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Rmd and stt

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  • Rmd and stt

    I have been welding gtaw roots in many different alloys over the past 10 years.
    For er70,80,and 90 no purge. Works good( as long as the tube has no draft through it and it clean).
    The place I am working at now wants me to tryout there stt Lincoln machine(similar to millers RMD.)
    I have a really hard time believing that any stainless root beads can be put in without a back purge.
    Anytime molten stainless is exposed to oxygen it will sugar.
    I understand what miller and Lincoln say about there processes. It makes sense to me.
    If anyone has been using either of these processes could they post a pic of one of these open root beads.
    I still think these processes are snake oil.


  • #2
    Rmd and stt

    By snake oil I am referring to open roots beads without a backing gas.


    • #3
      Unfortunatly I dont have any pictures to prove it, but I have used the Miller Pipeworks Machine for the RMD Process on SCH 10 Stainless. It was done on a project for GE at a company called E.P.I.C. Systems. EPIC stands for Electronic Process Instrumentation Control. I worked there for about 6 months a couple years back. We put our pipe on pipe rollers and there was some kind of monitoring lead that had to be as close to the weld as possible to send info back to the computer on board the welder. It was constantly changing the temp and the wire speed. We would get out tacks in and then knife edge the tacks. When the roller would start it was two passes on a piece of 6in pipe and you were done. No purge and no quarting it out. 2 passes 360 degrees around the pipe. HOWEVER..... You will sugar it everytime if the RMD Lead is not attached and if the welder is not set perfect. It took us a week of trial and error with a Miller rep and their engineers to get it right. It was truly amazing though.


      • #4 ei=yfZ9UaauIM-vqQGK9IDYDA&usg=AFQjCNECuWxU637IPfKom4Rr_pmzmO7tyA


        • #5
          Actually quite the opposite, Millers RMD is almost but not quite simular to Lincolns STT. Stt was first to the process, Miller came around later and tried to simulate it. Cost them quite alot of coin so far, and almost have it right.

          Stick with the Stt process. Its tried and true!


          • #6
            Rmd and stt

            Thanks for the replies. I have still to see a shinny stainless root bead put in with either of these processes.
            A lot of the procedure and welding tests done around hear must meet certain corrosion resistance standards.
            All of the burnt or dark roots I have seen do not pass these tests.


            • #7
              Call Lincoln powerwave support. They will design and test program for you and email it to you. You download it into the machine, and presto your up and running


              • #8
                Rmd and stt

                I am going to give that a try tomorrow. I am still waiting on wire.



                • #9
                  I am working out in the field this week. There is a pile of spools welded with the stt process by a different shop.

                  Some of the spools don't fit so I have to cut the odd joint apart to revise the spool.
                  I have still yet to see a root that would meet any corrosion standards I have seen. And the whisker should have been a repair?
                  Is this what the root are supposed to look like?
                  Attached Files


                  • #10
                    No, those are really, really poor.

                    But I've seen a lot of sterling beads off STT (for a long time now), and heard of the same from the Miller equivilant.

                    These aren't "new" tech, they've been used for several years now across the globe with good success.


                    There's not a code in America that would even begin to buy those beads. I don't even think they'd fly on junk iron no code water pipe. But those process' will do a lot better work than that.
                    Last edited by JTMcC; 05-15-2013, 05:12 PM.


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