Impact of Temperature Difference Within Channel on Flange Sealing Performance for Shell and Tube Heat Exchanger

Abstract Shell and tube heat exchangers are extensively used in oil and gas plants due to their efficiency and reliability in transferring heat between two fluids. Heat exchangers are typically designed based on established codes and standards, such as ASME Section VIII Division 1 Part UHX [1] and API 660 [2J. These codes and standards ensure that the mechanical strength of the heat exchangers is sufficient to withstand the design pressures and temperatures they will encounter. However, while these codes and standards provide a solid foundation for design, they do not fully address all potential issues that may arise during operation. One such issue is the impact of significant temperature differences on the sealing performance of flanged joints. API 660 Clause A4.5.2 recommends additional analysis to account for these temperature differences, although it does not clearly define the evaluation methods or countermeasures. This recommendation is particularly relevant when the operating temperature difference between the inlet and outlet nozzles on the channel side exceeds 110°C (200°F). The concern is that such a temperature difference could lead to leakage at the flanged joints, compromising the integrity of the heat exchanger. Despite this recommendation, the mechanism of leakage due to temperature differences and the validity of this temperature criteria are not well known. In the past, special countermeasures (e.g., change of heat exchanger type, additional analysis, etc.) have not been implemented because the leakage incidents by failure to meet the recommendation have rarely occurred. However, in recent years, there has been a growing demand from the clients for more detailed analyses in various locations. This demand has prompted increased interest in developing and validating evaluation methods and countermeasures to address the potential for leakage. In this study, the flanged section of a shell and tube heat exchanger with a pass partition plate was modeled based on the past EPC (Engineering, Procurement, and Construction). The analysis focused on the flanged joint, considering the temperature differences within the channel. The gasket contact pressure was evaluated to understand the leakage mechanism and assess the validity of the criteria for the temperature difference in API 660 Clause A4.5.2. Additionally, the impact of the pass partition plate on the flange strength was examined. The results of the evaluation provided valuable insights into the parameters related to sealing due to the temperature differences. Specifically, the study reported on the increased rate of the initial sealing pressure and the initial gasket contact pressure. These findings are crucial for understanding how temperature differences affect the sealing performance of flanged joints and for developing effective countermeasures to prevent leakage.