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Welding Cast Iron to Steel

Jimbo_5
Jimbo_5 Member Posts: 218
Have to weld 10" steel pipe to old 10" cast iron tee.  Just checking for suggestions on the best welding rods to use.  Any ideas?

Comments

  • Rod
    Rod Posts: 2,067
    Welding Cast Iron

    Successfully welding cast iron to steel isn't what you would call easy. I guess that threading a steel nipple into the tee isn't practical? It's much easier to weld steel to steel.  If this is a low pressure application I think even with screwed up leaky threads it would be better to go with threaded piece of steel pipe and use epoxy on the joint to seal it.

    welding- Be sure to use someone who has experience with doing welding like this otherwise you maybe opening a BIG can of worms.  Ideally you would preheat the cast iron part but it doesn't seem like this is a situation where you can do that so keeping the heat low and peening the weld may be your only option. Here's a link that explains it better than I could. http://www.weldingtipsandtricks.com/welding-cast-iron.html

    Good luck! Sometimes it works and other times it don't.

    - Rod
  • icesailor
    icesailor Member Posts: 7,265
    CI To Steel:

    Brazing with brass rod and the proper flux would be something I would try first. Welding CI is an art form.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I sent the two previous messages to my friend,

    a trained and certified welder. She can weld from 1/4" up to 4" including aluminum, stainless, high pressure boilers, ships, ..., and has taught welding for several years.  Her answer went like this:



    "Not enough information here for a really good answer.

    "True that, when working w/cast iron, you have to preheat it (the suggestion it can be done some other way is BS) ..but my first thought was.. couldn't he remove the offending part before the bound threads and simply hard solder the new part there???"



    I do not have the answer to her question, but my prejudice is against soldering of any kind in a steam system. I do not know what she means by hard solder; surely not any lead-tin alloy. But does she mean silver solder, or brass, or what? I suppose I could ask her.
  • Jimbo_5
    Jimbo_5 Member Posts: 218
    Not My Choice

    I have no choice in the matter.  We were hired to do a job begone by others and bid by yet another.  The CI tee in question had a plug from hell at the end and a 45 coming off the bull.  Here is a photo of it just prior to removal of the reminder of the plug.  Now we need to weld on a 10" elbow.  Any ideas?
  • icesailor
    icesailor Member Posts: 7,265
    Welding, Brazing, Soldering

    I think that the welder is speaking of using high temperature brazing like brass rod that is melting at over 2000 degrees.

    A lot of folks call "silver solder", by a discription when in fact, it is silver brazing with high temperatures. High enough so that you need oxygen with the acetylene. It differs from "silver soldering" with silver bearing solder that is lead free and you heat with a air/acetylene torch. Silver brazing can't be done with air/acetylene but can be done with oxy/acetylene.

    I once had a blind cleanout plug on a grease trap in a pit that needed to come out. I made a tool to get it out. A 1 1/4" plug square head fit the blind plug. I took the 1 1/4" plug, scewed it into an 1 1/4" coupling and screwed it into a scrap threaded piece of 1 1/4" pipe. I brass brazed the whole works together, stuck it in the blind plug, and with a 2' pipe wrench, convinced the plug to come out. It did. The plug is cast iron BTW.

    Like my home made nipple holders that I made so I can make nipples if I don't have the right size. And my die stock that can make crooked threads so I can get a pipe into true. Why would you make a crooked thread I am asked? Ever come out of the top of a boiler and it isn't trapped true and the riser pipe is not plumb? Crooked thread. Gets you back to plumb.
  • TonyS
    TonyS Member Posts: 849
    Have you removed the threads

    from the T ? Cant really see from the picture. After you removed the rest of that plug were the threads stiil there or are we looking to butt weld a 90 onto whats left of a T?
  • Jimbo_5
    Jimbo_5 Member Posts: 218
    Still There

    The ring where the threads are is still there.  We have hammered, cut with a grinder, burned with a cutting torch and the threads refuse to budge.  So it appears we will be welding right over them.  Suggestions?
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    At this point I'd cut deeper

    That is if the threads are still intact in the tee. You might cut a bit of the inner threads but a good sealant will take up the mis-cut . I accidentally cut into a 6 inch tee once and it held .



    Cut one spot deep then hit the piece with a chisel . You can use pump pliers to spin the rest out at that point . Good luck Jimbo , looks like a doozie !
  • TonyS
    TonyS Member Posts: 849
    Sometimes on smaller fittings

    when I am trying to remove a nipple from a 2-1/2 or 3 inch cast fitting to no avail, I will cut the nipple off flush with the face of the fitting and then go in with a oxyacetylene cutting tip. Cutting out a strip of the nipple. Little or no damage to the threads occur because the gap between the interfacing threads stops the burning action. After I remove a small strip I chisel the nipple in, decreasing its diameter and then pull it out.

    If I booger the threads a little I wrap a little plumbers wicking on the threads to get a good seal.

    I do not use a plasma cutter in these cases because the burn would not stop at the thread interface.

    If Im looking at your picture right, it looks like you just need to burn a small slice of that plug out and you could break the rest inward to get to your thread. Even if you damage the thread, a little wicking or peening some lead wool would take up the leak and that would leave you with the ability to install a nipple.

    Welding cast iron is a real trick and would require heating the entire T in an oven and obviously thats not possible. even brazing requires red hot heat and that alone could easily break that fitting. I would rather deal with a bad thread than have to replace that T. Good Luck Jimbo
  • icesailor
    icesailor Member Posts: 7,265
    Removing Plug:

    Ron & Others,

    Cut carefully in two spots at the point where it is easiest to hit it with a chisel. Cut the two spots as wide as the chisel. I always use a beater screw driver but I haven't done a 10" plug lately. Make another cut 120 degrees from both sides of the dual cut. Cut ALL the way through on a level plane to the top of the threads. You are cutting parallel to the run of the fitting. Use a sawzall blade and cut so you can tell when you get to the top of the female threads, the fitting. I find that a 14 tooth works best on cast iron. It helps if you have someone to watch to see if you are cutting parallel to the threads. When you have the blade tipped so you are cutting 10 or 15 degrees from parallel, close the angle so you are cutting the back of the fitting/plug. That's where the extra eye comes in. It's hard to tell. I know. I do it all the time. Because I always work alone, I must use a short level and a combination square. Try to get to the top of the threads along the whole plane. Then, drive the piece out with the chisel. The plug remains are under tremendous compression. Removing that piece will release that compression and you can spin it out with a pair of pliers. The other cuts help relieve the pressure. All those cuts in the pictures don't have cuts that are effective. Three cuts done properly would have done it. Four cuts is the most needed. The more cuts, the easier to get the pieces out.

    Cast Iron fittings are the easiest to get out. Steel pipes and nipples are the hardest. The Cast Iron cracks easier. Steel bends.

    If you do it properly, it won't take a hard hit to break out the piece. If you hit it hard and it doesn't break, you probably haven't cut enough. Cut more. If you prepare and make all the cuts before you try to get the small piece out, you may have released the compression.

    If you are uncomfortable, go get a fitting and do a dry run by trying it. It works. Don't worry about scratching the threads. Get a roll of 3/4" Blue Monster Teflon tape and wind many turns. I don't know what you use for a thread lubricant/pipe dope but use that too. I've put dope on the male threads, taped it, doped it and doped the female threads. Screwed it all together and had no leaks. I usually just do the tape and dope. The extreme was just a precaution. 
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314
    Want me to come down?

    Seriously you pay travel and a days time I will get it out. I could do it on this coming Saturday.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314
    That plug sure looks

    familiar doesn't it guys? I think I saw this one a few posts back.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
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