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.

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 ◽  
Frank 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.

Study of Dynamic Stresses in Pipe Networks and Pressure Vessels Using Fluid-Solid-Interaction Models

2007 ◽  
Author(s):  
Philip Diwakar ◽  
Lorraine Lin
Keyword(s):  
Heat Transfer ◽  
Thermal Stresses ◽  
Traditional Approach ◽  
Fluid Model ◽  
Pressure Vessels ◽  
Piping System ◽  
Atmospheric Conditions ◽  
Flow Induced Vibration ◽  
Element Analysis ◽  
Fluid Solid Interaction

A lack of understanding of the fluid-structure interactions has resulted in a number of infamous structural failures in the past. For example, the collapses of the Tay Bridge in Scotland in 1879, the Tacoma Bridge in 1948 and three tall cooling towers in Ferrybridge/England in 1965 have been intrinsically related to fluid forces acting on the structure. Flutter, flow-induced vibration, divergence and related phenomena may be studied using the Fluid-Solid-Interaction (FSI) approach. This paper gives three examples of the FSI approach and shows the innovative application of state-of-the-art computational methods to improve realism and accuracy in engineering analyses. Case 1: Study of Hydrodynamic Sloshing Loads: The sloshing of liquid in large vessels under seismic loads is a timely topic. The movement of the free surface of the liquid is simulated using a two-phase volume of fluid model at various liquid heights. The transient forces generated by the fluid on the vessel wall and internals are superimposed as loads on a dynamic non-linear calculation and the fatigue and stresses are computed in an explicit finite element analysis. This approach calculates the local sloshing effects on internals as opposed to the traditional approach of using spring-mass elements. Case 2: Bending of Large Pipes due to Temperature Differentials: Pipe temperature differentials can be caused by either extremely cold liquids or hot liquids flowing at the bottom of a piping system while the top is exposed to atmospheric conditions. Differential expansion can cause pipe deformation resulting in pipe lift-off at its supports and failure at the weld locations and T-joints. Heat transfer from complex multi-phase flows was simulated using CFD. The predicted pipe wall temperatures were then input to an FEA grid and analyzed for heat transfer and thermal stresses. These stresses were compared to ASME standard allowable limits. Based on this analytical approach, a design guide for various diameters of flare header pipes, supports and tees has been established. Details of this paper were previously published in [Ref 1] and are not described in this paper. Case 3: Establishing velocity limits and line sizing criteria in pipes: The original guidelines in Fluid Flow Manuals were developed over the last fifty years based on project experience and economic and best practices technology of the time. The criteria have proven out as good, but overly conservative with regards to line size. Compressor discharge guidelines are based on the erosion velocity limits. Based on a dynamic analysis approach — using unsteady flow rates from compressors — stresses due to flow-induced vibration, noise and fatigue, hydraulic transients such as waterhammer effects for long lines (greater than 1000 feet), flashing and control valve cavitations may be studied. FSI was used to determine if the velocity limit guidelines hold in the current designs and use a parametric approach to mitigate the bottlenecking by supplying a simple fix to the problem. Furthermore the approach was used to define the correct velocity limit and establish optimal layout for the piping network.

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.

A Review of Temperature Reduction Methods in Codes and Standards for Pipe Supports

2020 ◽  
Author(s):  
Alex Mayes ◽  
Phillip Wiseman ◽  
Kshitij P. Gawande
Keyword(s):  
Heat Transfer ◽  
Computational Models ◽  
Thermal Stresses ◽  
Geometrical Parameters ◽  
Atmospheric Conditions ◽  
Closed Form Solutions ◽  
Temperature Reduction ◽  
Reduction Methods ◽  
American Society ◽  
Transient Thermal

Abstract American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 1, Subsection NF, Subparagraph NF-3121.11 does not require that thermal stresses in supports be evaluated. Historically, pipe support engineers have not been concerned with thermal stresses of pipe and component supports, but determining material temperature limits and allowable stresses have been a major role in designing and analyzing supports. Thus, heat transfer is often investigated in finding the temperature of pipe supports and parts of pipe supports that are not in direct contact with pipe or pipe components. There are also other Codes and standards that permit a reduction of temperature away from the outer surface of pipe or pipe components. In some but not all cases, Codes and standards explicitly address reduction of temperature for applications of utilizing thermal insulation. Additionally, the temperature distribution is established by specific geometrical parameters and their respective equations for employment by the pipe support engineer. These reductions are explored by utilizing fundamentals of heat transfer. Additionally, steady-state and transient thermal Finite Element Analyses (FEA) are used to establish computational models of simple geometric bodies in a range of atmospheric conditions. The effects of insulation on the thermal distribution are also represented through closed form solutions and FEA. The results of these analyses allow for assessment of, and recommendations for, the treatment of temperature reduction in Codes and standards.

Thermal Barrier Coating on IC Engine Piston to Improve Engine Efficiency

2017 ◽  
Vol 9 (1) ◽  
pp. 47 ◽  
Author(s):  
Balbheem Kamanna ◽  
Bibin Jose ◽  
Ajay Shamrao Shedage ◽  
Sagar Ganpat Ambekar ◽  
Rajesh Somnath Shinde ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Stresses ◽  
Mechanical Efficiency ◽  
Project Work ◽  
Element Analysis ◽  
Ic Engine ◽  
Engine Efficiency ◽  
Piston Crown ◽  
Barrier Coating

The piston is considered as most important part of I.C engine. High temperature produced in an I.C engine may contribute to high thermal stresses. Without appropriate heat transfer mechanism, the piston crown would operate ineffectively which reduce life cycle of piston and hence mechanical efficiency of engine. The literature survey shows that ideal piston consumes heat produced by burnt gases resulting in decrease of Engine overall Efficiency. In this project work an attempt is made to redesign piston crown using TBC on piston surface and to study its Performance. A 150 cc engine is considered and TBC material with different thickness is coated on the piston. 3D modeling of the piston geometry is done 3D designing software Solidworks2015. Finite Element analysis is used to calculate temperature and heat flux distribution on piston crown. The result shows TBC as a coating on piston crown surface reduces the heat transfer rate within the piston and that will results in increase of engine efficiency. Results also show that temperature and heat flux decreases with increase in coating thickness of YSZ.

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.

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.

Response of Multiple Bend System to Multi Phase Flow

2021 ◽  
Author(s):  
H. Pereboom ◽  
S. P. C. Belfroid ◽  
N. Gonzalez-Diez ◽  
J. Reijtenbagh
Keyword(s):  
Phase 1 ◽  
High Amplitude ◽  
Free Vibrations ◽  
Second Phase ◽  
Phase 2 ◽  
Atmospheric Conditions ◽  
Pipe System ◽  
Piping Systems ◽  
Multi Phase Flow ◽  
Multi Phase

Abstract Multiphase flow can induce high amplitude vibrations in piping systems. Several experimental campaigns focused on the force spectrum on a single bend. To evaluate the evolution of the forces from bend to bend, experiments have been done on an air-water, one inch pipe system consisting of six bends at near-atmospheric conditions. In a first phase, all individual bends were clamped to measure the phase relation and correlation of the flow-induced forces on the subsequent bends. In a second phase, all clamps were removed to measure the free vibrations. In this paper which focusses on the phase 2 results, the vibration measurements were compared to the calculated vibrations. For the excitation forces and phase relations, the measured force spectra from phase 1 are used. Damping values are based on experimental results from phase 2. The results show a good match between modeled and measured vibrations levels. Including the measured correlation between forces at multiple bends, improves the modeled results for slug flow cases. It is possible to directly use extract damping values from the measured signals, however, robustness of the damping estimation needs to be improved. Using average damping values currently leads to the best match.

Evaluation of the Environmental Fatigue at a Long Radius Elbow of a Piping System under Transient Thermo Mechanical Stresses

2021 ◽  
Vol 412 ◽  
pp. 197-206
Author(s):  
Lenin Ramos-Cantú ◽  
Luis Héctor Hernández-Gómez ◽  
Rafael García-Illescas ◽  
Tanya Nerina Arreola-Valles ◽  
José Javier Moctezuma-Reyes ◽  
...  
Keyword(s):  
Nuclear Power ◽  
High Stress ◽  
Thermal Fluctuations ◽  
Mechanical Analysis ◽  
Piping System ◽  
Transient Effects ◽  
Stress Concentrations ◽  
Pipe System ◽  
Thermal Transients ◽  
Piping Systems

Thermal fatigue widely takes place in light water reactor (LWR) piping systems. It is an important aging mechanism of a nuclear reactor. Thermal transient effects occur at the startup and shutdown of a nuclear power plant. During the thermal transients, local and global cyclic stresses are induced in the piping systems. They are exacerbated by local geometric imperfections and environmental factors, which may lead to crack initiation. The elbows of such piping systems are subject to various combinations of loads (internal pressure, bending, and torsion, as well as thermal fluctuations) during their service life. As can be seen, high-stress concentrations are developed in these piping elements. Therefore, it is important to make a failure evaluation. In this paper, a 12” pipe system segment, which was made with SA 106 Gr C steel, has been considered. It was composed by two straight sections joined by a long radius elbow. Typical start-up and shutdown transient effects of a BWR-5 were considered. A computer-aided thermo-mechanical analysis was carried out using the finite element method. The linearization of the stresses was considered, based on the ASME B & PVC Code Section III, subsection NB. Under these conditions, environmental fatigue was analyzed after 40-and 60-years operation.

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.

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