Tank inspection cover help.

[wazza]

I wish to get into the water tanks to clean them. Has anyone an idea about this inspection cover on my water tank. Do I undo all the bolts around firstly, then the middle, that was my thought.
Has anyone any experience with similar tanks?
Help is greatly appreciated.
Warren

 

[MoodySabre]

Yes do the outside ones first. I expect that the centre one will will long and connect (and should remain connected) with a seal inside the tank which will wiggle out. A bit like this FLB-1 Inspection Hatch | Tek-Tanks look at the second picture.