I am a CWI (Certified Welding Inspector) so I will offer up my 2 cents. I would be worried if I looked from the back and didn't see any penetration. If that's the case grind out the weld in sections and reweld them. For no longer than it will take it's worth the piece of mind of not worrying about.
Tips:
1.0 Whenever welding with mig on metal heavier than sheet metal you always want to leave a gap for good penetration. It's also good to bevel weld prep the edges.
2.0 When doing a flush patch it's always better to drill large holes in the corners then cut out the piece. Or torch cut the corners as radii. These nice generous radiuses reduces the stresses considerably. Square corners can become cracks, and often times do on structural members such as frames that are subject to cyclic loading.
I hope this helps, and good luck!
Last edited by Hot Rod John; 12/31/2010 11:47 PM.
