Abstract: A fluid tube pass for a heat exchanger formed by a pair of plate members which have their edge portions joined together to form a refrigerant enclosure between plate midportions for flow. Fluid inlet and outlet manifolds are formed at either plate end by drawn, outwardly offset configurations. Between the manifolds, rows of separated ribs are similarly formed, each rib angled obliquely to the flow path between the manifolds and each row extending transversely normal to the flow path. The ribs in each row are staggered and overlap other ribs in the direction of flow to prevent linear flow across all the transverse rows between the inlet manifold and the outlet manifold but provide an interrupted linear flow path or by-pass across the middle of the transverse rows in addition to by-pass flow paths past the ends of the rows to improve heat transfer efficiency without substantially increasing pressure drop.