TD5 centrifugal drain pipe to sump LRJ100000 gasket leaking

Hi! Ive just replaced the water pump on my 110 TD5, I removed the centrifugal housing and pipe for better access and re-fitted with a new Oring and gasket for the drain to sump.

I've noticed its leaking at the drain to sump and this made me wonder wether the gasket is sided? if not I'll just nip it up.