Wind Induced Vortex Shedding of Process Columns Recommendations on Screening Criteria

Abstract Pressure vessels with height to diameter ratios above certain limits are known to experience wind induced vibrations due to vortex shedding. The susceptibility of pressure vessels to wind induced vibrations is dependent on several different factors such as the vessel’s length, diameter, mass, natural frequency, critical wind speed, and the mean hourly wind speed at the installation site. Development of a method for screening and evaluating pressure vessels for wind induced vibrations has been the subject of numerous papers and there are several different criteria and parameters used within the process industry to screen vessels for vortex shedding and wind induced vibrations. This paper will review the notable existing publications on wind induced vibrations which include, Determination of Aerodynamic Behavior of Cantilevered Stacks and Towers of Circular Cross Section by Zorrilla, along with the current criteria present in the different design codes or standards. There is no formal guidance provided in ASME Section VIII Division 1 or Division 2 for evaluating vortex shedding but screening is contained in EN 13445-3. The focus of this paper will be a review of the method in EN 13445-3 and the author’s recommendations on potential improvements of the existing criteria. The method outlined in EN 13445-3 utilizes a screening method based on different properties including the vessel’s height to diameter ratio, equivalent mass per unit length, structural damping parameter, and mass damping parameter. This paper will propose clarifications and refinements to the method provided in EN 13445-3 Section 22.10.2 including defining which cases need to be screened and possible recommendations regarding the structural damping value used in each case, increasing the range of vessels to be screened by lowering the height to diameter ratio, and modifying the mass damping parameter based on the Scruton number as seen in earlier editions of the CICIND Code and ASME STS-1.