Evaluation of Stress in Vibrating Cylindrical Shells due to Acoustic Loading Based on Theory of Shells

2016 ◽  
Author(s):  
Shunji Kataoka ◽  
Takahiro Hida
Keyword(s):  
Design Method ◽  
Cylindrical Shells ◽  
Piping System ◽  
Key Factors ◽  
Element Analysis ◽  
Numerical Studies ◽  
Piping Systems ◽  
Detailed Assessment ◽  
Past Experiences ◽  
Modal Stress

Acoustically induced vibration (AIV) is recognized as a vibration of piping systems caused by the acoustic loading at the downstream of the pressure reducing devices. For decades several industrial practices which are derived from past experiences, have been applied for the design of piping system, however it is known that the practices includes uneven design margins. Due to the increase of the large capacity reducing devices, the demands of the development of reasonable screening and design method for AIV are increasing. A detailed assessment of fatigue life using finite element analysis has become popular and clarified the effect of acoustic load on several specific components; however, there are no clear way to explain the susceptibility against AIV depending on its diameter and thickness. Therefore the discussions based on engineering principles are required. In this paper, the vibration of cylindrical shells due to acoustic loading was discussed based on the theory of cylindrical shells. Results of several numerical studies based on the theoretical formulas were presented on the natural frequency and modal stress of vibrating shells on various geometries. Thus, the key factors to affect the vibrating shell stresses were clarified and some simplified formula to evaluate the vibrating shell stress was proposed.

Creep Life Simulation and Assessment of High Temperature Piping Systems and Components

2012 ◽  
Author(s):  
Brian Rose ◽  
James Widrig
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Behavior ◽  
Material Behavior ◽  
Piping System ◽  
Remaining Life ◽  
Creep Life ◽  
Element Analysis ◽  
Piping Systems

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.

Performance-Based Analysis of Coupled Support Structures and Piping Systems Subject to Seismic Loading

2015 ◽  
Author(s):  
Oreste S. Bursi ◽  
Fabrizio Paolacci ◽  
Md Shahin Reza
Keyword(s):  
Seismic Design ◽  
Seismic Analysis ◽  
Design Method ◽  
Design Guidelines ◽  
Piping System ◽  
Support Structures ◽  
Limit States ◽  
Piping Systems ◽  
Allowable Stress Design

The prevailing lack of proper and uniform seismic design guidelines for piping systems impels designers to follow standards conceived for other structures, such as buildings. The modern performance-based design approach is yet to be widely adopted for piping systems, while the allowable stress design method is still the customary practice. This paper presents a performance-based seismic analysis of petrochemical piping systems coupled with support structures through a case study. We start with a concept of performance-based analysis, followed by establishing a link between limit states and earthquake levels, exemplifying Eurocode and Italian prescriptions. A brief critical review on seismic design criteria of piping, including interactions between piping and support, is offered thereafter. Finally, to illustrate actual applications of the performance-based analysis, non-linear analyses on a realistic petrochemical piping system is performed to assess its seismic performance.

Effects of High Frequency Hydrodynamic Loads on Structural Integrity and Mechanical Operability of Valves

2015 ◽  
Author(s):  
Yigit Isbiliroglu ◽  
Cagri Ozgur ◽  
Evren Ulku ◽  
Nish Vaidya ◽  
Kristofor Paserba
Keyword(s):  
High Frequency ◽  
Structural Integrity ◽  
Energy Content ◽  
Hybrid Approach ◽  
Piping System ◽  
Seismic Loads ◽  
Damage Potential ◽  
Element Analysis ◽  
Piping Systems ◽  
Number Of Cycles

In-line valves are qualified for static as well as dynamic loads from seismic and hydrodynamic (HD) events. Seismic loads are generally characterized by frequency content less than about 33 Hz whereas HD loads may exhibit a broad range of frequencies greater than 33 Hz. HD loads may also result in spectral accelerations significantly in excess of those due to the design basis seismic events. Current regulatory guidelines do not specifically address the evaluation of equipment response to high frequency loading. This paper investigates the response of skid and line mounted valves of piping systems under HD loads by using several independent rigorous finite element analysis solutions for various piping system segments. It presents a hybrid approach for the evaluation of the response of valves to HD and seismic loads. The proposed approach significantly reduces the amount of individual analysis and testing needed to qualify the valves. First, valve responses are evaluated on the basis of displacements since HD loads are generally characterized by high frequencies and small durations. Second, the damage potential of the loads on the valve actuators is represented by the energy imparted to the actuator quantified in terms of Arias intensity. The rationale for using the energy content is based on the fact that damage due to dynamic loading is related not only to the amplitude of the acceleration response but also to the duration and the number of cycles over which this acceleration is imposed.

An Experiential Optimization Design Method for Orthogonal Rib-Stiffened Thin Walled Cylindrical Shells under Axial Loading

2011 ◽  
Vol 110-116 ◽  
pp. 1773-1783
Author(s):  
Jia Mao ◽  
Yu Feng Chen ◽  
Wei Hua Zhang
Keyword(s):  
Optimization Design ◽  
Design Method ◽  
Mass Parameter ◽  
Cylindrical Shells ◽  
Reference Value ◽  
Buckling Load ◽  
Element Analysis ◽  
Buckling Loads ◽  
Load Optimization ◽  
Thin Walled

Parametric structural FEA (Finite Element Analysis) models of the orthogonal rib-stiffened thin walled cylindrical shells are established using APDL (ANSYS Parametric Design Language). An experiential optimization design method is then developed based on conclusions of series numerical analysis investigating the effects of parameters’ modification upon buckling loads and modes of the structure. The effects of single design parameter modification under both variational and fixed volume (mass) constraints upon the buckling loads and modes indicate that, only one design scheme is able to obtain maximum buckling load when deployment of the strengthening ribs and volume (mass) parameter were settled previously, and minimum mass would be obtained while this maximum buckling load equals to the required design load. Optimization calculations for aluminum alloy material and layered C/E (Carbon/Epoxy) composite material shells with three layering styles are implemented and discussed, and some useful conclusions are obtained. Method and approach developed in this paper provide certain reference value for the optimal design of such structures.

Simplified Seismic Response Analysis Method Using Reduced Model of Piping System

2018 ◽  
Author(s):  
Michiya Sakai ◽  
Ryuya Shimazu ◽  
Shinichi Matsuura ◽  
Ichiro Tamura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Seismic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Piping System ◽  
Element Analysis ◽  
Mass System ◽  
Piping Systems ◽  
Low Degrees

In the seismic response analysis of piping systems, finite element analysis is performed with analysis method guidelines [1]–[4] established based on benchmark analysis. However, since it takes a great deal of effort to carry out finite element analysis, a simplified method to analyze the seismic response of complex piping systems is required. In this research, we propose a method to reduce an equivalent spring-mass system model with low degrees of freedom, which can take into account the main mode of the complicated piping system. Simplified seismic evaluation is carried out using this spring mass system model with low degrees of freedom, and the accuracy of response evaluation is confirmed by comparison with finite element analysis.

Elastic-Plastic Analysis of Thick-Walled Toroidal Pressure Vessels

2008 ◽  
Author(s):  
R. Adibi-Asl
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Toroidal Shell ◽  
Piping System ◽  
Straight Pipe ◽  
Element Analysis ◽  
Process Industries ◽  
Piping Systems

Piping systems in process industries and nuclear power plants include straight pipe runs and various fittings such as elbows, miter bends etc. Elbows and bends in piping systems provide additional flexibility to the piping system along with performing the primary function of changing the direction of fluid flow. Distinctive geometry of these toroidal shell components result in a structural behavior different from straight pipe. Hence, it would be useful to predict the behavior of these components with acceptable accuracy for design purposes. Analytical expressions are derived for stresses set up during loading and unloading in a toroidal shell subjected to internal pressure. Residual stresses in the component are also evaluated. The proposed solutions are then compared with three-dimensional finite element analysis at different locations including intrados, extrados and flanks.

A Case Study on the Effect of Peaked Pipe Welds on Piping Life Expectancy

2010 ◽  
Author(s):  
Warren Brown ◽  
Martin Prager ◽  
Sarah Wrobel
Keyword(s):  
Material Properties ◽  
Life Assessment ◽  
Piping System ◽  
Creep Life ◽  
Element Analysis ◽  
Omega Method ◽  
Detailed Assessment ◽  
Creep Life Assessment ◽  
Pipe Geometry

This paper details a case study on the effect of weld peak geometry on the expected creep life of a piping system operating in a refining environment. Inspection of the 1-1/4 Cr piping system revealed significant peaked geometry at the longitudinal weld locations. A Finite Element Analysis (FEA) assessment of the remaining life was made using the Omega method of creep life assessment. The sensitivity of the results to modeled pipe geometry and assumed material properties was assessed. The variability of life prediction that was obtained indicated a necessity to perform further more detailed assessment of the pipe geometry and material properties by the removal of samples at the weld locations. The improvement obtained in the assessment accuracy and final life predictions from the sample analysis is presented in the paper and practical implications on the operation of the piping system are detailed. Suggestions and cautions for the practical assessment of similar peaked pipe problems are also discussed.

Mitigation of Bending Stress and Failure Due to Temperature Differentials in Piping Systems Carrying Multiphase Fluids: Using CFD and FEA

2005 ◽  
Author(s):  
Philip Diwakar ◽  
Vibhor Mehrotra ◽  
Franklin Richardson
Keyword(s):  
Heat Transfer ◽  
Thermal Stresses ◽  
Initial Stresses ◽  
Piping System ◽  
Atmospheric Conditions ◽  
Element Analysis ◽  
Pipe System ◽  
Piping Systems ◽  
The Dead ◽  
Piping Networks

The bending of large pipes due to temperature differentials between the bottom and top of the pipe is a very serious problem. The temperature differentials can either be caused by extremely cold liquids (such as methane or ethylene flowing from a lateral into a flare header) or hot liquids flowing at the bottom of a piping system (such as in a Vacuum transfer line) while the top is exposed to atmospheric conditions. In some cases liquids may be produced by Joule-Thompson cooling of high pressure cold gas as it expands through a safety-relief or emergency depressurization valve. The liquid so formed can accumulate, for example, on the dead leg side of a flare header. The differential expansion can deform the pipe so that it lifts off its supports. It takes a finite amount of time for the heat transfer by conduction to equilibrate the temperature to a more benign level. The initial stresses induced due to large thermal differential may even cause the pipe to crack in the region of the supports and T-joints to the laterals. This phenomenon has been observed in several industries, most predominantly in the petrochemical industry. This paper recounts the use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to study this important phenomenon. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow re´gime. Multiphase flows with heat transfer are analyzed using CFD. The temperatures on the walls of the pipe system are then transferred to the FEA and analyzed for heat transfer and thermal stresses. These stresses are compared to ASME standards to see if they are within allowable limits. This paper also recounts efforts to reduce the bending effect by preventing liquid accumulation on the dead leg side. Other methods that provide better supports for bent piping are studied. Further, methods of equilibrating the temperature faster to prevent the bowing of the pipe are also studied. It is hoped that this presentation will benefit people designing piping networks with varying liquid and vapor traffic by providing a safe environment free of cracks and spills.

Reduction in Stresses Shown in Piping Programs in Large Diameter Pipe Branch Connections by Applying Flexibilities Computed by Shell Finite Element Analysis

2004 ◽  
Author(s):  
Robert A. Robleto
Keyword(s):  
Finite Element Analysis ◽  
Large Diameter ◽  
Piping System ◽  
Bending Moments ◽  
Straight Pipe ◽  
Element Analysis ◽  
Large Diameter Pipe ◽  
Diameter Pipe ◽  
Piping Systems ◽  
Shell Finite Element

When designing branch connections in low pressure large diameter piping systems as in Figure 1, thicker is not always better. The flexibility factors in ASME B31.3 1 for branch connections do not assist the designer in taking credit for flexibility that may exist in a large diameter intersection. Since the stress intensification factors (SIFs) are relatively high for large diameter piping, many stub-in branch connections will require a pad to meet the code displacement stress limits. In an ASME B31.3 Piping analysis the stiffness of the branch connections is considered to be as stiff as a straight piece of pipe modeled as a beam. This is a simplifying assumption that can lead to expensive conservatism for the component and possibly non-conservatism for nearby equipment especially when large diameter pipe is considered. Branch connection flexibility is often negligible when compared with piping flexibility of straight pipe perpendicular to the deflection and bends which can ovalize under in-plane bending moments. However, studies at KBR show branch connections in large diameter pipe can contribute significant flexibility to a close coupled piping system.

Dealing With Heavy Loads in Large Diameter Piping

2012 ◽  
Author(s):  
Hector Rojas ◽  
Andrey Gutkovsky
Keyword(s):  
Large Diameter ◽  
Operating Conditions ◽  
Configuration Design ◽  
Piping System ◽  
Flow Conditions ◽  
Element Analysis ◽  
Piping Systems ◽  
Molten Sulfur ◽  
Heavy Loads

It is common in a refinery that some piping systems have to handle several flow conditions. However, when a new proposed condition implies the filling of an existing 68″ (1727 mm) line with molten Sulfur, which was initially designed for gas operation, a well thought engineering case study is required to guarantee that no damage will occur under the new operating conditions. This paper covers the procedures employed to qualify the integrity of a 68″ (1727 mm) piping system, initially designed to carry Sulfur vapors and required to handle occasional filling with molten Sulfur due to operational demands. The procedures of reviewing the initial configuration, design of modifications and reinforcements to the piping system and the use of Finite Element Analysis (FEA) in order to qualify several unique support configurations are explained in this paper.

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