On the Use of Belleville Washers to Reduce Relaxation in Bolted Flange Joints

2008 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Akli Nechache
Keyword(s):  
High Temperature ◽  
Analytical Model ◽  
Analytical Calculation ◽  
Calculation Procedure ◽  
Minimum Level ◽  
Target Value ◽  
Exact Number ◽  
Model Based ◽  
Material Creep ◽  
Bolted Flange

Bolted flange joints are prone to leakage when exposed to high temperature. In most cases this is due to relaxation that takes place as a result of material creep. One way to solve this problem is to use Belleville spring washers or longer bolt with spacers. However, there is practically no reliable analytical model that can evaluate the exact number of washers or length of the bolts required to reduce relaxation to a target minimum level. This paper describes an analytical model based on the flexibility and displacement interactions of the joint different elements including the axial rigidity of the flange and bolts, used to evaluate relaxation. The developed analytical flange model can accommodate either Belleville spring washers or longer bolts with spacer tubes to reduce the bolt load loss to a maximum target value. This model is validated by comparison with the more accurate FEA findings. Calculation examples on a bolted flanged joint are presented to illustrate the suggested analytical calculation procedure.

scholarly journals High Temperature Testing and Analysis of a Class 300 Bolted Flange Joint

2014 ◽  
Author(s):  
J. Adin Mann ◽  
Jeremy Hilsabeck ◽  
Cale Mckoon
Keyword(s):  
High Temperature ◽  
Bolted Joints ◽  
Flange Joint ◽  
Simulation Approach ◽  
High Temperature Testing ◽  
Material Creep ◽  
Fea Simulation ◽  
Bolted Flange ◽  
The Impact

When class 300 flange bolted joints are held at temperatures in the material creep range, it is documented that the bolt loads can relax. Tests and analysis are being performed with the goal of developing a validated FEA simulation approach to predicting the impact of creep on the bolt loads. The bolt load and gasket geometry are evaluated upon bolt up and after being heated to 1100 deg F. Tests are performed with and without a gasket to separate the impact of the gasket relaxation and flange material creep. The results of the tests and analysis approaches will be presented. Paper published with permission.

scholarly journals Generalized analytical model based on harmonic coupling for hybrid plasmonic modes: comparison with numerical and experimental results

2015 ◽  
Vol 23 (21) ◽  
pp. 27376 ◽  
Author(s):  
Mitradeep Sarkar ◽  
Jean-François Bryche ◽  
Julien Moreau ◽  
Mondher Besbes ◽  
Grégory Barbillon ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Results ◽  
Model Based

Effect of Creep on the Residual Stresses in Tube-to-Tubesheet Joints

2010 ◽  
Author(s):  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Analytical Model ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Environmental Safety ◽  
Maintenance Cost ◽  
Joint Interface ◽  
Plant Safety ◽  
Material Creep ◽  
Nuclear Power Plant Safety

Steam generators are the subject of major concern in nuclear power plant safety. Within these generators, in addition to the structural integrity, the gross tightness barrier, which separates the primary and secondary circuits, is primarily ensured by the presence of a residual contact pressure at the tube-to-tubesheet joint interface. Any leakage is unacceptable, and its consequences are very heavy in terms of the human and environmental safety as well as maintenance cost. Some studies have been conducted to understand the main reasons for such a failure. However, no analytical model able to predict the attenuation of the residual contact pressure under the effect of material creep relaxation behavior. The development of a simple analytical model able to predict the change of the residual contact pressure as a function of time is laid out in this paper. The results from the analytical model are checked and compared with those of finite elements.

Evaluation of Leakage Probability of Non-Asbestos Fiber Sheet Gasket at Elevated Temperature Based on Percolation Theory

2010 ◽  
Author(s):  
Masahiro Hagihara ◽  
Hirokazu Tsuji ◽  
Atsushi Yamaguchi
Keyword(s):  
High Temperature ◽  
Percolation Theory ◽  
Life Prediction ◽  
Prediction Method ◽  
Acoustic Tomography ◽  
Leakage Path ◽  
Temperature Environment ◽  
Fiber Sheet ◽  
Bolted Flange

A long-term life prediction method for a compressed fiber sheet gasket under a high-temperature environment is studied. Non-asbestos compressed fiber sheet gaskets are now being used as a substitute for asbestos in the bolted flange joint, for instance petrochemical factories. Consequently, there is a real need for a technology to predict the lifetime of non-asbestos compressed fiber sheet gaskets quantitatively. In this report, the facing surface of the gasket and flange is visualized with scanning acoustic tomography (SAT). Voids were observed on the facing surface of the gasket and increased with the increase in exposure time at high temperature. If a leakage path for inner fluids is created by the increasing number of voids, the leak occurs on the facing surface of the gasket. The probability of a leak due to voids and the lifetime of this gasket are predicted by applying the percolation theory, which describes the connectedness of clusters.

scholarly journals The Unresolved Definition of The Pressure-Viscosity Coefficient

2021 ◽  
Author(s):  
Scott Bair
Keyword(s):  
High Temperature ◽  
Equation Of State ◽  
Low Temperature ◽  
Film Thickness ◽  
Pressure Dependence ◽  
Analytical Calculation ◽  
Elastohydrodynamic Lubrication ◽  
Viscosity Coefficient ◽  
Classical Approach ◽  
Definition Of

Abstract In the classical approach to elastohydrodynamic lubrication (EHL) a single parameter, the pressure-viscosity coefficient, quantifies the isothermal pressure dependence of the viscosity for use in prediction of film thickness. Many definitions are in current use. Progress toward a successful definition of this property has been hampered by the refusal of those working in classical EHL to acknowledge the existence of accurate measurements of the piezoviscous effect that have existed for nearly a century. The Hamrock and Dowson pressure-viscosity coefficient at high temperature requires knowledge of the piezoviscous response at pressures which exceed the inlet pressure and may exceed the Hertz pressure. The definition of pressure-viscosity coefficient and the assumed equation of state must limit the use of the classical formulas, including Hamrock and Dowson, to liquids with high Newtonian limit and to low temperature. Given that this problem has existed for at least fifty years without resolution, it is reasonable to conclude that there is no definition of pressure-viscosity coefficient that will quantify the piezoviscous response for an analytical calculation of EHL film thickness at temperatures above ambient.

scholarly journals An analytical model based on radiative heating for the determination of safety distances for wildland fires

2011 ◽  
Vol 46 (8) ◽  
pp. 520-527 ◽  
Author(s):  
J.L. Rossi ◽  
A. Simeoni ◽  
B. Moretti ◽  
V. Leroy-Cancellieri
Keyword(s):  
Analytical Model ◽  
Radiative Heating ◽  
Wildland Fires ◽  
Model Based
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