Technical Basis for Code Cases on Design of Ellipsoidal and Torispherical Heads for ASME Section VIII Vessels

1999 ◽  
Vol 122 (1) ◽  
pp. 55-59 ◽  
Author(s):  
Mahendra D. Rana ◽  
Arturs Kalnins
Keyword(s):  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Plastic Collapse ◽  
Cycle Fatigue ◽  
Dimensional Changes ◽  
Division 1 ◽  
Section Viii ◽  
Technical Basis ◽  
Division 2 ◽  
Fatigue Criterion

ASME Boiler and Pressure Vessel (B&PV) Code Committees have approved Code Cases 2260 and 2261 on the design of ellipsoidal and torispherical heads for Section VIII Division 1 and Division 2 vessels, respectively. Burst and low-cycle fatigue failure modes have been considered. A rationale is provided for including the foregoing referenced failure modes, and not including other failure modes such as dimensional changes, plastic collapse, knuckle yielding, etc. The basis for the specified design formulas to satisfy the burst and low-cycle fatigue criterion is discussed. The paper also discusses limitations and other requirements that have been imposed in the Code Cases. [S0094-9930(00)01401-3]

Technical Basis for ASME Section VIII Code Case 2235 on Ultrasonic Examination of Welds in Lieu of Radiography

2000 ◽  
Vol 123 (3) ◽  
pp. 338-345 ◽  
Author(s):  
Mahendra D. Rana ◽  
Owen Hedden ◽  
Dave Cowfer ◽  
Roger Boyce
Keyword(s):  
Fracture Mechanics ◽  
Linear Elastic Fracture Mechanics ◽  
Acceptance Criteria ◽  
Ultrasonic Examination ◽  
Linear Elastic ◽  
Division 1 ◽  
Section Viii ◽  
Elastic Fracture ◽  
Technical Basis ◽  
Division 2

In 1996, Code Case 2235, which allows ultrasonic examination of welds in lieu of radiography for ASME Section VIII Division 1 and Division 2 vessels, was approved by the ASME B&PV Code Committee. This Code Case has been revised to incorporate: 1) a reduction in minimum usable thickness from 4″ (107.6 mm) to 0.5″ (12.7 mm), and 2) flaw acceptance criteria including rules on multiple flaws. A linear elastic fracture mechanics procedure has been used in developing the flaw acceptance criteria. This paper presents the technical basis for Code Case 2235.

Effect of Reinforcement on the Strength of Junctions Between Cylindrical and Conical Shells

1995 ◽  
Vol 117 (2) ◽  
pp. 135-141 ◽  
Author(s):  
A. Kalnins ◽  
D. P. Updike
Keyword(s):  
Failure Criterion ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Safety Margin ◽  
External Pressure ◽  
Cycle Fatigue ◽  
Conical Shells ◽  
Section Viii ◽  
Cyclic Service ◽  
Reinforcement Distribution

Two failure modes are addressed for cylinder-cone junctions under internal or external pressure: axisymmetric yielding and low-cycle fatigue. If the junction fails to meet the failure criterion of any one of the two modes, then it must be strengthened by reinforcement. It is shown in the paper that the degree to which a junction is strengthened depends on the distribution of the reinforcement. A placement of reinforcement on the cylinder alone, leaving the actual connection between the cylinder and cone unreinforced, adds strength with regard to axisymmetric yielding, but may not strengthen the junction sufficiently with regard to low-cycle fatigue. This means that the junction may appear reinforced, but is not strengthened. It is pointed out that the design rules of Section VIII, Div. 1 of the ASME B & PV Code (1992) set the need for reinforcement according to the failure criterion of low-cycle fatigue, while the distribution of the reinforcement is guided by the criterion of axisymmetric yielding. There is no assurance that the reinforced junction will meet the failure criterion of low-cycle fatigue. This means that the safety margin on the number of allowed cycles is less than that which is expected and that the junction may be unfit for cyclic service. It is also shown in the paper that a reinforcement distribution that requires minimum thicknesses for sections of both the cylinder and cone near the junction can satisfy criteria for both failure modes. This approach is already used in Code Case 2150 of Section VIII, Div. 1, for half-apex cone angles from 30 to 60 deg, and required in Div. 2 for cone angles from 0 to 30 deg. Its extension to angles from 0 to 60 deg for both internal and external pressure is recommended.

Technical Basis of Material Toughness Requirements in the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
David A. Osage ◽  
Martin Prager
Keyword(s):  
Impact Test ◽  
Major Change ◽  
Low Alloy Steels ◽  
Beneficial Effects ◽  
Division 1 ◽  
Alloy Steels ◽  
Section Viii ◽  
Assessment Procedures ◽  
Technical Basis ◽  
Division 2

The development of new toughness requirements for carbon and low alloy steels was a major part of the effort to rewrite the ASME B&PV Code, Section VIII, Division 2. The new toughness rules in this code were established using the fracture mechanics assessment procedures in API 579-1/ASME FFS-1 (Fitness-For-Service), Part 9. The major change in the toughness rules when compared to older editions of Section VIII, Division 2 (2004 and prior) and the current edition of Section VIII, Division 1 are for carbon and low alloy steel materials excluding bolting. The new toughness rules in Section VIII, Division 2 are based on a Charpy V-Notch impact requirement of 20 ft-lb (27 J) consistent with European practice and the beneficial effects of post weld heat treatment are included consistent with the procedures in API 579-1/ASME FFS-1. This paper provides a technical background to the new toughness rules including the development of material toughness requirements and the development of impact test exemption rules.

A Comparison of Design by Analysis Techniques for Evaluating Nozzle-to-Shell Junctions per ASME Section VIII Division 2

2015 ◽  
Author(s):  
Phillip E. Prueter ◽  
Robert G. Brown
Keyword(s):  
Stress Analysis ◽  
Failure Modes ◽  
Elastic Stress ◽  
Limit Load ◽  
Plastic Collapse ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Non Linear ◽  
Section Viii ◽  
Division 2

Part 5 of ASME Section VIII Division 2 offers several design by analysis (DBA) techniques for evaluating pressure retaining equipment for Code compliance using detailed computational stress analysis results. These procedures can be used to check components for protection against multiple failure modes, including plastic collapse, local failure, buckling, and cyclic loading. Furthermore, these procedures provide guidance for establishing consistent loading conditions, selecting material properties, developing post-processing techniques, and comparing analysis results to the appropriate acceptance criteria for a given failure mode. In particular, this study investigates the use of these methods for evaluating nozzle-to-shell junctions subjected to internal pressure and nozzle end loads. Specifically, elastic stress analysis, limit load analysis, and elastic-plastic stress analysis are utilized to check for protection against plastic collapse, and computational results for a given load case are compared. Additionally, the twice elastic slope method for evaluating protection against plastic collapse is utilized as an alternate failure criterion to supplement elastic-plastic analysis results. The goal of these comparisons is to highlight the difference between elastic stress checks and the non-linear analysis methodologies outlined in ASME Section VIII Division 2; particularly, the conservatism associated with employing the elastic stress criterion for nozzle end loads compared to limit load and elastic-plastic analysis methodologies is discussed. Finally, commentary on the applicability of performing the Code-mandated check for protection against ratcheting for vessels that do not operate in cyclic service is provided. The intent of this paper is to provide a broad comparison of the available DBA techniques for evaluating the acceptability of nozzle-to-shell junctions subjected to different types of loading for protection against plastic collapse. Predicted deformations and stresses are quantified for each technique using linear and non-linear, three-dimensional finite element analysis (FEA) methodologies.

Analytical and Numerical Evaluation of the Cyclic Yield Area Criteria for Shakedown Requirements

2002 ◽  
Author(s):  
Isoharu Nishiguchi ◽  
Asao Okamoto ◽  
Norimichi Yamashita ◽  
Mitsuru Aoki
Keyword(s):  
Pressure Vessel ◽  
Numerical Evaluation ◽  
Failure Modes ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Stress Evaluation ◽  
Division 1 ◽  
Section Viii ◽  
Division 2 ◽  
Stress Criteria

The rules in codes such as the ASME Boiler and Pressure Vessel Code Section III Division 1 and Section VIII Division 2, provide the concept of stress categorization to prevent inelastic failure modes based on the elastic analyses. The categorization of the stresses obtained by the FEM analysis, however, is not always clear and the Three Dimensional FEM Stress Evaluation in JPVRC (TDF committee) has been developed alternative criteria to dispense with the stress categorization. As for the evaluation of the primary plus secondary stress, criteria based on the concept of the Cyclic Yield Area (CYA) have been developed. In this paper, the recent results obtained in the committee are summarized to evaluate the validity and the usability of the criteria.

Technical Basis of Material Toughness Requirements in the ASME B&PV Code, Section VIII, Division 2

2010 ◽  
Author(s):  
David A. Osage ◽  
Martin Prager
Keyword(s):  
Major Part ◽  
Impact Test ◽  
Post Weld Heat Treatment ◽  
Low Alloy Steel ◽  
Beneficial Effects ◽  
Division 1 ◽  
Section Viii ◽  
Assessment Procedures ◽  
Technical Basis ◽  
Division 2

The development of new toughness requirements was a major part of the effort to re-write the ASME B&PV Code, Section VIII, Division 2. The new toughness rules in this code were established using the fracture mechanics assessment procedures in API 579-1/ASME FFS-1 Fitness-For-Service, Part 9. The major changes in the toughness rules when compared to older editions of Section VIII, Division 2 and the current edition of Section VIII, Division 1 are for carbon and low alloy steel materials excluding bolting. The new toughness rules in Section VIII, Division 2 are based on a Charpy V-Notch impact requirement of 20 ft-lbs (27 Joules) consistent with European practice and the beneficial effects of post weld heat treatment are included consistent with the procedures in API 579-1/ASME FFS-1. This paper provides a technical background to the new toughness rules including the development of material toughness requirements and the development of impact test exemption rules.

Failure Analysis of Thinned Wall Elbows Under Excessive Seismic Loading

2002 ◽  
Author(s):  
Masaki Shiratori ◽  
Yoji Ochi ◽  
Izumi Nakamura ◽  
Akihito Otani
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Local Buckling ◽  
Seismic Loading ◽  
Cycle Fatigue ◽  
Finite Element Analyses ◽  
Residual Thickness ◽  
Limited Period

A series of finite element analyses has been carried out in order to investigate the failure behaviors of degraded bent pipes with local thinning against seismic loading. The sensitivity of such parameters as the residual thickness, locations and width of the local thinning to the failure modes such as ovaling and local buckling and to the low cycle fatigue damage has been studied. It has been found that this approach is useful to make a reasonable experimental plan, which has to be carried out under the condition of limited cost and limited period.

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

2021 ◽  
Author(s):  
Gurumurthy Kagita ◽  
Krishnakant V. Pudipeddi ◽  
Subramanyam V. R. Sripada
Keyword(s):  
Stress Analysis ◽  
Failure Modes ◽  
Element Analysis ◽  
Design Rules ◽  
Area Method ◽  
Replacement Method ◽  
Local Stresses ◽  
Pressure Area ◽  
Section Viii ◽  
Division 2

Abstract 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.

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.

scholarly journals Probabilistic Low Cycle Fatigue criterion for nodular cast-irons

2020 ◽  
Vol 139 ◽  
pp. 105701
Author(s):  
F. Szmytka ◽  
E. Charkaluk ◽  
A. Constantinescu ◽  
P. Osmond
Keyword(s):  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Cast Irons ◽  
Fatigue Criterion
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