a flange and Oring inside the tank(there is a smooth surface inside the tank) then male threads go through the side of the tank and a nut goes on the outside to compress and seal the Oring. So far I have not found anything like this to use. Preferably it would provide 1" NPT threads on the outside of the tank.

Anyone know where I could find such fittings?

If I can't find that type of fitting, I am thinking about just drilling holes, threading them and then inserting a 1 1/4" X 1" reducer bushing into it. Since the tank walls are so thick I am inclined to think that will work OK. Any opinions on how well/if that will work?

Whatever I do, I will pressure test it after I modify it to make sure it withstands a good bit over the 60 PSI max that the system should see. Where it is at, it will not cause catastrophic damage if it leaks, or even if a fitting blows out.

 

[Mr_David]

you might try a fitting found on a sheet drain pan for a water heater

They are normally 1" it has a flange and a reverse thread nut to secure to penetration hole

The one I have seen are PVC. Probably not rated for pressure but may work.

I did a search and the only ones i found looked like male PVC adapters with electrical conduit nuts. Those wont work for what you need

here is what I got with a Search for water tank fittings

I got BULKHEAD FITTING

http://www.tank-depot.com/product.aspx?id=172

 

[speedbump]

I agree, Bulkhead Fittings are the way to go. But like I said on my Forum, I don't think this will work to remove silt. It doesn't settle out of the water fast enough to get to the bottom and stay there. Even after sitting all night, when you use water in the morning, the turbulence in the tank will probably just stir the silt up again.

 

[Joelk]

Thanks for the replies.

Bulkhead fittings like you linked to, are what I was thinking about, but I could not recall the appropriate name. Knowing the name should help if I try to find a suitable fitting.

I think I will put this Tank Modification Project on the back burner for now as I agree with speedbump that there will probably be too much water velocity in a tank this small to work with the fine silt I am dealing with.