Patent ID: 8683690

Claim:
A method of forming a heat exchanger tube, the method comprising: shaping a first sheet of material to form at least a portion of each of a first broad side, a first curved narrow side, and a second curved narrow side of a tube body, wherein the first and second narrow sides are opposite one another; shaping a second sheet of material to form at least a portion of each of a second broad side, the first curved narrow side, and the second curved narrow side of the tube body, wherein the first and second broad sides of the tube body are opposite one another and are joined by the first and second curved narrow sides of the tube body, and the first and second curved narrow sides are each bounded between a respective end of the tube body and a respective terminus of the curved shape of both the first and second sheets of material; shaping a third sheet of material to form an insert supported in an interior space of the tube body between the first sheet of material and the second sheet of material; overlapping the first and second sheets of material at the first and second curved narrow sides to double the thickness of the tube body across at least a majority of the first and second narrow sides, each of the overlapped areas of the first and second sheets of material extending over and beyond the respective terminus and terminating at locations within at least one of the broad sides of the tube body between the first and second curved narrow sides of the tube body, and nesting ends of the insert within the concave portions of the first and second curved narrow sides of the tube body; wherein nesting the ends of the insert includes, inserting a first edge of the insert into the concave portion of the first narrow side to define a nested relationship between the first edge of the insert and the first narrow side, and inserting a second edge of the insert into the concave portion of the second narrow side to define a nested relationship between the second edge of the insert and the second narrow side.