bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties of New Grades of FE-3Cr-W Alloys
Authors: Sikka Vinod K. , Klueh Ronald L. , Maziasz Philip J. , Babu Suresh , Santella Michael L. , Jawad Maan H. , Paules John R. , Orie Kenneth E.
Published: August 2008

This paper describes the development of two new grades of Fe-3Cr-3W(Mo) alloys at the Oak Ridge National Laboratory. The two grades are designated as A and B. The higher strength Grade B differs from Grade A in that it contains 0.10 wt % Ta. Both grades, when tested in normalized and tempered conditions, show a good combination of tensile strength and Charpy impact properties. Tensile properties of both A and B are over 150 MPa (20 ksi) higher than the highest strength commercial alloy T23. Grade B has higher creep-rupture strength than the T23 steel for the entire temperature range from 540 to 650°C. Grade B also exceeds creep-rupture strength of modified 9Cr-1Mo alloy (Grade 91) up to 615°C. Grade A exceeds the creep-rupture strength of T23 steel up to 600°C and match its values at the higher temperatures. Both grades have been scaled up to 50-ton-size commercial heats and processed into forgings and hot-rolled plates and bars.
Computational Models on Graphs for the Nonlinear Hyperbolic System of Equations
Authors: Kholodov Alexander S. , Kholodov Yaroslav A.
Published: August 2008

The problems in the form of nonlinear partial derivative equations on graphs (nets, trees) arise in different applications. As the examples of such models we can name the circulatory and respiratory systems of the human body, the model of heavy traffic in the big cities, the model of flood water and pollution propagation in the large river systems, the model of bar structures and frames behavior under the different impacts, the model of the intensive information flows in the computer networks and others.
Numerical Simulation of Load Deformation Behaviour of Cracked Piping Components Considering Crack Growth
Authors: Pavankumar T. V. , Chattopadhyay J. , Dutta B. K. , Kushwaha H. S.
Published: August 2008

Conventional elastic plastic fracture analysis does not consider the crack growth and thus it cannot give the complete load deformation behaviour of cracked components. In the present paper numerical methodology is proposed to simulated the load deformation behaviour of cracked components considering the crack growth. In the present analysis, the components under study are the 8” straight pipes/elbows and 12” straight pipes having circumferential through wall crack with different initial crack angles. The tests have been performed on these piping components and TPBB/CT fracture specimens under Component Integrity Test Program at Bhabha Atomic Research Center (BARC), India. 3-D elastic-plastic finite element analyses have been carried out on the specimens and piping components to investigate the stress triaxiality ahead of crack tip. The reference JR curve has been selected based on similar triaxiality level as that of piping components, which are to be analysed. Present paper verifies the importance of stress triaxility while selecting the specimen J-R curve and discusses the extrapolation of specimen J-R curve. The applicability of the proposed numerical methodology is shown by comparing with the experimental results.
Continuum Shape Sensitivity Analysis of Cracks in Functionally Graded Materials
Authors: Rao B. N. , Rahman S.
Published: August 2008

This paper presents two new methods for conducting a continuum shape sensitivity analysis of a crack in an isotropic, linear-elastic functionally graded material. These methods involve the material derivative concept from continuum mechanics, domain integral representation of interaction integrals, known as the M-integral, and direct differentiation. Unlike virtual crack extension techniques, no mesh perturbation is needed to calculate the sensitivity of stress-intensity factors. Since the governing variational equation is differentiated prior to the process of discretization, the resulting sensitivity equations are independent of approximate numerical techniques, such as the meshless method, finite element method, boundary element method, or others. Three numerical examples are presented to calculate the first-order derivative of the stress-intensity factors. The results show that first-order sensitivities of stress intensity factors obtained using the proposed method are in excellent agreement with the reference solutions obtained using the finite-difference method for the structural and crack geometries considered in this study.
Development of an Integrity Evaluation System on the Basis of Cooperative Virtual Reality Environment for Nuclear Power Plant
Authors: Kim J. C. , Choi J. B. , Choi Y. H.
Published: August 2008

Since early 1950’s fracture mechanics has brought significant impact on structural integrity assessment in a wide range of industries such as power, transportation, civil and petrochemical industries, especially in nuclear power plant industries. For the last two decades, significant efforts have been devoted in developing defect assessment procedures, from which various fitness-for-purpose or fitness-for-service codes have been developed. From another aspect, recent advances in IT (Information Technologies) bring rapid changes in various engineering fields. IT enables people to share information through network and thus provides concurrent working environment without limitations of working places. For this reason, a network system based on internet or intranet has been appeared in various fields of business. Evaluating the integrity of structures is one of the most critical issues in nuclear industry. In order to evaluate the integrity of structures, a complicated and collaborative procedure is required including regular in-service inspection, fracture mechanics analysis, etc. And thus, experts in different fields have to cooperate to resolve the integrity problem. In this paper, an integrity evaluation system on the basis of cooperative virtual reality environment for reactor pressure vessel which adapts IT into a structural integrity evaluation procedure for reactor pressure vessel is introduced. The proposed system uses Virtual Reality (VR) technique, Virtual Network Computing (VNC) and knowledge based programs. This system is able to support 3-dimensional virtual reality environment and to provide experts to cooperate by accessing related data through internet. The proposed system is expected to provide a more efficient integrity evaluation for reactor pressure vessel.
Analytical Determination of Material JR and Fracture Toughness Transition Curves Using Micro-Mechanical Modelling
Authors: Dutta B. K. , Samal M. K. , Sahu M. K. , Kushwaha H. S.
Published: August 2008

Local approach has been used to compute a) Jinitiation and JR curves at different temperatures and b) fracture toughness transition curves for German Reactor Pressure Vessel Steel 22NiMoCr37. Ductile fracture has been analyzed using Gurson material constitutive model and probability of cleavage failure is calculated using Beremin’s model. A variation of Gurson parameter q2 near crack tip region as a function of charpy energy is suggested to obtain Jinitiation as well as complete JR curve accurately at different metal temperatures.
Transient Thermal Finite Element Analysis Based on Field Measured Data and the Impact on Fatigue
Authors: Kirkpatrick Kenneth D. , Miller George A. , Millet Barry J. , Malek David W. , Antalffy Leslie P.
Published: August 2008

Many vessels experience significant thermal loads in operation. This paper discusses a method used to develop the internal thermal boundary conditions (film coefficients) required to evaluate thermal loads when the thermal properties of the internal fluid are unknown. In a thermal analysis it is critical to determine the correct film coefficients to achieve the proper behavior. Improperly quantified heat up rates can have a dramatic effect on the overall design. An example is provided to show how assumptions on thermal input can directly effect the results. The method described in this paper uses Finite Element Analysis (FEA) to determine internal film coefficients based on field measured thermocouple data.
Guidelines for FEA Modeling of Cylinder-to-Cylinder Intersection
Authors: Xue Liping , Widera G. E. O.
Published: August 2008

The purpose of this paper is to develop a definitive set of guidelines for carrying out finite element analysis (FEA) modeling of cylinder-to-cylinder intersections. By studying the stresses in the neighborhood of such intersections subjected to internal pressure and external moments (in-plane and out-of-plane moments) resulting from the use of various finite element models, the effects of number of elements along the nozzle circumference, number of elements through the wall thickness and element sizes in the direction perpendicular to nozzle circumference are investigated. Finally, general guidelines are proposed for setting up a FEA model of cylinder-to-cylinder intersections.
Effect of the Geometry of Groove on Connection Strength of the Hydraulically Expanded Tube-to-Tubesheet Joints of Heat Exchangers
Authors: Wang H. F. , Sang Z. F. , Widera G. E. O.
Published: August 2008

The object of this paper is to investigate the effect of geometry of a groove on the connection strength of hydraulically expanded tube-to-tubesheet joints of heat exchangers. Seven-tube models with different groove width, depth, spacing and location were fabricated under the same expansion pressure by commercial hydraulic expanders. Then the corresponding pullout forces were gained by experimental means. In addition, the process of hydraulic expansion of tube-to-tubesheet joints was simulated using the nonlinear finite element method based on a 2-D axisymmetrical model. The residual stress and deformation of joints were determined, and the effect of geometrical parameters of the grooves on the connection strength of joints was studied in terms of the average residual contact pressure of the joints. The experimental and calculation results indicate that the most important geometrical factor for determining the connection strength is the groove width. Groove depth, spacing and location have a secondary effect. Optimum geometrical sizes of grooves are proposed based on maximum axial strength. These can provide a reference for the revision of design and manufacturing codes.
Buckling Considerations and the Use of Code Case 2286-1 for Analyzing a Flue Gas Desulphurization Vessel
Authors: Williams Dennis K.
Published: August 2008

This paper describes some of the considerations for evaluating the structural adequacy of a hybrid tank-vessel-stack design where column-type instability must be considered. The equipment is utilized as a flue gas desulphurization (FGD) absorber/stack assembly in a petroleum refinery installation and is comprised of three major structural and geometric sections. The bottom section is considered to be very similar to an API 650 storage tank. The middle section is considered to be comprised of both cylindrical and conical pressure vessels. The third and upper most section is comprised of multiple ring sections of decreasing wall thicknesses as a function of elevation and resembles an ASME STS-1 stack. Because the height of the FGD absorber/stack exceeds 300 feet in combination with tank diameters of approximately 70 feet, wind loads, self-weight, and platform loads become a significant consideration in the design of the entire assembly. While no single nationally recognized code or standard fully addresses the buckling implications in the design and analysis of such a structure, a conglomeration of codes and standards, including ASME Code Case 2286-1 is reviewed and addressed in the following paragraphs with respect to the applicability and usefulness of the subject code case. Not withstanding, the interfaces and design considerations with respect to the other pertinent codes including, but not limited to, API Standard 650; ASME Section VIII, Divisions 1 and 2; and ASME STS-1 in combination with the suggestions contained within Code Case 2286-1 are also addressed herein. Finally, a consideration of the ultimate design factors of safety associated with each of the aforementioned codes is also discussed and revealed for the designer and owner in order to make an educated decision regarding the use of Code Case 2286-1.
Analysis of Shells of Noncircular Cross Section
Authors: Helms Jack E. , Guillot Michael W.
Published: August 2008

Minimum requirements for the design of shells of noncircular cross section are given in Appendix 13 of Section VIII, Division 1 of the ASME Code. The ASME Section XII Committee is re-examining the design of noncircular shells as part of their activities on cargo tank design. In this study finite element analysis is used to model a thin-wall noncircular shell. The results of the analysis are compared to experimental data provided by RTL, Inc.
Nonlinear Analysis of Flexibility and Local Stress Distribution at Nozzle-Shell Intersection Considering Refractory Lining Rigidity
Authors: Sato Takuya , Nomura Shingo
Published: August 2008

The reactors and re-generators in RFCC and FCC units in refineries are provided with concrete refractory linings. The influence of these linings on the flexibility of the nozzle-shell intersections and the local stress distributions around those intersections is not considered in present designs. In this paper, three-dimensional, nonlinear finite element analyses were performed to evaluate the influence of refractory lining rigidity on the flexibility of nozzle-head intersections. The results of these analyses can be applied to the thermal stress analysis of piping to obtain reaction forces and moments on nozzles. The application of flexibility factors results in a reduction of the reaction forces and moments. The influence of refractory lining rigidity on the local stress distributions around the intersections was also studied. To perform this investigation, three types of finite element models were adopted: • Nozzle-head intersections without refractory lining; • Nozzle-head intersections with refractory lining (adhesive boundary between steel and lining); • Nozzle-head intersections with refractory lining (contact boundary between steel and lining). Shell elements were applied to the nozzle, head and cylindrical shell, and solid elements were applied to the refractory lining. A boundary element was applied to express the contact boundary, which transfers only a compressive force. As a conclusion, a new design procedure for nozzle-head intersections with refractory linings is proposed.
ASME Section III Design-by-Analysis Criteria Concepts and Stress Limits
Authors: Slagis Gerry C.
Published: August 2008

The ASME Section III design-by-analysis approach provides stress criteria for the design of nuclear components. Stresses are calculated elastically for the most part, although plastic analysis is recognized. Limits are specified for primary, secondary, and peak stresses. Inherent in these limits are factors of safety against several modes of failure. The purpose of this paper is to explain the design-by-analysis criteria and fundamental concepts behind the approach. With this basis, some of the technical issues that have been identified are discussed.
Expander Inlet Piping Design
Authors: Klumpp P. T.
Published: August 2008

The interruption of electric power is always an extreme inconvenience in every sector of life, as was experienced during the massive Eastern United States blackout of 2003. Power shortages and interruptions in the refining industry are certainly no different, but the industry has responded to the uncertainties by approaching independence from the dominant utility grids through the installation of natural gas fueled co-generation units and/or the addition of flue gas driven expander power generation units, but of course the long term reliability of these systems is a major concern. A large hot gas expander, installed in a refinery, operating at a temperature of 705°C to 760°C, can be used to generate needed electric power [1]. However, these machines are very sensitive to the connected piping loads, and the long term operating reliability is most assuredly determined by the correct detail design of the inlet and outlet piping systems. This paper will only discuss in detail the design of the expander inlet piping system. This system is considered as one of the most complicated piping systems to analyze and design in the entire refinery.
Clamping and Failure Mode Transitions in Structural Shear Joints
Authors: Iyer K. , Hahn G. T. , Rubin C. A.
Published: August 2008

Applied-load-dependent evolutions of local gross- and net-section stress fields in aluminum and steel lap shear joints are examined in order to identify and define transitions between the frictional and bearing modes of load support. An airframe-type structural geometry is analyzed with an experimentally and numerically validated finite element model. Slip-resistant joints utilize fastener clamping to enhance frictional load support at panel-panel and bolt head-panel interfaces and postpone loading at fastener/panel-hole interfaces (bearing). In this work, nominal clamping strains of 0% and 0.5% are considered. Calculations without and with friction (μ = 0.2 and 0.4) are performed in order to separate effects of mechanical springback and friction on the transitions. The effective clamping is found to be only about one-third the nominal value.
Creep Modeling in Bolted Flange Joints
Authors: Bouzid Abdel-Hakim , Nechache Akli
Published: August 2008

Bolted flanged connections are used extensively in the petrochemical and nuclear industries. Under high temperatures, their leakage tightness behavior is compromised due to the loss of load as a result of creep of not only the gasket material but also the bolt and the flange materials. The relaxation of the bolt load and the corresponding loss of the gasket contact stress are not easy to assess analytically and consequently there is no established design calculation procedure. The objective of this paper is to present an analytical method that is part of the SuperFlange program [1] and is capable of predicting the load relaxation in a bolted joint when subjected to flange, bolt and gasket creep. The proposed method is validated by comparison with 3D FE models of different size flanges. In some cases, the relaxation caused by the flange and bolt materials is shown to be significant.
Load Factor Based Calculation for Bolt Load and Gasket Load Changes Due to Internal Pressure
Authors: Nagata Satoshi , Matsumoto Mitsuhiro , Sawa Toshiyuki
Published: August 2008

Gasketed flange connections should be designed taking actual behavior of the connections under their operating conditions into consideration. However, such actual behavior as bolt load change, gasket load change and flange rotation were not clear because adequate calculation method was not developed due to difficulty and complicacy to solve statically indetermine problem among three bodies, bolt, flange and gasket. In this paper, authors develop a method to calculate load factor for gasketed flange connection. Load factor describes bolt load change when an external force is applied to the connection. Load factor represents flange rigidity including gasket stiffness that dominates not only the behavior of joint after pressurising but also its sealing performance. By using the load factor, bolt load change as well as gasket load change due to internal pressure can be obtained by simple equations. When the required gasket stress is given to achieve a prescribed sealing thightness, the required initial bolt preload can also be calculated. Authors also proposed a load equilibrium diagram for gasketed flange connection with internal pressure. The diagram helps us to understand schematically how bolt load and gasket load change under pressurized condition. In addition, experimental tests are performed using 3 inch and 20 inch flange connections with spiral wound gasket in order to demonstrate validity of the proposed calculation method based on load factor and load equilibrium diagram. In conclusion, it is found that the proposed calculation method can estimate bolt load change and gasket load change under pressurized condition.
Determination of Gasket Effective Width Based on Leakage
Authors: Bouzid Abdel-Hakim , Diany Mohammed , Derenne Michel
Published: August 2008

The concept of the effective gasket width is used in the ASME code for flange designs to account for flange rotation. Its origin has never been revealed and it is suspected that only limited experimental testing was conducted for verification. In addition, with the new design rules based on the new gasket constants obtained from ROTT tests conducted on rigid platens, there is a need to revise the effective gasket width formulas. This paper presents some work development conducted under the auspices of the PVRC and related to the investigation of the effect of the non-uniform gasket contact stress due to flange rotation on the leakage behavior of sheet gasket materials. A experimental investigation coupled with some numerical work were conducted to determine the effective gasket width and its variation with gasket type, flange flexibility and load.
An Effect of Gasket Contact Stress Distributions on the Tightness Estimation in Pipe Flange Connections by Finite Element Analyses
Authors: Shoji Yasumasa
Published: August 2008

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.
An Experimental Investigation of the Effects of Clamped Length and Loading Direction on Self-Loosening of Bolted Joints
Authors: Zhang Ming , Jiang Yanyao , Lee Chu-Hwa
Published: August 2008

An experimental investigation was conducted to study the effects of clamped length and loading direction on the self-loosening behavior of bolted joints. Specially designed fixtures were used for the study. The experiments mimicked two plates jointed by an M12×1.75 Class 10.9 bolt and a nut. The joints were subjected to cyclic external loading. A constant preload of 25 kN was used for all the experiments conducted. During an experiment, the relative displacement between the two clamped plates, δ, was a controlling parameter. The reduction in clamping force, the applied transverse load, and the nut rotation were measured cycle by cycle. The relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening is referred to as self-loosening curve and was obtained for different clamped lengths and applied load directions. Similar to a fatigue curve, an endurance limit can be identified from the self-loosening curve. It was found that increasing the clamped length can enhance the self-loosening endurance limits in terms of the controlled relative displacement of the two clamped plates. However, the load carrying capability was not influenced significantly due to the thickness of the clamped plates. For a given bolted jointed structure, an angle of the external load from the pure shearing direction resulted in an increase in self-loosening resistance.
Stress Analysis and the Sealing Performance Evaluation of Pipe Flange Connections With Gaskets Subjected to Internal Pressure and External Bending Moment: Effects of Scatter in Bolt Preload
Authors: Sawa Toshiyuki , Maezaki Wataru , Nagata Satoshi
Published: August 2008

It has been well known that a scatter in axial bolt forces of pipe flange connections tightened by the torque control method is substantial. It is necessary for evaluating the sealing performance of the pipe flange connections with the gaskets subjected to internal pressure and external bending moment to know the contact gasket stress distributions due to the scatter of the axial bolt forces in the connections tightened by the torque control method. This paper deals with the leakage of the pipe flange connections with a spiral wound gasket subjected to internal pressure and external bending moment tightened by the torque control method. The scattered axial bolt forces were measured in the experiments. The contact gasket stress distributions at the interfaces between pipe flanges and the gasket were calculated under the measured axial bolt force by using elasto-plastic finite element method (FEM) taking into account hysteresis and non-linearity in the stress-strain curves of spiral wound gasket. The effects of the scatter in the axial bolt forces tightened by the torque control method on the gas leakage were also examined by using the actual pipe flange connections under internal pressure and external bending moment. By using the calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated. It is found that the sealing performance is worse in the actual pipe flange connection than that evaluated by PVRC procedure.
Thread Friction Torque in Bolted Joints
Authors: Nassar Sayed A. , Matin Payam H. , Barber Gary C.
Published: August 2008

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Results provided by these formulas are compared with those given by current practice that uses the average value of the minor and major thread radii. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. This makes critical the accuracy in the estimation of the friction torque components, as it directly affects the reliability, safety, and the quality of bolted assemblies, especially in critical applications. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using three assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single non-dimensional variable; namely, the ratio between the major and minor thread radii.
Strategy of Considering Microstructural Effect on Weld Residual Stress Analysis
Authors: Mochizuki Masahito , Toyoda Masao
Published: August 2008

Thermal distortion and residual stress are essentially generated by welding and it is well known that they affect the performance of welded structures such as brittle fracture, fatigue, buckling deformation, and stress-corrosion cracking. Welding distortions and residual stresses can be possible controlled and reduced by using some countermeasures. Not only thermal stress behavior but also prediction of microstructural phase during weld heat cycles are very important. High strength steels or martensitic stainless steels are used in a lot of power plant components, and the effect of phase transformation on mechanical behavior during welding in these steels becomes much larger than that of mild steels and austenitic stainless steels. Simultaneous simulation between thermal stress and microstructure during welding should be necessary in a precise evaluation. Analytical method and several applications to actual components are introduced in order to emphasize the effect considering microstructure on weld residual stress analysis.
Weld Modeling of Thin Structures With VFT Software
Authors: Yang Y. P. , Brust F. W. , Ezeilo A. , McPherson N.
Published: August 2008

Virtual fabrication technology (VFT) weld modeling software has been mainly used in thick-structure welding simulation. Recently both U. S. and European shipyards have shown strong interests in using the software to predict and control welding distortion of thin-plate ship panels. It is more complicated to simulate the welding of thin structures than thick structures because buckling distortion often occurs during the welding of thin structures. To evaluate the effectiveness of VFT for predicting distortion in thin structures, a bead-on-plate specimen, a butt joint of two large plates, and a long T stiffener were analyzed with VFT welding modeling software. By comparing the predicted distortions with those obtained by measurement, it was found that VFT can accurately predict welding-induced distortions of thin structures. Sensitivity studies show that pre-deformation induced by upstream fabrication processes and heat input are important factors influencing predicted distortions. Both distortion trends and magnitudes for thin structures are influenced by pre-deformation and heat input.
On the Mechanics of Residual Stresses in Girth Welds
Authors: Dong P.
Published: August 2008

In this paper, some of the important controlling parameters in governing weld residual stress distributions are presented for girth welds in pipe and vessel components, based on a large number of residual stress solutions available to date. The focus is placed upon the understanding of some of the overall characteristics in through-wall residual stress distributions and their generalization for vessel and pipe girth welds. In doing so, a unified framework for prescribing residual stress distributions is then outlined for fitness-for-service assessment of vessel and pipe girth welds. The effects of various joint geometry and welding procedure parameters on through thickness residual stress distributions are also demonstrated in the order of their relative importance.
Residual Stess Testing of Outer 3013 Containers
Authors: Dunn Kerry A.
Published: August 2008

The Department of Energy (DOE) Complex is packaging plutonium (Pu) containing materials for eventual storage at various sites in the complex. The Pu materials are packaged according to the DOE 3013 standard which outlines general requirements relevant to the planned DOE activities to stabilize Pu materials, package them in 3013 containers, and place them in long-term storage until future facilities are available to convert these materials to other forms. Container sections of the 3013, in both the as-fabricated condition as well as the closure welded condition, were evaluated per ASTM standard G-36-94, an aggressive testing procedure using boiling MgCl2 solution to reveal the relative stress corrosion cracking susceptibility of a material. Significant cracking was observed in the bottom half of the as-fabricated can near the base-to-can fabrication weld. This observation indicates that sufficient residual stresses exist to provide the stress component necessary for stress corrosion cracking in the as fabricated 3013 container. Additionally, cracks were observed in both the lid and the body of gas tungsten arc welded and laser beam closure welded containers as a result of this test technique. The presence of cracks in both of the closure welded container samples tested indicates that significant residual stresses are inherent in the closure welding process regardless of the closure weld method.
Fatigue Crack Propagation Tests on 304 Stainless Steel in High Temperature Water: Accelerated Cracking Rates and Transition to Lower Rates
Authors: Wire G. L. , Evans W. M. , Mills W. J.
Published: August 2008

Previous fatigue crack propagation (FCP) tests on a single heat of 304 stainless steel (304 SS) specimens showed a strong acceleration of rates in high temperature water with 40–60 cc H2/kg H2O at 288°C, with rates up to 20X the air rates. The accelerated rates were observed under fully reversed conditions (R = −1) (Wire and Mills, 2001) and high stress ratios (R = 0.7 and 0.83) (Evans and Wire, 2001). In this study, a second heat of 304 SS has been tested at 243°C and 288°C and lower positive stress ratios (R = 0.3, 0.5). The second heat showed the large acceleration of rates at 288°C observed previously. Rates were up to two times lower at 243°C, but were still 7–8X the air rates. A time-based correlation successfully correlates the accelerated rates observed, and is nearly identical to fits of literature data in hydrogen water chemistry (HWC), which has hydrogen added at a lower level of about 1 cc/kg H2O. The accelerated rates on the second heat were not stable under two different test conditions. In contrast to the first heat, the second heat showed a reduction in environmental enhancement at long rise times, accompanied by a change in fracture mode. Addition of a constant load hold time of 1200 s between cycles also caused a marked reduction in crack propagation rates in both heats, with reduction to nearly air rates in the second heat. The differing rise time effects between the two heats could be rationalized by time-dependent deformation. More hold time testing is required to define the material and loading conditions which lead to reduced rates.
Corrosion Fatigue Behavior of Low-Alloy Pressure Vessel Steels in High Temperature Water Under Multi-Factor Conditions
Authors: Wu Xinqiang , Katada Yasuyuki
Published: August 2008

The corrosion fatigue resistance of pressure vessel steels in simulated light water reactor coolant water is greatly influenced by the mechanical factor such as strain rate, environmental factor such as temperature and dissolved oxygen (DO) concentration in water, and material factor such as sulfur content in steels. In most of previous work, the mechanical or environmental conditions were usually fixed as a constant throughout an individual test. However, these factors may change frequently during actual operations in power plants. So, it is of great interest to investigate the effects of change of the above factors on fatigue resistance of components materials in service environments and to develop appropriate methods for evaluating the environmental effects on fatigue damage. The present work was to investigate the low cycle fatigue (LCF) behavior of low-alloy pressure vessel steels in high temperature water. Special attention was paid on the influence of strain rate change in an individual LCF test on fatigue resistance of the steels. The alternate sequence of strain rate in a test was also considered. Moreover, the influence of DO, temperature and sulfur content in the steels was investigated. The detailed cracking and fractographic features were examined to assist the understanding of underlying corrosion fatigue mechanisms.
A Parametric Study of ASME B16.5 Flanges Which Has Experienced Flange Face Corrosion
Authors: Nadarajah C.
Published: August 2008

Weld neck flanges on piping systems are susceptible to flange face corrosion when they are exposed to corrosive environments. This paper examines the maximum amount of corrosion a weld neck flange face could tolerate without loosing structural integrity and hence the flange is fit for service. A parametric study using finite element method was used to examine the entire range of weld neck flanges listed in ASME B16.5 Code, Pipe Flanges and Flanged Fittings. From the study, a number of tables were developed limiting the amount of corrosion for the various classes and sizes of flanges.
Analysis of a Hemispherical Head With Nozzle and Local Thin Area
Authors: Guillot Michael W. , Helms Jack E.
Published: August 2008

The ability to analyze the behavior of pressure vessels with structural defects has been greatly improved by the general availability of PC based finite element analysis programs. In this study a hemispherical head with a nozzle and a local thin area is analyzed using finite element models. The requirement to apply a 15 % stress adjustment is also examined in light of the results of the finite element analyses.
Outline of the JSME (Japan Society of Mechanical Engineers) Rules on Design and Construction for Nuclear Power Plants
Authors: Saito Itaru , Shimakawa Takashi
Published: August 2008

The JSME (Japan Society of Mechanical Engineers) published the rules on design and construction for nuclear power plants in 2001. The basic concept of this rule originates in the ASME Boiler & Pressure Vessel Code Section III, however, some articles in the JSME rules are modified from the ASME rules depending on the Japanese own investigations and thoughts. This paper presents the outline of the JSME rules and discussed the comparison between the JSME rules and the ASME rules. In Japan, rules for the design and construction for nuclear power plants had been used in the Japanese regulatory standards known as Notification 501 of MITI (Ministry of international Trade and Industry) for over 30 years. And the JSME code is also based on the Notification 501. Recently the Japanese regulatory authority had announced new policy to adapt non-government voluntary rules for the design and construction taking advantage of reflecting new technology and the code revision quickly. And, in November 2003, the new JSME rules are endorsed by the Japanese regulatory authorities as alternate rules of the Notification 501.
Outline of the JSME Rules on Design and Construction for Thermal Power Generation Facilities
Authors: Nishiguchi Isoharu , Fujita Masaaki , Hamada Seiichi
Published: August 2008

In order to develop and maintain the codes pertaining to mechanical equipment in the thermal facilities for power generation, the Subcommittee on Thermal Power was set up under the JSME Main Committee on Power Generation Facilities on October 1, 1997. The first edition of the JSME code for thermal power generation facilities was issued in January 2000, and its addenda was issued in April 2002. The latest 2003 edition was issued in January 2004. This paper presents an outline of the JSME Code including fundamental policy, the organization of the code, the relation with requirements of the Ministry of Economy, Trade and Industry Ministerial Ordinance in Japan and comparison with ASME Boiler & Pressure Vessel Codes.
Implementation of Regulatory Rules on Fitness-for-Service for Nuclear Power Plants in Japan
Authors: Nakamura Takehiko , Yamamoto Tetsuya , Oshima Iwao , Takasaka Kiyoshi , Hirano Yukio , Hiraoka Eiji
Published: August 2008

A set of new regulatory rules on nuclear power plants have been implemented in Japan effective October 1, 2003, in order to conduct the Inservice Inspection (ISI) effectively and to examine fitness-for-service properly. The new regulation utilizes the Japan Society of Mechanical Engineer (JSME) Codes on fitness-for-service for nuclear power plants. The rules are applied for the ISIs and for evaluation of structural integrity of the class 1 components and the core shrouds with flaws. Additional components will be subjected to the structural integrity examination, in accordance with the further development of the codes and with establishment of the performance demonstration system for non-destructive testing. Endorsement of other codes and standards are foreseen after technical review by the Nuclear and Industrial Safety Agency (NISA) of Japan. This new regulatory process, which utilizes the consensus codes and standards established by academic/public societies, would allow the NISA to accommodate recent technical progress in a more timely manner.
What’s New in Section I [2001 Through 2003]
Authors: MacKay John R.
Published: August 2008

It has been a three years since I last prepared a summary of significant revisions to the Section I of the ASME Boiler and Pressure Vessel Code. In addition to the routine maintenance and upgrade revisions that occur in each annual addenda to the Code, there are several major activities under way that will have a significant impact on Section I in the future. One of these is a contemplated new Part covering Heat Recovery Steam Generators. The second is the publication of the 2004 Edition of the Boiler Pressure Vessel (B&PV) Code in SI units.
What’s New in Section XI (Welding)
Authors: Feldstein Joel G.
Published: August 2008

Section IX establishes the rules for the qualification of welding and brazing used for the fabrication of boiler, pressure vessel and piping components. Initially published as a stand alone book in 1941, the basic methodology within Section IX for the qualification of procedures and performance has changed little in the 50+ years since Section IX has existed. However, as technology progresses and processes, techniques and materials used in design and fabrication change, the Code must adapt to keep pace with these changes. This paper highlights some of the changes recommended during the past three years by the Subcommittee on Welding (SC IX) that have been approved for incorporation into Section IX.
What’s New in Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components
Authors: Park Gary
Published: August 2008

The nuclear industry is a pretty dynamic industry, in that it is always on the move, changing every time we turn around. For that very reason, there is a need to keep up with the industry by providing changes to American Society of Mechanical Engineering Section XI, “Rules for Inservice Inspection of Nuclear Power Plant Components.” There have been many changes over the last three years. This paper addresses a few of those, but gives a feel for the number of changes from the 2000 Addenda to the 2003 Addenda, there have been a total of approximately 56 changes. Of those changes, 11 were in the repair/replacement requirements, 19 in the inspection requirements, 4 in the evaluation requirements, 18 in the nondestructive examination requirements, and 4 in the administrative requirements. The paper classifies the changes as “Technically Significant,” “Significant,” “Non-Significant,” or “Editorial.” The paper addresses only a few of those changes that were “Technically Significant.” The paper also includes some of the activities that the ASME Section XI Subcommittee is currently working on.
Background and Summary of Revisions to Appendix M of ASME Section VIII, Division 1: Stop Valves Located in the Pressure Relief Path
Authors: Basile Richard J. , Rodery Clay D.
Published: August 2008

Appendix M of Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code[1] provides rules for the use of isolation (stop) valves between ASME Section VIII Division 1 pressure vessels and their protective pressure relieving device(s). These current rules limit stop valve applications to those that isolate the pressure relief valve for inspection and repair purposes only [M-5(a), M-6], and those systems in which the pressure originates exclusively from an outside source [M-5(b)]. The successful experience of the refining and petrochemical industries in the application and management of full area stop valves between pressure vessels and pressure relief devices suggested that the time was appropriate to review and consider updates to the current Code rules. Such updates would expand the scope of stop valve usage, along with appropriate safeguards to ensure that all pressure vessels are provided with overpressure protection while in operation. This white paper provides a summary of the current Code rules, describes the current practices of the refining and petrochemical industries, and provides an explanation and the technical bases for the Code revisions.
Technical Basis for Acceptance of Flaws in Moderate Energy Class 2 and 3 Vessels and Tanks
Authors: Strauch Pat L. , Bamford Warren H. , Daftuar Sushil K.
Published: August 2008

New procedures and acceptance criteria for the evaluation of degradation, including through-wall flaws, in moderate energy Class 2 and 3 vessels and tanks have been prepared for implementation within Section XI of the ASME Code. The provisions are contained in a proposed Code Case and are focused on the structural integrity margin of the vessel or tank against gross failure. The assessment of the degraded condition is based on the flaw evaluation procedures already established in ASME Section XI. Additional provisions for periodic inspection and leakage monitoring are included to assure that analysis assumptions are conservative for the operating conditions. The precedent for permitting operation with degraded components was established in United States Nuclear Regulatory Commission (NRC) Generic Letter 90-05 and Code Case N-513-1 for piping, as well as several NRC-accepted plant-specific relief requests associated with leaking tanks. The technical basis for the procedures is presented, and the objectives and scope of its application are explained. The basis for the analytical procedures follows from evaluation rules contained in ASME Section XI, Appendix A. Other issues regarding consequences of leakage, growth of degradation, and augmented inspections and surveillance are also addressed, as well as reference crack growth curves for stress corrosion cracking for conditions appropriate for application of these procedures.
Validation of Pipe Flaw Evaluation Procedures in Section XI of the ASME Code Against Pipe Fracture Experiments
Authors: Hoang Phuong H. , Wilkowski Gery M.
Published: August 2008

Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code provides rules and requirements for maintaining pressure boundary integrity of piping during the life of a nuclear power plant. Evaluation procedures and acceptance criteria for the evaluation of flaws in nuclear piping in Section XI of the ASME Code were first published in 1983 and have been under revision for the past several years. The evaluation procedures and acceptance criteria cover: failure by plastic collapse as characterized by limit load analysis; fracture due to ductile tearing prior to attainment of limit load, as characterized by elastic-plastic fracture mechanics (EPFM) analysis; and brittle fracture as characterized by linear elastic fracture mechanics (LEFM) analysis. A major revision to the evaluation procedures and acceptance criteria was published in the 2002 Addenda to Section XI. A brief overview of the pipe flaw evaluation procedures published in the 2002 Addenda are provided in the paper. The evaluation procedures that were published in the 2002 Addenda have been validated against the results of a large number of pipe fracture experiments. The results of this validation exercise are summarized in this paper.