I have finally finished the repair of my toilet flange. I never learned if I have a glued on or screwed on floor flange. I was considering undoing the lag screws holding the flange into the sub-floor until I saw how rusted they were. I chickened out given we have house guests coming and the RV is their domicile. I didn't want to open another can of worms removing them and then the flange. So I took the easy way out suggested by Bob Rohrmann.
In case you missed it, Bob suggested using a stainless steel replacement flange that screws on over the existing one. Home Depot (and others) have this available.
https://www.homedepot.com/p/Oatey-1-...7782/303864005
The first task was to take care of the existing, damaged, flange. As you can see in the picture below, the toilet bolts (which hold the toilet to the flange) has been over tightened and cracked/broke the flange.
I "sanded' the flange to remove the high spots and level out the flange surface in preparation for the replacement ring. I used silicone to close the gaps in the existing flange to prevent any possible leakage.
The installation of the replacement flange was pretty straight forward. I did rotate the flange a tad to avoid the new screw holes being directly over the existing floor lag screws. I drilled pilot holes using a 1/8" bit and mounted the flange using #12 1 1/4" stainless screws. Once everything was screwed down, I ran another bead of silicone along the bottom edge of the new flange to prevent any leakage (where the red arrow is in the below picture). Lastly, i applied valve lubricant (akin to Plumbers Grease but thicker and stickier) around the ring and in the holes for the toilet bolts. Those bolts want to fall over and move when installing the toilet making it a major PIA otherwise.
A RV toilet is similar but different than a household one. A RV one uses a foam rubber-like doughnut as the gasket rather than a wax ring. Here is a picture of the bottom on the RV toilet with the doughnut.
I took a picture of the replacement ring (before installation) and how it interfaces with the toilet once installed. I used some more valve lubricant on the gasket to help ensure a tight seal with the ring.
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Hblick48 reports he used the ring and had odor issues afterward. I am hoping I sealed the fittings well enough to avoid this problem. If not, I have another project after Thanksgiving. Ugh!