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"welding" cast iron pipe

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  • "welding" cast iron pipe

    I want to make some adjustment feet to go under my Bridgeport mill base to allow me to level it up. I have a design in my head and it involves welding a nut inside a piece of some tubing.

    I have had other situations in the past where using a piece of common cast iron pipe would be easy (and cheap) and have been held back by the presumption that it cannot be welded, so thought I would ask about that here. I know there is a lot of experience here and that others may benefit from being able to make use of common materials like this, so thought I would ask here for the benefit of all.

    I know cast iron can be welded, but how about welding to steel? If so, what is the right material? I also know that dis-similar metals are most often joined with a brazing/soldering type process, but typical brazing seems so "weak" for a lot of things. Is my presumption that "welding" cast iron pipe to steel is a no-no or does it just take the right materials? I have an AC buzz box, a smallish 220v mig unit, and an Oxy-Acetylene torch as options.

    Paul Carpenter
    Mapleton, IL

  • #2
    Why not just use the standard "black iron pipe"? It is mild steel pipe that can be welded with normal process. Nothing special about it.
    Arbo & Thor (The Junkyard Dog)


    • #3
      So black iron pipe is not really iron? Maybe my assumptions were wrong about what I really have. I am talking about the stuff used for gas plumbing etc. It welds OK?

      Maybe this is a case where you should try something first

      Paul Carpenter
      Mapleton, IL


      • #4
        ironically, "black iron pipe" you buy now is actually caled...

        Black Steel Pipe.

        It welds ok. crap actually, I mean dont go build a racecar or heaven forbid an airplane with it, but For non critial applications not subject to repeated cyclic loading you will do fine welding it however you have available..


        • #5
          It welds fine. There's dozens of stock cars here using that for rollcages in the smaller diameters.
          Sched pipe...we weld that all the time.
          I have tools I don't even know I own...


          • #6
            ---ok, saturday night sportsman class racecar perhaps,

            -but don't build an airplane with it


            • #7
              Yeah-- I think the key there is "rollcage" and not frame In my case, the only load will be compression and not much per-pipe at that.

              It sounds like the tubing equivalent of rebar in that its actual content may be a bit variable while still meeting the need at hand.

              Now that I think of it, there is an obvious difference in the way black pipe cuts as compared to older cast iron sewer pipe I have dealt with...the latter did really seem to be cast iron.

              thanks to all for clarifying my bogus assumption....and politely at that!

              Paul Carpenter
              Mapleton, IL


              • #8
                There is nothing wrong with brazing cast iron to carbon steel. A good quality bronze brazing rod will make a join stronger than the base material. You can also use NiRod which is a nickle based welding rod but brazing is a better choice as the temperature is lower and there is less need to preheat the cast iron.

                However since you have black iron pipe it isn't cast at all.
                Free software for calculating bolt circles and similar: Click Here


                • #9
                  Evan is absolutely right about brazed joints being stronger than the base material being joined as long as the joint design is proper and the clearances are held very tight (i.e.. .001-.005). And as far as strength goes I would trust my life to a rollcage that was built with this material as long as it was properly designed and welded. Better to have a frame bend than a cage! Although strong enough for an airplane Ithink it might be a tad heavy. In other words yeah go ahead and use it,stick,mig or oxy acetylene you can't go wrong.
                  Home, down in the valley behind the Red Angus
                  Bad Decisions Make Good Stories​

                  Location: British Columbia


                  • #10
                    Weld it up

                    You are just worrying to much. The guys are right any of the methods you mentioned should work. I have literaly welded tons of it. Mosly 1 1/4 pipe to 3/8 mild steel plate, also lots of pipe to pipe for industrial railing. and pipe to mild steel ballisters by the hundred. of course we used mostly MIG.
                    Ad maiorem dei gloriam - Ad vitam paramus


                    • #11
                      Iron Pipe vs Steel Pipe

                      OK, so we now know you really have steel pipe. As the other guys have said, brazing is fine, especially if joining dissimilar materials, as in iron to steel, etc.
                      Steel pipe...weld it by what ever process you feel comfortable with, unless having to work to some code or specified proceedure. (Hopefully it's not just plumbing or gas piping...)
                      For roll cages, black pipe might be fine & the cheapest alternative. Did you compare prices with mech. tubing or struct. shapes...? Does bending save on buying any fittings in your application ?
                      As for aircraft fusalages...IIRC, there is/ was a guy in Alaska who built a plane out of EMT (conduit, think David Cofer special....?) and even sold plans. Photos were a maze of coped joints....


                      • #12
                        "welding" cast iron pipe

                        In the past, I've had to stick weld cast iron grates to steel frames.
                        Using 87% Nickel rod worked just fine.
                        A little pricey at about a dollar per 3/32" stick (in my area) but the results were worth it.


                        • #13
                          I've been welding for nearly 40 years, including black iron pipe (std black pipe ) and have never had a problem welding it. I'v even seen it used for builbing columns. For a mill support, not a problem.


                          • #14
                            I use black pipe all the time for frames and roll cages on go-karts and sprint cars. Now the go-kart frames are as skimpy as skimpy can get and still support me and never had a weld fail yet - there is one right between the rear axle and front axle but it hasn't even begun to crack (if it had i would no longer be tempting fate by riding it). I use 6013 rod on it and always had great results; bead sinks in nice and looks like a TIG weld when your done. I like welding it to be honest. Also cast iron pipe can be welded but its not usually recomended fro structural members. They make alot of seal welds (still holding up to 15,000 psi of steam) around cast iron pipe plugs and valves at the nuclear powerplant with no problems. All of the fittings for the pipe are cast iron but the pipe itself isn't as has already been mentioned.


                            • #15
                              15,000 PSI steam...?

                              Ooops, boiler guys jump in here. That would be way beyond even super-critical steam plant. For a nuke station, I doubt it....1500 psi, maybe.
                              Cast iron fittings & valves...nope, more like forged steel.
                              Piping welds would be to boiler & pressure vessel code, x-rayed, no doubt.
                              Even here in BC, pulp mill recovery & power boilers operate at 600-700 psig and superheated steam. Burrard Thermal plant is 1100 psi and some 1000 F (superheated).
                              One of the first super-critical plants was in New York, I believe the old Philo plant...highest net thermal efficiency for years....
                              Just had to mention that....