Water holding tank fittings broken

[fred1diver]

Hello all, I’m redoing the plumbing on my boat, everything is hooked up, but the supply hose threads on the tank are ripped out, I tried with a larger diameter thread, seems to work ( haven’t put water in to try)
But if I screw it completely the threads get loose
Any ideas ?
The tank is plastic, original from 1972, 22 gallons

the way it is set up I can’t install an access port to add a nut from the inside.
A friend suggested a motor boat drain plug to block the hole and drill into that? Not sure

 

[Peggie Hall HeadMistress]

If it's the 1.5" inlet fitting you may be able to drill it out and replace it with a Uniseal and short piece of sched 80 pvc that'll become the hose fitting. Check it out here UNISEAL and send me a PM to discuss discuss the details of how to do it.

--Peggie

 

[fred1diver]

It’s the outlet fitting that snapped off, ⅜

 

[fred1diver]

Tried a few things, but it still leaks
Thinking about replacing the tank for a bladder, would be simpler in a way, but how reliable are Plastimo bladders?

 

[Peggie Hall HeadMistress]

Thinking about replacing the tank for a bladder, would be simpler in a way, but how reliable are Plastimo bladders?

About as reliable as a "budget" version of any product. Spend a bit more for a Nauta. However you need to know that even the best quality bladders have only about a 15 year lifespan and can cost even more than a top quality rigid plastic tank of the same size.

But before you replace the tank...surely there are plastics fabricators in Ottowa. I strongly suspect you can find one who can spinweld a replacement threaded fitting into the tank if you can get it out and take it to them. That'll cost you a LOT less than a new tank. I'd measure it again though and also check the size of your fresh water plumbing...most fresh water fittings and hoses are 1/2" ID. And almost all plastic water and waste tanks are polyethylene, which is why a new fitting will have to be spinwelded into it.

--Peggie