Locating Exchanger Tube Leaks

Open the high point vent on the top of the channel head. I am assuming water is on the tube side of a horizontal shell and tube exchanger. If the exchanger is elevated by 30 or 50 ft, there may be no water pressure at this elevation. If so, temporarily close the cooling water outlet gate valve part way to push the water out of the vent. Now take the gas test meter (the one used by the operators to issue entry permits to vessels) and hold the sample probe above the water stream to test for hydrocarbons. 

Do not just plug the leaking tube and start back up. You need to determine the mechanism of the failure. The bad tube has to be extracted from the tube bundle. This is a somewhat difficult job usually requiring an outside contractor. 

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Tube leaks may occur in the reboiler, condenser, preheater, precooler, or any other heat exchanger linked with the column. Several experiences where leakage caused poor performance have been reported (71, 238, 239). The effect of a leaking heat exchanger tube depends on the magnitude, the direction, and the location of the leak. 

Testing Upon completion of shop fabrication and also during maintenance operations it is desirable hydrostatically to test the shell side of tubular exchangers so that visual examination of tube ends can be made. Leaking tubes can be readily located and serviced. When leaks are determined without access to the tube ends, it is necessaiy to reroll or reweld all the tube-to-tube-sheet joints with possible damage to the satisfactoiy joints. 

Air-cooled condensers are especially attractive at locations where water is scarce or expensive to treat. Even when water is plentiful, air coolers are frequently the more economical alternative. Elimination of the problems associated with the water side of water-cooled equipment, such as fouling, stress-corrosion cracking, and water leaks into the process, is an important advantage of air-cooled equipment. In many cases, carbon steel tubes can be employed in air-cooled condensers when more expensive alloy tubes would otherwise have been necessary. The use of air-cooled heat exchangers may eliminate the need for additional investment in plant cooling water facilities. 

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