scholarly journals Optimization of Flat Ends in Pressure Vessels

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4194 ◽  
Author(s):  
Bogdan Szybiński ◽  
Paweł J. Romanowicz
Keyword(s):  
Stress Concentration ◽  
Parametric Optimization ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Optimal Choice ◽  
Operating Pressure ◽  
Plastic Properties ◽  
Optimal Values ◽  
Relief Groove ◽  
Minimum Stress

The application of flat ends in pressure boilers is inevitably associated with the presence of stress concentration, which is observed in the vicinity of the junction of the cylinder and the closing flat plate. The analyzed flat end plates with stress relief grooves fall into the group of solutions recognized by the respective Standards of Calculations of Pressure Vessels. Unfortunately, no clear evidence is given in the Standards on how to choose the best groove parameters. This opens up the problem of the optimal choice of the groove parameters providing a minimum stress level. Even for the optimal values defining the stress relief groove geometry, certain plastic deformations are observed in the groove area for materials which exhibit elastic-plastic properties. Such a situation is completely unacceptable during exploitation, and a suitable reduction of the operating pressure is necessary. This paper discusses the effectiveness of other designs for flat ends used in pressure vessels. The proposed modifications took the form of external ribs applied around the top of the endplate circumference. The dimensions of these ribs were set using parametric optimization. The results of the study encouraged the authors to perform a more general analysis with the use of topology optimization. The results of all performed studies proved that the reduction of stress concentration and the full elimination of plastic deformation are possible. All numerical calculations were made using the finite element code (FEM), Ansys.

Design of Flat Ends in Pressure Boilers with Circular and Elliptical Stress Relieve Grooves

2013 ◽  
Vol 477-478 ◽  
pp. 49-53 ◽  
Author(s):  
Bogdan Szybiński
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Circumferential Stress ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Optimal Choice ◽  
Circular Shape ◽  
Relief Groove ◽  
Two Parameters

Flat ends in cylindrical pressure vessels are a certain alternative for commonly used in boilers dished ends. These ends can have different form and one of the admitted proposals is the plate with the internally introduced circumferential stress relief groove. In codes [1, the grooves of circular shape are recommended. Three parameters describe the groove configuration, namely the groove radius, the minimum endplate thickness under the relief groove and the chamfer angle. The respective formulas for calculations of the first two parameters are expressed in the form of inequalities. This means that a certain range of their variation is possible. The existing codes do not give the clear suggestion about the optimal choice of values of the groove parameters, leading to the minimal value of the stress concentration in the groove area. This is usually done by numerical analysis. The significant reduction of stress concentration is observed when changing the shape of the groove from the circular to the elliptical one, which is also shown in the paper.

Numerical Analysis and Optimization of Flat Ends Parameters in Pressure Vessels with Rectangular Shape

2014 ◽  
Vol 621 ◽  
pp. 107-112 ◽  
Author(s):  
Bogdan Szybiński ◽  
Paweł Romanowicz
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Cross Section ◽  
Pressure Vessels ◽  
Main Interest ◽  
Rectangular Shape ◽  
Minimum Stress

Cylindrical pressure vessels with circular cross section are commonly used in the construction of various pressure apparatus; however in certain cases other cross sections are applied. The vessels with rectangular and elliptical perpendicular cross section are of the main interest and certain formulas for their calculations are stated in the respective codes [1, 2]. In these appliances flat ends of various shapes are usually used as the vessels caps. Similarly, as for the cylindrical boilers, flat end plates with stress relieve grooves are recommended. Like in the flat ends for cylindrical pipes certain variation of the groove parameters is possible but again no clear suggestion is given how to choose the optimal groove parameters providing the minimum stress concentration [3]. In this paper the numerical analysis and optimization of the admitted by code [1] groove parameters is presented for the pipe with the rectangular cross section subjected to the internal pressure.

Numerical and Experimental Analysis of Stress and Strains in Flat Ends of High-Pressure Vessels

2011 ◽  
Vol 490 ◽  
pp. 226-236 ◽  
Author(s):  
Bogdan Szybiński ◽  
Paweł Romanowicz ◽  
Andrzej P. Zieliński
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Experimental Investigations ◽  
Engineering Practice ◽  
Junction Area ◽  
Definite Answer ◽  
Asme Code ◽  
Relief Groove

Application of flat welded ends with stress relief grooves in high-pressure vessels is a common alternative to use of dished vessel ends. It is well established and follows calculation rules given in codes: EN-12952-3 [1], EN-13445-3 [2], or in ASME code [3]. However the calculation rules do not give any definite answer what should be the choice of parameters defining a circular stress relief groove, for example, position of the groove and its radius. Usually the choice of them relies on engineering practice. The present paper clearly shows the influence of this choice on stress concentration in the cylinder-endplate junction area. The results of numerical study are verified in experimental investigations performed for a cylindrical high-pressure vessel.

Numerical Study of a Panel with Big Grooves Subjected to In-Plane Tension

2010 ◽  
Vol 102-104 ◽  
pp. 297-300
Author(s):  
Ning Huang ◽  
Ming Hui Huang ◽  
Li Hua Zhan
Keyword(s):  
Stress Concentration ◽  
Numerical Study ◽  
Main Idea ◽  
Stress Relief ◽  
Structure Design ◽  
The Body ◽  
Transition Structure ◽  
Calculation Results ◽  
Relief Groove ◽  
Close Distance

The purpose of the present study is to propose a new technical method for improving the fatigue life of a panel with big grooves by setting rounded transition structure and stress relief slots in the vicinity of it. The main idea of the method is to reduce the stress concentration at the edges of rounded transition structure. To confirm the effectiveness of the method, analyses were performed by using software for two-dimensional elastic problems based on the body-force method. The calculation results show that the existence of stress relief slots effectively reduced the stress concentration at the edges of rounded transition structure. A close distance between the rounded transition structure and the stress relief groove resulted in a little influence of stress concentration at the edge of rounded transition structure. Also, a lower stress concentration was obtained by increasing the diameter and numbers of stress relief grooves. Results prove the effectiveness and certain engineering practicability of this method. The method is helpful for structure design.

scholarly journals Determination of Optimal Flat-End Head Geometries for Pressure Vessels Based on Numerical and Experimental Approaches

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2520
Author(s):  
Paweł J. Romanowicz ◽  
Bogdan Szybiński
Keyword(s):  
High Pressures ◽  
Experimental Tests ◽  
Pressure Vessels ◽  
Optimal Choice ◽  
Residual Welding ◽  
Experimental Approaches ◽  
Relief Groove ◽  
Strain Gauge Measurements ◽  
Selection Of

The experimental and numerical analyses of the pressure vessels with different flat ends are presented and discussed in the paper. The main aim of the study is to propose the optimal flat head end geometry. The analyses are focused on the comparison of standardized geometries and with the proposed elliptical cut-out. The experimental tests with the application of strain-gauge measurements and numerical modeling of the pressure vessel are conducted. The behavior under low and high pressures and the influence of the residual welding stresses, material properties, and geometrical tolerances on the level of the plastic deformation in the flat end is discussed. It is presented that the rules given in the recent standard are not sufficient for optimal selection of the optimal geometry. It is observed that in certain geometries the deviations of the pipe thickness may lead to a significant increase of the equivalent stresses. The residual welding stresses have a significant influence on the stress and strain level—particularly in the stress relief groove (SRG). The performed study and comparison of the different geometries allow for the proposal of the optimal shape of the flat end. It appeared that the pressure vessels with SRG are the most optimal choice, particularly when elliptic shapes are in use. In some cases (i.e., pipe with wall-thickness equal to 40 mm and the flat end with circular SRG), the optimal configuration is reached for dimensions beyond the admissible by code range.

Stress Analysis and Structure Optimization for the Opening Flat Cover of Pressure Vessels

2012 ◽  
Vol 538-541 ◽  
pp. 3253-3258 ◽  
Author(s):  
Jun Jian Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Analysis ◽  
Structure Optimization ◽  
Pressure Vessels ◽  
Secondary Stress ◽  
Element Analysis ◽  
Primary Stress ◽  
Flat Cover

According to the results of finite element analysis (FEA), when the diameter of opening of the flat cover is no more than 0.5D (d≤0.5D), there is obvious stress concentration at the edge of opening, but only existed within the region of 2d. Increasing the thickness of flat covers could not relieve the stress concentration at the edge of opening. It is recommended that reinforcing element being installed within the region of 2d should be used. When the diameter of openings is larger than 0.5D (d>0.5D), conical or round angle transitions could be employed at connecting location, with which the edge stress decreased remarkably. However, the primary stress plus the secondary stress would be valued by 3[σ].

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