Cutting cast iron sewer pipe ?

Question

I need to a cut a 4" cast iron sewer line and am wondering whether to use a rental chain type cutter or buy those treated sawzall blade ?

Of course using cutoff wheel would be great if I didn't have to worry about potential explosion from sewer gas .

Speedy Jim · Accepted Answer

Cast iron is funny; some will cut like butter with a Sawzall,but others will resist all attack:-)If you have room to get the chain in, I'd do that.Jim

rb608 · Answer

Did this recently myself.  The sawzall was taking forever; so I put anabrasive cutting blade on the circular saw.  Worked like a charm.FWIW,Joe F.

Art Todesco · Answer

I too, did this recently.  I needed to move a toilet flange a few inches to the right.  I could use an offset flange which gives you 2", however, the original flange and pipe was cast iron in a concrete floor.  I used a 3" abrasive wheel on a 6" extender mounted in a router.  I used a variac to keep the router running at a slower speed so it wouldn't bend the extension shaft due to small unbalances in the wheel and the extension. Taking is slowly, I was able to make a clean cut about 5" below the floor level.  It really didn't take all that long, maybe 10 or 15 minutes.  I was then able to mount the offset flange with appropriate iron to plastic conversion hardware.  Big job for only 2", but it was necessary for the remodel job.rb608 wrote:

Happy Homeowner · Answer

a Milwaukee "AXE" blade on a sawzall will cut through cast iron pipe like butter. it will even cut through a cast iron tub..............3 blades and 2 hours later.

but the chain is always the easiest and fastest way (providing you have the room to wrap the chain around the pipe).

jriegle · Answer

I did it with a hacksaw because I don't own an electric. It was a lot ofwork and it takes two blades for the two cuts I made to remove a section. Idon't recall if I was using the better grade blades or not.John

Fake name goes here · Answer

next time do the math:  1 sledgehammer = 20 minutes

nospam4me · Answer

My inuition is warniing me  about a potential fire or explosion fromthe sewer  gas ( methane &  H2S )  if using a high speed sparkgenerating abrasive  wheel on a circular saw or angle grinder .  Iwonder if it is something to worry about .

Art Todesco · Answer

Oops, I forgot to mention, when I did it, I made a "plug" from a bunch of plastic grocery bags.  I tied a string around the bundle and pushed it into the pipe.  Did the cutting, and then pulled out the "plug."  This also prevented me from smelling the sewer gas.     wrote:

Walt Conner · Answer

I just made 2 cuts thru 4" cast iron soil pipe and 2 thru 2". I used a 4" Makita side arm grinder on recommendation of a couple of plumbers. I was surprised at how quickly it went. Started with a used cheap wheel and pretty well used it up in the process. I tried a DeWalt Recip. saw with a new hacksaw blade first and it just made a shinny place on the pipe.

Walt Conner

Cutting cast iron sewer pipe ?

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