PSI - Issue 17

Tamás Fekete / Procedia Structural Integrity 17 (2019) 464–471

465

Tamás Fekete / Structural Integrity Procedia 00 (2019) 000 – 000

2

geometric dimensions, typically operate at high-temperature and high-pressure regimes, and are in close contact with a harsh environment. They are designed, manufactured and commissioned with the following objectives: (1) to encompass the necessary amount of space for the implementation of the technological processes, (2) to fulfil safety functions: to separate the technology from the environment, during normal working conditions, as well as in cases of various emergency situations. The designed service lifetime of a given system is determined during the design phase. Contrarily, the technically allowed lifetime of a system is determined for the actual, completed structure. Strictly speaking, these computations are called Structural Integrity calculations. Currently a medium-term research is running in MTA EK with the ambition to develop a more physically sound, generalized methodology for future Structural Integrity calculations of large-scale pressure systems. First outcomes of the project were published in Fekete (2018). There, the main focus is on the role of modern Thermomechanics in solving Structural Integrity problems of accidental emergency events . Recently, the role of modern Thermodynamics in the development of new, innovative prediction strategies for the technically allowed lifetime calculations has been put into the focus of interest. Hereafter, the essence of our latest achievements will be presented in a nutshell. Due to the limited extent available for present paper, we focus on a conceptual explanation of the topic – following the ideas of Öttinger (2017) – , assuming that this more intuitive approach helps the reader grasp the heart of the matter. The more formal, technical details of the subject are left for forthcoming publications. The rest of the paper is organized as follows: in Section 2, the notion of Structural Integrity is explained. In Section 3, questions concerning the Structural Integrity of specific systems will be presented, while in Section 4, more general, methodological questions will be addressed, and in this context a new and significant result will be presented. Nomenclature ASME The American Society of Mechanical Engineers ESIS European Structural Integrity Society IAEA International Atomic Energy Agency MSIT Maintenance, Surveillance, Inspection and Testing OED Oxford English Dictionary PNAE Normative Rules for the Construction for Atomic Energy based Power Plants (Russian Norm) PTS Pressurized Thermal Shock Before explaining the need for the introduction of a generalized methodology for Structural Integrity calculations of large-scale pressure systems (for the sake of simplicity, hereinafter referred to as Systems), it is important to describe the contexts in which the phrase ‘ Structural Integrity ’ is used. One talks about two closely related, but – to a certain degree – different things, when the characteristic attributes of: (1) Structural Integrity for a particular System ; or (2) Structural Integrity as a scientific-engineering paradigm are put into the focus of interest. The close connection together with the inherent differences stems from the fact that in these two cases, the question concerns two different aspects of a complex, combined concept. Here, at first, we summarize the essence of the notion of Structural Integrity in cases (1) and (2); then the topic is explained in more detail. In case of a particular System (1), the phrase Structural Integrity is used to denote the whole set of coordinated activities, all designed and built up in order to ensure the safe operation of the System up to its technically allowed lifetime. Structural Integrity as a scientific-engineering paradigm (2) provides the patterns or models that show how to solve the problems – related to the technical limits (load, technically allowed lifetime) of a particular System – in a systematic and coherent way; otherwise phrased, it provides the methodologies which, if correctly used, lead to well engineered results at the accepted reliability level. 2. The notion of Structural Integrity