A Novel Methodology to Optimize the Tightening Sequence in Bolted Flange Joints

2019 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Experimental Tests ◽  
Elastic Interaction ◽  
Pressure Vessels ◽  
Successful Operation ◽  
Element Analysis ◽  
Bolt Preload ◽  
Safety And Reliability ◽  
Complex Structural ◽  
Leakage Failure ◽  
Bolted Flange

Abstract Bolted flange joints are the most complex structural components of pressure vessels and piping equipment. Their assembly is a delicate task that determines their successful operation during the service life. During bolt tightening, it is very difficult to achieve uniformity of the target bolt preload due to elastic interaction and criss-cross talk. The risk of leakage failure under service loading is consequently increased because of the scatter of the bolt preload. In previous work, an analytical model based on the theory of circular beams on linear elastic foundation was proposed to predict the bolt tension change due to elastic interaction. Based on this model, this paper presents a novel methodology for the optimization of the tightening sequence. The target preload and the load to be applied to each bolt in each pass can be calculated to achieve uniform final preload and avoid bolt tension reaching yield under a number of specified tightening passes. The validity of the approach is supported by experimental tests conducted on a NPS 4 class 900 welding neck flange joint and by finite element analysis on this bolted joint using the criss-cross tightening and sequential patterns. This study provides guidelines for bolted flange joints assembly and enhances its safety and reliability by minimizing bolt tension scatter due to elastic interaction.

Elastic Interaction in Bolted Flange Joints: An Analytical Model to Predict and Optimize Bolt Load

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong ◽  
Zaoxiao Zhang
Keyword(s):  
Analytical Model ◽  
Nuclear Power ◽  
Power Plants ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Element Analysis ◽  
Bolt Preload ◽  
Industrial Complexes ◽  
Leakage Failure ◽  
Bolted Flange

Bolted flange joints are widely used in the nuclear power plants and other industrial complexes. During their assembly, it is extremely difficult to achieve the target bolt preload and tightening uniformity due to elastic interaction and criss-cross talks. In addition to the severe service loadings, the initial bolt load scatter increases the risk of leakage failure. The objective of this paper is to present an analytical model to predict the bolt tension change due to elastic interaction during the sequence of initial tightening. The proposed analytical model is based on the theory of circular beams on linear elastic foundation. The elastic compliances of the flanges, the bolts, and the gasket due to bending, twisting, and axial compression are involved in the elastic interaction and bolt load changes during tightening. The developed model can be used to optimize the initial bolt tightening to obtain a uniform final preload under minimum tightening passes. The approach is validated using finite element analysis (FEA) and experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joint.

Analytical Modelling of Elastic Interaction in Bolted Flange Gasketed Joints

2017 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Analytical Model ◽  
Nuclear Power ◽  
Power Plants ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Industrial Complex ◽  
Element Analysis ◽  
Minimum Number ◽  
Leakage Failure ◽  
Bolted Flange

Bolted flange joints are widely used in the fossil and nuclear power plants and other industrial complex. During their assembly, it is extremely difficult to achieve the target bolt preload and tightening uniformity due to elastic interaction. In addition to the severe service loadings the initial bolt load scatter increases the risk of leakage failure. The objective of this paper is to present an analytical model to predict the bolt tension change due to elastic interaction during the sequence of initial tightening. The proposed analytical model is based on the theory of circular beams on linear elastic foundation. The elastic compliances of the flanges, the bolts, and the gasket due to bending, twisting and axial compression are involved in the elastic interaction. The developed model can be used to optimize the initial bolt load tightening to obtain a uniform final preload under minimum number of tightening passes. The approach is validated using finite element analysis and experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joint.

Numerical and Experimental Study of Elastic Interaction in Bolted Flange Joints

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Element Model ◽  
Interaction Coefficient ◽  
Pressure Vessels ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Bolted Flange

Bolted flange joints are widely used to connect pressure vessels and piping equipment together and facilitate their disassembly. Initial tightening of their bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The risk of failure due to leakage and fatigue under service loading is consequently increased. This paper presents a study on the effect of elastic interaction that is present during the tightening of bolted flange joints using three-dimensional nonlinear finite-element modeling and experimentation. The nonlinear nonelastic behavior of the gasket is taken into account in the numerical simulation. The scatter in bolt preload produced during the tightening sequence is evaluated. Based on the elastic interaction coefficient method, the initial target tightening load in each bolt for every pass is determined by using the nonlinear finite-element model to obtain a uniform preload after the final tightening pass. The validity of the finite-element analysis (FEA) is supported by experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joints using fiber and flexible graphite gaskets. This study provides guidance and enhances the safety and reliability of bolted flange joints by minimizing bolt load scatter due to elastic interaction.

Numerical and Experimental Study of Elastic Interaction in Bolted Flange Joints

2016 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Element Model ◽  
Pressure Vessels ◽  
Nonlinear Finite Element ◽  
Elastic Behavior ◽  
Element Analysis ◽  
Bolted Flange

Bolted flange joints are widely used to connect pressure vessels and piping equipment together and facilitate their disassembly. Initial tightening of their bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The risk of failure due to leakage and fatigue under service loading is consequently increased. This paper presents a study on the effect of elastic interaction that is present during the tightening of a bolted flange joints using three-dimensional nonlinear finite element modeling and experimentation. The nonlinear non-elastic behavior of the gasket is taken into account in the numerical simulation. The scatter in bolt preload produced during the tightening sequence is evaluated. Based on the elastic interaction coefficient method, the initial target tightening load in each bolt for every pass are determined by using the nonlinear finite element model to obtain a uniform preload after the final tightening pass. The validity of the FEA (Finite Element Analysis) is supported by experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joints using fiber and flexible graphite gaskets. This study provides guidance and enhances the safety and reliability of bolted flange joints by minimizing bolt scatter due to elastic interaction.

A METHOD TO REDUCE THE NUMBER OF ASSEMBLY TIGHTENING PASSES IN BOLTED FLANGE JOINTS

2021 ◽  
pp. 1-29
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Oil And Gas ◽  
Elastic Interaction ◽  
Pressure Vessels ◽  
Flange Joint ◽  
Linear Elastic ◽  
Bolt Preload ◽  
Leakage Failure ◽  
Bolted Flange ◽  
Number Of Passes ◽  
Nuclear Applications

Abstract Bolted flange joints are extensively used in the pressure vessels and piping equipment and rotating machinery. Achieving a uniform bolt preload during the assembly process is particularly important to satisfy in bolted flange connection of oil and gas and fossil and nuclear applications. However, it is a very difficult task when tightening all bolts one by one due to elastic interaction. The risk of leakage failure under service loading is consequently increased because of the scatter of the bolt preload. This paper takes the advantage of a developed analytical model based on the theory of circular beams on linear elastic foundation that simulate the elastic interaction of bolted flange joints to reduce the number of passes while achieving bolt load uniformity. As such, a novel methodology for the optimization of the tightening sequence strategies is suggested to obtain uniform bolt tension while avoiding yield under minimum tightening passes. In this regards, based on the target preload, the load applied to each bolt in each pass is suggested. The developed approach is validated both numerically using FEM (finite element method) and experimentally on a NPS 4 class 900 welding neck flange joint using the criss-cross tightening and sequential patterns.

Numerical Simulation of the Assembly Process of Bolted Flange Joints Used in Rotating Machinery

2020 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong ◽  
Zhenming Shi
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Elastic Interaction ◽  
Rotating Machinery ◽  
Least Square ◽  
Bolted Joints ◽  
Fe Method ◽  
Element Analysis ◽  
Bolt Preload ◽  
Bolted Flange

Abstract Bolted joints are widely used to connect structural components in rotating machinery. However, the initial tightening of the bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The scatter in the bolt preload has a major impact on the concentricity and consequently the dynamic behavior of rotating machinery. The risk of failure due to vibration and fatigue under service loading becomes an issue. This paper treats the effect of elastic interaction on the eccentricity during the tightening of bolted joints of rotating machinery using finite element (FE) method. In this regard, a two-component bolted flange joint of a high pressure compressor (HPC) of an aero-engine is investigated. The component surface tolerances measured by Rotary Precision Instruments (RPI) are taken into account in the numerical simulation. A method is proposed to calculate the concentricity of components obtained from the radial runout data based on the Least Square method (LSM). The scatter in bolt preload under different interference fit, surfaces tolerance, initial preload, and tightening sequence are evaluated. Furthermore, the influence of these structures and tightening sequence parameters on the concentricity are investigated. The validity of the finite element analysis is supported by experimental tests conducted on scaled specimens of HPC. This study can provide guidance and enhance the dynamic performance of bolted joints for rotating machinery.

Assembly of Gasketed Bolted Flange Joints Using Torque Control of Preload Method: FEA Approach

2013 ◽  
Author(s):  
Muhammad Abid ◽  
Yasir Mehmood Khan ◽  
David H. Nash
Keyword(s):  
Control Method ◽  
Nonlinear Finite Element ◽  
Torque Control ◽  
Flange Joint ◽  
Element Analysis ◽  
Stress Variation ◽  
Elastic Interactions ◽  
Bolt Preload ◽  
Torque Values ◽  
Bolted Flange

This paper presents the results of the assembly of a gasketed bolted flange joint employing the torque control of preload method using nonlinear finite element analysis. It has been observed that bolt preload scatter due to elastic interactions, flange stress variation, bolt bending due to flange rotation and gasket contact stress variation are very difficult to eliminate when using the torque control method. The behaviour of a gasketed joint using two different target torque values is discussed in detail.

Design of a Large Rectangular Flange

2006 ◽  
Author(s):  
Bharat Batra
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Horizontal Plane ◽  
Element Analysis ◽  
Acceptable Solution ◽  
Bolt Preload ◽  
The Finite Element Analysis ◽  
Section Viii ◽  
Design Challenge ◽  
Bolted Flange

A large rectangular flange (5’ wide × 12.5’ Long) was designed using finite element analysis for a horizontal mixer vessel. The mixer vessel contained a large horizontal agitator with the shaft protruding through the two flat ends of the vessel. The horizontal vessel was split in the middle horizontal plane creating a large rectangular opening to be sealed by the two large rectangular flanges. The size of the flange, the type of gasket, the bolt preload required to obtain a reasonable seal made it a design challenge to design this bolted flange assembly. To start with, an estimate was made based on the calculation of the thickness of the flange using an equivalent circular flange. The finite element analysis of the whole assembly was preformed using the FEA software ANSYS. After several iterations, an acceptable solution was found with acceptable flange and bolt stresses. The seating stress in the gasket was also above the recommended gasket seating stress. Thus, the flanged joint was designed to be in compliance with ASME B&PV Code, Section VIII, Div-1. The vessel and the bolted flange assembly was successfully fabricated and hydrotested based on this design and it is successfully operating in the field.

An Effect of Gasket Contact Stress Distributions on the Tightness Estimation in Pipe Flange Connections by Finite Element Analyses

2004 ◽  
Author(s):  
Yasumasa Shoji
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Elastic Interaction ◽  
General Purpose ◽  
Pressure Vessels ◽  
Plastic Behavior ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Bolt Stress ◽  
The Relationship

Recently bolting procedures for flanged connection is one of the important research topics, and several procedures for bolting process are proposed or about to be issued. These procedures are based on bolting experimental and/or analytical results, namely by Finite Element Analyses. Among these researches, only a few are addressing the relationship between bolt tension scatter and gasket contact stress distribution. Bolt tension scatters in nature due to elastic interaction of the bolts as the bolts are tightened one by one. In order to obtain a uniform, or nearly uniform, tension along all the joint bolts, many “rounds” or “passes” are necessary to eliminate this elastic interaction. If the installer does not iterate this tightening process, gasket stress will be distributed undesirably due to the bolt tension scatter. The bolt tension scatter is now mostly calculated using the analysis programs that are developed by research laboratories themselves. In this paper, the author suggests to use a general purpose finite element analysis code for bolt stress, gasket stress and flange stress, which accommodates such advanced functions as bolt pretension and gasket plastic behavior. The author will show that it is possible to analyze the bolt tension, gasket stress and flange stress at the same time using a market sold analysis code, ABAQUS, and examine how many “rounds” are necessary to achieve uniform gasket contact stress. This paper also describes the relationship between the gasket contact stress and the bolt tension scatter, and the effect of internal pressure of piping or pressure vessels. Based on these results, the tightness parameters are estimated and the methods in the standards are verified in the aspect of allowable and achieved leakage.

A New Approach to Model Bolted Flange Joints With Full Face Gaskets

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Hichem Galai
Keyword(s):  
Elastic Interaction ◽  
Bolted Joints ◽  
Element Analysis ◽  
New Approach ◽  
Flexibility Analysis ◽  
Load Change ◽  
Proposed Model ◽  
Numerical Finite Element ◽  
Full Face ◽  
Bolted Flange

The poor leakage performance of flanges with full face gaskets is attributed to the low reliability of the existing design methods, and in particular, their lack of assessing accurately the bolt and gasket load changes. The prediction of tightness of bolted joints relies very much on the level of precision of the gasket contact stress during operation. The accurate evaluation of this stress requires a flexibility analysis of the joint that includes the flange, gasket, and bolts, and the interaction between them. This paper analyzes the distribution of gasket stress and the load change in bolted joints with full face gaskets. It proposes a simple analytical approach capable of predicting flange rotation and bolt load change during operation. The method is based on the gasket-bolt-flange elastic interaction, including flange rotational flexibility. The proposed model is supported by comparison with numerical finite element analysis of different size flanges.

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