Building an exhaust heater for a gold dredge in Nome, AK. The construction requires welding 42- 2" 060 steel washers into 060 slots cut into the side of a 1.75 steel tube. This tube will be enclosed in a 3" outer steel tube, carrying sea water for heating. The inner pipe/washers section collects then transfers the exhaust heat via the washer to the outer chamber , where sea water is heated then discharged. Iam currently planning on using 024 solid steel wire and Ar 84 CO2 16 shielding gas. My goal is to produce 84+ water&air tight welds on both sides of these 42 washers. I could use any advice on how to get nice continuous welds in these materials where the surfaces are at 90 degrees and require a simple filet weld. Also any suggestions on better alternate consumables to use. Both metals are very clean. (Zinc removed from washers with muriatic acid.) Any and all advice and experiences welcome.