Whatcha call this whatchamacallit?

[ToughButterCup]

I'm making a rain garden out of a plasterer's bath. I need to make an overflow out of 40mm pipe. Like this :

The overflow is simply the top end of the 40mm pipe.

I need to make a 41mm hole in the bottom of the bath and seal the pipe in place. With a gland of some sort. (The green shape above)

The gland would need to screw into the bottom and the top of the bath base and allow the 40mm pipe to fit it , top and bottom .

 

But I cant for the life of me think what such a fitting is called. Spent an hour on SF and TS, got nowhere.

Hard of Thinking Lancaster.

[Tom]

tank connector?? https://www.diy.com/departments/floplast-push-fit-straight-waste-tank-connector-dia-40mm/152672_BQ.prd

[Russell griffiths]

Why put it in the bottom, it will always be under water, fitting it at the high water mark keeps it up out of the water a lot of the time.