Announcement

Collapse
No announcement yet.

7018 root

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 7018 root

    Are there situations where a 7018 root pass in pipe would be used, or where a code would call for it? Thanks for any input.

  • #2
    I don't have any pipe cert but I read in the Lincoln book that lo-hi rod can be used for the root if there is a backup ring in the pipe. BTW I have never seen a backup ring, so I don't know what it's supposed to look like. But it seems like it would cause flow restriction in the pipe. Maybe that's why I've never seen them use in oilfields or plants.

    Comment


    • #3
      Rob

      I'm no expert but I have never heard of using 7018 for root pass, also never saw or heard of a backing ring being used in process piping. I have saw backing rings used on sectional steel pipe pilings. These were being installed under/ very close to an exsisting pipe rack so a reg pile driver could not be uesd.. The pilings were like 12" pipe welded together every 6 to 8 ft. and drove on down. I do not recall what rod was used for these pilings.

      Comment


      • #4
        A long time ago when we used to build power plants in this country, backing rings were allowed in certain carbon steel (A53) piping (3" and larger) fitups that had been poorly prepped for butt welding. The prep usually consisted of a 37.5 degree bevel that was done in the field. These were thin rings, but wide enough to cover the root gap. Sometimes they had 3 small pins at 120 degrees apart to assist in getting the gap set properly and the pins would then be consumed during the welding process. Depending on the weld procedure, the root pass for this joint would be either TIGed using E70S2 or sometimes with 6010 stick, then welded out and capped with 7018. I don't recall if the root was ever run with 7018 on these but its possible. These type of joints/prep were eventually eliminated due to the ring causing corrosion/erosion problems inside the pipe. I can remember looking at the NDE x-rays done on these joints and one could easily see the backing ring in the x-ray. This procedure was eventually done away with and replaced with strictly an open butt, properly prepped 37.5 degree joint. The root was then TIGed with E70S2 only and no more 6010 stick root passes.
        Also, on some heavy wall, high pressure, high chrome content pipe joints, the procedure would sometimes call out using a "consumable insert". These joints were usually J-bevel prepped from the factory (in constrast to the 37.5 degree field bevel in the above) and the insert was placed in the gap at the root. The insert was consumed in the root pass which consisted of TIGing with either E80S2 or E90S2 depending upon the chrome content of the pipe and then stick welded out with either 8018 or 9018 accordingly. These welds were usually pre-heated prior to welding, interpass temperatures were monitored closely and then were stress-relieved after successful NDE x-ray.
        I think I'm giving my age away with this post.......
        Last edited by lgjhn; 07-16-2005, 11:27 AM.

        HH187
        Stars & Stripes BWE signed by Andy
        TA185TSW w/Miller Radiator 1
        DHC2000 & Victor O/A
        Parker Plasma 40

        Comment


        • #5
          I have ran root 7018 with backup on tests.
          http://www.facebook.com/cary.urka.urkafarms

          Comment


          • #6
            7018 root

            it can and is done...you can take a U69 pipe test with 7018 as a root..i think they refer to it as a "chrome" ticket

            Comment


            • #7
              Makes sense to me. With the backup ring, you can crank up the 7018, get good penetration and not burn thru as compared to using 6010 with no ring. Sound about right??
              ______________________________________
              Bakery Mechanic
              Licensed Electrician
              check out: www.mattesbydesign.com great for vinyl lettering
              "Why do i ask such difficult questions? 'Cause i know the answers to the easy one's!"
              *****Heineken*****
              -any questions or discussions on 'gout' are welcome-

              Comment


              • #8
                Been welding pipe for 20 + years and i have have never tested with a lo-hi root. Once took a plate test and we used 7018 as a root but without a backing bar.

                Comment


                • #9
                  Low Hydrogen Root Electrodes

                  Typically you wouldn't use a E7018 / E8018 etc in a OPEN root ( without backing ) because of the possibility of lack of fusion. By design cellulosic electrodes like E6010 / E7010 have a dig aggresively and relatively low depostion ( high depostion in a vertical down can get you in trouble ). By definition a E7018 has iron powder in the coating ( kinda like a Jet rod ) to increase deposition

                  The problem now and in the future is much of the new pipelines are made of much higher strength material. There are now more X80 ( 80ksi yield strength ! ) , X100 even X110 . In these steels, hydrogen in the weld deposit content is the kiss of death

                  The typical cellulosic electrodes like E6010 ( Fleetweld 5P+ ) have hydrogen contents of 30 to 50 ( units are ml / 100g of weld metal ) . A typical low hydrogen stick electrode is 2 to 8 .....waaaaay less ). These new pipeline steels require low hydrogen deposits

                  This problem has led to the development and more use of low hydrogen root electrodes. One such electrode is the Lincoln Pipeliner 16P ( which is a E7016....a E7018 without the iron powder to reduce the deposition ). These electrode are designed to run vertical up ( vertical down use can lead to lack of penetration )

                  This has also lead to more use of MIG ( yes even in the field ) in the root because MIG by nature a low hydrogen process and handles open root welding well.

                  BTW the reason for the backing ring is not to crank up the amps to ensure good penetration compared to an open root, but rather you can now open up the gap / feather the edge to ensure you get to the ID of the pipe. Obviously if you just open up the gap without a backing ring using a stick electrode you would end up with more metal inside the pipe than in the joint. This is where MIG type processes lends itself well to excessive gaps . Typically if you are using backup ring, you can open the gap equal to the diameter of the electrode and most often with a feathered edge

                  Conclusion ( finally ! ), low hydrogen electrodes are used with a backup ring . Without a backup ring, a typical low hydrogen like a E7018 is not a good idea. The exeption to this rule are the low hydrogens that are designed for open root pipe welding...which are much harder to find

                  Truth of the matter is most pipe that is welded you don't really need a low hydrogen electrode anyways so why not just use the proper electrode for root pass....a E6010

                  Comment


                  • #10
                    Thanks TRG-42.......
                    ______________________________________
                    Bakery Mechanic
                    Licensed Electrician
                    check out: www.mattesbydesign.com great for vinyl lettering
                    "Why do i ask such difficult questions? 'Cause i know the answers to the easy one's!"
                    *****Heineken*****
                    -any questions or discussions on 'gout' are welcome-

                    Comment


                    • #11
                      Back up ring for Root SMAW 7018 pipe

                      [IMG][dsc][/IMG] Here are back up rings for pipe. Smaw electrode 7018 for the root. If you need any more questions answered let me know i will help you. Hope this helps

                      Comment


                      • #12
                        I have done pipe tests where your root pass was done with 7018 and the pipe was held at a 45 degree angle when doing the test.

                        Comment


                        • #13
                          Jay, are the pins to keep gap between the pipes? Whats the rule for what the gap should be?
                          ______________________________________
                          Bakery Mechanic
                          Licensed Electrician
                          check out: www.mattesbydesign.com great for vinyl lettering
                          "Why do i ask such difficult questions? 'Cause i know the answers to the easy one's!"
                          *****Heineken*****
                          -any questions or discussions on 'gout' are welcome-

                          Comment


                          • #14
                            Not trying to answer for the guy but I was told 1/8". Pipe must be beveled down to 1/8" at a 37 degree angle, gapped 1/8" and welded. Thats what I taught to do is what I do when I practice.
                            Last edited by Ryan225; 07-17-2005, 04:29 PM.

                            Comment


                            • #15
                              For all sizes? Or is there a formula or chart?
                              ______________________________________
                              Bakery Mechanic
                              Licensed Electrician
                              check out: www.mattesbydesign.com great for vinyl lettering
                              "Why do i ask such difficult questions? 'Cause i know the answers to the easy one's!"
                              *****Heineken*****
                              -any questions or discussions on 'gout' are welcome-

                              Comment

                              Working...
                              X