Similar to our discussion of wind design last month, seismic forces should be considered in pressure vessel design. Earthquakes are rare, but if not properly accounted for, a pressure vessel that is damaged during an earthquake could become extremely dangerous. Like wind, seismic loads act horizontally on a vessel. Building codes such as 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. Stresses in the vessel and supports are calculated, and design changes are made if needed. Contact us if you have any questions about seismic design.