Perforated tubes form a part of the reactor regulating and protection system in Indian Pressurized Heavy Water Reactors (IPHWRs). These tubes are being analyzed for design basis and beyond design basis seismic loading conditions. Experimental studies have been carried out on full scale shutdown system sub-assembly to evaluate the responses of the perforated tube under multi support seismic excitation. Dynamic characterization of the tube subjected to seismic excitation, simulating rock site and alluvium soil condition, has been carried out. In order to study the interaction of these tubes with the nearby structure/assemblies under beyond design basis seismic excitation, experimental studies have also been carried out to quantify the variation of impact forces with gap sizes, and their influence on the dynamic behavior of these tubes. Non-linear analytical calculations have been carried out simulating the above test conditions. Responses from experimental and analytical studies have been compared, and are found to be in good agreement.