LPI’s Testimony for ROHR2

LPI provides a variety of engineering services for nuclear power plants. In recent years, some uprated plants have experienced increased pipe vibrations for which we have found a solution by installing viscous dampers with non-linear damping characteristics. However, the pipe stress program we have used for many years is not capable of performing dynamic analyses with such non-linear boundary conditions. Not only did we need a program with the numerical ability to model accurately the dynamic behavior of the piping, but we also needed to verify that the program’s mathematical algorithms in fact matched with measurements that we took in a laboratory.

Fortunately we discovered ROHR2, which not only has the capability to perform dynamic analyses with non-linear boundary conditions, but also has the damping characteristics of the dampers we intended to use in their database (included with the software). ROHR2’s customizable load case generation was also crucial for us since matching the many “analysis of record” load combinations can present another challenge for many programs. ROHR2’s interface is simpler and more capable than what we have seen thus far, minimizing potential errors. For example, the way that the fluid hammer load case results had to be combined required many load cases in our other pipe stress program – where ROHR2 performed this same calculation in one single load case. In addition, the custom “extreme value” formulations in ROHR2 allowed us to produce exactly the output that we needed for our structural department’s further evaluations.

Ultimately, working with ROHR2 and receiving a high level of technical support from Pipe Stress Inc resulted in completing our difficult engineering tasks in a timely and cost effective manner. Our client received an engineered solution that exceeded expectations by resulting in lower vibrations than projected.

LPI strives to satisfy our clients with the best engineering solutions that are available in the world today. ROHR2 has become one of the tools that helps us achieve that goal.

Sontra Yim, Director