Sealing Performance of Various Pass Bar Rib Gasket Styles

Abstract This study researches the sealing performance of different pass bar rib gasket styles used on heat exchanger applications, where pass partition plates are utilized to separate two or more substances. Pass bar rib gaskets are typically situated on the channel to tube sheet joint, channel cover flange and floating head. Higher demands are being placed on plant equipment and therefore the safety, efficiency and emissions of these units must be to the highest possible standard. When a leak occurs on the main seal of a flange, it can often be apparent to the operator. However, this is not the case for a leak on the pass bar rib section of the gasket, due to the seal being enclosed inside the heat exchanger body. If leakage is present, it can greatly reduce the efficiency and output of the process and ultimately effect the quality of the product. There is currently limited leakage test data available for the different styles of pass bar rib gasket combinations. Most common heat exchanger gasket designs are legacy and as such, may not be suitable for modern day process unit heat exchangers. This project will provide gasket, heat exchanger manufacturers and plant operations with a better understanding of the performance of the pass bar rib section of the gasket, in combination with the outer main seal. There are many different combinations of gasket types and pass bar rib styles that are used in heat exchanger applications. This study evaluates twelve different combinations of outer seal and pass bar rib gaskets, which are available as standard from gasket manufacturers. When two different gasket styles are used in a heat exchanger pass partition application (ring and pass bar rib), there are different compression rates, which can result in varying gasket stresses across the main sealing element and pass partition seal. Each gasket style also has different minimum seating stress values, which can result in varying leakage rates on the same bolted flange joint. Results from this project will show leakage rates across the pass partition section of the gasket at different gasket stresses. Each test gasket will replicate a heat exchanger design, circular main seal and a pass bar rib which is situated on the gasket’s inner diameter. Compression data will also be recorded for the main gasket seal and pass bar rib section throughout testing. This will provide a better understanding of the relationship between compression, gasket stress and resulting leakage. The aim of this study is to provide engineers and end users with the data required to select the appropriate combination of pass bar rib and gasket style to achieve a safe and efficient bolted joint on heat exchanger flanges that have pass partition plates.