I use both types of brake cleaner Terry. The non-chlorinated stuff mostly but the chlorinated stuff when cleaning for Loctite. The chlorinated stuff can indeed create phosgene gas when passed through a flame and I am very careful to avoid that. Always have been. I like brake cleaner netter than carb cleaner for weld zone cleaning because it leaves no residue. Grind out the cracks and porosity, clean with the flammable brake cleaner as a final clean, heat before welding to drive off any water or cleaners, and weld. One thing I like about TIG is that if there is any dirt in the weld zone you can tell right away. Then the metal can be cleaned properly and welding can start again. Eric