Plate Welding 101 with Prof. Jamie
**I APOLOGIZE FOR THE LATENESS OF THIS POST AND FOR IT’S INCOMPLETION, HOWEVER YOU WILL GET THE GIST OF IT BASED ON WHAT I HAVE
Also: Please note that there are other processes of plate welding; this is just how we are taught in class.
- Get your material - For plate welding, we use plain carbon steel such as this, but much thinner. You get one piece that measures 60” x 8”, along with five backing strips that measure about 10” x 1.5”.
- Cut your plates - From the large 60” x 8” sheet, you must cut ten 6” plates by hand using an oxy acetylene cutting torch—the kit looks similar to this:
[the shorter tank is your fuel gas, the acetylene, and the taller tank is your oxygen; the red hose always connects your fuel, and the green hose is always the oxygen]
You can check out this video to see the proper setup and operation of a cutting torch (skip to 4:33 for torch lighting and adjustments; skip to 5:44 for the cutting). - Grind the edges - Once all ten plates are cut, and after you’ve shut down your cutting torch system and cleaned up and put everything away, you are ready to grind the edges of your plates. The purpose of this step is to prep your plates for the beveling step. This is a simple process, but it’s time consuming due to the forty edges you must grind. It can also get very tiring, as the grinders we use in class are 15lb DeWalts.
- Bevel - Now you must cut one beveled edge on each plate. We do so with a track cutting torch so as to get a precise angle measurement and a perfectly straight cut. Setting up the torch is exactly the same for the hand-cutting I mentioned in step two, and you may see the operation of a VICTOR table cutter here (skip to 1:33 for cutting action). The only difference from that video to what we do in class is the angle of the torch—you must adjust the torch to 22° in order to create the desired bevel for your weld. The purpose of the bevel will be to create a weld valley that measures 1/4” at the bottom, and 9/16” at the top. We’ll get to the weld valley in step six.
- Grind again - Back out to the grinders to smooth out those edges some more. Clean, flat edges make for stronger wire penetration, ultimately creating a stronger bond when you weld.
- Measure & tack - This is my least favorite step out of everything combined. You must tack up your materials so that the beveled edges on two of your plates sit a certain distance apart on top of your backing strip. I get terribly frustrated because I can never get the measurements JUST RIGHT simply because I’m human and error occurs when you inadvertently grind off too much of an edge or grind an edge at a wrong angle—this effects both how the plates lay on the backing strip as well as how far apart the bottom will sit in relation from the top. I know that sounds very confusing, but if you were here right now with me and I were to explain it to you, you’d understand perfectly. Instead, here’s a lame diagram I drew up to show you:
As I stated in step four: The top of your weld valley should measure 9/16”, and the bottom should be 1/4”. When your measurements are laid out, you may tack up. - Welding - Ahhh finally, what you’ve all been waiting for: the actual welding. It takes an awful lot before you can actually start, doesn’t it? Anyway, the vertical position requires three passes: one root, one fill, and one cap.
Because your work (the plates) is standing upright (so that the weld valley is positioned vertically), you are working against gravity and must push the weld upward. You must use a zig-zag motion from side to side, making sure to push the electrode (your gun’s wire) right into the valley corners to create the needed penetration. For the root pass, you must hold your gun at each corner for a two second count. For the fill pass, it is a two and a half second count; and for the cap, it’s back to a two second count. This, my friends, is welding. - Cool time & inspection - Please be aware that after each pass you make, no matter what it is you’re welding, you must cool your work down. Failure to do so will cause your work to overheat and fuse incorrectly. Now, since it’s vertical we’re talking about, the passes must air-cool—normally you can just dunk your work in a water trough, but for some reason vertical and overhead must air-cool. These in-between cooling times are when you want the instructor to check your work. If your pass is okay-ed, you may continue on, business as usual. If your pass is flawed, go dunk your work and proceed to the next pass, adjusting your technique for improvement.
- Can you coupon? - Given that your passes all turned out okay, you are now ready to make coupons for your bend tests.
- melt off backing strip
- cut sides off plates so there are 3” of material on either side of weld
- cut two 2” strips for testing—the “coupons”
- determine which will be the cap and which will be the root and stamp accordingly
- grind edges
- grind welds & backs
- buff with flapper wheel
- round out edges
- you are ready to bend
