The Effects of External Pressure on Thin-Shell Pressure Vessel Heads

1962 ◽  
Vol 84 (2) ◽  
pp. 205-216 ◽  
Author(s):  
Edward O. Jones
Keyword(s):  
Experimental Data ◽  
Pressure Vessel ◽  
Thin Shell ◽  
External Pressure ◽  
The Other ◽  
Thin Wall

This paper is concerned primarily with the effects of external pressure on thin-wall torispherical, toriconical, and ellipsoidal pressure vessel heads including the determination of the collapse pressures. Two test vessels, one having torispherical and 120-deg toriconical heads and the other having ellipsoidal and 90-deg toriconical heads, were used in the study. Longitudinal and circumferential stresses per psi external pressure were plotted for the regions at which the vessel heads had been welded to the cylindrical portions of the vessels. Deflection values were plotted for the torispherical and ellipsoidal heads. Both the stress values and deflection values were determined from experimental data.

Buckling Design of Axially Compressed Cylindrical Shells Based on Energy Barrier Approach

2021 ◽  
pp. 2150165
Author(s):  
Haigui Fan ◽  
Wenguang Gu ◽  
Longhua Li ◽  
Peiqi Liu ◽  
Dapeng Hu
Keyword(s):  
Experimental Data ◽  
Energy Barrier ◽  
Thin Shell ◽  
Design Method ◽  
Lightweight Design ◽  
Cylindrical Shells ◽  
Design Criterion ◽  
The Other ◽  
Shell Structures ◽  
Buckling Loads

Buckling design of axially compressed cylindrical shells is still a challenging subject considering the high imperfection-sensitive characteristic in this kind of structure. With the development of various design methods, the energy barrier concept dealing with buckling of imperfection-sensitive cylindrical shells exhibits a promising prospect in recent years. In this study, buckling design of imperfection-sensitive cylindrical shells under axial compression based on the energy barrier approach is systematically investigated. The methodology about buckling design based on the energy barrier approach is described in detail first taking advantage of the cylindrical shells whose buckling loads have been extensively tested. Then, validation and discussion about this buckling design method have been carried out by the numerical and experimental analyses on the cylindrical shells with different geometrical and boundary imperfections. Results in this study together with the available experimental data have verified the reliability and advantage of the buckling design method based on energy barrier approach. A design criterion based on the energy barrier approach is therefore established and compared with the other criteria. Results indicate that buckling design based on energy barrier approach can be used as an efficient way in the lightweight design of thin-shell structures.

A Study of the Conservatism in ASME BPVC Section VIII Division 2 Opening Design for External Pressure

2019 ◽  
Author(s):  
Barry Millet ◽  
Kaveh Ebrahimi ◽  
James Lu ◽  
Kenneth Kirkpatrick ◽  
Bryan Mosher
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
External Pressure ◽  
The Other ◽  
Finite Element Analyses ◽  
Division 1 ◽  
Section Viii ◽  
Allowable Compressive Stress ◽  
Division 2

Abstract In the ASME Boiler and Pressure Vessel Code, nozzle reinforcement rules for nozzles attached to shells under external pressure differ from the rules for internal pressure. ASME BPVC Section I, Section VIII Division 1 and Section VIII Division 2 (Pre-2007 Edition) reinforcement rules for external pressure are less stringent than those for internal pressure. The reinforcement rules for external pressure published since the 2007 Edition of ASME BPVC Section VIII Division 2 are more stringent than those for internal pressure. The previous rule only required reinforcement for external pressure to be one-half of the reinforcement required for internal pressure. In the current BPVC Code the required reinforcement is inversely proportional to the allowable compressive stress for the shell under external pressure. Therefore as the allowable drops, the required reinforcement increases. Understandably, the rules for external pressure differ in these two Divisions, but the amount of required reinforcement can be significantly larger. This paper will examine the possible conservatism in the current Division 2 rules as compared to the other Divisions of the BPVC Code and the EN 13445-3. The paper will review the background of each method and provide finite element analyses of several selected nozzles and geometries.

Experimental Determination of the Static Equivalent Pressures of Detonative Explosions of Stoichiometric CH4/O2/N2-Mixtures and CH4/O2-Mixtures in Long Pipes

2016 ◽  
Author(s):  
Hans-Peter Schildberg
Keyword(s):  
Experimental Data ◽  
Experimental Determination ◽  
Process Design ◽  
Pressure Vessel ◽  
Gas Mixture ◽  
Detonation Pressure ◽  
Recent Past ◽  
Static Loads ◽  
Present Experimental Data

In the recent past (PVP2013-97677, PVP2014-28197, PVP2015-45286) we had started to determine the static equivalent pressures pstat of the eight detonative pressure scenarios in long and short pipes for different detonable gas mixtures. The pstat-values are of vital importance for process design: by assigning static equivalent pressures to the highly dynamic detonative pressure peaks it is possible to apply the established pressure vessel guidelines, which can only cope with static loads, for the design of detonation pressure resistant pipes. One important finding was that the ratio R between pstat at the location where transition from deflagration to detonation occurs and pstat in the region of the stable detonation strongly depends on the reactivity of the gas mixture. In this paper we present experimental data showing the variation of R over the entire explosive range of Methane/O2/N2 mixtures. Qualitatively, the results should be representative for all other combustible/O2/N2-mixtures. Furthermore, recommendations for estimating pstat values of short pipe scenarios on basis of the long pipe scenarios are given.

scholarly journals The thickness functions of the shells of revolution subjected to axisymmetrical loads

2005 ◽  
Vol 27 (2) ◽  
pp. 66-73
Author(s):  
Ngo Huong Nhu ◽  
Pham Hong Nga
Keyword(s):  
Differential Equations ◽  
Thin Shell ◽  
Numerical Solutions ◽  
External Pressure ◽  
Shells Of Revolution ◽  
Varying Thickness ◽  
Shell Design ◽  
Mathematical Difficulties ◽  
Thickness Function

The inverse problems for determining the meridian shape or varying thickness function of momentless shells of revolution under given loads were concerned in many works [2, 3, 4]. However, for the complexity of loads or configuration of a shell these problems haven' t bee.n solved perfectly because of its mathematical difficulties. In this paper, the problem for determining the thickness function of shells of revolution such as a parabola, sphere arc! under axisymmetrical loads is considered. The general integro-differential equations for determination of the meridian form and shell thickness are obtained. A solution of differential equations by semi-analytical and numerical methods for the thickness is presented. The numerical solutions are given for the parabola under external pressure, the sphere immerged in the fluid and the sphere arc. Obtained results may be used in the thin shell design.

Use of Stress-Strength Model in Determination of Safety Factor for Pressure Vessel Design

1996 ◽  
Vol 118 (1) ◽  
pp. 27-32 ◽  
Author(s):  
S. Quin ◽  
G. E. O. Widera
Keyword(s):  
Safety Factor ◽  
Pressure Vessel ◽  
External Pressure ◽  
Strength Model ◽  
Design Practice ◽  
Factors Affecting ◽  
Normal Distributions ◽  
Combined Loads ◽  
A Value

In pressure vessel design, the values of safety factor are still determined on the basis of engineering experience. Thus, they cannot properly reflect the influence of the consequences of failure and the variabilities in stress and strength. As a result, designsare often excessively conservative, while on the other hand, the possibility of failure still exists. Two approaches for determining the value of the safety factor, which are based on reliability analysis, are presented in this paper. As a result of a comparison, one approach based on a stress-strength model is found to be appropriate for pressure vessel design practice. By transforming the interference parts of the distributions of stress and strength into equivalent normal distributions, the approach allows stress and strength to have arbitrary distributions. Three examples, one in which a vessel is subjected to internal pressure, one in which a tall vessel is subjected to combined loads, and one in which a vessel is subjected to external pressure, are given in the paper. From threexamples, the principles for determining target reliability and the factors affecting the safety factor are discussed. It is concluded that by using the approach presented in this paper for pressure vessel design, different consequences of failure as well as variabilities in stress and strength can be taken into account. The approach yields a value for the safety factor that leads to a design which will be safer and yet more economical.

Boundary Effect and Weld Reinforcement of Large Opening With Flush Nozzle in Ellipsoidal Head Pressure Vessel

2005 ◽  
Author(s):  
Chongzhi Guo ◽  
Wenxin Chen
Keyword(s):  
Experimental Data ◽  
Pressure Vessel ◽  
Thin Shell ◽  
Shell Theory ◽  
Boundary Effect ◽  
Head Pressure ◽  
Large Opening ◽  
Weld Root ◽  
Joint Range ◽  
Thin Shell Theory

By the analysis of the single and double boundary effect of the large opening structure with flush nozzle in pressure vessel with ellipsoidal head in terms of Thin Shell Theory, stress distribution of the two cases are obtained in this paper. Then numerical and experimental verifications are carried out by finite element method (FEM) and experiments. Comparing theoretic and numerical results with experimental data respectively; it is found that FEM or theoretic results accord with the experimental data well, while there is some non-consistence between the FEM or theoretic results and the experimental data within joint range. According to the consistence between the analysis results of FEM and those of thin shell theory in weld roots, a newly weld reinforce effect calculation approach of the welt joint is proposed by considering the size of the weld joint and using the results of thin shell theory in the roots of the weld. Example presented indicates that, as a quick and convenient evaluation means, using the results of thin shell theory in weld root to evaluate joint strength is available and reliable.

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