Is this True about converters??

Tig welding a convertor is the best way to weld in the fins,as opposed to furnace welding,as this is a assembly line welding through a oven/furnace using a copper past.Check out the link,mrmopartech
http://heattreatment.linde.com/international/web/lg/ht/like35lght.nsf/repositorybyalias/apps_brazing/$file/Furnace%20brazing.pdf