[CEP]

Here are two good articles from ESAB on the subject.
http://www.esabna.com/EUWeb/MIG_handbook/592mig10_3.htm
http://www.esabna.com/EUWeb/MIG_handbook/592mig10_5.htm


And another one on destructive testing. A quick and dirty way to see how much penetration your welds are getting. Some members here believe a fillet weld break tests shows nothing, I guess they know more than ESAB about welding.
http://www.esabna.com/us/en/education/knowledge/weldinginspection/Destructive-Testing-of-Welds.cfm

 

[CEP]

I don't see where there would be anymore chance of increasing the haz, than a 3, 6, 12, etc pass fillet weld.

 

[CEP]

I would on an undercut weld, but first I'd run a grinder down through it.

 

[CEP]

That just scratches the surface.
http://www.lincolnelectric.com/en-us/support/process-and-theory/pages/preheat-detail.aspx

 

[CEP]

everyday i pick up something from u awesome welders

You and me both!