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  • aluminum fuel tank - best welding practice

    Good morning,

    Looking for suggestions or bookmarks for best welding practices of aluminum fuel tank.

    GTAW
    5052 0.125" ALUMINUM
    Approximate dimensions of 48" x 48" x 12"
    I am making two units for diesel tank replacement for a sailboat.

    Cuts and fits are tight, I am looking for beat practices on welding methods - back stepping my welds? Suggested bead length, if any?

    I admit I am much stronger with carbon and stainless, but have limited time running aluminum.

    Thanks.
    Stainless process piping - welder & fitter

    Miller Dynasty 280DX
    Jet band saw
    Dewalt chop saw
    Assorted IR air tools and Metabos

  • #2
    I would use a 3/32 filler rod, bend up as much as possible with a press brake.

    Just go through and tack it up and then weld it up.

    The biggest thing to do is corner to corner welds so you can get a nice thick weld.

    what I mean is dont overlap the plate onto the other, bring your edges together and put the tack when the first meet.

    Comment


    • #3
      Originally posted by CODE4 View Post
      Good morning,

      Looking for suggestions or bookmarks for best welding practices of aluminum fuel tank.

      GTAW
      5052 0.125" ALUMINUM
      Approximate dimensions of 48" x 48" x 12"
      I am making two units for diesel tank replacement for a sailboat.

      Cuts and fits are tight, I am looking for beat practices on welding methods - back stepping my welds? Suggested bead length, if any?

      I admit I am much stronger with carbon and stainless, but have limited time running aluminum.

      Thanks.
      More questions than answers...

      How many baffles and confifuration..?? "H" shape baffle..?

      Rounded edge or sharp..?? ( Radius bent corners spread the stresses... sharp ones concentrate stresses)

      Strap mounts or tabs??

      Mounting place.. flat and supported or will it support itself over an open area..??

      lets see... 12 Cubic foot = 90 gallons..(89.76623376 US Fluid Gallons)

      90 X 7.15 Lbs Per Gal = 643 Lbs... fuel weight..

      and SEVERAL times that in a pounding following sea during a storm...

      .. things to consider

      How about some pics of the proposed mounting place..?? and old tank..??
      Last edited by H80N; 03-22-2015, 06:53 AM.
      .

      *******************************************
      The more you know, The better you know, How little you know

      “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

      Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

      My Blue Stuff:
      Dynasty 350DX Tigrunner
      Dynasty 200DX
      Millermatic 350P w/25ft Alumapro & 30A
      Millermatic 200

      TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

      Comment


      • #4
        Definitely more questions than answers

        No problem. The owner is installing them in his older 45 ft sailboat. They are going to be fully fiberglassed into the floor, replacing the original rotted out carbon steel tanks.

        They will be supported on 48" x 48" side, laying flat.

        Baffles will be installed before the last panel is welded on, H shape is pretty accurate.

        I understand what you mean regarding butting the edges up on the corner seams, to make an outside corner weld vs a modified Tee joint with weaker weld joint.
        Stainless process piping - welder & fitter

        Miller Dynasty 280DX
        Jet band saw
        Dewalt chop saw
        Assorted IR air tools and Metabos

        Comment


        • #5
          Originally posted by CODE4 View Post
          Definitely more questions than answers

          No problem. The owner is installing them in his older 45 ft sailboat. They are going to be fully fiberglassed into the floor, replacing the original rotted out carbon steel tanks.

          They will be supported on 48" x 48" side, laying flat.

          Baffles will be installed before the last panel is welded on, H shape is pretty accurate.

          I understand what you mean regarding butting the edges up on the corner seams, to make an outside corner weld vs a modified Tee joint with weaker weld joint.
          I had a 41ft Morgan 416 Out Island and she could pound pretty hard in a blow... round bottom... fin keelers on the other hand can really be really brutal...

          type and make boat..?? Columbia 45 maybbe...??
          .

          *******************************************
          The more you know, The better you know, How little you know

          “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

          Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

          My Blue Stuff:
          Dynasty 350DX Tigrunner
          Dynasty 200DX
          Millermatic 350P w/25ft Alumapro & 30A
          Millermatic 200

          TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

          Comment


          • #6
            I am not boat savvy by any means, and I have not see the actual boat either. He cut the tanks out and brought them to his garage where I measured out the existing ones.

            Next time I meet him I will see what I can get for boat specs.

            I will be sure to snap some pictures of the fit up, before and after pictures.

            The tanks are going to get several NPT bungs, fill ports, and sending unit flanges cut and welded in as well.
            Stainless process piping - welder & fitter

            Miller Dynasty 280DX
            Jet band saw
            Dewalt chop saw
            Assorted IR air tools and Metabos

            Comment


            • #7
              Originally posted by CODE4 View Post
              I am not boat savvy by any means, and I have not see the actual boat either. He cut the tanks out and brought them to his garage where I measured out the existing ones.

              Next time I meet him I will see what I can get for boat specs.

              I will be sure to snap some pictures of the fit up, before and after pictures.

              The tanks are going to get several NPT bungs, fill ports, and sending unit flanges cut and welded in as well.
              May sound like an odd point.... but..

              make sure the owner grounds the metal of the tanks to the bonding or grounding point in the boat...
              Basicly running a metal strap or wire from the tanks to the boat's common ground... otherwise salt water electrolytic corrosion can damage them in pretty short order....
              .

              *******************************************
              The more you know, The better you know, How little you know

              “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

              Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

              My Blue Stuff:
              Dynasty 350DX Tigrunner
              Dynasty 200DX
              Millermatic 350P w/25ft Alumapro & 30A
              Millermatic 200

              TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

              Comment


              • #8
                process and welder....

                Originally posted by CODE4 View Post
                Good morning,

                Looking for suggestions or bookmarks for best welding practices of aluminum fuel tank.

                GTAW
                5052 0.125" ALUMINUM
                Approximate dimensions of 48" x 48" x 12"
                I am making two units for diesel tank replacement for a sailboat.

                Cuts and fits are tight, I am looking for beat practices on welding methods - back stepping my welds? Suggested bead length, if any?

                I admit I am much stronger with carbon and stainless, but have limited time running aluminum.

                Thanks.
                What kind of welders do u have? If it were me, i would pulse weld the unit together, with my optima and xmt. Also everything would be press braked, where it could be. When i make fuel tanks i overlap the seams..ie think of to L's being sligthly overlapped. Same with the ends, much easier then trying to fill the end gap, but if you have a nice tig setup ie dynasty thats not much of a probelm. Also on the end caps i set inside the seam by 1/8 or so. Also besure to pressure test the tanks. Fyi besure to reinforce the tanks, ie use a baffle in the center with the corners cut off weld it in before the sides of course.
                Kevin
                Lincoln ranger 305g x2
                Ln25
                Miller spectrum 625
                Miller 30a spoolgun
                Wc115a
                Lincoln 210mp
                F550 imt service truck

                Comment


                • #9
                  Originally posted by CODE4 View Post
                  Good morning,

                  Looking for suggestions or bookmarks for best welding practices of aluminum fuel tank.

                  GTAW
                  5052 0.125" ALUMINUM
                  Approximate dimensions of 48" x 48" x 12"
                  I am making two units for diesel tank replacement for a sailboat.

                  Cuts and fits are tight, I am looking for beat practices on welding methods - back stepping my welds? Suggested bead length, if any?

                  I admit I am much stronger with carbon and stainless, but have limited time running aluminum.

                  Thanks.
                  Why don't you make an exact replacement tank that won't rust out of stainless steel? By using aluminum you are changing the design of the tank. Hence, you are taking unnecessary risk. For instance, how do you know if the aluminum tank can handle the slosh loads on a sailboat?

                  Comment


                  • #10
                    Originally posted by Tryagn5 View Post
                    What kind of welders do u have? If it were me, i would pulse weld the unit together, with my optima and xmt. Also everything would be press braked, where it could be. When i make fuel tanks i overlap the seams..ie think of to L's being sligthly overlapped. Same with the ends, much easier then trying to fill the end gap, but if you have a nice tig setup ie dynasty thats not much of a probelm. Also on the end caps i set inside the seam by 1/8 or so. Also besure to pressure test the tanks. Fyi besure to reinforce the tanks, ie use a baffle in the center with the corners cut off weld it in before the sides of course.
                    Kevin
                    Kevin,

                    I have a Dynasty 280DX on hand - I was under the impression that an outside corner joint to fill would yield a stronger weldment than a butted L Shape fit?

                    I am planning on pressure testing the tanks as well as baffling them.


                    Originally posted by Arizona Joe View Post
                    Why don't you make an exact replacement tank that won't rust out of stainless steel? By using aluminum you are changing the design of the tank. Hence, you are taking unnecessary risk. For instance, how do you know if the aluminum tank can handle the slosh loads on a sailboat?
                    Arizona Joe,

                    I suggested stainless to the guy, Russ, however he wanted AL - his call. I brought up several points to consider including the strength of the assembly, etc.
                    Stainless process piping - welder & fitter

                    Miller Dynasty 280DX
                    Jet band saw
                    Dewalt chop saw
                    Assorted IR air tools and Metabos

                    Comment


                    • #11
                      Originally posted by CODE4 View Post
                      Kevin,

                      I have a Dynasty 280DX on hand - I was under the impression that an outside corner joint to fill would yield a stronger weldment than a butted L Shape fit?

                      I am planning on pressure testing the tanks as well as baffling them.




                      Arizona Joe,

                      I suggested stainless to the guy, Russ, however he wanted AL - his call. I brought up several points to consider including the strength of the assembly, etc.
                      Yes a corner joint is stronger, but if doing it with a spoolgun or push pull gun it is difficult even set on pulse. Since you have a dynasty should be rather easy, but will be a long weld. As long as there is a baffle in the tank it will be fine.
                      Kevin
                      Lincoln ranger 305g x2
                      Ln25
                      Miller spectrum 625
                      Miller 30a spoolgun
                      Wc115a
                      Lincoln 210mp
                      F550 imt service truck

                      Comment


                      • #12
                        Originally posted by CODE4 View Post
                        Kevin,

                        I have a Dynasty 280DX on hand - I was under the impression that an outside corner joint to fill would yield a stronger weldment than a butted L Shape fit?

                        I am planning on pressure testing the tanks as well as baffling them.
                        .
                        That Dyn 280 is plenty enough machine for the job...
                        But then again... I am a bit prejudiced... I prefer TIG when I can..

                        If it were me I would go with the rounded fuel tank corners... they distribute the stresses instead of concentrating them...

                        Be careful pressure testing... it does not take much pressure to baloon a tank like that and destroy it...(lots of surface area there) I would be very conservative... like ONE HALF PSI or LESS..and go over the seams with bubble water.. and look for bubbles...

                        just my 2cents worth...
                        .

                        *******************************************
                        The more you know, The better you know, How little you know

                        “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                        Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                        My Blue Stuff:
                        Dynasty 350DX Tigrunner
                        Dynasty 200DX
                        Millermatic 350P w/25ft Alumapro & 30A
                        Millermatic 200

                        TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

                        Comment


                        • #13
                          I've got to think the odds of a porous weld are reduced with a good TIG weld. I wouldn't have the nerve to try with any other process.
                          Dynasty 280DX
                          Bobcat 250
                          MM252
                          Spool gun
                          Twentieth Century 295
                          Twentieth Century 295 AC
                          Marquette spot welder
                          Smith torches

                          Comment


                          • #14
                            Don't forget

                            Comment


                            • #15
                              The father of an OLD girlfriend spent his life with milk trucks. He would always volunteer for the 350 mile middle of the night round trips to avoid daytime local farm pick ups. A full or empty truck doesn't slosh. He described the air ride suspensions as REALLY unstable. I'd be surprised if 90 gallon tanks would be a big problem. I'd still keep the holes in baffles small, maybe only at the bottom. Two per tank wouldn't be a bad thing.
                              Dynasty 280DX
                              Bobcat 250
                              MM252
                              Spool gun
                              Twentieth Century 295
                              Twentieth Century 295 AC
                              Marquette spot welder
                              Smith torches

                              Comment

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