They are the covers for flow frame access.
I’ve had to clean a couple of my flow frames and just used some warm (34oC) water through a pressure cleaner. I’m not sure I’d have the patience to use a steam cleaner.
I pulled mine apart. I might try your way and clean whilst in one piece.
Your hive looks really good. What is the controller for? I like the access points too. How many kilos per season of honey do you get?
The pressure cleaner did make it easier. I just lay it down and work with the angle of cells by squirting from the top down.
The controller is for a wifihivescale that gives me regular weight readings.
Get an average of 30kg ish, having said that it has been such a poor season others in my area I haven’t taken any this summer yet. Over the last two months they have put away enough winter stores (20kg ish) and I’m hoping I’ll get a banksia flow and be able to take a bit.