Abstract: Impingement plates for shell and tube heat exchangers are positioned between the inlet openings and the tubes with the surfaces of the impingement plates being normal to the flow path of the liquid entering the shell from the inlet openings and having a plurality of openings through which a portion of the liquid passes before contacting the tubes. The openings can be formed as elongated parallel slots that are positioned parallel to the tubes and function to enhance the fluid flow, especially in the area that is immediately downstream from the impingement plates, thereby reducing fluid stagnation, fouling and tube erosion and prolonging the useful life and time in service between maintenance shut downs.