Black water tank connection

[Dmaxx85]

Hey guys we’re getting started on our conversions and things have been going pretty good. We’re planning the tanks out now and we have an old 25 gallon that we want to use for our black water tank. My question is how can I connect 3” pvc to the tank with out plactic welding? I’ve found some flange options but not really gonna be a good seal on the bottom for the drain. Just wondering what my options are
Thanks

[PNW_Steve]

Uniseal or spin-weld fitting.

Spin-weld is for polyethylene only and requires a special tool ($100).

The larger Uniseal's work well but can be a pain to assemble. I have used a roundover bit in a router to ease the end of the pipe and make it easier to assemble. Also, I use Windex as a lube.

[Dmaxx85]

Ok I saw the Uni seal on amazon and was sure how they worked. Do they just stick on with an adhesive or what is used for the attachment?

[PNW_Steve]

Originally Posted by Dmaxx85

Ok I saw the Uni seal on amazon and was sure how they worked. Do they just stick on with an adhesive or what is used for the attachment?

The uniseal goes through the hole in the tank. Then the pipe is pressed into the seal. The pipe is just slightly larger than the opening in the seal. When you force the pipe in it compresses the seal.

So:

Drill hole

Insert uniseal

Lubricate

Insert pipe

[PNW_Steve]

Gotta love YouTube :

https://www.google.com/url?sa=t&sour...N8ZFOD4xbU2nov

[PNW_Steve]

OK... The link doesn't work.

Google brstv uniseal and you will find a video showing Uniseal installation.

[Dmaxx85]

What would it take to weld a flange on the bottom of this plastic tank?