Elastic-Shakedown Analysis of Axisymmetric Nozzles

2003 ◽  
Vol 125 (4) ◽  
pp. 365-370 ◽  
Author(s):  
Martin Muscat ◽  
Donald Mackenzie
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lower Bound ◽  
Pressure Vessel ◽  
Element Analysis ◽  
Shakedown Analysis ◽  
Elastic Plastic ◽  
Section Viii ◽  
Elastic Shakedown ◽  
Division 2

An investigation of the shakedown behavior of axisymmetric nozzles under internal pressure is presented. The analysis is based on elastic-plastic finite element analysis and Melan’s lower bound shakedown theorem. Calculated shakedown pressures are compared with values from the literature and with the ASME Boiler and Pressure Vessel Code Section VIII Division 2 primary plus secondary stress limits. Results obtained by the lower bound method are also verified by cyclic elastic-plastic finite element analysis.

A New Method of Stress Linearization for Design by Analysis in Pressure Vessel Design

2014 ◽  
Vol 598 ◽  
pp. 194-197
Author(s):  
Hong Jun Li ◽  
Qiang Ding ◽  
Xun Huang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
New Method ◽  
Stress Distributions ◽  
Bending Stress ◽  
Element Analysis ◽  
Stress Tensors ◽  
Section Viii ◽  
Division 2

Stress linearization is used to define constant and linear through-thickness FEA (Finite Element Analysis) stress distributions that are used in place of membrane and membrane plus bending stress distributions in pressure vessel Design by Analysis. In this paper, stress linearization procedures are reviewed with reference to the ASME Boiler & Pressure Vessel Code Section VIII Division 2 and EN13445. The basis of the linearization procedure is stated and a new method of stress linearization considering selected stress tensors for linearization is proposed.

Design of Ellipsoidal Heads Using Elastic-Plastic Finite Element Analysis

2002 ◽  
Author(s):  
Donald J. Florizone
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Large Strain ◽  
Large Diameter ◽  
Spherical Shape ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Section Viii ◽  
Design Calculations

Traditional design techniques result in excess material being required for ellipsoidal heads. The 2001 ASME Boiler and Pressure Vessel Code Section VIII Division 1, UG-32D and Section VIII Division 2, AD-204 limit the minimum design thickness of the heads. ASME Boiler and Pressure Vessel Code Case 2261 provides alternate equations that enable thinner head design thickness. VIII-2 Appendix 3 and 4 methods potentially could be used to further optimize the head thickness. All the equations in the code use one thickness for the entire head. On large diameter thin heads the center or spherical area is often thicker than the knuckle area due to the method of manufacture. Including this extra material in the design calculations results in an increase of the MAWP of large diameter thin heads. VIII-2, AD-200 of the code permits localized thinning in a circumferential band in a cylindrical shell. Applying these same rules to elliptical heads would permit thinning in the knuckle region as well. Engineers have powerful finite element analysis tools that can be used to accurately determine levels of plastic strain and plastic deformed shapes. It is proposed that VIII-2 Appendix 4 and 5 methods be permitted for the design of elliptical heads. Doing so would permit significant decreases in thickness requirements. Different methods of Plastic Finite Element Analysis (PFEA) are investigated. An analysis of a PVRC sponsored burst test is done to develop and verify the PFEA methods. Two designs based on measurements of actual vessels are analyzed to determine the maximum allowable working pressures (MAWP) for thick and thin heads with and without local thin regions. MAWP is determined by limit analysis, per VIII-2 4-136.3 and by two other proposed methods. Using Burst FEA, the calculated burst pressure is multiplied by a safety factor to obtain MAWP. Large deflection large strain elastic perfectly plastic limit analyses (LDLS EPP LL) method includes the beneficial effect of deformations when determining the maximum limit pressure. Elliptical heads become more spherical during deformation. The spherical shape has higher pressure restraining capabilities. An alternate design equation for elliptical heads based on the LDLS EPP LL calculations is also proposed.

Qualification of a Jacketed Vessel Using Finite Element Analysis

2003 ◽  
Author(s):  
Yogeshwar Hari ◽  
Ram Munjal ◽  
Chawki Obeid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
External Pressure ◽  
Element Analysis ◽  
Ring Location ◽  
Section Viii ◽  
Specific Configuration ◽  
Inner Vessel ◽  
Vessel Bottom

The main objective of this paper is to improve a jacketed vessel. The jacketed vessel is usually chosen to heat the contents of the vessel. The chamber or annulus contains fluid under pressure to heat the inner vessel contents. The initial over-all dimensions of the vessel are based on the capacity of the stored liquid. The design was in accordance with the ASME Boiler & Pressure Vessel Code, Section VIII, Div 1. The jacketed vessel bottom head and jacket bottom head are being improved to withstand internal and external design pressures. Bottom head of the jacket can be reinforced in one of the three ways, namely: (1) rings which are radial (these rings also create flow for the fluid); (2) attachment of the rings to the bottom jacket head with stays, since rings cannot be physically welded to the bottom jacket; or (3) there is a possibility, the new bottom head and jacketed head combination can be cast, but that would not be economically feasible. This leads to the following six configurations considered in this paper and they are: (1) internal pressure of 50 psi, (2) external pressure + vacuum pressure of 65 psi, (3) reinforcement with 5 rings with external pressure of 65 psi, (4) rings welded with the bottom jacket head with external pressure of 65 psi, (5) welded with stays on ring location (stay diameter of 1 inch) with external pressure of 65 psi, and (6) welded with stays on ring location (stay diameter of 1.5 inch) with external pressure of 65 psi. The pattern of stays chosen for this analysis is one of uniform distribution on ring locations, which are radially situated. The design dimensions based on Code sizing are used to recalculate the stresses for the jacket vessel. The dimensional jacketed vessel is modeled using STAAD III Finite Element Analysis (FEA) software. The design is found to be safe for the specific configuration considered herein with stays.

Application of Elastic-Plastic Design Data in the New ASME B&PV Code Section VIII Division 2

2010 ◽  
Author(s):  
David J. Dewees
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Plastic Material ◽  
Kinematic Hardening ◽  
Strain Curve ◽  
Design Data ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Section Viii ◽  
Division 2

The updating and re-writing of the ASME Boiler and Pressure Vessel Code, Section VIII Division 2 (2007) [1] has introduced several new and unique features. One of these features is the inclusion of specific materials data for use in elastic-plastic analysis of pressure vessel components. Both monotonic and cyclic stress strain curve models are provided, with supporting constants for a range of materials and temperatures. The elastic-perfectly plastic material model has been used in commercial Finite Element (FE) codes for many years to perform limit load and ratcheting analyses. The new material models and data of Section VIII Division 2 (S8D2) include strain hardening and are intended for use in deformation assessments, and for determining cyclic plastic strain ranges in fatigue evaluations. This paper presents one possible implementation of the Code models and data into a standard cyclic hardening model; the multiple backstress, nonlinear kinematic-hardening model of Chaboche, as implemented in the commercial Finite Element program Abaqus, versions 6.8 and later.

Comparison of Different Methodologies for Stress Analysis of Reinforcing Pads

2003 ◽  
Author(s):  
Michael W. Guillot ◽  
Jack E. Helms
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Software Package ◽  
Research Council ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Division 1 ◽  
Section Viii ◽  
Design Requirements

Finite element analysis is widely used to model the stresses resulting from penetrations in pressure vessels to accommodate components such as nozzles and man-ways. In many cases a reinforcing pad is required around the nozzle or other component to meet the design requirements of Section VIII, Division 1 or 2, of the ASME Pressure Vessel Code [1]. Several different finite element techniques are currently used for calculating the effects of reinforcing pads on the shell stresses resulting from penetrations for nozzles or man-ways. In this research the stresses near a typical reinforced nozzle on a pressure vessel shell are studied. Finite element analysis is used to model the stresses in the reinforcing pad and shell. The commercially available software package ANSYS is used for the modeling. Loadings on the nozzle are due to combinations of internal pressure and moments to simulate piping attachments. The finite element results are compared to an analysis per Welding Research Council Bulletin 107 [2].

A Study of a Non-API Flange

2017 ◽  
Author(s):  
Shah Alam ◽  
Ulan Dakeev
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Oil And Gas ◽  
Band Width ◽  
Element Analysis ◽  
Acceptance Criterion ◽  
Elastic Plastic ◽  
Section Viii ◽  
Leak Tightness

API rated flanges [1] are used in oil and gas industries frequently. The current practice is to select a flange and its seal/gasket from a tabulated range of load and area of application. Some applications may require a unique flange or seal for a pressure and temperature that is not listed on the table. To design such non-API flange (geometry such as thickness, number of bolts, bolts pattern, etc. are different from API flange) that meets system requirements is a challenge. Currently there is no standard available as per authors knowledge to design non-API flange. Therefore, in this study, a finite element analysis with new acceptance criterion for the 5”-15-ksi non-API flange connection for different pressure and temperature has been performed. Elastic-plastic finite element analysis method is used to check the leak tightness [2]. A fatigue calculation based on elastic-plastic analysis with twice yield method as per ASME Section VIII, Division 2 [3], sec. 5.5.4, has also been performed. A new acceptance criterion based on industry practices are used for leak tightness. The contact pressure and contact pressure band width are used to check the leak tightness. The results showed that for all load cases seals have enough contact pressure and contact pressure band width to prevent leakage and they meet the acceptance criteria. The calculated fatigue life was found more than the required life for an application.

Development of Design Rules for Nozzles in Pressure Vessels for the ASME B&PV Code, Section VIII, Division 2

2011 ◽  
Author(s):  
Zhenning Cao ◽  
Les Bildy ◽  
David A. Osage ◽  
J. C. Sowinski
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Working Pressure ◽  
Element Analysis ◽  
Design Rules ◽  
Pressure Area ◽  
Section Viii ◽  
Division 2

The theory behind the pressure-area method that is incorporated in the ASME B&PV Code, Section VIII-2 is presented in this paper. Background and insight to the nozzle rules of ASME B&PV Code, Section VIII, Division 2, Part 4, paragraph 4.5 are also provided. Recommendations for modifying the current nozzles rules, those published in ASME B&PV Code, Section VIII, Division 2, 2010 Edition, is given based on continuing research and development efforts. A comparison between experimental results, results derived from detailed finite element analysis (FEA), the rules prior to the VIII-2 Rewrite (2004 Edition), and the rules in VIII-2 are provided in terms of a design margin and permissible maximum allowable working pressure (MAWP) computed with the design rules. A complete description of the theory including a commentary and comparison to experimental results is provided in WRC529 [1].

scholarly journals Elastic-Plastic Analysis of the PVRC Burst Disk Tests With Comparison to the ASME Code Primary Stress Limits

2000 ◽  
Vol 122 (2) ◽  
pp. 146-151 ◽  
Author(s):  
D. P. Jones ◽  
J. E. Holliday
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
High Strength ◽  
High Ductility ◽  
Test Results ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Primary Stress ◽  
Asme Code

This paper provides a comparison between finite element analysis results and test data from the Pressure Vessel Research Council (PVRC) burst disk program. Testing sponsored by the PVRC over 20 yr ago was done by pressurizing circular flat disks made from three different materials until failure by bursting. The purpose of this reanalysis is to investigate the use of finite element analysis (FEA) to assess the primary stress limits of the ASME Boiler and Pressure Vessel Code (hereafter the Code), and to qualify the use of elastic-plastic (EP-FEA) for limit-load calculations. The three materials tested represent the range of strength and ductility found in modern pressure vessel construction and include a low-strength, high-ductility material, a medium-strength, medium-ductility material, and a high-strength, low-ductility, low-alloy material. Results of elastic and EP-FEA are compared to test data. Stresses from the elastic analyses are linearized for comparison of Code primary stress limits to test results. Elastic-plastic analyses are done using both best-estimate and elastic-perfectly plastic (EPP) stress-strain curves. Both large strain-large displacement (LSLD) and small strain-small displacement (SSSD) assumptions are used with the EP-FEA. Analysis results are compared to test results to evaluate the various analysis methods, models, and assumptions as applied to the bursting of thin disks. The test results show that low-strength, high-ductility materials have a higher burst capacity than do high-strength, low-ductility materials. Linearized elastic FEA stresses and ASME Code primary stress limits provide excessive margins to failure for the burst disks for all three materials. The results of these studies show that LSLD EP-FEA can provide a best-estimate analysis of the disks, but the accuracy depends on the material stress-strain curve. This work concludes that SSSD EPP analysis methods provide a robust and viable alternative to the current elastic linearization method of satisfying the primary stress limits of the Code. [S0094-9930(00)01602-4]

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