Well it comes after a stopple connection and a ??EQ connection so my guess is that it is a connection intended to insert "MUD" into the pipe.
Now given we don't know where this pipe goes, what sort of plant it is, have any details of the fluid, a P&ID or even all of the GA drawing it's not easy to add anything more I feel...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.