A Novel Approach to Evaluating Spiral-Wound Gaskets in Bolted Flange Joint Calculations

2006 ◽  
Author(s):  
Trevor G. Seipp ◽  
Christopher Reichert ◽  
Mathew Schaeffer
Keyword(s):  
Solid Metal ◽  
Flange Joint ◽  
New Approach ◽  
Novel Approach ◽  
Division 1 ◽  
Bolt Stress ◽  
Section Viii ◽  
Bolted Flange ◽  
Spiral Wound

In this paper, the authors introduce a compound gasket approach to performing calculations on bolted flange joints with spiral wound gaskets. The spiral windings and the solid-metal centering ring are treated independently. Using the calculation methodologies of ASME Section VIII, Division 1, Appendix 2 and EN-1591-1, the authors calculated the assembly bolt stress for multiple bolted flange joint sizes over a range of classes. The calculations assumed that the flange sealed on the solid-metal centering ring as well as on the spiral windings. This bolt stress required to achieve this seal was added to the bolt stress required to compress the spiral windings fully to the centering ring. The resulting total bolt stresses are similar to the practical bolt stresses recommended by ASME PCC-1. Thus, using this new approach to the spiral wound gasket provides a better understanding of bolt stresses required to achieve an adequate bolted flange joint.

Improving Flange Designs Based on ASME Section VIII Div. 1, Appendix 2

2020 ◽  
Author(s):  
Chris W. Cary
Keyword(s):  
Pressure Vessel ◽  
End User ◽  
Analysis Methods ◽  
Division 1 ◽  
Bolt Stress ◽  
Section Viii ◽  
Input Variables ◽  
Improved Methods ◽  
Very High ◽  
Design Pressure

Abstract Although improved methods for flange design have been under development for many years, ASME Boiler and Pressure Vessel Code Section VIII, Division 1 Appendix 2 continues to be the basis for the design of most custom pressure vessel flanges. While the method does a reasonably good job of calculating flange stress and rotation from the design loadings, it does not closely constrain some of the design input variables, such as gasket width and geometry, allowing the designer to produce poorly-performing designs. Also, the gasket loading factors (m & y values) have long been recognized as needing improvement. These weaknesses occasionally result in flanges which are difficult to seal, even with very high assembly bolt stress. In response to these weaknesses in the Appendix 2 method, various attempts to improve the method may be employed, and are sometimes required by end-user specifications. This paper provides an assessment of the effectiveness of various improvement techniques by examining the actual effects on flange designs across a range of diameter and design pressure, and makes recommendations for the use of such techniques. The analysis methods in PCC-1 and WRC Bulletin 538 are used as the basis of the evaluation, with a focus on gasket stress as fundamental to sealing.

Relaxation of the Bolted Flange Connection

2020 ◽  
Author(s):  
Robert Taylor
Keyword(s):  
Internal Pressure ◽  
Temperature Cycling ◽  
Bolted Connection ◽  
Relaxation Properties ◽  
Flange Connection ◽  
Bolt Stress ◽  
Bolted Flange ◽  
Spiral Wound

Abstract This study researches the total relaxation of a bolted flange connection, taking into account, the relaxation of various bolt grades in conjunction with different semi-metallic gaskets. The test temperatures are: 300 °F (149 °C), 500 °F (260 °C), 650 °F (343 °C) and 800 °F (427 °C), where each temperature setting will cycle three times to obtain the relaxation value for each cycle. The three types of bolt materials for evaluation include ASTM A193 B7, ASTM A193 B16 and ASTM B8M CL2 along with gaskets styles of spiral wound gasket with inner ring, spiral wound gasket with NO inner ring and the kammprofile gasket (grooved metal gasket with covering layers), all in accordance to ASME B16.20 – 2017. The above variations and conditions will be tested at two different initial bolt stresses of 35,000 psi (241 MPa) and 65,000 psi (448 MPa) with a constant internal pressure of 150 psi (10.3 Bar). The results will show relaxation values for the different bolt and gasket types versus the various temperature cycling conditions indicated above. Focusing on: does a certain gasket style offer lower relaxation properties through less creep and/or higher recovery? Does a certain bolt grade offer better stress retention? Is there variation in initial bolt stress for the different style of gasket? How does the initial bolt stress affect the relaxation properties of the bolted connection?

Development of a Protocol to Determine the Minimum Operating Stress of Compressed Non-Asbestos Gaskets

2013 ◽  
Author(s):  
Ana C. Silva ◽  
Gabriele Rodrigues ◽  
Lucas Xavier
Keyword(s):  
New Method ◽  
Test Results ◽  
Flange Joint ◽  
Stress Determination ◽  
Complex Approach ◽  
Bolt Stress ◽  
Operating Stress ◽  
Bolted Flange ◽  
Minimum Operating

The ASME PCC-1-2010 Guidelines for Pressure Boundary Bolted Flange Joint Assembly [1] introduced a new method for an appropriate assembly bolt stress determination across bolted flange connections. The method introduced in APPENDIX O of the ASME PCC-1-2010 has recently received substantial attention by several gasket researchers. In this new method, calculation is based in a complex approach that considers the integrity of each joint component. However, almost no information is found about some essential parameters. Therefore, the intent of the present study is to introduce a protocol for the determination of one of these factors: the minimum gasket operating stress (Sgmin-o). This value is defined as “the gasket stress that should be maintained on the gasket during operation in order to assure the leakage does not occur”. This paper will show a detailed study for a protocol to determine the minimum gasket operating stress and actual test results for compressed non-asbestos gaskets. Furthermore, the device used in the research will be defined in detail afterwards.

Background of New Code Rules for Integral Flat Heads with a Large, Central Nozzle

1981 ◽  
Vol 103 (1) ◽  
pp. 116-119
Author(s):  
R. W. Schneider
Keyword(s):  
Head Diameter ◽  
Central Nozzle ◽  
Division 1 ◽  
Central Opening ◽  
Section Viii ◽  
Bolted Flange

Paragraph UG-39 (c) of ASME Section VIII, Division 1, 1980 Edition states: “Flat heads that have an opening with a diameter that exceeds one-half of the head diameter or shortest span, as defined in UG-34, shall be designed as a flange in accordance with the Rules for Bolted Flange Connections given in Appendix 2.” The application of Appendix 2 to such configurations is subject to various interpretations, accordingly, rules have been written for the specific case of a single, large central opening (nozzle) in integral flat heads. The new rules will appear in the Winter 1980 Addenda; for configurations not provided for the designer is referred to U-2 (g).

scholarly journals Solving the Puzzle of Bolted Joints

2011 ◽  
Vol 133 (06) ◽  
pp. 48-52
Author(s):  
Edward Hayman ◽  
Clyde Neely
Keyword(s):  
Best Practices ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Flange Joint ◽  
Unit Load ◽  
Bolt Stress ◽  
Torque Values ◽  
Bolted Flange ◽  
Joint Integrity ◽  
Joint Assembly

This article discusses the various ways of solving the puzzle of bolted joint assembly. In 2001, The PCC-1-2000 Guidelines for Pressure Boundary Bolted Flange Joint Assembly presented with knowledge and practices specific to the assembly of bolted flange joints. The puzzle solution that came from this box was the most definitive to date and allowed those dealing with bolted joints to assemble the variables by methods that had been used successfully for many years by many people. This document is helping people across industry not only to assemble bolted flange joints, but also to establish joint integrity programs, procedures, and best practices. PCC-1-2010 shifts the emphasis to gasket stress and gasket type and provides instruction and information pertinent to bolt torque values. The 2010 document contains, for instance, a whole section on bolt stress—the unit load that should be put on the bolts—and includes tables as well.

scholarly journals The discovery of biological subphenotypes in ARDS: a novel approach to targeted medicine?

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Karin Wildi ◽  
Samantha Livingstone ◽  
Chiara Palmieri ◽  
Gianluigi LiBassi ◽  
Jacky Suen ◽  
...  
Keyword(s):  
Age Groups ◽  
Geographical Location ◽  
High Morbidity ◽  
Shock State ◽  
Pharmacological Agents ◽  
New Approach ◽  
Novel Approach ◽  
Active Research ◽  
Targeted Medicine ◽  
Core Features

AbstractThe acute respiratory distress syndrome (ARDS) is a severe lung disorder with a high morbidity and mortality which affects all age groups. Despite active research with intense, ongoing attempts in developing pharmacological agents to treat ARDS, its mortality rate remains unaltered high and treatment is still only supportive. Over the years, there have been many attempts to identify meaningful subgroups likely to react differently to treatment among the heterogenous ARDS population, most of them unsuccessful. Only recently, analysis of large ARDS cohorts from randomized controlled trials have identified the presence of distinct biological subphenotypes among ARDS patients: a hypoinflammatory (or uninflamed; named P1) and a hyperinflammatory (or reactive; named P2) subphenotype have been proposed and corroborated with existing retrospective data. The hyperinflammatory subphenotyope was clearly associated with shock state, metabolic acidosis, and worse clinical outcomes. Core features of the respective subphenotypes were identified consistently in all assessed cohorts, independently of the studied population, the geographical location, the study design, or the analysis method. Additionally and clinically even more relevant treatment efficacies, as assessed retrospectively, appeared to be highly dependent on the respective subphenotype. This discovery launches a promising new approach to targeted medicine in ARDS. Even though it is now widely accepted that each ARDS subphenotype has distinct functional, biological, and mechanistic differences, there are crucial gaps in our knowledge, hindering the translation to bedside application. First of all, the underlying driving biological factors are still largely unknown, and secondly, there is currently no option for fast and easy identification of ARDS subphenotypes. This narrative review aims to summarize the evidence in biological subphenotyping in ARDS and tries to point out the current issues that will need addressing before translation of biological subohenotypes into clinical practice will be possible.

scholarly journals Unimodular vs nilpotent superfield approach to pure dS supergravity

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Sukruti Bansal ◽  
Silvia Nagy ◽  
Antonio Padilla ◽  
Ivonne Zavala
Keyword(s):  
String Theory ◽  
General Framework ◽  
Recent Progress ◽  
High Energy ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
New Approach ◽  
Sitter Spacetime ◽  
Novel Approach ◽  
De Sitter Vacua

Abstract Recent progress in understanding de Sitter spacetime in supergravity and string theory has led to the development of a four dimensional supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua, also called de Sitter supergravity. One approach makes use of constrained (nilpotent) superfields, while an alternative one couples supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action. These two approaches have been shown to give rise to the same 4D action. A novel approach to de Sitter vacua in supergravity involves the generalisation of unimodular gravity to supergravity using a super-Stückelberg mechanism. In this paper, we make a connection between this new approach and the previous two which are in the context of nilpotent superfields and the goldstino brane. We show that upon appropriate field redefinitions, the 4D actions match up to the cubic order in the fields. This points at the possible existence of a more general framework to obtain de Sitter spacetimes from high-energy theories.

scholarly journals Compiling Life-Oriented Moral Education Textbooks for Elementary Schools in China: The Mimetic Approach in Morality and Law

2021 ◽  
pp. 209653112098296
Author(s):  
Yan Tang
Keyword(s):  
Elementary Schools ◽  
Moral Education ◽  
Life Events ◽  
Theoretical Perspective ◽  
Building Blocks ◽  
Learning Activities ◽  
Design Approach ◽  
New Approach ◽  
Novel Approach

Purpose: This study explores a novel approach to compiling life-oriented moral textbooks for elementary schools in China, specifically focusing on Morality and Law. Design/Approach/Methods: Adopting Aristotle’s Poetics as its theoretical perspective, this study illustrates and analyzes the mimetic approach used in compiling the life-oriented moral education textbook, Morality and Law. Findings: The mimetic approach involves imitating children's real activities, thoughts, and feelings in textbooks. The mimetic approach to compiling life-oriented moral textbooks comprises three strategies: constructing children's life events as building blocks for textbook compilation, designing an intricate textual device exposing the wholeness of children's life actions, and designing inward learning activities leading to children's inner worlds. Originality/Value: From the perspective of Aristotle's Poetics, the approach to compilation in Morality and Law can be defined as mimetic. And the compilation activity in the life-oriented moral education textbook also can be described as a processes of mimesis. So this article presents a new approach to compile moral education textbooks, and  an innovative way to understand the nature of one compiling activity.

A Novel Approach for Metal Surface Modification

2007 ◽  
Vol 280-283 ◽  
pp. 1805-1806
Author(s):  
Zhi Jun Cao ◽  
Jia Chen Liu ◽  
Li Bin Liu ◽  
Hao Ye ◽  
Yan Qiu Wei
Keyword(s):  
Surface Modification ◽  
Wear Rate ◽  
Charge State ◽  
Metal Surface ◽  
Surface Hardness ◽  
Metallic Surface ◽  
New Approach ◽  
Novel Approach ◽  
Complex Shapes ◽  
Enhanced Surface

A new approach was developed for surface modification of metallic surface. By treating nano-zirconia particles and metal surface in different charge state, nano-zirconia particles can be dispersedly inlaid in metal surface owing to electrostatic and nanometer effects. By using this method, metal components of complex shapes, especially those having inside surfaces, might be easily improved, i.e., enhanced surface hardness and wear rate.

Finite Element Analysis of a Gasketed Flange Joint Under Combined Internal Pressure and Thermal Transient Loading

2007 ◽  
Author(s):  
Muhammad Abid ◽  
Javed A. Chattha ◽  
Kamran A. Khan
Keyword(s):  
Finite Element Analysis ◽  
Steady State ◽  
Internal Pressure ◽  
Thermal Loading ◽  
Flange Joint ◽  
Element Analysis ◽  
Transient Loading ◽  
Thermal Transient ◽  
Transient Thermal ◽  
Bolted Flange

Performance of a bolted flange joint is characterized mainly by its ‘strength’ and ‘sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. In the available published work, thermal behavior of the pipe flange joints is discussed under steady state loading with and without internal pressure and under transient loading condition without internal pressure. The present design codes also do not address the effects of steady state and thermal transient loading on the structural integrity and sealing ability. It is realized that due to the ignorance of any applied transient thermal loading, the optimized performance of the bolted flange joint can not be achieved. In this paper, in order to investigate gasketed joint’s performance i.e. joint strength and sealing capability under combined internal pressure and transient thermal loading, an extensive nonlinear finite element analysis is carried out and its behavior is discussed.

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