Experimental Data on Seismic Response of Piping Components

Experimental data from the EPRI Piping and Fitting Dynamic Reliability Program are evaluated. High-amplitude, seismic time history loads were applied to 32 piping components in a cantilevered configuration. Components included elbows, tees, reducers, a reinforced fabricated tee, a nozzle, and lugs. The test levels were about 2 to 8 times Level D. The seismic capability of elbows is shown to be remarkable. The seismic performance of lugs is judged to be poor. The tests demonstrate that collapse is a potential failure mode, particularly in low-frequency systems. The tests also demonstrate that a fatigue failure in a single, high-level, seismic event is possible. Of the 15 nonelbow tests that failed by fatigue, six (40 percent) failed during the first high-level seismic test. Design and fabrication details are crucial to seismic performance. Trends in the data need to be assessed to determine appropriate Section III stress limits for seismic loads. In particular, the impact of component frequency on seismic capability has to be quantified.