A few examples of Storage Tanks Design / Analysis performed by Pressure Equipment Engineering Services, Inc. are as follows:
Fitness for service evaluation was performed for a storage tank when the hot liquid at 400 °F was to be suddenly introduced in the tank. The finite element analysis was performed using ANSYS software to complete the evaluation. The temperature distribution due to thermal gradient was calculated in the tank. Subsequently, this temperature distribution was used to calculate the thermal stresses in the tank. The evaluation of stresses was based on ASME, B&PV, Sec. VIII, Div.-2, Appendix – 4 rules. At the requested 400 °F, the thermal stresses were above the acceptable limits. Subsequent case runs concluded that it was safe to use maximum temperature limit of 350 °F for the hot liquid entry. Hence, based on the fitness-for-service evaluation, it was concluded that the temperature of the hot liquid for sudden introduction in the tank be limited to 350 °F.
Fitness for service evaluation has been performed for several storage tanks where the storage fluid has higher density as compared to the density of the storage fluid. Fitness for service evaluation has also been performed for storage tanks where the storage tank walls are corroded as compared to the original walls of the storage fluid. Both of these scenarios lead to the tank wall stress levels above the allowable stress levels listed in the appropriate code. To avoid these high stresses in the tank walls, the fill height can be adjusted. Thus the final result of the fitness for service evaluation is the specification of the maximum fill height that is allowed for the given tank and the given storage fluid.