Wow. Never encountered anything on body panels that went up like that!!! What rod you planning on using?? You should probably use 1/16" or 3/32" 6013. It's designed as a sheet metal rod and there's very little sparks. Especially compared to 6010/6011.... It's not an explosive situation, co...

What process are you welding with? If you have the availability to tig weld it, I wouldn't worry about it. If you're mig welding it, I would just take it slow and just keep a fire extinguisher on hand just in case. The insulation shouldn't be flammable but the adhesive to tack it to the floor panel ...

Wet down the insulation

I third that motion.... No need to scrap!

Bigger is ok, unless there's a specific reason it can't be like a larger weld interfering with fit-up of a secondary part, throwing something out of balance, or called out on the spec that it can not exceed a certain size. It my experience, the LEG size of a fillet weld should be 1t (one material th...

Are you wanting to modify an existing manifold to attach a turbo to? Not sure what you're trying to accomplish. Any brazing operation would certainly fail due to the fact that copper/bronze alloys can not be put into service at those temperatures much less adding some back pressure from the exhaust....

If your line has a small leak, depending on what you consider small, it could leak when the system has pressure built up in it but when you are welding and the gas is flowing, you could be creating a draft sucking in outside air.... The neoprene washer I spoke of is exactly that, the white insulator...

TIGHT as possible, clamp aluminum or copper backing bars behind both edges of the weld, keep a very tight arc, and use lay wire.

I would use either ER-410 NiCrMo, ER-309L, or ER-312. In that order, depending on what I had on hand.

Make sure you're using the proper neoprene "washer" behind the ceramic cup. Sounds like you're getting atmospheric gases pulled in.

This is a 6"x6" square plate 2" thick, 3/8" stainless round stock as the "finger" and "legs", with 1-1/4" ball bearings as the "feet" tig welded with 625 Inconel filler...

-Tony

I have not had the chance to try this out for myself, but, I would like to see a video done showing an attempt to use pure Nitrogen as the primary shielding gas on various base materials... I know it's used in addition to other gasses for a "hotter" or more stable arc (up to approximately ...