Holtec’s HI-MAX (Holtec International MAXimum reliability) is a transformative air cooled condensing (ACC) technology characterized by a stainless steel obround tube (referred to as the Core tube) whose flat stainless steel surfaces are equipped with closely spaced aluminum fins oriented in the transverse direction to the axis of the tube. The uniqueness of HI-MAX lies in the strength of the bond between the aluminum fins and the stainless steel core tube. The thickness, height and spacing of the fins have been optimized using state-of-the art computational fluid dynamics codes to provide maximum fin efficiency for air flow parameters.