Hello, just thought I'd ask what 6mm welds stand for? I work for AEP steel fabs and have been welding for the past year and have been messing about with welding machines since a young age as my dad owns B&E Erection Services. I work for my uncle at (AEP) and have a test coming up for horizontal fillet weld. I'm 17 and I'm fairly confident I can pass! But can someone please tell me what 6mm welds mean? Sounds pretty stupid I know, but no one at work has ever told me.