My sewer line runs under my bath. I am going to remodel my bath and need to know how to tie into an existing cast iron sewer line. Will cutting the line pose any explosion hazards? Would I just get an ASB connection and secure it with the clamped rubber couplings?

There is a very very slight chance that you would get any kind of flash back from the sewer line as you are cutting it. In many years of working with such I have only had one time that the gas made a puff and then it was gone.

Going with the neoprene adapter with the stainless bands is a very good way to go from cast iron to PVC.

You aren't going to blow up but shut off your water while doing this job and tape down the lids of all toilets and washers. What are you tieing into sizewise, a 3" ABS line maybe? Fernco makes a saddle strap connector but I have never checked to see if it would pass a code inspection.

I redid the plumbing on an old house I had and ran into same situation I cut the cast iron pipe it was 4in. I cut it with a small hand grinder. Then I used a 4in. Blk. Rubber coupling. Clamped cast iron tailpipe coming from bottom of toilet flange joined it with coupling to the new 4in. Pvc sewer line.it is still there and working fine this was in 1998. Good luck...

As said above: cut it with 4" grinder ( wear good pair of gloves and goggles ). Insert ABS connection and connect CI and ABS with Fernco fittings. These fittings are sold in all possible sizes and configurations and Home Depot / Lowe's carries some of the basic ones. You can also visit Fernco Couplings, Flexible Couplings, Flexible Pipe Connectors, Fernco Fitting, Shielded Couplings, Fernco Donut, Pro-Flex Coupling, Large Diameter Couplings, Sewer, Drain, Waste, Plumbing Flexible Couplings, Plumbing Pipe Leak Repair | Fernco to see their catalog.

Keep us posted about the progress..

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Originally Posted by chaparralx

My sewer line runs under my bath. I am going to remodel my bath and need to know how to tie into an existing cast iron sewer line. Will cutting the line pose any explosion hazards? Would I just get an ASB connection and secure it with the clamped rubber couplings?

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In all my years I've never had a sewer line explode so put your mind at ease there.

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Would I just get an ASB connection and secure it with the clamped rubber couplings?[/

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Let me walk you through the process. You will come off the sewer with either a wye or combination eighth bend and wye,(see images). You will prime and glue a 6" piece of ABS into each end of the fitting to be used. Now, with the pieces glued intothe fitting, measure end to end and add 3/8" an d that will be your cut. You will cut the cast iron with a hand grinder, a set of cast iron cutters or a Saws-All with a metal blade. Use Fernco Shielded Couplings,(see image) do not use rubber couplings under ground. Slip the metal bands over each end of the cast iron and roll back the neoprene gasket on the cast iron ahead of the metal clamps.
Now place the fitting to be used in the opening and snap the neoprene gaskets over the bald ends of the fitting. Ypu may now slip the metal bands over the coupling and tighten the bolts. Be sure to give the branch of the fitting a little pitch before you tighten the couplings. More questions? I'm as close as a click. Good luck and thank you fer rating my answer. Tom

Speedball
You say not to use rubber couplings underground. What should I use to tie into a 4inch cast iron sewer line that is under the slab in the basement? I have exposed the pipe and want to tie pvc pipe into it with a wye as you suggest but then I want to cover it again.

There are two couplings you can use: Flex Seal coupling ( all rubber with 2 ss bands ) and Sheilded coupling ( rubber with steel collar and 2 ss bands ). As far as my Code goes, you can use both types. Actually the Flex Seal coupling may be easier to use for HomeOwner. See pictures: First one is Shielded coupling, the second one is All rubber coupling.

We do not use rubber couplings under ground. The reason is that a shielded metal coupling will give the joint a more ridged connection then a rubber coupling. A shielded metal coupling, (see image) will not sag and cause a uneven connection.
Good luck, Tom