Capping a sewer pipe

Here’s the situation: I have a toilet in my basement, with the flange set directly into the concrete floor. Said toilet is riddled with cracks, and I don’t need a toilet at that location anyway. So I want to pull said toilet out, and seal up the pipe. This toilet is located between the street and the main stack of the house, so I’m guessing that it’s sited directly over a stub rising vertically from the main outflow pipe. Of course, everything is under concrete, so I can’t exactly see. In any event, the pipes will be cast iron of some vintage.

So how is this situation typically handled?

A plug should work. Page four of this pdf shows some brass plugs for use with cast iron piping. I wouldn’t seal over it or anything, just in case a future owner wanted to use it.

Should you need to seal the cap in a workmanlike manner,obtain some lead wool from a plumbing supplier. When malleted around a joint it becomes monolithic.

you can use a test plug , which costs about 3 bucks. No tools required and takes about 2 minutes to install. It’s just not something you’d want to concrete over or bury.

Thanks, all. The test plug sounds promising. Or maybe I’ll wimp out and call the plumber!