Weld Joint Efficiency in Design by Analysis

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.

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

Volume 3: Design and Analysis ◽

10.1115/pvp2019-93565 ◽

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 ◽

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.

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

Volume 1: Codes and Standards ◽

10.1115/pvp2014-28081 ◽

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 ◽

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.

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

10.1115/1.1376719 ◽

2000 ◽

Vol 123 (3) ◽

pp. 338-345 ◽

Cited By ~ 2

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 ◽

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

Volume 5: High Pressure Technology ◽

10.1115/pvp2020-21723 ◽

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 ◽

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.

Heat Treatment of Fabricated Components and the Effect on Properties of Materials

Volume 1: Codes and Standards ◽

10.1115/pvp2019-93616 ◽

2019 ◽

Author(s):

Shyam Gopalakrishnan ◽

Ameya Mathkar

Keyword(s):

Heat Treatment ◽

Pressure Vessel ◽

Test Specimen ◽

Stress Relieving ◽

Division 1 ◽

Asme Code ◽

Alloy Steels ◽

Section Viii ◽

Properties Of Materials ◽

Abstract Most of the heavy thickness boiler and pressure vessel components require heat treatment — in the form of post weld heat treatment (PWHT) and sometimes coupled with local PWHT. It is also a common practice to apply post heating/ intermediate stress relieving/ dehydrogenation heat treatment in case of alloy steels. The heat treatment applied during the various manufacturing stages of boiler and pressure vessel have varying effects on the type of material that is used in fabrication. It is essential to understand the effect of time and temperature on the properties (like tensile and yield strength/ impact/ hardness, etc.) of the materials that are used for fabrication. Considering the temperature gradients involved during the welding operation a thorough understanding of the time-temperature effect is essential. Heat treatments are generally done at varying time and temperatures depending on the governing thickness and the type of materials. The structural effects on the materials or the properties of the materials tends to vary based on the heat treatment. All boiler and pressure vessel Code require that the properties of the material should be intact and meet the minimum Code specification requirements after all the heat treatment operations are completed. ASME Code(s) like Sec I, Section VIII Division 1 and Division 2 and API recommended practices like API 934 calls for simulation heat treatment of test specimen of the material used in fabrication to ascertain whether the intended material used in construction meets the required properties after all heat treatment operations are completed. The work reported in this paper — “Heat treatment of fabricated components and the effect on properties of materials” is an attempt to review the heat treatment and the effect on the properties of materials that are commonly used in construction of boiler and pressure vessel. For this study, simulation heat treatment for PWHT of test specimen for CS/ LAS plate and forging material was carried out as specified in ASME Section VIII Div 1, Div 2 and API 934-C. The results of heat treatment on material properties are plotted and compared. In conclusion recommendations are made which purchaser/ manufacturer may consider for simulation heat treatment of test specimen.

Continuing and Changing Priorities of the ASME Boiler & Pressure Vessel Codes and Standards ◽

Part A: Lessons Learned Based on Section VIII, Division 1. Part B: Lessons Learned Based on Section VIII, Division 2

10.1115/1.860199_ch24 ◽

2014 ◽

pp. 24-1-24-22

Keyword(s):

Lessons Learned ◽

Division 1 ◽

Section Viii ◽

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

10.1115/1.4005854 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 4

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 ◽

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.

Increased Allowable Stresses for Earthquake and Wind Loads in Section VIII, Division 1

10.1115/1.3264823 ◽

1986 ◽

Vol 108 (4) ◽

pp. 518-520

Author(s):

A. Selz

Keyword(s):

Pressure Vessel ◽

Wind Loads ◽

Membrane Stress ◽

Allowable Stresses ◽

Division 1 ◽

Section Viii ◽

The Subject ◽

Short Time ◽

Creep Regime ◽

There has been a need for some time to provide rules for allowable stresses for short-time and infrequent loading such as earthquake and wind loads in Section VIII, Division 1 of the Boiler and Pressure Vessel Code. Such rules exist in Section VIII, Division 2, in Section III, and in many other Codes. Division 1 has been silent on the subject. This has caused some manufacturers to make their own rules, and some to overdesign their hardware. Neither situation is without problems. Therefore, in 1979 the Boiler and Pressure Vessel Committee undertook to develop rules for Section VIII, Division 1. This work resulted in the addition of paragraph UG-23(d) to the Code, in the Summer, 1983 Addenda. The paragraph permits an increase in general primary membrane stress of 20 percent for earthquake and wind loads for temperatures below the creep regime.

Review of Section VIII, Division 1 and 2 Changes, 2008–2010

ASME 2010 Pressure Vessels and Piping Conference: Volume 1 ◽

10.1115/pvp2010-25107 ◽

2010 ◽

Author(s):

Thomas P. Pastor

Keyword(s):

Pressure Vessel ◽

Pressure Vessels ◽

Major Event ◽

The Past ◽

Division 1 ◽

Section Viii ◽

Three years ago the major event within Section VIII was the publication of the new Section VIII, Division 2. The development of the new VIII-2 standard dominated Section VIII activity for many years, and a new standard has been well received within the industry. As expected with any new standard, some of the material that was intended to be published in the standard was not ready at the time of publication so numerous revisions have taken place in the last two addenda. This paper will attempt to summarize the major revisions that have taken place in VIII-2 and VIII-1, including a detailed overview of the new Part UIG “Requirements for Pressure Vessels Constructed of Impregnated Graphite”. I have stated in the past that the ASME Boiler and Pressure Vessel Code is a “living and breathing document”, and considering that over 320 revisions were made to VIII-1 and VIII-2 in the past three years, I think I can safely say that the standard is alive and well.

Allowable Stresses for Nonrectangular Sections Under Combined Axial and Bending Loads

10.1115/1.3265585 ◽

1988 ◽

Vol 110 (2) ◽

pp. 188-193

Author(s):

S. Chattopadhyay

Keyword(s):

Cross Sections ◽

Rectangular Cross Section ◽

Shape Factors ◽

Division 1 ◽

Asme Code ◽

Depth Study ◽

Section Viii ◽

Bending Loads ◽

Interaction Curves ◽

The design stress allowables for various loading conditions involving bending in Section III, Division 1 and Section VIII, Division 2 of the ASME Boiler and Pressure Vessel Code are based on the assumption of a rectangular cross section of the structural members. These allowables do not necessarily provide the same level of safety for all general cross sections. In this work, stress allowables have been proposed for design, level C and test condition loadings to provide adequate safety for all combinations of axial and bending loads. The limits are based on an in-depth study of the interaction curves for the fully plastic condition under combined axial and bending loads. These proposed limits are intended to replace the existing ones in the ASME Code. These modifications apply to the design, level C and testing limits. (NB-3221.3, NB-3224 and NB-3226) of Section III, Division 1, and to the Design and Testing limits (AD-140 and AD-151) of Section VIII, Division 2 of the ASME Code. The modified limits are based on the inclusion of shape factors of individual cross sections.