Seismic Proving Test of Ultimate Piping Strength: Design Method Confirmation Test

The proving test of a large-scale piping system with a piping bore of 200A (8B) and made from carbon steel material was conducted to assure the safety margin of the current and new design codes for piping. Two test models were used, one for the design method confirmation test and one for the ultimate strength test. The design confirmation test model reflected the structural features and vibration characteristics of piping systems. For the ultimate strength test, the piping system was modified by adding one more mass and removing one horizontal support. The original seismic wave to the input seismic wave was selected to be the “S₂” seismic wave for a PWR building. The time-pitch and the excitation level were then modified to meet the test conditions. For the design confirmation test, a series of tests was initiated at a level of the current allowable primary stress limit (3Sm) for the “S₂” seismic wave (off-resonance), culminating in an elasto-plastic response test up to 4.5 times the allowable primary stress limit (on-resonance as an extreme case) with no evidence of piping failure. Pre-test and post-test analyses were performed. The post-test analysis results, which considered some differences of actual input acceleration and damping ratio, compare well with the design confirmation test results of elasto-plastic global response and local strain.