Prep cast iron for no hub couplings

[wrench187]

What's the best way, or preferred way to prep an underground / underslab cast iron waste line for new no hub couplings?

I'm tying into and replacing a section of 2" CI waste, and there is scale / build up on the pipe - wondering what the best prep is to provide a smooth surface for the new no hub couplings.

Any thoughts and experience is greatly appreciated! Thanks

 

[Mr_David]

Sometimes I find a layer of scale and dirt that I have to tap off with a hammer . tap to hard and you crack the old pipe.

chip off any lump with a metal putty knife. I have also use a very coarse rasp to clean bottom side that are hard to reach with a scraper. Fitting brush (type for cleaning copper fitting) in a drill also helps.

one big problem with some old cast iron is it is truly cast and can have a seam from the casting mold. use a grinder or a stone wheel in a drill to smooth it out. When its really bad, I cheat and put some pipe dope on the inside of the coupling. Mission coupling neoprene is a little thicker than no-hub coupling and can seal a little better on the old cast. If you are installing plastic then you will want to use the mission bands anyway as transition coupling

 

[frodo]