Another O/A welding question

Joel_BC · #1 01/19/10, 03:07 PM

I've read in the past (don't have the book on-hand) that you can successfully make a stronger weld - say on a thick-stock T joint - using a 'double pass' method.

Let's say I want to weld a strong T joint with 1/4" steel. My understanding of the method is that you run initial beads, insuring that you get good penetration, on both sides - and you'd have to use a good-size tip, like say a Victor #3 or #4. Then you pass back over, puddling the steel stock, the original bead, and adding more filler from the rod. This then makes the second, more substantial bead, which of course you'd do on both sides.

I realize that this (a T joint in fairly thick stock) can be done more quickly using an arc welder, but I don't have one and won't be buying one too soon. So I'm interested in a method that can be used with O/A.

Have I got the concept of the method correct here? Tips from experienced welders about the method will help me a lot.

moocow · #2 01/21/10, 06:51 AM

The strongest way to make a weld is make the weld "throat" as thick as the material. So if your material is 1/4in the you weld should be a 1/4in thick looking at it's profile. A smaller weld than your material makes your weld the weak point and a bigger weld makes the material the weaker point assuming the weld is good. So a good balance is make the weld the same size as material even if it means multiple passes. I hope this answers you question.

moocow · #3 01/21/10, 07:04 AM

When you make your beads fill the corner of you T up evenly. Make normal size beads don't make huge beads. It will take alot of passes and rod to make a 1/4" weld. I would be saving my pennys for a arc welder if you plan on doing much of this 1/4 inch welding.

wicker762 · #4 01/24/10, 01:54 PM

Normal width welds have greater penetrations/fusion than wide pass beads. You're better off with multiple passes of normal bead than one big one.

Bevel any metal over 3/16" for correct penetration. On a the T you will want to bevel each edge of your upright. If you bevel to a 1/8" land (tip of 2 sided bevel that is not removed but original edge) you should end up with 100% penetration through both sides.

Depending on the application you don't "have to have" 100% penetration but if you are using 1/4" I'm going to assume it's a heavy duty application.