In industry, fluids are commonly used to perform production processes under different operating conditions. In many cases, pipelines are used to traort these fluids, which in some working conditions, these pipelines are displaced or changed in length; For this purpose, expansion joints are usually used to compensate for these displacements. One of the most widely used of these fittings is Bellow expansion joints, which are used in large industries such as oil, gas and steel. The aim of this study was to estimate the life of Bellow expansion joints under the influence of heat and stresses. To achieve the thermal stresses applied to the device, the temperature distribution in the device must be obtained. Therefore, in addition to mechanical simulation, a thermal simulation must be performed to distribute the temperature on the device to Available. In this research, ANSYS software is used to perform the simulation process. First, thermal simulation is performed, in such a way that a three-dimensional model of expansion joint is considered and the fluid passage enters this part of the solution, and after making the necessary adjustments and performing the solution, the temperature distribution on the device is obtained. Then transfer these results to a mechanical solution to obtain the thermal stress and strain applied to the device. To verify the simulation results, the modeled sample was tested experimentally. For this purpose, the expansion joint is prepared and using heating furnace a fluid with a temperature of 420°C is passed through the device. After a certain time using the indicator clock, the displacement created in the part is obtained. The results of these two methods show a good qualitative agreement by considering possible errors in simulation and experimental experiments. Finally, put up the simulation results in the Caffeine-Manson life estimation equation to obtain the device life in different cases. The results of life estimation show that the applied thermal stresses reduce the life of this kind expansion joint between 60 to 70 percent. Key Words Bellow expansion joint, Thermal simulation, Mechanical simulation, Life estimation, Thermal stress
