34 includes a plug 38 the plugs 38 seal the ends to prevent fluid in the headers 24 from entering the shielding channels and leaking out of the heat exchanger 20 the plugs 38 may by made of wire with cladding on it so that the plugs 38 will be welded to the ends of the shielding channels 34 during a brazing process the heat exchanger 20 undergoes during assembly of course other types of sealing means may be employed to seal the ends of the shielding channels 34 from the fluids in the headers 24 if so desired in addition each of the shielding channels 34 may include a cutout 36 also one or two of the reinforcements 30 may be eliminated as compared to a conventional heat exchanger tube in order to compensate somewhat for material added for the shielding channels 34 the tubes 22 can be manufactured using conventional extrusion or folding techniques used to form tubes in conventional heat exchangers thus the complexity of manufacture is not increased significantly by adding the shielding channels 34 to the tubes 22 moreover the shielding channels 34 can be formed integral with the flowing channels 28 of the tubes 22 the term u201c integral u201d as used herein means that the particular elements are formed as a single monolithic piece.