On the Modelling of Anisotropic Fiber Reinforced Polymer Flange Joints

Author(s):  
Abdel-Hakim Bouzid ◽  
Ali K. Vafadar ◽  
Anh-Dung Ngo

Abstract Fiber Reinforced Plastic composite flanges have recently experienced a spectacular development in the area of pressure vessels and piping. The current procedures used for the design of these flanges are a major concern because of their inappropriateness to address the anisotropic behavior of composite materials. The current ASME code section X related to the design procedure of composite flanges uses the same analytical method as the one of section VIII division 2 which treat the flanges as isotropic materials such as metallic flanges. This study deals with FRP bolted flange joints integrity and bolt tightness. A new developed analytical FRP model that treats anisotropic flanges with and without a hub is presented. The model is based on the anisotropy and a flexibility analysis of all joint elements including the gasket, bolts and flanges. It is supported experimentally with tests conducted on a real NPS 3 class 150 WN FRP bolted flange. Furthermore, three different numerical models based on 3D anisotropic layered shell and solid element models were conducted to further compare and verify the results obtained from the new developed analytical approach. The results show that the new model has potential to be used as an alternative tool to FEM if an accurate method to analyses the stresses and deformation of problematic FRP bolted joint applications.

Author(s):  
Ali Khazraiyan Vafadar ◽  
Abdel-Hakim Bouzid ◽  
Anh Dung Ngô

Abstract Fiber Reinforce Plastic composite flanges have recently experienced a spectacular development in the area of pressure vessels and piping. The current procedures used for the design of these flanges are a major concern because of their inappropriateness to address the anisotropic behavior of composite materials. The current ASME code design procedure of composite flanges of section X uses the same analytical method as the one of section VIII division 2 which treat the flanges as isotropic materials such as metallic flanges. This study deals with FRP bolted flange joints integrity and bolt tightness. A new developed analytical FRP model that treats anisotropic flanges with and without a hub is presented. The model is based on the anisotropy and a flexibility analysis of all joint elements including the gasket, bolts and flanges. It is supported experimentally with tests conducted on a real NPS 3 class 150 FRP bolted flange. Furthermore, three different numerical models based on 3D anisotropic layered shell and solid element models were conducted to further compare and verify the results obtained from the new developed analytical approach. The results show that the new model has potential to be used as an alternative tool to FEM if an accurate method to analyses the stresses and deformation of problematic FRP bolted joint applications.


Author(s):  
Douglas Eisberg

Over the past several years, many industries have grown to recognize that Fiber Reinforced Plastic (FRP) pressure vessels must be built to established industrial safety standards to help ensure consistently safe products. End Users and Engineers familiar with Section VIII of the ASME Code typically turn to Section X as the standard recognized to govern the fabrication of fiber-reinforced vessels. However there tends to be confusion concerning Section X and how design integrity is maintained. There is a belief held by some that a composite pressure vessel designed in accordance with the Section X, Class I meets the essence of the Code. The feeling is that complete compliance is an unnecessary expense and third party certification is of minimal value. Section X is very specific in pointing out the fundamental error in this thinking. Section X recognizes that, unlike metal construction, the fabricator of a fiberglass vessel is responsible for the creation of a new and very temperamental material every time a part is fabricated. With this chance of inconsistency, even a fundamentally sound design can be executed poorly and with disastrous results. The purpose of this paper will be to describe the design and procedure qualification process used for Class I pressure vessels and how the integrity of the design in maintained throughout the fabrication of ASME Code Stamped pressure vessels.


2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez

The available design formulas for flat heads and blind end closures in the ASME Code, Section VIII, Divisions 1 and 2 are based on bending theory and do not apply to the design of thick flat heads used in the design of high pressure vessels. This paper presents new design formulas for thickness requirements and determination of peak stresses and stress distributions for fatigue and fracture mechanics analyses in thick blind ends. The use of these proposed design formulas provide a more accurate determination of the required thickness and fatigue life of blind ends. The proposed design formulas are given in terms of the yield strength of the material and address the fatigue strength at the location of the maximum stress concentration factor. Introduction of these new formulas in a nonmandatory appendix of Section VIII, Division 3 is recommended after committee approval.


2021 ◽  
Author(s):  
Finn Kirkemo ◽  
Przemyslaw Lutkiewicz

Abstract High-pressure applications such as process piping, pressure vessels, risers, pipelines, and subsea production systems use bolted flange connections. Design of flanged joints may be done by design by rules and design by analysis. This paper presents a design by rules method applicable for flanges designed for face-to-face make-up. Limit loads are used to calculate the structural capacity (resistance) of the flanges, bolts, and metallic seal rings. Designers can use the calculation method to size bolted flange connections and calculate the structural capacity of existing bolted flange connections. Finite element analyses have been performed to verify the analytically based calculation method. The intention is to prepare for an ASME code case based on the calculation method presented in this paper.


Author(s):  
Richard C. Biel ◽  
Gregory Cano

Adoption of composite reinforced pressure vessels (CRPV) into the ASME Boiler and Pressure Vessel Code represented advancement in the technology of pressure vessels. The advantage of this construction technique is that the weight of a CRPV for compressed gas service built may be reduced to about one-half conventional pressure vessel of the same capacity. The concept of hoop wrapping fibers in a plastic composite (>90% fiber fill) makes full utilization of the fiber strength as the fibers share the hoop load with a metal cylinder. With reduced hoop stresses in the metal, a substantial reduction in wall thickness is attainable. The process of adoption of this technology presented several challenges and some robust administrative hurdles. These included coordination with ASME BPV Code Section X for the composite application and Section VIII for the steel design and overall acceptance of the Case. The most vexing technical challenge was the inspection of an unfinished weld on the inside of the shell from the outside of the shell. The next challenge was to gain consensus on the testing criteria for the acceptance of finished vessels. Case 2390 was drafted in the winter of 2000 and spring of 2001 and approved for publication after nine revisions with an approval date of October 9, 2002. The Case was subsequently adopted into the body of ASME BPV Code Section VIII, Division 3 [1] (VIII-3) in the 2010 edition.


2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Thomas A. Duffey ◽  
Kevin R. Fehlmann

Abstract High-explosive containment vessels are often designed for repeated use, implying predominately elastic material behavior. Each explosive test imparts an impulse to the vessel wall. The vessel subsequently vibrates as a result of the internal blast loading, with amplitude diminishing exponentially in time after a few cycles due to structural damping. Flaws present in the vessel, as well as new flaws induced by fragment impact during testing, could potentially grow by fatigue during these vibrations. Subsequent explosive tests result in new sequences of vibrations, providing further opportunity for flaws to grow by fatigue. The obvious question is, How many explosive experiments can be performed before flaws potentially grow to unsafe limits? Because ASME Code Case 2564-5 (Impulsively Loaded Pressure Vessels) has just been incorporated in Section VIII, Division 3 of the 2019 ASME Boiler and Pressure Vessel Code, evaluation of remaining life and fitness-for-service of explosive containment vessels now draws upon two interrelated codes and standards: ASME Section VIII-3 and API-579/ASME FFS-1. This paper discusses their implementation in determining the remaining life of dynamically loaded vessels that have seen service and are potentially damaged. Results of a representative explosive containment vessel are presented using actual flaw data for both embedded weld flaws and fragment damage. Because of the potentially large number of flaws that can be detected by modern nondestructive inspection methods, three simplifying assumptions and a procedure are presented for conservatively eliminating from further consideration the vast majority of the flaws that possess considerable remaining life.


Author(s):  
John J. Aumuller ◽  
Vincent A. Carucci

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.


Author(s):  
J Y Zheng ◽  
P Xu ◽  
L Q Wang ◽  
G H Zhu

Flat steel ribbon wound pressure vessels have been adopted by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 and Division 2. An excellent safety and service record has been built up in the past 34 years. Based on the interfacial friction model proposed by Zheng [1], a more accurate method for predicting the stresses in a flat steel ribbon wound pressure vessel is offered in this paper, taking account of the axial displacement, the change in the helical winding angle, the interfacial friction between ribbon layers and the effect of lamination. Comparison between experimental results of five test vessels with an inside diameter varying from 350 to 1000 mm, four different helical winding angles (18, 24, 27 and 30°), two width—thickness ratios of the ribbon (20 and 22.86) and results of calculation using the stress formulae available demonstrates that the method in this paper is more accurate and that interfacial friction gives a marked strengthening contribution to the axial strength of the vessel.


Author(s):  
Kang Xu ◽  
Mahendra Rana ◽  
Maan Jawad

Abstract Layered pressure vessels provide a cost-effective solution for high pressure gas storage. Several types of designs and constructions of layered pressure vessels are included in ASME BPV Section VIII Division 1, Division 2 and Division 3. Compared with conventional pressure vessels, there are two unique features in layered construction that may affect the structural integrity of the layered vessels especially in cyclic service: (1) Gaps may exist between the layers due to fabrication tolerances and an excessive gap height introduces additional stresses in the shell that need to be considered in design. The ASME Codes provide rules on the maximum permissible number and size of these gaps. The fatigue life of the vessel may be governed by the gap height due to the additional bending stress. The rules on gap height requirements have been updated recently in Section VIII Division 2. (2) ASME code rules require vent holes in the layers to detect leaks from inner shell and to prevent pressure buildup between the layers. The fatigue life may be limited by the presence of stress concentration at vent holes. This paper reviews the background of the recent code update and presents the technical basis of the fatigue design and maximum permissible gap height calculations. Discussions are made in design and fabrication to improve the fatigue life of layered pressure vessels in cyclic service.


1990 ◽  
Vol 112 (1) ◽  
pp. 50-56 ◽  
Author(s):  
A. E. Blach ◽  
V. S. Hoa ◽  
C. K. Kwok ◽  
A. K. W. Ahmed

Design Rules in the ASME Code, Section VIII, Division 1, cover the design of unreinforced and reinforced rectangular pressure vessels. These rules are based on “infinitely long” vessels of non-circular cross section and stresses calculated are based on a linearized “small deflection” theory of plate bending. In actual practice, many pressure vessels can be found which are of finite length, often operating successfully under pressures two to three times as high as those permitted under the Code rules cited. This paper investigates the effects of finite length on the design formulae given by the ASME Code, and also a design method based on “large deflection” theory coefficients for short rectangular pressure vessels. Results based on analysis are compared with values obtained from finite element computations, and with experimental data from strain gage measurements on a test pressure vessel.


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