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Can you unscrew 100 year old pipe? Welding?

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Chuck_17
Chuck_17 Member Posts: 145
This is a curiosity question (I am not a fitter). Lets say you have a 100 year old steam system and need to make a connection to a steam main. How?
1. Unscrew at the closest fittings and replace the length of pipe with the tee fitting in it?
2. Cut the pipe and weld in the (tee) fitting?
3. Weld on a weld-o-let (spelling?) and cut a hole?
4. Other?

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  • ChrisJ
    ChrisJ Member Posts: 15,784
    edited February 2015
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    I'm a homeowner and only do this as a hobby.

    Depends on the situation but it's usually easiest to cut a pipe and cave it in so you can unscrew it from a fitting. If you cut it off around 1/2" from the fitting you can then use a cold chisel to fold it in on it self and it will unscrew.

    Another option is cutting and then splitting the fitting, but I found this more difficult. Some guys shatter cast iron fittings using two large hammers but I've been too scared to attempt it. To split the fitting I used a grinder and stopped just before I got to threads and then a cold chisel and hammer to crack it.

    Here are pictures of the last one I did. I never took pictures of caving a pipe in to save the fitting, but as I said I found it easier.

    A third option would be cutting a pipe and threading it in place if you have a portable threader.

    Now all of that said, yes, you will need to replace the length of pipe and install a tee and likely a union depending on where you are in the main.










    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Abracadabra
    Abracadabra Member Posts: 1,948
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    Chuck said:

    This is a curiosity question (I am not a fitter). Lets say you have a 100 year old steam system and need to make a connection to a steam main. How?
    1. Unscrew at the closest fittings and replace the length of pipe with the tee fitting in it?
    2. Cut the pipe and weld in the (tee) fitting?
    3. Weld on a weld-o-let (spelling?) and cut a hole?
    4. Other?

    For me it would depend on what size pipe we are talking about. Both what the existing main is and what the takeoff will be.

    Even though I'm able to thread up to 6" pipe, if it's a >2" main I'll probably cut and weld in a fitting. Anything smaller and I'd probably cut and thread pipe, unless of course the main won't move to let me screw in fittings and a union, then I'll weld that too.
  • Tinman
    Tinman Member Posts: 2,808
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    Like Chris said, give the hub of a cast iron fitting a few really good whacks with as big a hammer as you can swing and its toast.
    Steve Minnich
  • Tinman
    Tinman Member Posts: 2,808
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    Controlled whacks to be more exact. Surgical, would be even better.
    Steve Minnich
    jonny88
  • jonny88
    jonny88 Member Posts: 1,139
    edited February 2015
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    Agree with Chris .if you have no play to install Union on reassembly I like to use 2 sets of flanges .but if your in a bad mood and need to release some agression get a pair of wrenches.Stephen I have yet to see a surgical whack.Usually the words motherf..... or other nice words are used.I hope surgeons dont use the same language as they work on us.