The persuasion of vaccine allocation models during Covid-19. Rhetoric, ethics and science

The swift development of effective vaccines against the new coronavirus was an unprecedented scientific achievement. In this paper, we discuss what models have been proposed for distributing vaccines locally and globally through the application of Aristotelian rhetoric. This discussion, therefore, focuses on a specific question: how are the different models of vaccine administration and distribution justified on an ethical-argumentative level? This report also examines what has come to be known as “vaccine nationalism” through the lens of the early experience with the COVID- 19 vaccination process. To this end, this report proceeds as follows: Section I explains the rhetorical method applied to ethical principles, and Section II explains the chosen criteria for the analysis. Section III looks at the Fair Priority Model; Section IV examines the COVAX and GAVI model; Section V presents the weighted lottery model. Section VI proposes a summary table of the analysis of the proposed models and Section VII focuses on the ethical problem of vaccine nationalism and its implications in relation to the models, that were taken into consideration during the previous sections. Section VIII offers brief conclusions; solidarity conceived as an argument of reciprocity should be, according to this analysis, the guiding value to address ethical problems in the area of resource allocation.

Finite Element Analysis of Gasket in Pressure Vessel

Pressure vessel is a closed container designed to hold liquids or gases at a pressure which are higher than the surrounding atmospheric pressure. These pressure vessels are not made as a single component but manufacture with an assembly of many other components and connected through bolted joints or riveted joints or welded joints. These joints are susceptible to failure and cause leakage of the liquid or gas which are very dangerous and sometimes causes heavy loss of life, health and property. Hence proper care has to be taken during the design analysis processes by following ASME section VIII division 1 which specifies the design-by-formula approach while division 2 contains a set of alternative rules based on design by Analysis (FEA) to determine the expected deformation and stresses that may develop during operation. The ASME section-VIII division-2 standards are used for the design of pressure vessel. Leakage in gasketed flanged joints have always been a great problem for the process industry. The sealing performance of a gasketed flanged joints depends on its installation and applied loading conditions. The present project work involves the design procedure and stress analysis (Structural Analysis) for the leak proof pressure vessel at the gasket under three different gasket conditions. Keywords: 1. FEM, 2. ASME, 3. ANSYS, 4. Gasket,5. Displacement,6. Stress

Failure Mode Determination of API 12F Shop-Welded Tanks with a New Roof-to-Shell Junction Detail

The API 12F is the specification for vertical, aboveground shop-welded storage tanks published by the American Petroleum Institute (API). The nominal capacity for the twelve tank designs given in the current 13th edition of API 12F ranges from 90 bbl. (14.3 m3) to 1000 bbl. (159 m3). The minimum required component thickness and design pressure levels are also provided in the latest edition. This study is a part of a series research project sponsored by API that dedicates to ensure the safe operation of API 12 series storage tanks. In this study, the twelve API 12F tank designs presented in the latest edition are studied. The elastic stress analysis was conducted following the procedures presented in the ASME Boiler and Pressure Vessel Code 2019, Section VIII, Division 2 (ASME VIII-2). The stress levels at the top, bottom, and cleanout junctions subject to the design pressures are determined through finite element analysis (FEA). The bottom uplift subjected to design pressures are obtained, and the yielding pressure at the roof-shell and shell-bottom junctions are also determined. The specific gravity of the stored liquid is raised from 1.0 to 1.2 in this study. A new roof-shell attachment detail is proposed, and a 0.01 in. (0.254 mm) gap between the bottom shell course and the bottom plate is modeled to simulate the actual construction details. In addition, the flat-top rectangular cleanout presented in the current edition of API 12F is modeled.

Investigation of Nozzle on Knuckle Region of Dished Head

ASME Code Section VIII Division 1 [1] provides rules for the shape of openings, size of openings, strength and design of openings, however, the existing rules do not provide any restrictions on the specific location of the nozzle on the dished head knuckle region. Many corporate guidelines/ user design requirements meant for pressure vessel design and specification suggest avoiding placement of any type of nozzle in the knuckle area of a dished head and generally state in their design specification to limit the placement of a nozzle including its reinforcement within the crown area. This applies to Torispherical and Ellipsoidal dished heads. Code [1] rule UG-37(a) provides the benefit in reinforcement by reducing the required thickness (tr) of the dished head when the nozzle is in the spherical portion of the dished head for the Ellipsoidal and Torispherical dished head. High stresses occur in the knuckle region of the dished head due to the edge bending effect caused as the cylinder and head try to deform in different directions. For various reasons the user design requirements insist on placing the nozzle in the knuckle region, further compounding the complexity of the stress pattern in the knuckle area. The work carried out in this paper was an attempt to check whether it is safe to locate a nozzle in the knuckle region of the dished head since the knuckle portion is generally subjected to higher stresses in comparison to the crown portion of a dished head and the Code [1] and [2] does not impose any restrictions for the placement of nozzles in the knuckle region. Also, in this paper an attempt was made to evaluate the induced stresses when equivalent sizes of nozzles are placed in the crown as well as the knuckle portion of the dished head.

Applicability of Design Rules for Openings in Shells, ASME B&PV Code, Section VIII, Division 2 - A Case Study

The Pressure-Area method is recently introduced in the ASME Boiler and Pressure Vessel (B&PV) Code, Section VIII, Division 2 to reduce the excessive conservatism of the traditional area-replacement method. The Pressure-Area method is based on ensuring that the resistive internal force provided by the material is greater than or equal to the reactive load from the applied internal pressure. A comparative study is undertaken to study the applicability of design rules for certain nozzles in shells using finite element analysis (FEA). From the results of linear elastic FEA, it is found that in some cases the local stresses at the nozzle to shell junctions exceed the allowable stress limits even though the code requirements of Pressure-Area method are met. It is also found that there is reduction in local stresses when the requirement of nozzle to shell thickness ratio is maintained as per EN 13445 Part 3. The study also suggests that the reinforcement of nozzles satisfy the requirements of elastic-plastic stress analysis procedures even though it fails to satisfy the requirements of elastic stress analysis procedures. However, the reinforcement should be chosen judiciously to reduce the local stresses at the nozzle to shell junction and to satisfy other governing failure modes such as fatigue.

Failure Modes for Acrylic Polymers in Section VIII Pressure Vessels

Section VIII of the Boiler and Pressure Vessel Code is introducing the use of acrylics as a pressure vessel material. The design method is specified in ASME PVHO-1, Safety Standard for Pressure Vessels for Human Occupancy. The current method relies upon an empirical method developed in the 1960–70’s. It does not use “allowable stress” or other mechanical properties traditionally used to calculate design dimensions, but instead uses a fixed range of dimensions for specific shapes and determines the wall thickness using a curve. Understanding the PVHO-1 design assumptions and typical failure modes is important for a non-PVHO pressure vessel designer using acrylics. An ASME Codes & Standards task group is developing a “design by analysis” method (DBA) for acrylics and other glassy polymers for pressure vessel components. The proposed DBA methodology uses Verification and Validation (V&V) techniques and Finite Element Method (FEM) as the design method framework in order to advance the use of glassy polymers as pressure vessel materials.

Study on Influence of Branch Connection That Affects to Design Length of Pressure Design Under External Pressure

Pressure design of straight pipe under external pressure is performed in accordance with ASME B31.3 and Section VIII, Division 1 of Boiler and Pressure Vessel Code. And design length of straight pipe shall be defined in accordance with UG-28 and UG-29. However, there is no specific guideline about the design length which includes branch connection in piping system. Even though the branch connection is not a stiffening component, calculated result shows that increased design length can be considered for piping including the branch connection compared to straight pipe. This paper presents the study result that shows a tendency depending on several geometry parameters (e.g. Ratio of a diameter of header pipe to a thickness of header pipe.) using elastic buckling analysis performed in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 2. In addition to the result, this paper compares the design length of straight pipe with that of piping system including the branch connection under about the same eigenvalue condition which is called as a “Buckling load multiplier”. Shell element is enough to check the tendency and compare various results by comparison with solid model, because the result is related to overall structural integrity rather than local stress. Shell element is used in the elastic buckling analysis.

A Comparative Study of Radial Nozzle Criteria; Section VIII, Division 2, Part 4.5.5 to Part 5.2.2

A study is presented which compares nozzle thickness requirements based ASME Section VIII, Division 2, Parts 4 and 5[1]. Specifically, the simplified geometry of a set-in, radial nozzle without inward projection or repad is considered. The comparative technique considers a design pressure at the capacity of the shell and identifies the minimum nozzle thickness that satisfies applicable stress limits. For Part 4, the methodology of 4.5.5 is used. For Part 5, the elastic method in 5.2.2 is used. The study employs these techniques for R/t geometries of 20 to 180 and d/D ratios of 0.01 to 0.3. The comparison indicates elastic analysis Part 5 methods can improve the design from that of Part 4 over some, but not all, configurations within the study’s scope. The bounds of where the elastic analysis Part 5 methods benefit are identified. In the process of the study’s effort, numerous responses are identified and compared between design methodologies. The comparison is one of needed nozzle thickness for similar geometries. Behavior responses are shown from the range of configurations in the large simulation set created by the Part 5 method. For the Part 4 response, charts are shown that identify the required nozzle thickness based on the varying reinforcing limit logic employed in that method.