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.

Generation of Plastic Collapse Load Boundaries of a Pressurized Cylindrical Vessel/Radial Nozzle Structure Subjected to Nozzle Bending Loadings Utilizing Various Plastic Collapse Load Techniques

This research focuses on generating the plastic collapse load boundaries of a cylindrical vessel with a radial nozzle via employing three different plastic collapse load techniques. The three plastic collapse load techniques employed are the plastic work curvature (PWC) criterion, the plastic work (PW) criterion, and the twice-elastic-slope (TES) method. Mathematical based determination of plastic collapse loads is presented and employed concerning both the PWC and the PW criteria. A validation study is initially conducted on a pressurized 90-degree pipe bend structure subjected to in-plane closing bending via finite element analyses along with an elaborate explanation of the mathematical approaches for determining the plastic collapse loads via the PWC and the PW criteria. Outcomes of the validation study revealed very good outcomes for the three techniques. Accordingly, the aforementioned three techniques are utilized to determine the plastic collapse load boundaries of a pressurized cylindrical vessel/nozzle structure subjected to in-plane (IP) and out-of-plane (OP) bending loadings applied on the nozzle one at a time. The TES method revealed considerate limitations when applied within the medium to the high internal pressure spectra. It is shown that both the PWC and the PW criteria outperform the TES method in computing the plastic collapse loads. The vessel/nozzle structure revealed relatively higher plastic collapse moment boundaries under IP bending as compared to OP bending. Conclusively, methodical steps are devised for determining the plastic collapse loads via the PWC and the PW criteria for the ease of systematic application on pressurized structures in general.

Effect of Pad Reinforcement on the Plastic Limit Load for Nozzle Connection of Cylindrical Vessel

The objective of this paper is the further investigation of the shell intersection problem. The pad reinforced nozzle connections of the cylindrical vessel under internal and external loads are investigated using elastic–plastic analysis and the stress analysis in intersecting shells (SAIS) special-purpose computer program. The method for determining the plastic limit load based on the maximum criterion of the rate of the change of the relative plastic work and program module LOAD_PL for its realization are presented. The results of comparisons with the twice elastic-slope (TES) method were considered for determining the plastic limit load using known experimental data for models of a pad reinforced cylindrical vessel with a radial nozzle under a transverse force. The results of a parametric study of unreinforced and pad reinforced vessel models with a nozzle under internal pressure, in-plane moment, and out-plane moment loadings are discussed.

Evaluation of a solid stream radial nozzle on fixed-wing aircraft, for penetration of spray within a soybean canopy

Experiments were conducted to evaluate the Accu-Flo multiple orifice nozzle for penetration of spray into a soybean (Glycine max L.) canopy by comparing results to those from a popular straight stream nozzle and rotary atomizer. A mixture of water + Induce® adjuvant was applied at three different spray release heights in a random sequence, using an Air Tractor 402-B agricultural aircraft. Sampler stands were placed at twenty-four locations in the field. Water sensitive paper (WSP) cards were clipped onto rigid stands just above the canopy and 30 cm off the ground within the canopy. Weather data were recorded using two different stations on-site. Wind was predominantly from the west and parallel to the direction of the spray runs. The spray delivery systems compared were the Accu-Flo nozzles, (64 needle 0.020 opening), CP®-09 straight stream with 5 degree deflection, and Micronair® AU5000 atomisers (14 mesh screen) at a low volume spray rate of 18.7 l/ha. A total of 54 spray runs were made over three days, and heights were varied at 3.7 m, 4.9 m and 6.1 m. Water sensitive papers were scanned and analysed for coverage per unit card area using an image analysis system. Altitude and [Nozzle X Altitude] interaction were significant effects on coverage at the 0.01 and 0.07 significance levels, respectively, for the top cards. Nozzle type was not a significant effect on coverage for the top cards, but was significant at the 0.01 level for the bottom cards. Altitude alone had no obvious effect on coverage for the bottom cards, although it had an effect for the top cards. The highest percentage area of spray coverage was observed from the Accu-Flo nozzles, especially for the bottom cards. Average spray coverage from the Accu-Flo nozzles was 1.7 times higher than coverage from the CP® nozzles or Micronair® atomisers in the lower portion of the canopy.

Parametric Study of Nozzle Connections in Ellipsoidal Head Pressure Vessel

This paper presents 3-D solid structural modeling and stress analysis of radial nozzle connections in ellipsoidal heads vessel subjected to internal pressure and various external loadings. Finite Element Analysis (FEA) method was utilized to determine the stress distribution at the intersection of a radial nozzle attached to the ellipsoidal head. In order to get better understanding of the structure behavior, a parametric study was carried out to determine influences of the geometrical parameters. All the results analysis was presented as graphs of non-dimensional parameters against stress concentration factor (SCF) for each load case applied.

Stress Analysis of Shell Intersections With Torus Transition Under Internal Pressure Loading

Thin shell theory and finite element method were used to investigate shell intersections with torus transition. The developed special-purpose computer program SAIS is employed for elastic stress analysis of the shell intersections. Comparison of calculated results with experimental data are presented. The parametric study of models for the radial nozzle connections in shells under internal pressure loading was performed. The results are presented in graphical form. Nondimensional geometric parameters are considered to analyze the effects of changing these parameters on stress ratios in the shell intersections.

Photoelastic investigation of stress intensifications in the interacting nozzle attachment region of pressure vessels

In this paper, the problem of determining the opening mode (mode I) stress intensity factor (SIF) from the photoelastic isochromatic fringe pattern associated with a surface crack located in the ligament region between two radial nozzle-cylinder junctions of pressure vessel has been investigated. The objective is to determine the influence of geometry, size and location of the surface flaw with respect to the radial nozzles. Starting from the crack tip stress field formulation of Etheridge and Dally using three parameters (1)† a new method suited to the analysis of photoelastic data obtained from a single isochromatic fringe loop to extract the SIF has been introduced. This new method has been used to predict SIFs for a range of pressure vessel nozzle spacings when photoelastic models are subjected to internal pressure loading.