Header tank rib design for a heat exchanger

A tank for a heat exchanger includes a casing including a substantially planar header opening formed therein and a foot disposed around a perimeter of the header opening. The foot forms an outwardly extending flange from which a pair of oppositely arranged walls extend, the oppositely arranged walls forming an arcuate shape including a spine extending along an apex of the arcuate shape. The oppositely arranged walls each have a corrugated profile adjacent the foot due to the presence of outwardly projecting ribs formed in the oppositely arranged walls. Each of the ribs extend lengthwise from the foot toward the spine, wherein a distal end of each of the ribs is formed adjacent a neutral stress portion of the casing which undergoes a minimal stress when the casing is subjected to an internal pressure from a fluid flowing there through.