Its always good to bevel. It gives the weld a place to go, and it gets you more penetration. even in tube work, it would be better. Even if its not a 100% pen with a bevel but say you bevel with a land half the thickness of the metal its a plus. Even fillet welds its a plus, a fillet weld pretty much has no penetration at the root. So the strength comes from the weld re enforement its self, you remove the piece breaks. you weld with a bevel and re move the re enforcement, it wont as easily, if its a partial pen, full pen it wont.
I make a lot of frames for tables and such, with.065 wall and up tube, I always bevel the edge.
Now I will say this, I do a lot of fillet welds too on the thickness, and I dont bevel, because Im not removing the re enforcement.
The negitive side to bevel a fillet weld, it takes time. And is that extra strength need for a fillet weld, depends.Are fillet welds done without a bevel, all the time, is it fine yes.
The evidence that you are doing sound welds? Yes thats your weld cert test you took. Sometimes a inspector will even watch you weld, bead by bead.
I talk about all this, and how its done, because even though it might not be done on trucks here a lot, it is good to know if you need to weld something thick, or critical. Making bumpers and welding suspension work should be done with the best way you can.
