Heat exchanger and method of making thereof

A heat exchanger comprising:

• an inner tube extending longitudinally along a central axis and having an inner surface bounding a product chamber and an outer surface having a plurality of channels disposed at circumferentially spaced intervals in alternating relationship with a plurality of fins about the circumference of the outer surface of the inner tube;
• and
• a longitudinally extending outer tube disposed coaxially about and circumscribing the inner tube in radially spaced relationship, the outer tube having an inner surface contacting the plurality of fins of the inner cylinder, the outer surface being welded to the fins at a plurality of weld locations;
• the plurality of weld locations comprising at least two circumferential weld locations about an outer surface of the outer tube and orthogonal to the central axis, the circumferential weld locations spaced from each other along a longitudinal axis of the outer tube, wherein the at least two circumferential weld locations extend around the entire circumference of the outer tube.