Performing Under Pressure – Design Guidance for High-Pressure, High Cycle Piping System

Abstract

Plant owners are responsible for specifying piping fluid service categories and determining the applicability of ASME B31.3 Chapter IX for high-pressure piping. However, the code only defines the design for high-pressure fluid service piping, and many designers and engineers are not fully aware of the best design practices for low-stress and high-cycle applications. Using innovative industry approaches and harmonic response analysis, dynamic stress levels of piping are calculated, and finite element analysis (FEA) used to calculate stress from the cycle range. This includes piping system design pressure at 10,200 psig with expectations of more than 1,000,000 stress cycles in a single day. A thermal flexibility analysis of the piping system along with a fatigue analysis for the entire piping components within the system is performed in accordance with ASME BPV code Section VIII Division 3. The fatigue stress ranges of a properly designed vibrating piping system are typically well below the ASME BPV code limit. High-pressure, unlisted piping fitting components such as reducers, tees, elbows and flanges, are also analyzed using the FEA and ASME BPV code design procedures. This paper discusses the design process and deviations from the base code for piping design requirements as well as special techniques to consider for high-pressure and high-cycle piping.