... tubes:15pcs,18pcs,20pcs,24pcs,30pcs3,Outer tank material:202stainless steel with 0.31mm4,Inner tank material:SUS304-2Bstainless steelthickness :0 ... .5mm2,Insulation:50mm polyurethan foam3,Outer tank:0.5mm thickness galvanized steel material4,P/T relief valve ,electrical heater element with terminator5 ...