Welding Tips and Tricks

First off hi everyone I'm new around here. I'm in welding school for my company right now, I'm already qualified for 1/4 fillet and tack welding, but I'm back in for full plate in all 3 positions. My main question is for my vertical 3G my instructor wants me to run two vertical welds for the root, burning into the backing strap really well and not really biting into the bevels that much. After practicing for a while I got pretty good with it being able to lay in two pretty flat welds side by side, but I was wondering is there any reason for this? Seems to me running two beads into the root would be a bigger chance of trapping junk in there, instead of just a nice single root weld. Just curious to see if anyone has any answers or opinions. Btw it's carbon steel I'm using 7018 at 110 amps 3/4 plate with 1/4 gap.

I don't know how you could even fit (2) 1/8 rods in there.
Two stringers ??

That's misguidance right there.

A slight weave would work really nice.

Get us a pic if you can.

No stringers overlapping weave it ends up looking pretty good and flat if you get it right, sadly I'm not allowed to use cameras where I work at, and the welding school is part of the company.

Ok do you mean you are putting one pass in from the bottom and when you run out of rod (being roughly the center of plate) you start a second root from center and continue to the end of the test plate or are you putting one root bead in on the right side of the root and then coming back in on the left side of the root? I am a little confused.
Here is a excellent video by Jody, are you doing it the way he is?
http://www.weldingtipsandtricks.com/sti ... -test.html
-Jonathan

I agree a two-stringer root is "unorthadox" to say the least for 1/4" gap, but it's doable, and if that's what they want... Well, they sign the checks. Personally, I'd prefer a 5/32 7018 at 155-160 amps, one pass...

Personally, I'd bump the heat up to 115-118, turn up arc-force if available, and run a dead-tight stringer. Ideally, feeling as though jambing the rod into the corner, to reduce the chance of trapping slag between the first stringer and the opposite land.

Glad I'm not you... You can do it, though.

Steve S

No the root is 2 separate beads, not stringers slight weaving and the test has a 1/2 gap the practice stuff was 1/4 gap for some reason, and believe it or not it looks pretty good after I got it down. Sadly I work in a shipyard for the navy so I can't take pictures, not deviate from what they want and just run a single pass in the root

I work in a shipyard that does work for the navy too. Pipe welding though.

Joejoe8455 wrote:No the root is 2 separate beads, not stringers slight weaving and the test has a 1/2 gap the practice stuff was 1/4 gap for some reason, and believe it or not it looks pretty good after I got it down. Sadly I work in a shipyard for the navy so I can't take pictures, not deviate from what they want and just run a single pass in the root

Let's get straight, here... A weave is NOT two separate beads. It's ONE bead, done with a weave technique. No wonder you're confusing us...

"A" stringer is a bead. "Parallel stringers" is two beads. A single-pass weave is ONE bead.

The topic makes more sense, now.

This procedure, now that I know what the heck you're talking about, is perfectly normal.

Steve S

Lol sorry for the confusion, I've always been under the assumption a stronger was just one straight bead

Joejoe8455 wrote:Lol sorry for the confusion, I've always been under the assumption a stronger was just one straight bead

That's cool, but unless I'm misunderstanding, there's still a slight confusion here. A stringer is one straight bead, where you don't weave more than the diameter of the rod itself (you can move back and forth 1/8" for a 1/8" rod, and still call it a stringer... This interpretation varies with the weld inspector... Some purists will say you can't weave at all and call it a stringer, but in general, a rod-width is allowed.)

If you are weaving two rod-widths, to center your arc on the land on each side of a 1/4" gap with a 1/8" rod, it shouldn't be called a stringer.

If your instructor is having you weave one rod-width from the centerline of the root, for a stringer, I, too, would be suspicious of trapping slag and getting inadequate tie-in, since the center of the arc is always just inside the edges of the material, and your penetration is in the backing bar, rather than the parent metal.

I look forward to hearing more detail, since I suspect I'm just not fully understanding what you're describing.

Steve S

Ok so it's not 1/4 it's 1/2 gap, some kid tacking the plates that day messed up, anyways I'll try to explain the best I can since I can't take pics, anyways the first bead is put in the left corner barely nipping the bevel and weaving it to about 1/16 to the right bevel. Clean slag grind the toes if needed. Second bead starts at the right bevel and weaves to about 3/4 of the first weld. Clean slag grind toes if needed. Now believe me, it makes a pretty flat weld for a root pass. Hope this helps explain a little bit more.

Okay, it does make more sense with a 1/2" gap. Much more working room to avoid trapping slag. As long as you're coming up the land and nipping the bevel, you should have good tie-in.

It also helps that grinding the toes is permitted.

That's a big gap for that material, but since this is in-house training, it certainly meets their WPS.

Steve S

The test is 3/4 plate with 1/2 gap

When using 3/32" Lincoln Jet LH 78 H4R to perform a vertical up open-groove weld, if I set the machine for DCEN (focusing the heat on the base metal) and use a lower amperage, will this create a tighter arc, cause the rod to burn more slowly and provide better penetration?

I have no arc control/dig on my AC/DC tombstone stick welder.