Tried a different weld prep on some 3/8 inch plate and got a surprise

On a job last month, we had to join some 3/8 inch carbon steel plate for a small pressure vessel. The spec called for a standard 37.5 degree bevel. I had always done it that way, but another guy on site swore by a tighter 30 degree angle with a smaller root face. He said it gave him a cleaner, stronger root pass with less filler. I tried it on a test piece, and the first pass went in smooth as butter, way less spatter than I'm used to. But when I went to cap it, the heat input felt different and I ended up with a slightly convex bead profile that took some extra grinding to clean up. It saved time on the root but cost it on the finish. Has anyone else played with bevel angles outside the book specs and found a sweet spot?

3 comments

3 Comments

the_anthony2mo ago

Ngl, that's interesting but my experience was the total opposite. I ran into major issues with lack of fusion on the side walls when I went tighter than the book. The heat just wasn't washing in right for me. I stick with the standard angle now because it's more forgiving, especially if your fit-up isn't perfect. Saving a minute on the root isn't worth a bad cap or rework later.

king.eric2mo ago

Yeah, I get that. It's all about the machine and your hand speed. I ran a tight drag angle on some 3/8" plate last week, but I had the volts cranked up. If your heat is too low, it just rides the root and never touches the sides. The book settings are a safe bet, but sometimes you gotta push past them if everything else is dialed in. A bad fit-up will kill any angle though, no argument there.

dylan_brown302mo ago

Wasn't there a study on travel angle and sidewall fusion?

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