Dynamic response of high pressure steam pipe in a fossil fuel power plant

Piping systems in power plants are usually flexibly supported to allow thermal expansion. As a result, natural frequencies of the lower modes are low, and the systems are susceptible to damage due to dynamic disturbances such as earthquakes. The dynamic behavior of a high pressure steam pipe in the fossil fuel power plant of Unit No. 3 of the Tennessee Valley Authority at Paradise, Kentucky is investigated. This piping system connects the header at the top of the steam generator to the turbine at the ground level. The pipe is assumed fixed at the ground level and either fixed or attached to a shear beam model that represents the frame structure of the power plant. Free vibrations are first studied. Dynamic responses of the system subjected to the NS component of the ground acceleration in the El Centro 1940 earthquake record are obtained. The effects of damping, the material stiffness, and the frame structure on the piping responses are investigated.