Selection of tube box gaskets
Thread Content
Is the selection of tube box gaskets solely determined by the design pressure and temperature in the tube side? For example, if the design temperature for the hot water in the tube side is 50 degrees Celsius while it is 300 degrees Celsius on the shell side, is it appropriate to use polytetrafluoroethylene for the tube box gaskets?
1. Consider the flange connection method between the control box and the housing, as well as the impact of bolt tension； 2. Medium, pressure, and temperature compatibility!
Theoretically, it’s feasible: during operation, it starts at a low temperature, and when shut down, it also cools down gradually at a low temperature; thus, there should be no issues with pressure. The temperature needs to be slightly higher, mainly because heat transfer requires a temperature difference. But there is no need to design it for the high-temperature side directly, after all, the gasket is on the low-temperature side and the operating temperature is close to that of the low-temperature side
If the shell side is in the gas phase, there’s no problem； If the shell side is in liquid phase, the temperature of the tube sheet should be considered.
Consider whether the tube sheet transfers the temperature from the shell side to the tube box gasket, as PTFE standards allow only up to 100 degrees Celsius, and even RPTFE can only handle up to 200 degrees Celsius. For this gasket, it is necessary to take into account the design pressure of the tube sheet, the temperature, as well as whether the shell-side temperature will affect its use
The actual operating temperature of the gasket can exceed the temperature specified in the standards, but for design purposes, it is better to comply with the standards