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Drain pipe Old flange removed

The old PVC flange appeared to be sealed to the iron pipe by a rubber coating, which is not something I've encountered (in my limited research).

Will a simple push-tight toilet flange like this be good enough without additional welding? Its product page mention that it can be used inside cast iron pipes.

user7014
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See how the broken remnant of your old flange is marked "For Cast Iron"? The product you linked to in your question specifically says it's for PVC.

You should use a heavy duty product made for use with cast iron, and screw it securely to the floor with stainless steel screws after you set it. Something like this:

enter image description here

Jimmy Fix-it
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  • Thanks for the tip. Would I need to apply any type of seal between the flange and the pipe? – user7014 Aug 13 '16 at 11:45
  • I've used something similar in one of my bathrooms. It's been working fine, 5 or 6 years now. Key is 1) having a good, air-tight seal to the cast iron pipe and 2) fastening it down tightly to the floor. – SteveSh Apr 23 '20 at 23:15
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I would recommend getting a 4" (or 3" depending on your cast iron pipe) coupling like this.

You may also want to clean up the cast iron a bit if you are able to. If the top of the pipe is jagged or pitted, you could take a file or a flap-disk angle grinder to it to polish it up. Maybe not a huge deal, but I'm kind of a perfectionist. It theoretically shouldn't make much difference.

Also, while you have the flange off, you might want to make sure the cast iron isn't rotted through in any visible part that you can see with a light. if it is, you'll need to replace the whole toilet drain with something like PVC or ABS (which wouldn't be a bad idea even if it's not rotted!).

tbox
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It was a specialized part, designed to work with cast iron. You need another one to same specs (look up "cast iron PVC flange", like the one sold here) or replace part of the iron pipe with PVC and use "cast iron PVC coupling" like it was done here

They almost always use rubber (often just a rubber insert), because those 2 materials have very different thermal expansion coefficients and they will literally keep moving against each other..

Using the part you linked would be risky, as it may not guarantee seal to cast iron pipe.

Community
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Agent_L
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    I was having trouble finding a 3-inch cast-iron PVC flange for my pipe. Regarding the seal, the Sioux Chief closet flange product page mentioned this- "The Push Tite works well with various piping materials – ABS, PVC, cast iron, and even some copper and lead pipes." – user7014 Aug 13 '16 at 11:51
  • @user7014 If the maker explicitly states that it works with cast iron I'd go for it. I just couldn't find such info on the site you linked. – Agent_L Aug 15 '16 at 07:55