Corrosion Under Insulation(CUI) of carbon steel and low alloy steel in oil refinery and petrochemical plants is the most important degradation phenomena of equipment materials. Since the characteristics of CUI have not been fully understood the accurate prediction and estimation of CUI is difficult actually. In this study, data collection of CUI was carried out in actual plants. This information is analyzed for clarifying the controlling factors of CUI. The modification of CUI Technical Module published by API is examined based on this analysis. From this study, it become obvious that the corrosion rates of CUI may follow Gumbel distribution, and CUI are controlled by types of equipments, temperature and structure design. In particular, corrosion rate of CUI is accelerated at impediment to drainage area such as stiffening ring of tower. Based on the present results, the modification of CUI technical module was established for the more accurate prediction and estimation of CUI.
The fire damage FFS assessment is based on the material degradation associated with heat exposure. The proposed identification of heat exposure zone will be provided in the API 579-1/ASME FFS-1 Standard. As the useful judgments, temper colors and mechanical properties such as tensile strength, hardness, impact energy, ductility and so on for the damaged materials.
However, the reference temper colors are shown only by the names of colors without photographic examples and the details of metallurgical analysis are not available in the Standard.
This paper presents the temper color reference shows by presenting several photographic examples of different exposed temperature, elapsed time and cooling rates for carbon steel and stainless steel.
The metallurgical analysis guide describes typical degradations in mechanical properties and appearances in microstructure observed in the materials exposed to fire, evaluation criteria, procedure for replica preparation, personnel qualification and so on.
This research consists of three parts. First is the study about the flow influenced by the pile dike in the river. Second is an examination of whether regions in pile dikes are suitable as a habitat for fish. Third is a numerical analysis concerning the relationship between the flow and the behavior of fish.To complete the first part, velocity of flow and water depth in an open channel is measured. In the second part, fresh water fish (Tribolodon hakonensis) are released into the flow and their behavior is observed by video camera. Finally, the two-dimensional shallow water equation is used to examine the profile of the flow. The random walk method is adopted to examine the behavior of fish in the flow.The flow and the behavior of fish in the channel become clean through our experiment and numerical analysis.
The collection of the actual damage data and statistical analysis are introduced by some case studies in order to apply them to the practical maintenance in chemical plant. In the case of the radiation tube with oxidation, the inspection data were grouped by the actual damaged condition and the life prediction by the statistical analysis was conducted. From the result, the replace plan was clarified. In two case studies on external corrosion, the corrosion data and associated information were collected from the actual plant and statistical analysis was conducted. From the result, the acceleration factors of the external corrosion were quantitatively clarified by the distribution of the corrosion rate. Based on the results, the technical module was developed. And in actual plant, the inspection was planned and carried out From these case studies, it is recognized that understanding the characteristics of the degradation is important for the statistical analysis of damage data.
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