Get a piece of plate it needs to be slightly larger than the intake opening and some Angle iron 1" will work. and a 2" nipple and a 2" ball valve, and 2 bolts long enough to extend into the pit by 2"
cut the hole and weld the nipple to the middle of the plate make a flange that will fit snug in the opening and weld it to the plate. weld a bolt on each side of the hole cut a piece of A/I that will extend 1" to either side of the intake opening mark and drill the holes for the bolts to attach through. Apply a bead of High temp RTV at the joint of the flange and the plate and install it. let it sit 24 hrs to cure the RTV.
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