Patent ID: 7377039

Claim:
In the construction of a shell and tube heat exchanger for cooling fluids by non-contact heat exchange with sea water comprising an outer horizontal cylindrically shaped shell and an enclosed bundle of horizontally disposed corrosion-resistant alloy tubes with each end of each tube passing through an opening in a supporting carbon steel tube sheet, said shell and tube heat exchanger comprising a closed outer shell with an inlet for introducing said fluid into the shell and an outlet for removing said fluid, a removable tube bundle comprising a plurality of corrosion-resistant alloy tubes spaced apart from each other and contained in said shell, a first cover with an inlet for introducing sea water into the tubes, and a second opposing cover with an outlet for removing sea water from said tube heat exchanger, the opposing ends of said tubes extending, respectively, through first openings formed in a wall of a carbon steel tube sheet clad with a single solid corrosion-resistant alloy tube sheet that is in contact with the sea water, the ends of the tubes expanded into at least one annular groove formed in the walls of the first openings of the carbon steel tube sheets, said corrosion-resistant alloy tube sheet including a second opening associated with each alloy tube extending therethrough, and each second opening being lined with a liner having an interior radial groove for securing a circumferential ridge of the alloy tube, wherein the second opening in the alloy tube sheet is in the form of a recess that extends from the exterior surface and partially through the alloy tube sheet to thereby provide a water-tight mechanical seal between the corresponding tube ends and each of the alloy tube sheets, a method for protecting said carbon steel tube sheets from corrosion by contact with the sea water, the method comprising, (a) covering the exterior face of said carbon steel tube sheet with the corrosion-resistant alloy tube sheet containing a plurality of openings corresponding to the openings in said carbon steel tube sheet, the surrounding wall of each said opening in each tube sheet being provided with at least one annular groove; (b) passing a corrosion-resistant alloy tube through a pair of aligned openings in (a); (c) inserting a tube expander into the end of said tube and radially expanding said tube radially at locations corresponding to said annular grooves in (a) to form a circumferential ridge; and (d) simultaneously forcibly driving the circumferential ridge formed in (c) into a corresponding annular groove to form a watertight joint, whereby the watertight joint in the alloy tube sheet prevents the sea water from coming into contact with the carbon steel tube sheet.