Stress Limits for Pressurized Piping Branch Junctions Under In-Plane Run Pipe Simulated Seismic Loadings

This paper summarizes results from 420 tests on 23 fabricated or machined, pressurized piping branch junctions subjected to simulated seismic loadings that induce resonant in-plane run pipe bending. The general background to this research contribution is outlined and some justifications for the chosen material, type of loading and geometries are given, with simple indications to situate this testing program in the general overall picture of simulated seismic testing of piping components and systems. Brief descriptions of the experimental program are also included. The various parameters of ASME III Eq. (9), which forms the basis of the current Code rules for nuclear power plant, are discussed next and the test load levels are assessed with reference to the current allowables of the aforementioned equation and those being proposed in the current debate for future Code revisions. The results presented here indicate strong support for these proposed Code revisions. A summary of strain data is also included and it is concluded that the proposed design philosophy to limit the total accumulated effective strain, averaged through the thickness, to 5 percent in 10 cycles may still be conservative.