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Thread: Is methane dangerous when cutting cast iron?

  1. #1
    Programmer mbauer's Avatar
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    Default Is methane dangerous when cutting cast iron?

    Hi all! I found myself here by way of the John Bridge tile forum. I'm doing a bathroom renovation on a 1950's slab foundation in North Texas. I'm wanting to go back in with a Kerdi drain and waterproofing membrane. In preparation for it, I'm wanting to replace the existing trap with PVC. In the attached pics you can see what I have. I'm basically wanting to cut it right behind the bell with a carbide tip blade in my sawzall and transition with a Fernco connector into the PVC trap.

    So, as my question says, is methane a danger when cutting cast iron? I really don't want my first big plumbing project to end in disaster. Any other comments or suggestions are more than welcome.

    Thanks!

    Matt
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    Forum Admin, Expert Plumber Terry's Avatar
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    No worries about gas.
    The roof of your home has plumbing vents that prevent buildup of gas.

    Plumbers use couplings with a shielded couping to prevent the pipes from shifting like these


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    Programmer mbauer's Avatar
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    Thanks Terry. I'm going to have a few more questions about this project before everything is done. Could you change the title of the thread to "1950's Bathroom Renovation"? I guess you might want to move it to the renovation or shower forum as well. I'll keep all other related questions here.

    I thought I had seen a comment in the tile forum regarding the fernco connector. They mentioned that using a flexible connector gives a little more ability to adjust the final level of the Kerdi drain. With the drain slope, I'm assuming a more rigid connection would make my final level a little bit off. Maybe I'm splitting hairs and the final shower pan that I build will even it all out?

    Thanks!
    Last edited by mbauer; 01-12-2009 at 10:06 AM.

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    DIY Senior Member gardner's Avatar
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    Quote Originally Posted by mbauer View Post
    I'll keep all other related questions here.
    CX and the gang have you well trained, don't they?

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    Programmer mbauer's Avatar
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    Ha! Yea, I don't want to ruffle any feathers over here too.

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    Forum Admin, Expert Plumber Terry's Avatar
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    I kind of like the title.
    It's a good question.

    Before I became a plumber, somone was trying to scare me about removing the toilet in a bathroom.
    Nobody even notices all of those pipes coming up through the roof.

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    Programmer mbauer's Avatar
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    I'm just extra careful ( paranoid ) I suppose.

    Thanks for confirming. I'll stop by HD and try to get a shielded connector and see the difference in the ability to adjust my final floor level.

    On to the next question...

    It looks like their was a problem with the slab in this house at some point and the hot water line supplies were all abandoned. They took the hot water out of the water heater, directly up through the closet ceiling into the attic and branched it off from there. Flexible copper was used to run across the attic, down through the furr downs and fire blocks for the two baths. All hot connections were severed and tied to the flex copper coming from the attic instead of the original copper that was run under the slab.

    I want to fix this in the bathroom I'm renovating. For one reason, I'm removing the furr downs and the shower wall is changing a little. I need the copper to run straight down the wall. I would like to run rigid up the wall, through the top plate and into a 90 that is connected to the flex. I've heard that flex can't be used in walls but I wasn't sure about the attic.

    The first pic shows the shower hot water faucet. Notice the line was cut and the feed comes from above. The second pic shows the flex coming through the furr down. And finally, you can see that the flex comes down the wall and extends out close to the abandoned hot water. Notice that neither of the hot lines are capped.

    I was hoping to cap the hot water right above the entrance from the slab and extend the feed on the right up through the top plate. This would get everything back in order. So, my question is, can flexible copper be run through the attic and transitioned into rigid at the top plates?
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    Last edited by mbauer; 01-12-2009 at 02:57 PM.

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    Moderator & Master Plumber hj's Avatar
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    Default methane

    Since I have used oxy-acetylene torches on sewer lines without blowing anything up, or even having minor fire, you should not have any problem. There is almost no way you could get the concentration needed to become combustible unless you really tried to do it for insurance purposes.

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    DIY Member edlentz's Avatar
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    I am NOT a plumber but I tried to cut a 4" CI pipe with my Recip saw. It didn't work to good. I went to HD and got a diamond blade for my angle grinder and within 3 minutes that sucker was gone. Word to the wise WEAR a face shield whatever way you do it. Have you considered using PEX?

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    Master Plumber Dunbar Plumbing's Avatar
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    Quote Originally Posted by edlentz View Post
    I am NOT a plumber but I tried to cut a 4" CI pipe with my Recip saw. It didn't work to good. I went to HD and got a diamond blade for my angle grinder and within 3 minutes that sucker was gone. Word to the wise WEAR a face shield whatever way you do it. Have you considered using PEX?


    The blade, or the pipe?


    I get all my diamond blades from harbor freight and you can't kill them.


    One blade usually gets me 40-45 cuts...that's quite a few jobs. I cheat and cut copper and everything else with it when need be.


    If you wiped out a diamond blade from HD, take it back demanding money. They are not cheap there and I will never buy a blade from them. The cheap ones are 3 for 9.99
    Read what the end of this sentence means.

  11. #11
    DIY Senior Member Nate R's Avatar
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    Is this a good way to cut cast for a one time job, Rugged? (ie: I don't do it every day, so will an angle grinder work just fine for the one time in this house I need to cut cast?)

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    DIY Senior Member Nate R's Avatar
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    Quote Originally Posted by Terry View Post
    No worries about gas.
    The roof of your home has plumbing vents that prevent buildup of gas.

    Plumbers use couplings with a shielded couping to prevent the pipes from shifting like these

    So this doesn't happen:



    If you think this looks bad, imagine this on the horizontal, the waste has to hop up and over to get by.
    Nice picture.
    Terry
    Last edited by Terry; 01-14-2009 at 10:09 AM.

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    Quote Originally Posted by mbauer View Post
    I'm basically wanting to cut it right behind the bell with a carbide tip blade in my sawzall and transition with a Fernco connector into the PVC trap.
    I've given up cutting cast with saws. What a frustrating experience. If I need to cut cast, I use a soil pipe cutter. Google RIDGID Model 246 Soil Pipe Cutter and you can see the one I rent as needed - it's worth every penny and then some. Last 4" cast I had to cut took me about 3 minutes.

    If a guy can borrow one so much the better.


    RIDGID Model 246 Soil Pipe Cutter
    Last edited by Terry; 01-14-2009 at 10:14 AM.

  14. #14
    DIY Member edlentz's Avatar
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    Rugged--

    The pipe was gone. It was messy though! Really old CI I am married to a wonderful woman who has Chrons disease and believe me when I work on the waste systems in the house I need to get it back in service in a hurry!

    The blade I bought was crap. I also found other uses for the diamond blade for the angle grinder (like cutting tile). So the expense hasn't been just for that job.

  15. #15
    Master Plumber Dunbar Plumbing's Avatar
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    Wow,


    Sorry to hear of your bad experience with a diamond blade. I've been using them for years. It happened by accident in using one one day when I was in a jam and didn't have my wheeler chain snap cutter.


    It allows me to cut cast iron that is thinning at the top or bottom and not crush it all in when the chain clamps down on the pipe.


    I use it to cut tiled walls when doing shower faucet reworks, along with cutting copper piping whether it is water or dwv when you just have to save a pipe or can't get a cutter in there to spin around.

    Chrons disease is a rough one. Have you considered one of Terry's bidet toilet seats?

    It will pay itself off in the toilet paper you use at your home, I promise. Lot less clogs and cleaner feeling.


    I've had one since last year *BB-50* and even though it's the most economical, I am a bed of fresh daisies between my legs now, in my nooks n' crannies so to speak. I thought I'd let everyone know how clean I am.
    Read what the end of this sentence means.

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