Cutting cast iron pipe - PeachParts Mercedes-Benz Forum

kerry · #1 05-27-2010, 09:20 PM

Got an old 2" cast iron drain pipe that has cracked lengthwise about 2'. I've temporary repaired it with plumber's epoxy but I will eventually have to cut out the section and replace with PVC. I tried cutting it with my reciprocating saw today but it just shined up the surface. What's the best way to cut it? It's in the basement and up near the ceiling so I can't get a full turn on a pipe cutter. I'm also a little concerned about about crushing the pipe with a cutter. I need to leave stubs intact on either end so I can use rubber fittings to join the PVC to the cast. There's only about 5" of uncracked pipe at one end. Ideas?

strelnik · #2 05-27-2010, 09:23 PM

Quote:

Originally Posted by kerry

Got an old 2" cast iron drain pipe that has cracked lengthwise about 2'. I've temporary repaired it with plumber's epoxy but I will eventually have to cut out the section and replace with PVC. I tried cutting it with my reciprocating saw today but it just shined up the surface. What's the best way to cut it? It's in the basement and up near the ceiling so I can't get a full turn on a pipe cutter. I'm also a little concerned about about crushing the pipe with a cutter. I need to leave stubs intact on either end so I can use rubber fittings to join the PVC to the cast. There's only about 5" of uncracked pipe at one end. Ideas?

If a sawzall-type saw and good blade can't do it, consider drawing a ring around the area where you would cut, get a face shield and use a small diamond wheel on a die grinder, at speeds below 2000 rpm.

Kyle Blackmore · #3 05-27-2010, 09:29 PM

Hi Kerry, plumbers usually cut it with a chain cutter, it snaps it. Unfortunately with the crack that would probably shatter it. Can you reach it with a grinder with a cut off disc on it? I work for a civil contractor, we have different blades on gas powered saws to cut different pipe materials, they're friction blades. You might burn through a couple of small blades, and have a shower of sparks too. Good luck.

Chad300tdt · #4 05-27-2010, 09:37 PM

I was going to suggest a cut-off wheel too.

tonkovich · #5 05-27-2010, 09:58 PM

i just cut a 2" cast iron drain pipe last month using the "sawzall". might want to check your blades, get some new ones of the appropriate type? the pipe was an original from the 20's i think - is that what you're dealing with ?

kerry · #6 05-27-2010, 09:59 PM

Guy on here swears by a diamond blade on an angle grinder. I'll probably give that a try.

http://www.ridgidforum.com/forum/showthread.php?t=15823

kerry · #7 05-27-2010, 10:02 PM

Quote:

Originally Posted by tonkovich

i just cut a 2" cast iron drain pipe last month using the "sawzall". might want to check your blades, get some new ones of the appropriate type? the pipe was an original from the 20's i think - is that what you're dealing with ?

Probably from 1890. I was using a hacksaw blade. I had a grit blade for cast iron but it was a long one and it was hitting objects in the vicinity so I couldn't use it. If the diamond blade on an angle grinder won't work, I'll try a short grit blade on the sawzall.

tonkovich · #8 05-27-2010, 10:03 PM

Quote:

Originally Posted by kerry

Guy on here swears by a diamond blade on an angle grinder. I'll probably give that a try.

http://www.ridgidforum.com/forum/showthread.php?t=15823

hey, whatever works. i'm usually just a painter, but duty called. the hardest part is breaking the surface. (the noise and dust and heat are also not very pleasant either.)

chilcutt · #9 05-27-2010, 10:04 PM

2 in pipe huh...are you sure it isnt galvanized??.I have never ...not been able to cut galvanized pipe with a saw-zall..w/metal blade. Even if it is cast-iron...there are cast iron blades for the saw-zall.When you go to install the rubber firmco's...using a little vaseline helps to manuver them in place.

SwampYankee · #10 05-27-2010, 10:29 PM

We've been cutting out all of the steel and cast iron steam and water pipes from our old steam heating system and after going through two 5-packs of Sawzall Metal cutting blades (which did actually work fairly well) we discovered the Sawzall Tungsten Carbide blades specifically for cast iron. We were cutting through the cast iron traps just to see what they looked like inside. Amazon has a pretty good price on them, our local hardware store had them for $25/3 pack.

Sawzall Tungsten Carbide Blades

Sparks and flying cast iron bits in close quarters would make me a tad nervous.

TnBob · #11 05-27-2010, 11:09 PM

Down there it would sure be nice to have a fire bottle with you prior to firing up any grinder.

kerry · #12 05-27-2010, 11:10 PM

Not to mention a diamond blade spinning at 13k rpm's a foot or so from my head.

A 9" blade won't work in the close quarters. I had a long grit blade for cutting cast iron which I had used on a 4" pipe before but it was hitting the joists. I might be able to find a shorter version.

When I bought my house it had a hot water radiator system which had been left full of water at 25 degrees below zero. There were lots of broken fittings and radiators. It had black iron threaded pipes but cast iron fittings. I found that the easiest way to get sections out for repair was to use a chisel and sledge on the cast iron joints. Usually I could bust a joint in no more than three blows even laying on my back and hitting above my head in the crawl space. I'd then replace the cast fittings and put a union in the pipe run.

t walgamuth · #13 05-27-2010, 11:22 PM

Quote:

Originally Posted by Kyle Blackmore

Hi Kerry, plumbers usually cut it with a chain cutter, it snaps it. Unfortunately with the crack that would probably shatter it. Can you reach it with a grinder with a cut off disc on it? I work for a civil contractor, we have different blades on gas powered saws to cut different pipe materials, they're friction blades. You might burn through a couple of small blades, and have a shower of sparks too. Good luck.

I have a chain cutter. If the pipe is intact where you want it cut I would try that. Whatever you try it could shatter anyway and the chain cutters are pretty clean.

I am not sure how well it would work on 2" pipe (just noticed).

Chas H · #14 05-28-2010, 01:03 AM

Quote:

Originally Posted by kerry

Not to mention a diamond blade spinning at 13k rpm's a foot or so from my head.

A 9" blade won't work in the close quarters. I had a long grit blade for cutting cast iron which I had used on a 4" pipe before but it was hitting the joists. I might be able to find a shorter version.
.

Use the diamond blade in an angle grinder to cut the sawzall blade to the proper length. The sawzall blades made for cast iron pipe work quite well.

SwampYankee · #15 05-28-2010, 08:49 AM

Quote:

Originally Posted by Chas H

Use the diamond blade in an angle grinder to cut the sawzall blade to the proper length. The sawzall blades made for cast iron pipe work quite well.

While this might be a stupid question it's not meant to be.

Would the resulting heat from cutting the blade have any effect on it (i.e. making it more brittle)? I've got a couple applications at home where a shorter blade would make things a lot easier and I'll have an extra blade when we're finally done.