Analysis of small dimension piping

Utifrån en ny syn på konsultrollen erbjuder Epsilon ett brett urval av expertis inom teknik och systemutveckling. Med en organisation som är nyfiken, alert och flexibel skapar vi lösningar som tillför våra kunder och medarbetare betydande växtkraft, både på kort och lång sikt. Keywords: Piping, Stress analysis, Dynamic analysis, FE-analysis, Plasticity, Damping Background Within the discipline of mechanical engineering, a basic and fundamental requirement in Nuclear Power Plant industry is to secure structural- and pressure integrity for pressure vessels and piping. In Sweden, general design criteria?s is regulated by Swedish national laws and in detail in the code Boiler and Pressure Vessel code ASME III. The code sets boundaries for the design, and the main task for the piping analyst is to assure that the system fulfils requirements of the code. In law and code there is a high focus on safety and the plant should even be able to withstand events like earthquake. To verify the system for such event, normally advanced dynamic analysis is performed. This kind of analysis aim to predict the behaviour of a certain piping system and by that give the system a sufficient safety factor against collapse. Common industrial methods used suits well for evaluation of piping systems of larger dimensions. However, when it comes to smaller dimension the methods, used for dynamic analysis, often gives unpredictable and in some cases unrealistic results. Besides this, the dynamic FE-analysis is time consuming and an expensive way to qualify small piping. Task Description The aim is to increase understanding of the behaviour of piping with small dimensions exposed to large amplitude dynamic loadings, such as earthquake. In a recently published (2009) Master?s thesis accomplished at Epsilon in cooperation with Chalmers and Ringhals a number of practical dynamical tests in a laboratory were carried out. Initial analytical models and FE-analyses were also performed in this Thesis. However, further studies need to be carried out to understand real behaviour when load in the pipe is close to collapse load. A more detailed analysis of real behaviour might lead to enhanced evaluation criteria?s for this kind of piping. The main part of this project will be to investigate existing test data from the laboratory and try to describe the behaviour within FE analysis. Parameters to investigate could be damping and plasticity. The objectives of the work are to: - Search existing literature, articles and studies of small piping exposed to large amplitude dynamic loading. Investigate requirements within the Nuclear Piping Code ASME III. - Perform analyses on small piping in a FE-software and to investigate in what ways different parameters (damping, plasticity, number of cycles, beam, shell or solid elements) influences the result. - Elaborate and develop the FE-analysis by comparing results to real test data. In a long term the intention is to use those results when forming a methodology on how to evaluate small piping in Nuclear Power industry. (This may not be within the scope of the Master?s Thesis). Välkommen med din ansökan på www.epsilon.nu!