Black tank to dump valve coupling

[Johnnie-HILO]

My dump valve pipe slides into my black tank extension and is secured with a hose clamp. Over time it works loose. No fun. So I ordered a 3 inch flexible coupling that has 2 hose clamps thinking, since it’s rubber, it would fit over the black tank extension. It fits the valve side fine but won’t fit the tank side because it’s slightly larger. The valve extension fits snugly into the tank side which is the slightly larger diameter. I’m not sure what to do next. Any ideas? Thanks

 

[Johnnie-HILO]

I found out that the way to couple the valve and tank is to put polyurethane sealer on the valve pipe and use a hose clamp at the tank flange.

 

[sam-HILO]

Welcome to the forum.

Glad you got your problem solved. We will answer any questions you may have. Many happy adventures await you.

 

[Johnnie-HILO]

I used Sikaflex 252

 

[Lvnv]

From your initial reply about sealing with polyurethane, I am thinking:
1. the Sika 252 was applied in a bead around the valve pipe and then the pipe was inserted into the blackwater tank opening?
2. the hose clamp was simply placed on the blackwater flange and then tightened, and the flange was flexible enough to squeeze down on the pipe?

(loose clamp on first, then insert pipe and tighten)

thanks