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Submitted Chris Haslego, Nov 21 2011 11:21 AM | Last updated Nov 21 2011 01:29 PM

Category:	Heat Transfer Technology
Question:	When is an expansion joint needed on the shell side of a shell and tube heat exchanger?
Keywords:	shell,tube,heat,transfer,exchangers,expansion,joint,shell,side
Answer:	A fixed tube sheet exchanger does not have provision for expansion of the tubing when there is a difference in metal temperature between the shell and tubing. When this temperature difference reaches a certain point, an expansion joint in the shell is required to relieve the stress. It takes a much lower metal temperature difference when the tube metal temperature is hotter than the shell metal temperature to require an expansion joint. Typically an all steel exchanger can take a maximum of approximately 40 ⁰F metal temperature difference when the tube side is the hottest. When the shell side is the hottest, the maximum is typically 150 ⁰F. Usually if an expansion joint is required, it is because the maximum allowable tube Compressive stress has been exceeded. According to the TEMA procedure for Evaluating this stress, the compressive stress is a strong function of the unsupported tube span. This is normally twice the baffle spacing. Source: Gulley Computer Associates