F Numbers: Quick lookup of filler metal groupings for welding procedure and performance qualification. Lookup includes classifications with respective descriptions of intended use. Data is provided by C-spec. F-numbers and A-numbers assignments are based on ASME Section IX Table QW-432 and QW-442, ASME Section II Part C, AWS B2.1 Table B1 and B2, and AWS A5.1 through AWS A5.36.