In pressure vessel design, seismic forces refer to the forces generated by earthquakes or ground vibrations that act upon the vessel and its supporting structures.
These forces can have a significant impact on the structural integrity and safety of the pressure vessel, and they must be considered during the design process to ensure that the vessel can withstand the effects of seismic events.
Earthquakes are rare, but if not properly accounted for, a pressure vessel that is damaged during an earthquake could become extremely dangerous. Seismic loads act both horizontally and vertically on a vessel. Building codes such as the American Society of Civil Engineers’ ASCE 7 specify what seismic design loads should be used based on the vessel’s final location and soil type. Some unexpected areas have high seismic design parameters, such as locations near the Mississippi River. In the vessel calculation software, seismic loads are applied to the vessel and combined with other loads such as internal pressure.
Here are other key points to consider when addressing seismic forces in pressure vessel design:
Hazard analysis: The first step is to conduct a seismic hazard analysis for the specific location where the pressure vessel will be installed. This analysis involves studying the local seismic activity, geological conditions and historical earthquake data to determine the potential magnitude and frequency of earthquakes that the vessel may experience.
Design categories: Based on the seismic hazard analysis, the location is categorized into a seismic design category. This category helps define the level of seismic forces that the pressure vessel and its supports should be designed to withstand. The International Building Code in the U.S., for example, provides guidelines for seismic design categories.
Load calculation: The next step is to calculate the seismic loads that the pressure vessel would experience during an earthquake. These loads include both vertical and horizontal forces as well as rotational moments. The loads are typically calculated based on the design category, the vessel’s mass and its dynamic response characteristics.
Dynamic analysis: Pressure vessels are usually not designed to accommodate large displacements and deformations. Therefore, dynamic analysis may be performed to assess how the vessel and its supports would respond to seismic forces while maintaining structural integrity. This analysis involves simulating the response of the vessel to the dynamic loading using computer models and finite element analysis.
Support design: The supports and foundations of the pressure vessel must be designed to withstand seismic loads. This includes ensuring the supports are adequately anchored to the ground and that they have sufficient strength and flexibility to absorb and dissipate seismic energy.
Material selection: The material used for constructing the pressure vessel must have appropriate ductility and toughness to withstand the deformation and stress caused by seismic forces. Brittle materials are more prone to sudden failure under dynamic loading conditions.
Code compliance: Pressure vessel design codes, such as ASME Boiler and Pressure Vessel Code, often have specific provisions and guidelines for addressing seismic forces. Designers must ensure that their designs adhere to these codes to maintain safety and regulatory compliance.
Testing and verification: Prototype testing or simulations can be conducted to verify the response of the pressure vessel to seismic forces. This may involve subjecting scaled models to controlled seismic forces to observe their behavior and assess their performance.
Overall, the consideration of seismic forces in pressure vessel design is crucial for ensuring the safety of the equipment, personnel and surrounding environment. It requires a multidisciplinary approach that involves structural engineering, geotechnical engineering and seismic engineering expertise.
For more information, visit wardvesselandexchanger.com or call (704) 568-3001.
