Pressure vessel design by analysis

Abstract

Every new construction of pressure vessels and boilers has been designed to ensure safe and reliable performance necessary during its operational life span. Understanding how the pressure vessel fails is one of key criteria to avert any unnecessary catastrophic accident. Applying the right tools in the design phase, will not only ensure reliability and safety but also promises uninterrupted business operation that is important to the operator’s perspective.

In the analysis, fatigue is regarded as the primary criteria for the pressure vessel failure. In order to assess the behavior leading to fatigue failure when pressure and thermal loads are applied, a mandatory procedure established by the American Society of Mechanical Engineers (ASME) in Section VIII Division 2, provides detailed technique. In this study, prior to applying the ASME code, computer aided design software was used to model the pressure vessel. ANSYS, a computing tool, assessed the model based on Finite Element Method, providing numerical stress values that reflect the changes in behavior. Fatigue Assessment is finally conducted using Microsoft Excel’s mathematical function to compute a ratio known as usage factor.

Assessment conclusively shows that highly stressed regions yield usage factor below passing requirements and hence, the pressure vessel will unlikely pass the ASME code. In addition, remodeling and refining the parameters was performed but did not yield improvement.