The TEMA standard requires gasket joints in all Class ‘R’ heat exchangers to be confined type. What is a confined gasket joint? These are joints that have a solid metal retaining element outside the gasket that prevents a direct radial leak path to the environment in the event of a gasket blowout. In other words, the ring confines the gasket to hold it in place. The retaining element can be a recess machined into a flange such as in a tongue and groove joint. It can be a solid metal outer ring on the gasket, separate from the sealing element, such as on a spiral wound gasket. Although modern gaskets rarely experience blowouts, they are possible. Confined joints should be considered for the most critical applications such as high pressure or temperature designs, or when the exchanger contains hazardous fluids.
