A Comparative Study of Concentrically and Eccentrically Pierced Flat Unstayed Heads

2017 ◽  
Author(s):  
Dipak K. Chandiramani ◽  
Shyam Gopalakrishnan ◽  
Ameya Mathkar ◽  
Suresh K. Nawandar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Comparative Study ◽  
Pressure Vessels ◽  
Stress Pattern ◽  
Element Analysis ◽  
Replacement Method ◽  
Division 1 ◽  
Section Viii ◽  
Nozzle Opening

Clause UG - 39 of ASME Section VIII Division 1 [1] provide rules for compensation of openings in flat stayed/ flat unstayed heads having fitted nozzles. The rules provided in Clause UG - 39 and its sub clauses apply to all openings other than small openings covered by UG - 36 (c)(3)(a) and provide rules for compensation of openings to those geometries which confirms to the geometric limitations specified therein. The rules provided in Clause UG - 39 of ASME Section VIII Division 1 are based on area replacement method. This method is also elaborated in WRC Bulletin 335 Aug 1988[4]. The conclusion of this bulletin is applicable to ASME Section VIII Div 1, ASME Section I, ASME B 31.1 and ASME Section III Class 2 and 3. This method requires that the metal cut out by an opening be replaced by reinforcement within a prescribed zone around the opening. This methodology is relatively simple and vast majority of the piping and pressure vessels with openings conforming to this methodology have given satisfactory service. In Code [1], as such there appears to be no restriction on the location of the nozzle opening, i.e., a header flat head pierced concentrically or eccentrically to locate the nozzle opening as long as the required area is obtained and the stresses are within allowable limits. While both these alternatives would be acceptable in Code [1] constructions, the actual stresses at the header flat heads/nozzle junction may vary considerably. The work reported in this paper was undertaken to make a comparative study on the effect of unstayed flat head pierced concentrically or eccentrically by using ASME Section VIII Division 1 and to study the stress pattern in both the cases using Finite Element Analysis (FEA) as a referral methodology.

Large Openings in Cylindrical Pressure Vessels: An Assessment Based on Absolute Size

2014 ◽  
Author(s):  
Dipak K. Chandiramani ◽  
Shyam Gopalakrishnan ◽  
Ameya Mathkar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Absolute Size ◽  
Replacement Method ◽  
Wide Range ◽  
Division 1 ◽  
Section Viii ◽  
The Absolute

Clauses UG-36 through UG-43 of ASME Section VIII Division 1 [1], describe the method of calculating the adequacy of compensation of openings in shells, using an area-replacement method. The method is based on determining and suitably replacing the missing metal area along any section, with metal available or provided, within the limits of reinforcement on the shell and nozzle. Clause UG-36 (b) of ASME Section VIII Division 1 provides limits on the size of the opening for applicability of Clauses UG-36 through UG-43. If these limits are exceeded, supplemental rules of Clause 1-7 of Appendix 1 need to be complied with or alternatively the rules of Clause 1-10 of Appendix 1 may be applied. The rules for large openings as stated in the Code are not dependent upon the absolute size of the nozzle and shell. For example, same calculations would be required to be carried out whether a nozzle of NPS 1 is attached to a shell of NPS 1.5 or a nozzle of NPS 16 is attached to a shell of NPS 24. The work presented in this paper is an attempt to determine whether the additional calculations in Clause 1-7 need to be carried out for finished openings exceeding the limits of UG-36(b) irrespective of the absolute size of the nozzle and shell. This has been done by carrying out calculations for a wide range of nozzle-shell combinations and comparing the results so obtained with the results of a Finite Element Analysis.

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].

Using Finite Element Analysis Combined With Strain Gage Testing to Do Proof Test to Establish MAWP

2004 ◽  
Author(s):  
Donald J. Florizone
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Gage ◽  
Element Analysis ◽  
Proof Testing ◽  
Division 1 ◽  
Test Pressure ◽  
Section Viii ◽  
Non Destructive ◽  
Made In

An amine reboiler was constructed with very large openings in one semi-elliptical head. The openings extended beyond the “spherical” portion of the head into the knuckle region. The vessel was designed to 1998 ASME Section VIII Division 1 (VIII-1). Initially the manufacturer of the amine reboiler vessel chose the proof test after the calculations submitted to the approval agency were not accepted. Non-destructive strain gage proof testing per VIII-1 UG-101(n) was planned, but the minimum proof test pressure to achieve the desired MAWP exceeded the maximum firetube flange test pressure therefore an alternate method was chosen. Finite element analysis (FEA) was done in addition to the strain gage testing. The strain gage results at the maximum hydrotest pressure were used to verify the FEA calculations. The FEA calculated strains were higher than the measured strains. This indicated that the assumptions made in the computer model were conservative. By combining FEA with strain gauge testing, the design was proven to meet Code requirements.

scholarly journals Development of a Web-Based Interface for the Automatic Finite Element Analysis of Pressure Vessels

2004 ◽  
Author(s):  
Colin Russell ◽  
David H. Nash
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessels ◽  
The Internet ◽  
Element Analysis ◽  
Web Based ◽  
User Input ◽  
Division 1 ◽  
Complex Models ◽  
Input Variables

The Internet presents an opportunity to facilitate the design of pressure equipment in a new and different way. Current industrial design practice employs computer programmes that perform design-by-formula (DBF) calculations in accordance with ASME VIII Division 1 or other international codes and standards. Design-by-analysis (DBA), however is only undertaken by experienced vessel engineers or general finite element analysis (FEA) consultancy specialists. The present work has established an interface between the Internet and a commercial FEA program for use by designers in the pressure vessel industry. The interface allows users to input variables for a pre-delivered model, obtained from a library of verified models, which may be analysed automatically and the results returned for review. The outcome of the work has been that an interface has been fully established in the form of an interactive dynamically operating web site. It has extensive error checking facilities for user input variables, and is fully operational for the available models, which, for example, includes a reinforced nozzle located in an elliptical end with multiple loadings. The system has been tested by industry and new opportunities have resulted for the training of engineers by allowing access to complex models only after suitable training has been undertaken and levels of competence have been achieved.

Writing and Reviewing FEA Reports Supporting ASME Section VIII, Division 1 and 2 Designs: Practical Considerations and Recommended Good Practice

2014 ◽  
Author(s):  
Trevor Seipp ◽  
Mark Stonehouse
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Good Practice ◽  
Engineering Practice ◽  
Element Analysis ◽  
Professional Engineer ◽  
Division 1 ◽  
The Finite Element Analysis ◽  
Section Viii ◽  
Code Compliance

Finite element analysis (FEA) is used, with increasing frequency, to supplement or justify the design of an ASME Section VIII, Division 1 or 2 pressure vessel. When this occurs, good engineering practice indicates that a competent engineer should review the finite element analysis report. In some jurisdictions, it is required that a Professional Engineer review and certify the report. This paper discusses some of the practical aspects of both writing and reviewing a good quality FEA report — both in the context of the technical perspective and in the context of Code compliance. This paper will serve as a practical assistant to an engineer reviewing an FEA report, as well as a guide to an engineer preparing an FEA report. Aspects such as properly following Code requirements, following appropriate Design By Analysis methodologies, and applying good design practices will be discussed.

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].

Stress Analysis and Structure Optimization for the Opening Flat Cover of Pressure Vessels

2012 ◽  
Vol 538-541 ◽  
pp. 3253-3258 ◽  
Author(s):  
Jun Jian Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Analysis ◽  
Structure Optimization ◽  
Pressure Vessels ◽  
Secondary Stress ◽  
Element Analysis ◽  
Primary Stress ◽  
Flat Cover

According to the results of finite element analysis (FEA), when the diameter of opening of the flat cover is no more than 0.5D (d≤0.5D), there is obvious stress concentration at the edge of opening, but only existed within the region of 2d. Increasing the thickness of flat covers could not relieve the stress concentration at the edge of opening. It is recommended that reinforcing element being installed within the region of 2d should be used. When the diameter of openings is larger than 0.5D (d>0.5D), conical or round angle transitions could be employed at connecting location, with which the edge stress decreased remarkably. However, the primary stress plus the secondary stress would be valued by 3[σ].

Maximum Stress at Intersecting Bores of Pressurized Blocks

1994 ◽  
Author(s):  
Ajay Garg
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Stress ◽  
Element Model ◽  
Maximum Tensile Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Empirical Methods ◽  
Element Analysis ◽  
Matched Design

Abstract In high pressure applications, rectangular blocks of steel are used instead of cylinders as pressure vessels. Bores are drilled in these blocks for fluid flow. Intersecting bores with axes normal to each other and of almost equal diameters, produce stresses which can be many times higher than the internal pressure. Experimental results for the magnitude of maximum tensile stress along the intersection contour were available. A parametric finite element model simulated the experimental set up, followed by correlation between finite element analysis and experimental results. Finally, empirical methods are applied to generate models for the maximum tensile stress σ11 at cross bores of open and close ended blocks. Results from finite element analysis and empirical methods are further matched. Design optimization of cross bores is discussed.

Finite element analysis for optimal design of fuel cell pressure vessels

2020 ◽  
Vol 2020.28 (0) ◽  
pp. 104
Author(s):  
Riku SUZUKI ◽  
Noboru KATAYAMA ◽  
Kiyoshi DOWAKI ◽  
Shinji OGIHARA
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fuel Cell ◽  
Optimal Design ◽  
Pressure Vessels ◽  
Element Analysis
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