Global Journal of Researches in Engineering, E: Civil & Structural, Volume 23 Issue 2

ii. Using Accessories and Sensors Just as it is good sizing is necessary for the inlet and vent nozzles of the tanks, it is necessary to use sensors and devices for redundant guarantees against overpressure or vacuum, such as: pressure and vacuum relief valves, emergency pressure valves, high-level, high-high sensors, level radars, measuring rod and or pressure sensors, combined to guarantee overpressure or vacuum and temperature control. In this way all these items must be considered by the designer. Accessories ensure efficient work of tanks, balance fluid fluctuations in the tank and regulate its internal pressure. The use of sensors allows activating and opening the accessories only, when necessary, thus reducing losses due to VOC emissions - air pollution - and, consequently, the environmental impact. Therefore, care must be taken when calculating the thickness of the pressure relief valve cover, so that it does not cause mechanical damage due to non- opening or environmental damage due to unnecessary opening. The following example shows the correct sizing of the thickness of the pressure relief valve cover. Figure 2 shows the actions of pressure on the cover of an emergency valve, basically counterbalanced with the cover's own weight. Figure 2: Examples of emergency relief valve sizing (Oliveira, 2020b) iii. Internal Floating Ceilings The internal floating roof has the objective of eliminating the vapor space between the seal and the surface of the stored liquid, to avoid the fugitive emission in the storage of fuels and chemical products with low vapor pressure. In this way, the use of this type of accessory reduces the emission of VOCs. According to Oliveira (2015), the application of internal floating roofs compared to fixed roofs provides a reduction in VOC emissions of up to 98% on average, depending on the application conditions. The application of internal floating roofs, in accordance with Appendix H of API-650 (API, 2010), has become a more practical alternative in terms of design, manufacture, assembly and costs in sizing tanks (LIMA et al., 2014). This type of ceiling is a simple construction device, lightweight and an excellent financial alternative for reducing emission losses (OLIVEIRA, 2017; OLIVEIRA, 2020a). Figure 32 illustrates the constructive details of the internal floating roof. Source: Vector-Mathias (2015) Figure 3: Constructive details of internal floating roof Global Journal of Researches in Engineering © 2023 Global Journals ( ) E Volume XxXIII Issue II Version I 6 Year 2023 Atmospheric Storage Cylindrical Tanks: Project Optimization Considering Environmental Criteria