A General Comparison of the Design Margins and Design Rules for ASME Section VIII, Divisions 1 and 2

2018 ◽  
Author(s):  
Nathan Barkley
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Historical Background ◽  
Design Rules ◽  
Component Design ◽  
Division 1 ◽  
Class 1 ◽  
Section Viii ◽  
Division 2 ◽  
Design Margin

Beginning with the 2017 Edition of the ASME Boiler and Pressure Vessel Code, vessels designed according to the rules of Section VIII, Division 2 shall be designated as either Class 1 or Class 2. One of the key differences between Class 1 and Class 2 is the applicable Design Margin of 3.0 and 2.4 against the Ultimate Tensile Strength of the material, respectively. Vessels designed in accordance to Section VIII, Division 1 have a Design Margin of 3.5 against the Ultimate Tensile Strength of the material. Code Case 2695 allows the vessel designer to utilize the design rules of Section VIII, Division 2 for a Section VIII, Division 1 vessel while maintaining the tensile strength Design Margin of 3.5. However, Design Margins against the Ultimate Tensile Strength of the material are not the only applicable margins that must be considered. This paper reviews the procedure for deriving the allowable stresses of materials under tensile loading based on the required Design Margins for each Division and Class with some historical background provided. Discussion and comparisons of some of the relevant differences between the design rules of Section VIII, Division 1 and 2 and how the differing Design Margins affect the component design is presented. Carbon Steel with joint efficiencies of 1.0 are used for simplicity.

Technical Basis for Conversion of Non-Mandatory Appendix F of Section III of the ASME Boiler and Pressure Vessel Code to a Mandatory Appendix: Part I — Appendix Rewrite

2017 ◽  
Author(s):  
Jie Wen ◽  
Suzanne McKillop ◽  
Timothy M. Adams ◽  
Robert Keating
Keyword(s):  
Allowable Stress ◽  
Design Rules ◽  
The Past ◽  
Component Design ◽  
Safety Margins ◽  
Division 1 ◽  
Class 1 ◽  
Asme Code ◽  
History Of ◽  
Technical Basis

In 1974, the Level D Service Limits for Section III, Division 1, Class 1 components were published in Non-Mandatory Appendix F titled “Rules for Evaluation of Service Loading with Level D Service Limits”. Over the past 40 years, the scope of Appendix F has been expanded to be applicable to certain Class 1, Class 2 and Class 3 components and supports in Division 1 as well as in Division 3 and Division 5. With each addition, the organization and implementation of the rules in Appendix F became more cumbersome for the user and consistency between the Appendix and the Code Books1 was not maintained. At the same time, the use of these rules has evolved to the point where the non-Mandatory Appendix is essential the default for Level D Service Limits. Starting in the 2017 Code edition, the component design rules will reference Mandatory Appendix XXVII when Design by Analysis is used to determine Level D Service Limits. This paper describes the methodology utilized to convert Non-Mandatory Appendix F to Mandatory Appendix XXVII which includes the history of the Level D Rules in the ASME Code, the philosophy taken to convert Non-Mandatory Appendix F to Mandatory Appendix XXVII, and an overview of the new Appendix XXVII. The approaches to ensure identical safety margins are maintained and the basis for adding or clarifying three allowable stress limits are also included.

Technical Basis for Conversion of Non-Mandatory Appendix F of Section III of the ASME Boiler and Pressure Vessel Code to a Mandatory Appendix: Part II — Associated Code Book Updates

2017 ◽  
Author(s):  
Suzanne McKillop ◽  
Jie Wen ◽  
Robert Keating ◽  
Timothy M. Adams
Keyword(s):  
Pressure Vessel ◽  
Design Rules ◽  
The Core ◽  
The Past ◽  
Component Design ◽  
Division 1 ◽  
Class 1 ◽  
Service Loading ◽  
Technical Basis ◽  
Code Book

In 1974, the Level D Service Limits for Section III, Division 1, Class 1 components were published in Non-Mandatory Appendix F titled “Rules for Evaluation of Service Loading with Level D Service Limits”. Over the past 40 years, the scope of the Appendix F has been expanded to be applicable to certain Class 1, Class 2 and Class 3 components and supports in Division 1 as well as in Division 3 and Division 5. With each addition, the organization and implementation of the rules in Appendix F became more cumbersome for the user and consistency between the Appendix and the Code Books1 was not maintained. At the same time, the use of these rules has evolved to the point where the non-Mandatory Appendix is essential the default for Level D Service Limits. Starting in the 2017 Code edition, the component design rules will reference Mandatory Appendix XXVII when Design by Analysis is used to determine Level D Service Limits. In particular, the component design rules, or rules specific to design of components and not Design by Analysis, were removed from Appendix XXVII and placed in the appropriate Code Book. This approach resulted in noteworthy updates to the support rules in Subsection NF, the core support rules in Subsection NG, the valve rules in NB-3500, and the piping rules in NB/NC/ND-3600. The detailed approach used to incorporate the component design rules into each Code Book are presented in this paper.

General Criteria and Evaluations for the Selection of ASME Section VIII, Division 1 or 2 for New Construction Pressure Vessels

2020 ◽  
Author(s):  
Nathan Barkley ◽  
Matt Riley
Keyword(s):  
Pressure Vessels ◽  
Design Rules ◽  
Advantages And Disadvantages ◽  
Division 1 ◽  
New Construction ◽  
Section Viii ◽  
Division 2 ◽  
Design Pressure ◽  
Selection Of

Abstract For new ASME pressure vessel designs that have a design pressure less than 10,000 psi (70 MPa), it is commonly questioned whether Section VIII, Division 1 or Division 2 should be used as the code of construction. Each code offers specific advantages and disadvantages depending on the specific vessel considered. Further complicating the various considerations is the new Mandatory Appendix 46 of Division 1 which allows the design rules of Division 2 to be used for Division 1 designs. With the various options available, determining the best approach can be challenging and is often more complex than only determining which code provides the thinnest wall thickness. This paper attempts to address many of the typical considerations that determine the use of Division 1 or Division 2 as the code of construction. Items to be considered may include administrative burden, certification process, design margins, design rules, and examination and testing requirements. From the considerations presented, specific comparisons are made between the two divisions with notable differences highlighted. Finally, sample evaluations are presented to illustrate the differences between each code of construction for identical design conditions. Also, material and labor estimates are compiled for each case study to provide a realistic comparison of the expected differential cost between the construction codes.

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.

Weld Joint Efficiency in Design by Analysis

2016 ◽  
Author(s):  
Trevor G. Seipp
Keyword(s):  
Weld Joint ◽  
Joint Efficiency ◽  
Division 1 ◽  
Section Viii ◽  
Division 2

In the original ASME Section VIII, Division 2, no consideration was given to partial weld joint efficiencies (values of the factor E less than 1.0) because that version required full radiography and only permitted weld joint efficiencies of unity. In the new (post-2007) Section VIII, Division 2, partial weld joint efficiencies as small as 0.85 are now permitted. Furthermore, much Design By Analysis work is performed on vessels fabricated to ASME Section VIII, Division 1 and the ASME B31 Codes, which all permit partial weld joint efficiencies. However, no guidance is provided on how to account for these values in Deign By Analysis to ASME Section VIII, Division 2, Part 5. This paper provides the technical justification for the proposed changes to ASME Section VIII, Division 2, Part 5 and API RP-579/ASME FFS-1 regarding weld joint efficiency. Guidance is also provided on how to incorporate this change into ASME Section VIII, Division 1 by way of U-2(g) and the B31 Codes.

Evaluation of ASME Pressure Vessel Code Prohibitions on Rod and Bar Stock and Potential Remedies

2014 ◽  
Author(s):  
John J. Aumuller ◽  
Vincent A. Carucci
Keyword(s):  
Pressure Vessels ◽  
Early 20Th Century ◽  
Economic Disadvantage ◽  
User Experiences ◽  
The Public ◽  
Division 1 ◽  
Asme Code ◽  
Billet Material ◽  
Section Viii ◽  
Division 2

The ASME Codes and referenced standards provide industry and the public the necessary rules and guidance for the design, fabrication, inspection and pressure testing of pressure equipment. Codes and standards evolve as the underlying technologies, analytical capabilities, materials and joining methods or experiences of designers improve; sometimes competitive pressures may be a consideration. As an illustration, the design margin for unfired pressure vessels has decreased from 5:1 in the earliest ASME Code edition of the early 20th century to the present day margin of 3.5:1 in Section VIII Division 1. Design by analysis methods allow designers to use a 2.4:1 margin for Section VIII Division 2 pressure vessels. Code prohibitions are meant to prevent unsafe use of materials, design methods or fabrication details. Codes also allow the use of designs that have proven themselves in service in so much as they are consistent with mandatory requirements and prohibitions of the Codes. The Codes advise users that not all aspects of construction activities are addressed and these should not be considered prohibited. Where prohibitions are specified, it may not be readily apparent why these prohibitions are specified. The use of “forged bar stock” is an example where use in pressure vessels and for certain components is prohibited by Codes and standards. This paper examines the possible motive for applying this prohibition and whether there is continued technical merit in this prohibition, as presently defined. A potential reason for relaxing this prohibition is that current manufacturing quality and inspection methods may render a general prohibition overly conservative. A recommendation is made to better define the prohibition using a more measurable approach so that higher quality forged billets may be used for a wider range and size of pressure components. Jurisdictions with a regulatory authority may find that the authority is rigorous and literal in applying Code provisions and prohibitions can be particularly difficult to accept when the underlying engineering principles are opaque. This puts designers and users in these jurisdictions at a technical and economic disadvantage. This paper reviews the possible engineering considerations motivating these Code and standard prohibitions and proposes modifications to allow wider Code use of “high quality” forged billet material to reflect some user experiences.

Comparison of German KTA and ASME Nuclear Design Codes for Class 1, 2, 3 Components and Piping

2011 ◽  
Author(s):  
Daniel Hofer ◽  
Henry Schau ◽  
Hu¨seyin Ertugrul Karabaki ◽  
Ralph Hill
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Design Codes ◽  
Nuclear Facility ◽  
Design Standards ◽  
Design Rules ◽  
Design Specifications ◽  
Division 1 ◽  
Class 1 ◽  
Standard Organization

This paper compares the design rules of the ASME Boiler and Pressure Vessel Code, Section III, Division 1, Rules for Construction of Nuclear Facility Components, with German nuclear design standards for Class 1, 2, 3 components and piping. The paper is focused on a comparison of the equations for Design by Analysis and on Piping equations. The ASME Section III Code has been used in combination with design specifications for design of German nuclear power plants. Together with manufacturers, inspectors and power plant owners, the German regulatory authority decided to develop their own nuclear design standards. The current versions being used are from 1992 and 1996. New versions of KTA design standards for pressure retaining components (KTA 3201.2 and KTA 3211.2) are currently under development. This comparison will cover the major differences between the design rules for ASME Section III, Div. 1 and KTA standards 3201.2 and 3211.2 as well as code or standard organization by sections, paragraphs, articles and code development.

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.

Continued Study on the Effect of Mean Stress on Ground Storage Vessels for Hydrogen Fueling

2020 ◽  
Author(s):  
Daniel T. Peters ◽  
Myles Parr
Keyword(s):  
High Pressure ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Gaseous Fuels ◽  
Division 1 ◽  
Section Viii ◽  
Pressure Storage ◽  
Cyclic Service ◽  
The Impact ◽  
Division 2

Abstract The use of high pressure vessels for the purpose of storing gaseous fuels for land based transportation application is becoming common. Fuels such as natural gas and hydrogen are currently being stored at high pressure for use in fueling stations. This paper will investigate the use of various levels of autofrettage in high pressure storage cylinders and its effects on the life of a vessel used for hydrogen storage. Unlike many high-pressure vessels, the life is controlled by fatigue when cycled between a high pressure near the design pressure and a lower pressure due to the emptying of the content of the vessels. There are many misunderstandings regarding the need for cyclic life assessment in storage vessels and the impact that hydrogen has on that life. Some manufacturers are currently producing vessels using ASME Section VIII Division 1 to avoid the requirements for evaluation of cylinders in cyclic service. There are currently rules being considered in all of ASME Section VIII Division 1 and Division 2, and even potentially for Appendix 8 of ASME Section X. Recommendations on updating the ASME codes will be considered in this report.

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