bluuebunny/crossref_metadata_2025 huggingface dataset:
STYLE Project: Assessment of Transferability of Fracture Material Properties From Specimens to Large Components by Local Approach to Fracture
Authors: Le Delliou Patrick , Moinereau Dominique , Keim Elisabeth , Nicak Tomas
Published: November 2014

Within the framework of the FP7 European project STYLE, a large scale experiment was performed at EDF R&D on a cladded ferritic pipe (Mock-Up 3). The objective of this experiment was to investigate the transferability of material properties from small specimens to large scale components.

The large scale experiment involved applying 4-point bending under displacement control at room temperature to a clad ferritic steel pipe with an inner surface crack. The goal of the experiment was to initiate ductile crack growth and track the resulting stable crack growth until the surface flaw breaks through the wall.

The pipe was representative of a surge line, consisting of a clad ferritic pipe with an outer diameter of 424 mm, and base metal wall thickness of 31 mm, with an austenitic stainless steel cladding layer 5 mm thick on the inner surface. The base metal is a low alloy 20 MnMoNi 5 5 steel (corresponding to the specifications of an SA 508 Grade 3, Class 1 steel).

The pipe test was conducted in 2012 in the EDF R&D 4-point bending frame. Following the experiment, various specimens were taken from the mock-up to identify the material behavior and provide data to investigate the transferability of the material fracture properties.

This paper recalls briefly the large scale experiment results and presents the main experimental results from the specimens. Then the results of the local approach finite element computations with the Rousselier model are presented and compared with the experimental results.
The Use of FFS Methodology for Determining the Residual Life of a High Pressure Autoclave Reactor
Authors: Keltjens Jan
Published: November 2014

Autoclave reactors at SABIC Geleen were typically inspected at a four year interval. The inspection consisted of UT and eddy current inspection of the bore and cross-bores of the reactor. The possibilities of extending this interval were assessed using FFS methodologies from API 579-1/ASME FFS1 [1] in addition to the ASME VIII Division 3 [2] rules. ASME VIII Division 3 is primarily a design code, although Appendix B from the 2013 edition includes guidance on extension of inspection frequency. This work was performed in 2010 when this appendix was not included in the code.

This paper describes the study, the results and indicates further opportunities of FFS methodology in high pressure equipment.
Review of Earthquake Damages of Aboveground Storage Tanks in Japan and Taiwan
Authors: Yoshida Shoichi
Published: November 2014

Severe damages in aboveground storage tanks (AST) have been often experienced due to earthquakes in Japan and Taiwan. In this paper, earthquake damages of ASTs which occurred for the last several decades are reviewed. These are damages in the 1964 Niigata Earthquake, the 1978 Miyagi Earthquake, the 1983 Sea of Japan Earthquake, the 1995 Kobe Earthquake, the 2003 Hokkaido Earthquake and the 2011 Great East Japan Earthquake in Japan. Damages of ASTs in the 921 Earthquake in Taiwan are also included in this paper. The damages of ASTs can be classified into 3 types in accordance with the causes. These are the impulsive motion due to a high frequency earthquake, the sloshing motion due to a low frequency earthquake and the tsunami attack. In the impulsive motion, buckling of sidewall plates and uplift of sidewall-to-bottom joints occurred. In the sloshing motion, sinking of floating roofs into liquid and buckling of sidewall-to-roof joints occurred. In the tsunami attack, ASTs moved and overturned to leak oil.
Simplified Development Method of FEA Code for Sloshing of Floating Roof Tanks (Lagrangian Formulation for Axisymmetric Linear Problem)
Authors: Yoshida Shoichi
Published: November 2014

Floating roofs are widely used to prevent evaporation of content in large cylindrical aboveground oil storage tanks. The 2003 Hokkaido Earthquake caused severe damages to the floating roofs due to sloshing. These accidents became a cause to establish structural integrity of the floating roof tanks in sloshing. However, many designers do not have a solution for the sloshing of floating roof tanks except for three-dimensional FEA computer codes. The three-dimensional FEA requires a long computational time and expenses. The sloshing of floating roof tanks is a coupling vibration problem with fluid and structure. The simplified and convenient method has been desired for this solution. This paper presents a simplified development method of a FEA code in the axisymmetric linear problem. It is performed to modify an existing structural analysis code. The fluid behavior is formulated in terms of displacement as the Lagrangian approach.
Elastic Stresses and Limit Bending Moments of Concentric and Eccentric Reducers Subjected to Bending Moments
Authors: Chen Sun-yi , Chen Jin , Wang Zhengdong , Wang Chen
Published: November 2014

In order to assess the safety of concentric reducers and eccentric reducers, the meridian stress and circumferential stress of the reducers subjected to in-plane bending moments are calculated based on the membrane theory. Solutions of limit bending moments are derived by using the approach with the equivalent stress and engineering coefficient. The solutions for both reducers are identical, as the formulas are composed of a base term multiplied by a bending moment coefficient. The limit bending moments are dominated by the small end of the reducers. The value of limit bending moment of the reducers is 14.6% more than that of a thin wall reducing elbow with same diameter and thickness when corresponding bending coefficient λ>3.0. But comparison with a straight pipe which has the same diameter and thickness as the small end of the reducers, the limit bending moment of the reducers is 11.1% lower and the constant in the formula for the reducers is 3.6 instead of 4.0 for straight pipe. It could be dangerous to determine the limit bending moment of concentric reducers and eccentric reducers directly from the formula of limit bending moment for a thin wall pipe.
Design of an Underwater Towfish Using Design by Rule and Design by Analysis
Authors: Muscat Martin , Formosa Mark , Salgado Martin German A. , Sinatra Rosario , Cammarata Alessandro
Published: November 2014

The European unfired pressure vessel code EN13445-3 [1] has been used to design a preliminary prototype of a towfish. The towfish is essentially an underwater vessel equipped with various sensors, cameras, hydroplanes and control systems that are used to capture data on the levels of pollutants in the sea and at the same time monitor plankton and jellyfish levels. The towfish is towed behind a surface ship and is designed to dive to a depth of 50m below sea level. The depth of dive can be controlled by means of hydroplanes. Data, signals and electrical power are transferred from the towfish to the surface ship and vice versa via the towing line. From a structural point of view the towfish is a vessel acted upon by external pressure and local loads. Design by rule (DBR) was first used to calculate some of the various dimensions and thicknesses of the towfish components. The various components were designed mainly to prevent failure due to buckling. Design by analysis (DBA) based on Annex B of the pressure vessel code EN13445-3 [1] was then used to carry out further buckling checks that were not possible to do using design by rule. At the end of the paper the results from the two design approaches are compared and any major differences are highlighted.
Transient Thermal-Hydraulic Responses of the Nuclear Steam Generator Secondary Side to a Main Steam Line Break
Authors: Jo Jong Chull , Moody Frederick J.
Published: November 2014

This paper presents a multi-dimensional numerical analysis of the transient thermal-hydraulic response of a steam generator secondary side to a double-ended guillotine break of the main steam line attached to the steam generator at a pressurized water reactor plant. A simplified analysis model is designed to include both the steam generator upper space where steam occupies and a part of the main steam line between the steam generator outlet nozzle and the pipe break location upstream of the main steam isolation valve. The transient steam flow through the analysis model is simulated using the shear stress transport turbulence model. The steam is treated as a real gas. To model the steam generation by heat transfer from the primary coolant to the secondary side coolant for a short period during the blow down process following the main steam line break accident, a constant amount of steam is assumed to be generated from the bottom of the steam generator upper space part. Using the numerical approach mentioned above, calculations have been performed for the analysis model having the same physical dimensions of the main steam line pipe and initial operational conditions as those for an actual operating plant. The calculation results have been discussed in detail to investigate their physical meanings and validity. The results demonstrate that the present CFD model is applicable for simulating the transient thermal-hydraulic responses in the event of the MSLB accident including the blowdown-induced dynamic pressure disturbance in the SG. In addition, it has been found that the dynamic hydraulic loads acting on the SG tubes can be increased by 2 to 8 times those loads during the normal reactor operation. This implies the need to re-assess the potential for single or multiple SG tube ruptures due to fluidelastic instability for ensuring the reactor safety.
Effects of Uncertainties in Boundary Conditions on Dynamic Characteristics of Industrial Plant Components
Authors: Bursi Oreste S. , Abbiati Giuseppe , Caracoglia Luca , Reza Md Shahin
Published: November 2014

Seismic risk assessment of industrial plants is of paramount importance to ensure adequate design against earthquake hazards. Seismic vulnerability of industrial plant components is often evaluated through a fragility analysis to conform to structural safety requirements. Fragility curves of single components are usually developed by neglecting the effect of actual boundary conditions. Thus, an incorrect evaluation of individual fragility curves can affect the overall fragility curve of a system. This may lead to “erroneous” seismic risk evaluation for a plant in comparison with its real state. Hence, it is important to study the effect of uncertainties, introduced at the boundaries when coupling effects are neglected, on the dynamic characteristics of a system.

Along this line, this paper investigates the effects of uncertain boundary conditions on the probability distributions of the dynamic properties of a simple chain-like system with increasing number of degrees of freedom. In order to describe the uncertain boundary condition, a modified version of the well-known β distribution is proposed. Subsequently, the Analytical Moment Expansion (AME) method is employed to estimate the statistical moments of the output random variables as an alternative to more computationally-demanding Monte Carlo simulations. Finally, a preliminary extension of the proposed approach to a realistic piping system connected to a class of broad/slender tanks is discussed.
How Potrero Utililized Flush Patches to Manage Localized Under Deposit Corrosion Damage in Waterwall Tubes
Authors: Mazzeo Joseph M.
Published: November 2014

Flush Patch repair of boiler tubes, in which a circular section of tube is replaced to repair an isolated flaw, is typically considered to be a temporary repair. This paper reviews the successful flush patch repair program at the Potrero Power Plant in San Francisco. Over an 11-year period, a total of 294 flush patch repairs were utilized to repair isolated locations of under deposit corrosion in high flux areas of the water wall tubes. In this time period, three patches were replaced due to leaks found in hydro testing. Most of the repairs were performed in the early part of a decade when the unit was on line for an average of over 7,100 hours a year.
Fast Simulation for Multi-Pass Welding Process Using Iterative Substructure Method: Investigation of Optimization and Efficient Computation
Authors: Maekawa Akira , Kawahara Atsushi , Serizawa Hisashi , Murakawa Hidekazu
Published: November 2014

Residual stress caused by welding processes affects characteristics of strength and fracture of equipment and piping in power plants. Numerical thermal elastic-plastic analysis is a powerful tool to evaluate weld residual stress in actual plants. However, the conventional three-dimensional precise analysis for a welding process such as multi-pass welding, machining and thermal treatment requires enormous computation time though it can provide accurate results. In this paper, the finite element analysis code based on the iterative substructure method that was developed to carry out thermal elastic-plastic analysis efficiently, with both high computational speed and accuracy, was proposed to simulate the welding process of plant equipment and piping. Furthermore, optimization of the proposed analysis code was examined and the computational efficiency and accuracy were also evaluated.
Numerical Approach for Containment Assessment of Transport Packages Under Regulatory Thermal Test Conditions
Authors: Sterthaus Jens , Ballheimer Viktor , Bletzer Claus , Linnemann Konrad , Nehrig Marko , Wille Frank
Published: November 2014

The requirements of the IAEA safety standards for Type B(U) packages include the thermal test as part of test sequences that represents accident conditions of transport. In comparison to mechanical tests, e.g., 9 m drop onto an unyielding target with short impact durations in a range of approximately 10 ms to 30 ms, the extended period of 30 min is defined in regulations for exposure of a package to a fire environment. Obviously, the required containment capability of the package has to be ensured not only after completing the test sequence but also over the course of the fire test scenario.

Especially, deformations in the sealing area induced by the non-uniform thermal dilation of the package can affect the capability of the containment system. Consequently, thermo-mechanical analyses are required for the assessment.

In this paper some aspects of finite element analysis (FEA) of transport packages with bolted closure systems under thermal loading are discussed. A generic FE model of a cask is applied to investigate the stress histories in the bolts, lid, and cask body as well as the deformations in the sealing area and the compression conditions of the gasket. Based on the parameter variations carried out, some recommendations in regard to modeling technique and results interpretation for such kind of analyses are finally given.
Alternative Characterization Rules for Quasi-Laminar Flaws
Authors: Lacroix Valéry , Dulieu Pierre , Couplet Damien
Published: November 2014

During the 2012 outage at Doel 3 and Tihange 2 Nuclear Power Plants, a large number of quasi-laminar indications were detected, mainly in the lower and upper core shells. As a consequence, both units remained core unloaded pending the elaboration of an extensive Safety Case demonstrating the Structural Integrity of the RPVs in all operating modes, transients and accident conditions.

A large part of this demonstration consists of the Flaw Acceptability Assessment inspired by the ASME XI procedure but adapted to the nature and number of indications found in the Doel 3 and Tihange 2 RPVs. In particular, ASME XI IWB-3300 article requires combining closely spaced flaws in order to account for their mechanical interactions. However, it appeared early that the strict application of the current ASME XI proximity criteria for laminar flaws to the actual flaw indications found at Doel 3 led to unrealistic results and conclusions. Therefore, an alternative methodology to derive suitable characterization rules applicable to specific flaws observed at Doel 3 and Tihange 2 RPVs has been successfully developed, implemented and validated.
Assessment of Residual Stress Profiles for Fitness for Service Assessment of Pipe Girth Welds
Authors: Dong Pingsha , Song Shaopin , Zhang Jinmiao
Published: November 2014

This paper aims to provide a detailed assessment of some of the existing residual stress profiles prescribed in widely used fitness-for-service assessment codes and standards, such as BS 7910 Appendix Q, by taking advantage of some comprehensive residual studies that become available recently. After presenting a case study on which residual stress measurements are available for validating finite element based residual stress solution procedure, residual stress profiles stipulated in BS 7910 for girth welds are evaluated in the context of a series of parametric finite element results and a shell theory based full-field residual stress estimation scheme. As a result, a number of areas for improvement in residual stress profile development are identified, including some specific considerations on how to attain some of these improvements.
Welding Distortion Can be Mitigated if Welding Current and Traveling Speed Vary Optimized Along a Weld Path
Authors: Asadi Mahyar , Goldak John , Weck Arnaud
Published: November 2014

Typically, the distortion from welding is mitigated with the use of fixtures, clamps, tack welds and so on. Also the welding current and traveling speed are normally set constant during welding along a weld-path. The authors have developed and implemented an advanced control method that adaptively changes welding current and traveling speed depending on the state of deformation, in order to mitigate the final distortion without the use of additional hardware such as fixtures, clamps, and/or tack welds. It predicts the distortion before actual happening and adjusts parameters to counteract the deformation during welding. The present work implements this advanced method by applying an optimized, varying welding current and traveling speed on an edge-welded bar of Aluminum 5052-H32. A comparison is made between the final welding distortion with the new method, versus the regular method at constant welding current and traveling speed. A virtual predictive model was established to simulate and control the adaptive change of welding current and traveling speed, the optimized profile of the process parameters were performed by a robot, and the transient distortion was measured by state-of-the-art 3D photogrammetry cameras in real–time.
Intentional Destructive Testing: A Means for Establishing Mechanical Integrity in Plants, Facilities, and Pipelines
Authors: Alexander Chris , Vyvial Brent
Published: November 2014

Operators of plants, facilities, and pipelines have at their disposal multiple resources for evaluating the integrity of identified features and anomalies. With advances in inspection technology, industry is being called upon to evaluate an ever-increasing number of features. When a feature is identified as a threat and severe enough to warrant repair or replacement, operators are faced with sometimes significant costs.

In this paper the authors provide guidance on the benefits associated with full-scale testing for evaluating mechanical integrity, referred to Intentional Destructive Testing (IDT). Unlike many analysis techniques that require the development and implementation of assumed operating and boundary conditions, well-designed IDT programs are able to replicate in situ conditions to provide operators with a clear understanding regarding the behavior of anomalies and their response to simulated operating conditions. Case studies are included to demonstrate the merits of the IDT approach. In using IDT, operators have improved confidence in predicting the behavior of identified features to ensure that maintenance resources are properly allocated for either continuing operation or repairing anomalies.
Pipeline Parameter Identification and Leak Localization Using Experimental Data
Authors: Moustafa Kamal , Haik Yousef
Published: November 2014

Pipeline systems are important in many fields of real life to distribute fluids from one location to another. Leakage from such pipeline systems poses serious problems from the technical, environmental and economic points of view. Early leak detection and localization is, therefore, important for real life applications. In this paper, an experimental study is conducted to collect the pressure head measurements at a number of nodes along a pipeline carrying oil for both the healthy and leaky cases. The experimentally measured data are utilized to identify the leak factor and coefficient of friction of the considered pipeline. The identified parameters are utilized by the propose localization scheme to determine the leak location. The identification is implemented by a window marching technique that uses the collected pressure head measurements and seeking the minimum objective function that represents the mismatch between the measured and numerically modeled pipeline variables. Monte Carlo simulation results are reported to demonstrate the effectiveness of the proposed parameter identification and leak localization techniques.
Composite Repair Performance at Elevated Temperatures
Authors: Alexander Chris , Souza Jim , Whalen Casey
Published: November 2014

For the better part of the past 20 years composite materials have been used to repair damaged piping and pressurized components in plants, refineries, and pipelines. The use of composite materials has been accompanied by comprehensive research programs focused on the development and assessment of using composite technology for restoring integrity to damaged piping and pressurized components. Of particular interest are composite repair standards such as ISO 24817 and ASME PCC-2 that provide technical guidance in how to properly design composite repair systems.

The vast body of research completed to date has involved assessments at ambient conditions; however, at the present time there is significant interest in evaluating the performance of composite repair materials at elevated temperatures. This paper is focused on the topic of high temperature composite repairs and addresses the critical role of utilizing temperature-based mechanical properties to establish a composite repair design. The backbone of this effort is the development of composite performance curves that correlate change in strength as a function of temperature. A discussion on supporting full-scale pressure test results are included, along with guidance for users in how to properly design composite repair systems for applications at elevated temperatures.
Strain Based AIV Evaluation
Authors: Mann J. Adin , Fagerlund Allen C. , Eilers Daniel
Published: November 2014

A framework for Acoustic Induced Vibration (AIV) evaluation is outlined which is based on estimating the pipe surface strain for an evaluation framework of structural fatigue. Critical to this approach is that the assessment is implemented with frequency based formulations. The frequency based formulation allows for more accurate determination of the pipe’s structure response and combining different sources, such as the valve and piping elements. The approach relies on internationally recognized standards as the core technology, in particular the IEC 60534-8-3 control valve aerodynamic noise prediction standard and the fatigue assessment in design codes, such as the ASME Boiler and Pressure Vessel code. These are augmented with system noise predictions using a non-dimensional testing based model for piping component noise predictions. Components of this approach have been described in previous papers and are presented here in a more complete form.
Sustained Stress Indices (SSI) in the B31.3 2010 Edition
Authors: Becht Charles , Paulin Tony , Edwards Don , Stonehouse Mark , Lock William Santiago , Becht Charles
Published: November 2014

The 2010 version of B31.3 introduced sustained stress indices (SSI’s) in paragraph 320. Using methods in references [1],[2],[3],[4],[5], and [11], a test procedure was developed to evaluate these SSI’s for standard metallic piping components. The test procedure has been incorporated into draft versions of B31J so that the sustained stress index can be produced at the same time stress intensification or flexibility factor tests are performed for a particular component. This paper describes the sustained stress index and the B31J test procedure used to determine the SSI.
Clamp Load Decay in Preloaded Dissimilar Lightweight-Material Joints due to Cyclic Temperature
Authors: Nassar Sayed A. , Kazemi Amir , Dyab Mohamad
Published: November 2014

Experimental and Finite Element methods are used for investigating the effect of cyclic thermal loading on the clamp load decay in preloaded single-lap bolted joints that are made of dissimilar-materials. Joint material combinations include steel and lightweight materials such as aluminum and magnesium alloys, with various different thicknesses. The range of cyclic temperature profile varies between −20°C and +150°C. A computer-controlled environmental chamber is used for generating the desired cyclic temperature profile and duration. Real time clamp load data is collected using high-temperature load cells. Percent clamp load decay is investigated for various combinations of joint materials, initial preload level, and test specimen thicknesses. Thermal and material creep finite element analysis is performed using temperature-dependent mechanical properties. FEA result has provided insight into interesting experimental observations regarding model predictions and the experimental data is discussed.
The Transient Stress and Life Analysis of a Gun Tube
Authors: Cheng Xu , Wu Yonghai , Guan Xiaorong
Published: November 2014

A thermo-solid coupling model of a gun tube is established. The inner boundary conditions of the tube are obtained by carrying out the computations of the boundary-layer model and the core-flow model of interior ballistics. The finite element method is employed here to numerically solve the thermo-solid coupling model. The transient stress and temperature of the coupling field of gun tube subjected to high-frequency periodic dynamic pressure and thermal pulse are computed. The overall state of the stress field and the thermoelastic coupling effect are attained. The strength of gun tube subjected to dynamic pressure load, thermal load and joint load is analyzed respectively, and the cases under the above three kinds of working conditions are compared. The life of gun tube is also studied. A life test system is set up, and detailed measurements about temperature and erosion are performed. A model to estimate the maximum radial wear rate of gun tube is built. Based on the computational results of temperature, the ablation wear extent and the limit life of a gun tube subjected to successive shooting are computed. The models and the analytical techniques adopted here provide important references for gun-tube design and life improvement.
Influence of Mean Strain on Fatigue Life of Stainless Steel (Effect of Constant and Ratcheting Mean Strain)
Authors: Kamaya Masayuki
Published: November 2014

The influence of mean strain on fatigue life was investigated for Type 316 stainless steel at room temperature in ambient environment. Two types of mean strain were simulated in the fatigue tests: constant and increasing (ratcheting) mean strains. In order to apply the constant mean strain, prestraining was induced prior to fatigue tests. Although the stress amplitudes became larger due to the prestraining, fatigue lives were almost the same as those obtained using non-prestrained specimens for the same strain range. Change in the maximum peak stress and stress amplitude due to the prestraining had little influence on the fatigue life. It was shown that the mean strain showed little influence on the fatigue life under the same strain range. The ratcheting mean strain was observed during the fatigue tests under mean stress. The fatigue life was reduced by applying the mean stress for the same strain range. The degree of the reduction was increased with the magnitude of the ratcheting mean strain. It was deduced that the increasing mean strain enhanced the crack mouth opening and increased the effective strain range. It was concluded that the ratcheting mean strain reduced the fatigue life for the same strain range, and the reduction in fatigue life could be predicted conservatively by assuming the crack mouth was never closed during the fatigue tests.
Technical Basis for Application of Collapse Moments for Locally Thinned Pipes Subjected to Torsion and Bending Proposed for ASME Section XI
Authors: Hasegawa Kunio , Li Yinsheng , Bezensek Bostjan , Hoang Phuong H. , Rathbun Howard J.
Published: November 2014

Piping components in power plants may experience combined bending and torsion moments during operation. There is a lack of guidance for pipe evaluation for pipes with local wall thinning flaws under the combined bending and torsion moments. ASME B&PV Code Section XI Working Group is currently developing fully plastic bending pipe evaluation procedures for pressurized piping components containing local wall thinning subjected to combined torsion and bending moments. Using elastic fully plastic finite element analyses, plastic collapse bending moments under torsions were obtained for 4 (114.3) to 24 (609.6) inch (mm) diameter pipes with various local wall thinning flaw sizes. The objective of this paper is to introduce an equivalent moment, which combines torsion and bending moments by a vector summation, and to establish the applicable range of wall thinning lengths, angles and depths, where the equivalent moments are equal to pure bending moments.
Wind Tunnel Measurements of Flow-Induced Vibration of a NACA0015 Airfoil Model
Authors: Šidlof Petr , Vlček Václav , Štěpán Martin , Horáček Jaromír , Luxa Martin , Šimurda David , Kozánek Jan
Published: November 2014

The paper reports on interferometric measurements of flow over a NACA0015 airfoil model during flutter limit cycle oscillations. The airfoil model is fixed on an elastic support allowing motion with two degrees of freedom — pitch and plunge. The structural mass and stiffness matrices can be tuned to certain extent, so that the eigenfrequencies of the two modes approach as needed. The model is equipped with dynamic pressure probes and sensors measuring the airfoil vertical position. The flow field around the airfoil was measured by Mach-Zehnder interferometer and registered using a high-speed camera synchronously with the mechanical vibration and pressure measurements. The Mach number of the incident airflow was gradually increased and the response of the aeroelastic system to initial impulse measured, until the flutter instability onset occurred. Flutter boundaries were evaluated for various additional masses attached (i.e., for various plunging mode eigenfrequencies), and post-critical behavior of the system investigated. The interferograms recorded by the high-speed camera were postprocessed, yielding pressure distribution around the airfoil during its vibration and an estimate of the total aerodynamic force and energy transfer from the airflow to the structure.
Advances in Universal Scaling for Broadband Turbulent Noise in Internal Flow Devices
Authors: Violato Daniele , de Jong Arjen , Golliard Joachim
Published: November 2014

This paper focuses on the scalability of broadband turbulent noise in internal pipe flows. It discusses a universal scaling approach for broadband turbulent noise that is based on surface acoustic power modeled by ANSYS Fluent. This investigation proposes a strategy for amplitude scaling at frequencies above the onset frequency for non-planar acoustic waves, offering a generalized formulation for circular and rectangular pipes. Information based on the surface acoustic power, wall shear stress, kinetic energy and dynamic pressure is explored in view of improving the frequency scaling approach. For short, long and mitred bends, the reversed method is applied to reconstruct the broadband noise spectra, which compare well with the experimental ones. Finally, the noise spectra reconstruction is performed for T-joint and tees geometries.
Validation of the (4δt, σ22c) Failure Criterion to Explain the Test Specimen Thickness Effect of A533 Grade B Steel in the Ductile-to-Brittle Transition Temperature Region
Authors: Fujiwara Yuki , Lu Kai , Takamura Ryota , Fujita Yusuke , Meshii Toshiyuki
Published: November 2014

In the ductile–to–brittle transition (DBT) temperature region, the specimen thickness B and fracture toughness Jc are correlated (Jc ∝ B−1/2) [1, 2]; this is true even for standardized specimens. This has been described as the test specimen thickness (TST) effect based on the weakest link model [3]; however, it has been pointed out that Jc does not decrease indefinitely as B→∞, which contradicts this effect. This paper is an extension of our recent work [4] on the point that the TST effect on Jc. observed for the Shoreham reactor vessel steel (A533 Grade B) [5] was explained via the difference in crack tip constraint and demonstrating that the (4δt, σ22c) criterion can be applied to explain the effect.
Mass Flux and Hydrodynamic Forces of Two-Phase Cavitating Flow Through a Safety Relief Valve at Initial Subcooling Conditions
Authors: Pinho Jorge , Rambaud Patrick , Chabane Saïd
Published: November 2014

Previous experiments were conducted and reported in a safety relief valve. It was noticed that in presence of a cavitating two-phase flow, the mass flux tends to be reduced due to the two-phase mixture compressibility. Moreover, the forces acting on the valve are dependent on the dynamic pressure and therefore, characteristics may be affected by the presence of a gas phase. The goal of this study is to propose a mathematical model capable of predicting the mass flux and forces acting on a safety relief valve experiencing cavitation at initial high subcooling conditions. For the mass flux prediction, an extension of the actual recommended sizing equations of IEC 60534-2-3 is proposed, including a formulation of the semi-critical region based on the hypothesis that compressibility of a two-phase mixture may be considered as an ellipse. It is verified that at chocking flow conditions, the critical section is partially filled by vapor as the fluid velocity equals the local speed of sound. Finally, a theoretical analysis is proposed to estimate the hydrodynamic fluid forces acting on the disk of a safety relief valve, using a simplified axisymmetric system of a plate over a nozzle. Results show a good agreement against experimental data and underline the influence of the backpressure in the SRV flow characteristics.
Design Rules for Ratcheting Damage in AFCEN RCC-MRX 2012 Code
Authors: Lamagnère P. , Lejeail Y. , Petesch C. , Lebarbé T. , Matheron P. , Taheri S. , Martin A.
Published: November 2014

The paper describes the design rules for ratcheting in the 2012 edition of the RCC-MRx Code issued in French and English versions by AFCEN (French Association for the rules governing the Design, Construction and Operating Supervision of the Equipment Items for Electro Nuclear Boilers).

For austenitic stainless steels, the RCC-MRx Code uses the efficiency diagram concept to evaluate an effective primary stress, Peff. Peff is defined as a virtual stress that applied alone would cause the same strain as the combination of the primary static stress and the secondary cyclic strain really applied. This concept is extended to significant creep domain and includes corrections to take into account structures cases presenting secondary membrane stresses (e.g. cylinders subjected to axial thermal gradients varying with time and space) or short duration overloads (as a level A seismic load, or an overload due to rapid drain-out caused by a sodium-water reaction).

An alternative 3Sm design rule is proposed for all materials in the case of non-significant creep damage.
Difficulties in Predicting Cycles of Failure Using Finite Element Analysis of Acoustically Induced Vibration (AIV) Problems in Piping Systems
Authors: Ghosh Arindam , Niu Yaying , Arjunan Rajesh
Published: November 2014

While finite element modeling analysis is becoming more frequent for analyzing AIV problems, in the absence of experimental data in large diameter pipe, there is no industry wide accepted methodology for representing the pressure excitation for the pipe so accurate cycles to failure may be predicted. The assumptions involved in determining the actual amplitude of the acoustic excitation, which modes may develop and how they couple with the structure all contribute to the overall uncertainty of the problem.

Depending on the degree of correlation assumed between the structural and acoustical mode shapes the results vary dramatically. There are also variations based on the number of participating modes assumed. Relative strengths of a Weldolet®, an Insert Weldolet® that is a variation of Sweepolet® and a Reducing Tee connection were analyzed for a 24×6 inch Sch. 10S and STD connection assuming various degrees of correlation and mode participation. Wide fluctuations in the cycles to failure were observed based on the assumptions; however, the stress ratios between the connections are relatively stable. This suggests the use of an acoustic Stress Intensification Factor (SIF) in conjunction with Fatigue Strength Reduction Factors (FSRF) to determine suitability of connections in AIV service rather than an absolute value of cycles to failure.

Further investigation of the trends in the value of SIF as the D/d (branch to header diameter) and D/t (diameter to thickness) ratios over a range of pipe diameter are required before these SIF’s could be put into use. Experimental data for a few controlled failure cases are required to ground the finite element prediction in reality. As the experiment is more likely to be conducted with air the possible pitfalls in extending the results from air to commonly used process fluid are also discussed.
Development of Design Rules for Three-Segment Pipe Clamp Connectors
Authors: Bankston David O. , Kuo Hsin
Published: November 2014

The design rules for clamped connections in the ASME Boiler and Pressure Vessel Code (Section VIII, Div. I, Appendix 24) were developed for two-segment clamp connectors and must be modified to accommodate alternative clamp configurations.

Developing a simplified rule-based model for predicting three-segment pipe clamp connectors (3-PCC)connector pressure capacities will greatly simplify the evaluation of 3-PCC connectors.

The first goal of this paper is to develop a general parametric design rule set for multiple-clamp-segment pipe by expanding upon the published requirements of the ASME Boiler and Pressure Vessel Code for two-segment pipe clamp connectors and pipe flanges using basic principles. The next goal is to apply the design rule set to a typical 3-PCC design and to summarize the rules.

The results of this paper provide a parametric rule-based approach to evaluating the pressure capacity of a 3-PCC.

This paper has been developed in partial fulfillment of the requirements for the Master’s Degree Program at Washington State University.

This work is performed in support of the US Department of Energy, under contract to Bechtel National Inc., # DE-AC27-01RV14136.
Bi-Stable Flow in Parallel Triangular Tube Arrays With a Pitch-to-Diameter Ratio of 1.375
Authors: Keogh Daniel B. , Meskell Craig
Published: November 2014

A study of the bi-stable flow in parallel triangular tube arrays with a pitch to diameter ratio of 1.375 has been performed. Using surface pressure data from two instrumented cylinders (one cylinder with 36 circumferential pressure taps, one cylinder with 27 axial pressure taps) and particle image velocimetry (PIV) data, the bi-stable phenomenon has been investigated. Mode-averaged PIV was performed in a draw down wind tunnel with a test section cross-sectional area of 125mm2 using a tube array of 28 clear perspex tubes with a diameter of 13mm. The mode of each set of image pairs was determined by simultaneously capturing the images and gathering pressure data from the surface of the test section wall. Further tests were then conducted using two instrumented cylinders mounted in a test section with a cross section of 300×272mm using 28 tubes with a diameter of 38mm. It was found that at certain flow velocities, the pressure signals from each of the instrument cylinders were highly correlated. Using this data, the circumferential pressure distributions across the span of an instrumented cylinder were determined for each mode using pseudo modal decomposition (PMD).
Seismic Response Control of Base Isolated Structures by Using Dynamic Mass
Authors: Sone Akira , Ueyama Shinichi , Masuda Arata , Kato Sunao
Published: November 2014

This paper proposes the mechanism using lever and attached weight at point of action of lever, installed horizontally in the space between two floor slabs for the purpose of seismic response control of a base isolated building. This mechanism produces the dynamic mass related to the relative displacement between two slabs. The generated dynamic mass is shown to be effectiveness for the seismic response control of base isolated building from the point of view of the enlarged mass ratio of dynamic mass to mass of base isolated building.
Quantitative Analysis of Pre-Strain Effect on Mechanical Properties of the Austenitic Stainless Steel
Authors: Chen Zhiwei , Qian Caifu , Yang Guoyi , Li Xiang
Published: November 2014

The test of austenitic stainless steel specimens with strain control mode of pre-strain was carried out. The range of pre-strain is 4%, 5%, 6%, 7%, 8%, 9% and 10% on austenitic stainless steel specimens, then tensile testing of these samples was done and their mechanical properties after pre-strain were gotten. The results show that the pre-strain has little effect on tensile strength, and enhances the yield strength more obviously. According to the experimental data, we get a relational expression of S30408 between the value of yield strength and pre-strain. We can obtain several expressions about different kinds of austenitic stainless steel by this way. It is convenient for designers to get the yield strength of austenitic stainless steel after pre-strain by the value of pre-strain and the above expression.
Large-Eddy Simulation of Cross-Flow Induced Vibrations of a Single Flexible Tube in a Normal Square Tube Array
Authors: Berland Julien , Deri Enrico , Adobes André
Published: November 2014

The cross-flow induced vibrations in water of a single flexible tube in a normal square array of rigid tubes are investigated by means of large-eddy simulations, based on the classical Smagorinsky model. The flow configuration and the operating conditions are taken from the experiments of Granger et al. (J. Fluid Struct., 1993). A fully-coupled fluid-structure calculation is hence performed: the tube dynamics is modeled by a mass-spring-damper system, and the motion of the fluid domain is accounted for by a moving mesh technique.

The numerical results are compared to the experimental data in terms of amplitude and frequency of the flexible tube oscillations, for various inflow velocities. In addition, characteristics of the flow-induced forces are discussed: features of the power spectral densities of lift and drag forces, such as the envelope spectrum or the spanwise correlation length are investigated.
Hydrogen Assisted Fatigue Crack Growth in a Precipitation-Hardened Martensitic Stainless Steel Under Gaseous Hydrogen
Authors: Bilotta Giovambattista , Arzaghi Mandana , Hénaff Gilbert , Benoit Guillaume , Moriconi Clara , Halm Damien
Published: November 2014

In this study, the effect of gaseous hydrogen on the fatigue crack growth behavior in a precipitation-hardened martensitic stainless steel is investigated. It is known that the degradation in fatigue crack growth behavior derives from a complex interaction between the fatigue damage and the amount of hydrogen enriching the crack tip, which is dependent on the hydrogen pressure, loading frequency, and stress intensity factor amplitude. Therefore, fatigue crack growth tests were performed in a range of 0.09 to 40 MPa under gaseous hydrogen at a frequency of 20 and 0.2 Hz. The fatigue data as well as fracture morphologies obtained so far indicate a sharp increase in crack growth rates in a narrow range of stress intensity factor amplitudes. Also, it is shown that by decreasing the loading frequency to 0.2 Hz at a given pressure of hydrogen the transition occurs at lower values of stress intensity factor amplitudes accompanied by a change in fracture mode. Scanning electron microscope (SEM) observations of the fracture surfaces are used to support the explanations proposed to account for the observed phenomena.
Numerical Estimation of Flow Penetrating Depth Into Stagnant Branch Pipes for Thermal Fatigue Prediction
Authors: Ishikawa Yoshihiro , Okuda Yukihiko , Kasahara Naoto
Published: November 2014

In the nuclear power plants, there are many branch pipes with closed-end which are attached vertically to the main pipe. We consider a situation in which the high temperature water is transported in the main pipe, the branch pipe is filled with stagnant water which has lower temperature than the main flow, and the end of the branch pipe is closed. At the branch connection part, it is known that a cavity flow is induced by the shear force of the boundary layer which separates from the leading edge of the branch pipe along the main pipe wall. In cases where the high temperature water penetrates into the branch pipe, there is a possibility that a steep and large temperature gradient field, called “thermal stratification layer” is formed at the boundary between high and low temperature water in the branch pipe. If the thermal stratification layer is formed in a bend pipe, which is used for connecting the vertical branch pipe and to a horizontal pipe, at the same time, the temperature fluctuation by the thermal stratification layer motion occurs, there may cause the thermal stress in the piping material. Furthermore, keeping the piping material under the thermal stress, there might be a possibility of a crack on the surface of the bend pipe. For this reason, the evaluation of the position where the thermal stratification layer reaches is very important during early piping design process. And, deeply understanding regarding the phenomena, is also important. However, because of the complexities of the phenomena, it is difficult to immediately clarify the whole mechanisms of the thermal stress arising due to the temperature fluctuation by the thermal stratification layer change. The complete prediction method for the position of the thermal stratification layer based on the mechanisms that is able to be applied to any piping system, any temperature and any velocity conditions, is also difficult. Therefore, a practical approach is required.

The authors attempt to develop the practical estimation method for the thermal stratification layer position using the three-dimensional Navier-Stokes simulation which was based on the Reynolds-average in order to reduce the computational costs. In this paper, three different configurations of the piping were simulated and the simulation results were compared with the experimental results obtained by the other research group.