bluuebunny/crossref_metadata_2025 huggingface dataset:
Brittle Fracture Analysis of Dissimilar Metal Weld Joints
Authors: Blouin A. , Chapuliot S. , Marie S. , Bergheau J. M.
Published: August 2013

Demonstration of large components integrity is based on the demonstration that they could never undergo brittle fracture. In parallel, considering a conventional defect somewhere in the component, failure must prevent ductile crack propagation.

Connections between a ferritic component and an austenitic one have to respect these rules. The considered case is a Ni base alloy weld joint between a ferritic pipe and an austenitic one. For brittle fracture exclusion, the aim of the present study is to show that in the same loading conditions, the weld joint is less sensitive to the brittle fracture than the surrounding ferritic part of the component. That is to say that the demonstration should be focused on the ferritic base metal which is the weakest material.

For that purpose, Chapuliot developed a stress-based criterion model, using a threshold stress (σth) below which the cleavage cannot occur. It can be used to define the brittle crack occurrence probability, which means that it is possible to determine the highest loading conditions without any brittle fracture risk.

For the experimental part of this demonstration, two different mock-ups with DMW are used. The first one is composed of a 16MND5 (A508 cl. 3) steel pipe welded to a 316L stainless steel pipe with Ni base alloy 82. As for the second one, the materials are the 18MND5 (A533) steel, the 316L stainless steel and the Ni base alloy 52. Conventional defects have been considered in the ferritic part, close to the weld joint in the heat affected zone, and far away from the weld joint in the ferritic part. Two hundred specimens have been taken from the mock-ups: special tensile specimens, compact tensile specimens, single edge notch tension specimens, notched tensile specimens, smooth tensile specimens. All the materials have been characterized at −125°C/−130°C and −170°C/−175°C, even the heat affected zones. Finite element calculations have been done to complete the experimental investigations. The first results show that, due to the mismatch of the materials, the brittle fracture risk is much lower in the HAZ. Thus, DMW HAZ could not be a weak part concerning brittle fracture. This paper presents the criterion, the experimental work and the analyses made to evaluate the conservatism of the homogeneous ferritic case compared to the DMW.
A Simple Recipe for Solving all Refinery Sealing Issues
Authors: Reeves David , Brown Warren
Published: August 2013

Hundreds of papers have been written and presented over the years about bolted connections, what impacts reliability and how to get them to operate leak free. Are bolted connections really that complicated that only experienced, dedicated and highly educated engineers should be involved with the joint design, as well as the assembly of connections out in the field? Clearly not, or hundreds of companies could not stay in business. This paper summarizes some simple steps for making all kinds of bolted connections leak free, including heat exchangers and pipe flanges, and just about any other pressure boundary bolted connection found in a refinery.
Taylor Cylinder Testing of Anisotropic Materials
Authors: Conway Jennifer M. , O’Brien Kory T. , Barkey Mark E. , Jones Stanley E.
Published: August 2013

Frequently, Taylor cylinder specimens are fabricated from rolled plate stock. The rolling process induces an anisotropic response in the cylinder upon impact. If the rolling and transverse directions can be clearly identified, then it is possible to fabricate the cylinders so that the longitudinal axis of the cylinder is aligned with either direction. The response of specimens fabricated in this way is reasonably uniform, in spite of the fact that the cross sections have an elliptical geometry. Earlier work [1] provided a modified one-dimensional analysis with which data can be reduced from anisotropic cylinder tests and dynamic stress estimates can be made. The purpose of this paper is to report the results of tests performed on specimens taken from rolled copper. The results show that the cross sections of the specimens are clearly uniform ellipses with the major and minor axes of the ellipse roughly constant along the shaft. Very satisfactory estimates of dynamic strength using a modified one-dimensional, strain rate dependent theory may then be made. Fabrication of cylinders from the plates that are not axially aligned to the rolling or transverse directions permits testing of the theory by comparing simulations of the response to actual impacts.
Pressure Cycling of Steel Pressure Vessels With Gaseous Hydrogen
Authors: San Marchi C. , Harris A. , Yip M. , Somerday B. P. , Nibur K. A.
Published: August 2013

Steel pressure vessels are commonly used for the transport of pressurized gases, including gaseous hydrogen. In the majority of cases, these transport cylinders experience relatively few pressure cycles over their lifetime, perhaps as many as 25 per year, and generally significantly less. For fueling applications, as in fuel tanks on hydrogen-powered industrial trucks, the hydrogen fuel systems may experience thousands of cycles over their lifetime. Similarly, it can be anticipated that the use of tube trailers for large-scale distribution of gaseous hydrogen will require lifetimes of thousands of pressure cycles. This study investigates the fatigue life of steel pressure vessels that are similar to transport cylinders by subjecting full-scale vessels to pressure cycles with gaseous hydrogen between nominal pressure of 3 and 44 MPa. In addition to pressure cycling of vessels that are similar to those in service, engineered defects were machined on the inside of several pressure vessels to simulate manufacturing defects and to initiate failure after relatively low number of cycles. Failure was not observed in as-manufactured vessels with more than 55,000 pressure cycles, nor in vessels with relatively small, engineered defects subjected to more than 40,000 cycles. Large engineered defects (with depth greater than 5% of the wall thickness) resulted in failure after 8,000 to 15,000 pressure cycles. Defects machined to depths less than 5% wall thickness did not induce failures. Four pressure vessel failures were observed during the course of this project and, in all cases, failure occurred by leak before burst. The performance of the tested vessels is compared to two design approaches: fracture mechanics design approach and traditional fatigue analysis design approach. The results from this work have been used as the basis for the design rules for Type 1 fuel tanks in the standard entitled “Compressed Hydrogen-Powered Industrial Truck, On-board Fuel Storage and Handling Components (HPIT1)” from CSA America.
Unified Approach for Notch Stress Strain Conversion (NSSC) Rules
Authors: Adibi-Asl R. , Seshadri R.
Published: August 2013

There are several simplified methods, known as notch stress-strain conversion (NSSC) rules that provide an approximate formula to relate local elastic-plastic stresses and strains at the notch root to those estimated elastically. This paper investigates a unified approach that estimates non-linear and history dependent stress-strain behavior of the notches using the conventional NSSC rules. A non-linear interpolation method is adapted to estimate the elastic-plastic stress and strain at notches. A comparison is made between the finite element results for several notch configurations (with and without three dimensional effects) and those obtained from NSSC rules and the proposed formulation.
The Proposal of Wall Thickness Management Criteria of T-Pipes
Authors: Tsunokawa Kiyoharu , Ohira Taku , Miura Naoki , Kitajima Yasumi , Yoshimura Daisuke
Published: August 2013

Although the reinforcement for openings is checked in accordance with design / construction standard when thinning was observed in T-pipes, this evaluation becomes too conservative or requires much time and effort.

This paper describes additional parametric study results and proposes a guideline for thickness management of wall thinning T-pipes. On the other papers related to this project, the experiment and numerical simulation results are reported. This paper referred these results and performed further investigation.
Magnitude and Distribution of Retained Residual Stresses in Laboratory Fracture Mechanics Specimens Extracted From Welded Components
Authors: Hurlston R. G. , Sharples J. K. , Sherry A. H.
Published: August 2013

Quantifying material fracture toughness properties is an important step in ensuring structural integrity of industrial components. Welding of structural components can cause large magnitudes of residual stress to be generated, which can be defined as a stress that exists in a material when it is under no primary loading. These stresses can be retained in laboratory fracture mechanics testing specimens removed from non-stress relieved welds, making the quantification of valid material fracture toughness difficult.

The aim of this paper is to investigate, analytically, the levels and distributions of residual stresses retained in fracture mechanics specimens taken from welded components. This was achieved using parametric finite element analyses. Furthermore, in order to ensure the validity of fracture toughness measurements derived from components that contain residual stress, a robust method for the design of stress-free fracture mechanics specimens is proposed.

Significant weld residual stresses have been shown to be retained in certain laboratory specimens post extraction from non stress-relieved welds. The magnitude and distribution of retained residual stress has been shown to be dependant on material properties, specimen size, specimen type and removal location. In addition, the stress partitioning method has been shown to provide a useful approach for estimating the levels and distributions of residual stresses retained in fracture mechanics specimens extracted in certain orientations.
Microstructural Stability and Lattice Misfit Characterisations of Nimonic 263
Authors: Luo Quanshun , Chi Kuangnan , Li Shuxin , Barnard Pete
Published: August 2013

Nimonic 263 has been selected as a candidate header/piping material of advanced ultra-supercritical (A-USC) boilers for the next generation of fossil fuel power plant. Experimental assessments on the microstructural stability of this material are presented in this paper. Microstructural evolution has been quantified by high resolution field emission SEM and TEM. Electron diffraction and the combined XRD and Gaussian peak-fitting have been applied to investigate the coherency and lattice misfit between the gamma prime (γ′) precipitates and the gamma (γ) matrix. The micro structure subjected to solution and hardening treatment consists of γ-matrix and a network of carbide precipitates along the grain boundaries. Large quantities of fine γ′-Ni3(Ti,Al) precipitates were observed, with an average size of 17 nm and coherent with the matrix lattice. The overall misfit has been quantified to be 0.28%. After long term aging at 700 and 725 °C for various periods up to 20,000 hours, γ′ was still the predominant precipitate and mostly coherent with the matrix. A few needle-shape η-Ni3Ti intermetallic precipitates were found in the grain boundary regions. The γ′ size has grown progressively to 78 nm, accompanied by the γ′-γ constrained misfit increasing to 0.50%. Moreover, the M23C6-type grain boundary carbides were found to have experienced morphological evolution, including the nucleation of Widmanstatten-type needles and their initial growth towards the matrix.
Crack Propagation Under High Thermal Amplitude Cycles in a Ductile Material
Authors: Vallet Christophe , Chau The Hiep , Stéphan Jean-Michel
Published: August 2013

An experimental setup was built in order to study the fatigue crack propagation in high stressed structure with plastified zone.

This paper deals with results obtained in a first stage of the experiment program. Thermal cycles are applied on a simplified mock-up including four short pre-cracking defects. Local measurements (thermocouples, strain gages) and crack lengths are provided.

A numerical interpretation of the test was then performed and the results were compared to the experiment.
The Prediction of Global Temperature Profiles in Piping Systems Submitted to Thermal-Stratified Flow From Measured Temperatures on Outside Wall
Authors: Park Hong Sun , Kang Sun-yeh , Yoon Ki-seok , Choi Taek-sang , Song Min-sup , Lee Eui-suk
Published: August 2013

Thermal stratification is a common phenomenon in the surge line of Pressurized Water Reactors (PWR). The stratification temperature difference (ΔT) and cyclic behavior severities are the most prevalent during heat-up and cool-down operations of a PWR, when temperature difference between the pressurizer and the hot leg in the Reactor Coolant System (RCS) becomes the largest and inventory fluctuations in RCS are the highest. These behaviors cause cyclic damages and deformations of the pipe. In addition, USNRC recommended integrity evaluations of the piping system submitted to thermal stratified flow in USNRC Bulletin 88–11. In this reason, the importance of monitoring the fatigue induced by the thermal stratified flow in thick-wall pipes rises more and more. To raise the accuracy of solutions for the fatigue damage induced by thermal stratification, the exact global temperature profile is needed to be derived. Many studies have been performed to obtain these profiles. The purpose of this paper is to predict the global temperature profiles in the piping systems submitted to thermal-stratified flow from measured temperatures on the outside wall. It presents both the inverse transfer function method and the numerical-analysis method.
Hot Isostatic Pressing of Hardfacing and Stainless Steel Powders for PWR Components: Materials and Manufacturing Benefits
Authors: Burdett W. Barry
Published: August 2013

Hot Isostatic Pressing (HIP) has been used for many years to consolidate porosity in cast metal shapes to improve mechanical properties. When applied to fine metal powders, it is possible to produce Near Net Shape (NNS) items and more complex geometry components that are fully dense and offer an attractive set of properties at reduced cost.

NNS items from powder deliver cost savings by reducing initial material usage and subsequent machining costs. Powder production and HIP processing are automated methods, which provide protection against forging route obsolescence. Setup costs are lower and batch sizes smaller, particularly well suited to small numbers of high integrity components.

HIPped powder microstructures are isotropic and equiaxed, with uniformly fine grain sizes not normally achieved in heavy section components, which facilitates ultrasonic NDE examination. Improved features to facilitate NDE are readily incorporated into the HIP assembly. Inclusion contents are lower and of more benign geometry, easing fracture assessment.

Use of the technology has grown, particularly in the off-shore oil industry where it is already established in high integrity applications, particularly in place of welded joints. Take-up in the more conservative nuclear industry has been slow. The quality of HIPped powder items can provide through life cost savings since there is greater assurance of structural integrity compared to welded or wrought components.

This paper presents a materials perspective on the way in which Rolls-Royce has gained experience with HIPped powders since the 1990s, initially with hardfacing materials to minimise welding defects and provide a robust manufacturing route. Building on this database, we have now established that HIPped powder 316L/304L components, in items up to several tons in weight, have equivalent or slightly better strength, toughness and corrosion resistance to their forged or cast counterparts. This data is now part of a submission to ASME for inclusion in the Pressure Vessel Code.

Rolls-Royce now has a robust methodology in place to develop safety cases and is extending the number of applications in pressure boundary components on current and future classes of equipment. A strength-in-depth argument has been endorsed by external approval organisations and is supporting current submarine build programmes. Other applications in the growing civil nuclear market are now under consideration.
Drop Analysis of Structures and Development of Impact Energy Absorber
Authors: Babu Suresh , Grewal Inderdeep , Jategaonkar Ravi , Biswas Jay
Published: August 2013

Historic radioactive waste generated, due to various research and development activities at Chalk River Laboratories (CRL), as part of fuel development process are stored in containers in Tile holes. The fuel in the historic containers needs to be removed to new containers that provide improved storage conditions. A new above ground facility is being developed to store the historic containers along with their contents. It involves retrieval and transportation of the historic storage containers and their contents to the new facility, repackaging them into new containers, and storing them in steel storage tubes inside a concrete storage block protected from the environment by a steel overbuilding. During transportation, repackaging and storing of the historic storage containers, drop events might occur that could potentially compromise the structural integrity of the components of the packaging and storage systems. The present paper deals with the development of impact energy absorbing device (LOAD DISTRIBUTOR CAP) and the drop analysis that has been carried out to assess the structural integrity of the vacuum vessel assembly and the storage tube assembly structures for various drop events.
Bolted Joint Component Temperatures for Material Selection
Authors: Brown Warren , Rodery Clay , Brodzinski Richard
Published: August 2013

The selection of gasket, bolts and flange materials for elevated temperature service requires knowledge of the operating temperature that the joint components will see during service. There are guidelines in ASME B31.3 for approximate temperature reductions of 10% and 20% for the flange and bolts, respectively. However, it is not made clear if that approximation can also be applied to gaskets. In addition, the background for the limits and level of conservatism of the B31.3 approximations is unknown. This paper examines the operational temperature of joint components for a range of standard B16.5 and B16.47 flanges in different services in order to confirm the level of conservatism of the B31.3 limits, identify any limits to those approximations and outline appropriate gasket temperature assumptions.
Strain Limits for the Analysis of the Mechanical Behaviour of Pressurized Components
Authors: Herter Karl-Heinz , Schuler Xaver , Seidenfuss Michael
Published: August 2013

In technical codes and standards the strength assessment of pressurized components and systems is usually performed by limitation of fictitious elastic stresses as well as by limitation of the fatigue level. It shall be proven that the highest stresses resp. stress ranges caused by external loading show a specific margin against the resistance of the material used (concept of stress limitation). This concept is based on the principle that in a component with inhomogeneous stress distribution plastic deformation are allowed at the locations which sustain the highest loads. If in special cases the stress categorization is unclear, the effect of plastic deformation on the mechanical behavior shall be decisive. The same holds for postulated load levels with low occurrence probability (severe accidents) for which the stress limits do not utilize fully the deformation capacity of ductile materials. For that reason solutions that are based on the “Strain Limitation Concept” (SLC) shall be developed. Strength assessment using the concept of strain limitation relies on limiting strains to a specified allowable strain value, i.e. “Limit Strain Curve” (LSC). Within this presentation the approach of the concept of strain limitation is described with a special attention for the determination of the strain limits that can be allowed. With the help of Finite Element damage calculations (Rousselier model) on notched round bars the deformation behavior of an austenitic steel is described until failure. The dependency of the local failure strain on size, stress triaxiality and stress gradients is analyzed. In order to validate the numerical investigation these results are compared with experiments.
Multifunctional MWCNT Reinforced Self-Healing System
Authors: Ji Gefu , Li Guoqiang , Pang Su-Seng
Published: August 2013

Multi-Wall Carbon Nano Tube (MWCNT) reinforced composite structure has been widely researched. However, there are a few studies report the MWCNT as a sensor and an actuator integrated in the same composite structure to form a multifunctional composite. The composite used in this study was based on commercially available thermosetting epoxy polymer, dispersed with thermoplastic particles, and MWCNT. Multifunctional MWCNT reinforced epoxy polymer composite was fabricated and tested. The specimens were damaged by the three point bending load. The sensor and actuator system automatically detected the damage and triggered the out electric power to heal the damages. The healing efficiency was evaluated by measuring resistant of composite.
Influence of PWR Primary Water on LCF Behavior of Type 304L Austenitic Stainless Steel at 300°C: Comparison With Results Obtained in Vacuum or in Air
Authors: De Baglion Laurent , Mendez José , Le Duff Jean-Alain , Lefrancois André
Published: August 2013

Nowadays, it is well known that the low cycle fatigue (LCF) life of austenitic stainless steels can be affected in specific conditions of temperature, strain rate, strain amplitude or dissolved oxygen concentration by the effect of Pressurized Water Reactor (PWR) primary coolant environment. Nevertheless, questions remain about the best methodology that must be used to consider environmental effects for nuclear power plant licensing and for operating lifetime extensions.

These environmental effects are most commonly evaluated from a mean fatigue curve based on tests conducted in air at room temperature. However, it is well established that air is not a neutral environment for metallic alloys and its effect can be highly dependent on the temperature level.

Thus, in order to evaluate the intrinsic fatigue resistance of a 304L austenitic stainless steel at 300°C and the importance of complex fatigue – environment interactions in air or in PWR water, LCF tests were performed in both environments and specifically designed ones were conducted in secondary vacuum. Tests were performed on 304L cylindrical specimens at 20 or 300°C in vacuum or in air and only at 300°C in PWR water, under total axial strain control using a triangular waveform at strain amplitudes of ±0.3 or ±0.6% and strain rates of 4 × 10−3, 1 × 10−4 or 1 × 10−5 s−1.

It was found that compared with vacuum, air is responsible for a strong decrease in fatigue lifetime in this steel, especially at 300°C and low strain amplitude. The PWR water coolant environment is still more active than air and leads mainly to increased damage kinetics, with slight effects on initiation sites or propagation modes. More precisely, the decreased fatigue life in PWR water is essentially attributed to an enhancement of both crack initiation and “short crack” micropropagation stages. Furthermore, a detrimental influence of low strain rates on the fatigue lifetime at 300°C was observed in PWR water environment or in air, but also in vacuum without environmental effects, and was in the last case exclusively attributed to the occurrence of the dynamic strain aging (DSA) phenomenon.

So, the use of data obtained in a neutral environment as a reference allows the evaluation of the intrinsic effect of each environmental or loading condition. Moreover, in an active environment such as air or PWR primary water, damage evolutions as well as fatigue lives cannot be predicted by a simple multiplication of each parameter effect taken separately because they are the result of numerous interactions.

The last conclusion is supported by complementary results showing that the PWR water environment effect as well as the ground surface finish effect can be attenuated when LCF tests are performed with a more representative loading signal shape.
Research and Development of Viscous-Friction Hybrid Damper
Authors: Kawamura Tatsuya , Fujita Satoshi , Minagawa Keisuke
Published: August 2013

In the great east Japan earthquake of 2011, resonances of high rise structures as a consequence of a long period ground motion has been reported. The long period ground motion had a predominant period of from a few seconds to ten seconds. Additionally the duration time of the long period ground motion was more than a few minutes. Various viscous dampers have been proposed and applied to actual structures to suppress vibration response. However the vibration control performance decreases with the long duration time, because of a temperature rise of the viscous material. Therefore there is concern that these viscous dampers can not suppress vibration response in case of the long period ground motion. In order to solve this problem, the authors propose a viscous-friction damper in series. In this hybrid damper, the friction damper can absorb vibration energy as well in case of the long period ground motion. As a result, the temperature rise of the viscous material is suppressed, and the damper retains good performance. In this paper, seismic response analysis and component tests are conducted in order to confirm the fundamental performance and behavior of the hybrid damper.
Prediction of Initiation Toughness Under Small Scale Yielding (SSY) and J0.2BL vs. Q Fracture Locus Using Local Approach Methodologies in 304SS
Authors: Wasylyk A. , Sherry A. H. , Sharples J. K.
Published: August 2013

Structural integrity assessments of structures containing defects require valid fracture toughness properties as defined in national and international test standards. However, for some materials and component geometries, the development of valid toughness values — particularly for ductile fracture — is difficult since sufficiently large specimens cannot be machined. As a consequence, the validity of fracture toughness properties is limited by the development of plasticity ahead of the crack tip and the deviation of crack tip conditions at failure from small scale yielding. This paper described the use of local approach models, calibrated against invalid test data, to define initiation toughness in 304 stainless steel pipe material. Three fracture toughness geometries were tested, shallow cracked single edge cracked specimens tested under three point bending, deep cracked single edge cracked specimens tested under three point bending, and deep cracked single edge cracked specimen tested under tension. Initiation toughness and J-Resistance curves were defined for each specimen using the multi-specimen technique. All initiation toughness values measured were above the specimen validity limits. The fracture conditions at initiation were analysed using three local approach models: the Generalised Rice & Tracey, High Constraint Rice & Tracey and the Work of Fracture. The adequacy of local approaches to define the fracture conditions under large strains in 304 stainless steels was demonstrated. A modified boundary layer analysis combined with the local approach models was used to predict the “valid” initiation toughness under small scale yielding condition in this material by defining a J-Q fracture locus. The analytically derived fracture locus was compared to the J-Q values obtained experimentally and shown to be consistent.
Advanced Assessment of the Integrity of Ductile Components
Authors: Daly Michael , Sherry Andrew H. , Sharples John K.
Published: August 2013

Nuclear Reactor Pressure Vessels (RPV) are manufactured from medium strength low alloy ferritic steel, specifically selected for its high toughness and good weldability. The ability of the pressure vessel to resist crack growth is crucial given that it is one of the fundamental containment safety systems of the reactor. For most of their lifetime, the pressure vessel operates at sufficiently elevated temperatures to ensure the material is ductile. However, the development of ductile damage, in the form of voids, and the ability to predict the ductile crack growth in RPV materials requires further work.

The Gurson-Tvergaard-Needleman (GTN) model of void nucleation, growth and coalescence provides one tool for predicting ductile damage development. The model is normally calibrated against fracture toughness test data. However, recent work [1] has demonstrated the benefit of refining calibrations against measured void volume fractions generated from notched and pre-cracked specimen tests.

This paper described the measurement of void distributions below the fracture surface of a range of notched and pre-cracked specimens. The void distribution below the fracture surface is shown to be dependent upon the local stress triaxiality and plastic strain distribution. As a result, pre-cracked specimens show a greater concentration of voids close to the fracture surface, whilst notched tensile specimens show a lower volume fraction of voids close to the crack surface. In both specimen types, voids are observed to extend between 2.5 and 3.5 mm below the fracture surface.
An Evaluation of Energy Definitions for Bursting Pressure Vessel Modeling
Authors: Pierorazio Adrian , Syed Zaki
Published: August 2013

The most widely used definition of energy for predicting bursting vessels is Brode energy. There are, however, limitations to the application of this definition to many real-world problems due to the assumptions upon which it is based. This paper presents an evaluation of the applicability of the Brode equation, its common interpretation and limitations, and an evaluation of alternative definitions of energy for bursting vessel and Boiling Liquid Expanding Vapour Explosion (BLEVE) prediction. An illustrative example of the recommended approach is provided.
Managing Check Valve Flange Leaks: Technical Solutions and Challenges to Overcome
Authors: Ezekoye L. Ike , Densmore William E. , Turkowski William M. , Becse Robert E.
Published: August 2013

Check valves are the simplest valves in power plants. Their simplicity and passive nature, combined with their relatively low maintenance requirements, often mask their relative importance in piping systems. Compared to power operated valves (POVs), such as motor operated valves or air operated valves, check valves have very few parts. The more parts a valve has, the more likely failures will occur. As such, power operated valves tend to have more stringent requirements that cover periodic verification of operability, in-service testing (IST), and scheduled preventive maintenance to assure functionality. Check valves, on the other hand, do not require nearly the same amount of rigor to assure operability.

The passive nature of check valves often leads the user not to expect failures. Consequently, lacking of attention often results to inadvertent failures. One failure that has received significant attention from both the industry and the regulator is check valve body-to-bonnet joint leakage. In nuclear power plants this leakage can contaminate the general area where the valve is located, can lead to a plant shutdown, and pose personnel hazards.

In this paper, the technical solutions that can be used to manage check valve body-to-bonnet joint leakage will be presented. The merits of each technical solution and the associated challenges will be discussed. Also, as some of the leakage containment solutions are appurtenances to the valve, the paper will address the interface between the appurtenances and the valve.
Spiral Notch Torsion Test Use for Determining Fracture Toughness of Structural Materials
Authors: Wang Jy-An John , Ren Fei , Tan Ting
Published: August 2013

Spiral Notch Torsion Fracture Toughness Test (SNTT) was developed recently to measure the intrinsic fracture toughness (KIC) of structural materials. The SNTT system operates by applying pure torsion to uniform cylindrical specimens with a notch line that spirals around the specimen at a 45° pitch. The KIC values are obtained with the aid of a three-dimensional finite-element computer code, TOR3D-KIC. The SNTT method is uniquely suitable for testing a wide variety of materials used extensively in pressure vessel and piping structural components and weldments, including others such as ceramics, their composites, graphite, concrete, and polymeric composites. The SNTT test results for some of these structural materials are demonstrated in this paper.
Fracture Toughness Determined From Full-Scale Pipe
Authors: Mourad A-H. I. , Altarawneh J. , El Domiaty A. , Chao Y. J.
Published: August 2013

Fracture toughness for full scale steel pipe of API 5L grade X65 PSL1 (ASTM A694F65) medium strength grade pipeline steel has been measured by a new test specimen utilizing the same procedure of the standard test methods ASTM E 399-90 and E 1820-01. Full scale pipe with circumferentially machined notch is pulled axially by tensile load up to fracture. An external circumferential sharp notch has been machined in the wall of the pipe to simulate the crack. To insure a plane strain condition around the crack a well lubricated and axially free loaded plug has been mounted, symmetrically around the circumferential notch, inside the pipe. Evidences of cleavage fracture have been observed on the fracture surface. The measured value of the fracture toughness has been found to be very close to the values measured according to the standard test for steel plates of similar grade. The new proposed testing method for full scale pipe can be used regardless its dimensions since it appears to provide plane strain condition around the crack.
A Study of Formularization of Uplift Behavior at the Bottom Plate of Large LNG Storage Tanks During Earthquake
Authors: Hayashi Shoichiro , Taniguchi Tomoyo
Published: August 2013

In recent years, it has been found that seismic demand tends to be higher for LNG storage tanks and it requires detail estimations about the tank uplift. Generally FE analysis is performed for this aim, since the most of present design standards do not specify the design formula to calculate the stress of the bottom plate. In the case of establishing the bottom plate model with the uplift, several properties have to be considered, such as tank dimension and plate thickness, magnitude and distribution of dynamic liquid pressure that is affected by width and height of the uplift, elasticity of the bottom insulation, and bulging displacement of the tank sidewall. As an another approach for detail estimations including these properties, this study presents the mathematical solution of the bottom plate for estimating uplift height and stress distribution based on a theory of elastic bearing beam. To increase accuracy but maintain practicality, the thin cylindrical theory is also coupled to the bottom plate model for considering the influence of bulging displacement of the tank sidewall on the bottom plate. From the parameter study by the proposed model, it is found that the bulging displacement of the sidewall has significant effect to the uplift height of the bottom plate.
Proposal of a Guideline for Thickness Management of Wall Thinning T-Joints
Authors: Ochi Mayumi , Yamakami Katsuhiko , Hamaguchi Yoshinobu , Miyazaki Katsumasa , Naito Keita , Toyota Kiyoo , Teshima Kaina
Published: August 2013

Although the required minimum thickness (tsr) of T-joints (tees) of class 2, 3 and lower classes of nuclear power plants in Japan is calculated from the design pressure and temperature for design, there are neither any rules nor standards for thickness management of wall thinning T-joints for facilities maintenance.

This paper describes additional parametric study results and proposes a guideline for thickness management of wall thinning T-joints. In other papers related to this project, the experiment and numerical simulation results are reported. This paper refers to these results and performs further investigation under the consideration of JSME (The Japan Society of Mechanical Engineers) design, construction and maintenance codes and standards.
Containment of Low-Level Radioactive Waste at the DOE Saltstone Disposal Facility
Authors: Jordan Jeff , Flach Greg
Published: August 2013

As facilities look for permanent storage of toxic materials, they are forced to address the long-term impacts to the environment as well as any individuals living in affected area. As these materials are stored underground, modeling of the contaminant transport through the ground is an essential part of the evaluation. The contaminant transport model must address the long-term degradation of the containment system as well as any movement of the contaminant through the soil and into the groundwater. In order for disposal facilities to meet their performance objectives, engineered and natural barriers are relied upon. Engineered barriers include things like the design of the disposal unit, while natural barriers include things like the depth of soil between the disposal unit and the water table. The Saltstone Disposal Facility (SDF) at the Savannah River Site (SRS) in South Carolina is an example of a waste disposal unit that must be evaluated over a timeframe of thousands of years. The engineered and natural barriers for the SDF allow it to meet its performance obejective over the long time frame.
Study of Sensitivity of Damage Parameters c1, c2, c3 and c4 on FB2 Material Under Low Cycle Fatigue Test
Authors: Hormozi Mohammad R. , Biglari Farid , Nikbin Kamran M.
Published: August 2013

Many engineering components in power generation plants, gas turbines and petro-chemical industries operating at high temperatures undergo creep-fatigue loading conditions and they are almost invariably submitted to static, combined cycle loading or even both simultaneously. The failure can, therefore, be due to net section rupture, crack growth or a combination of both. To assess the life of such components, fracture mechanics assessment models are required throughout the entire life of the components in order to avoid potential catastrophic failures in the future. Some materials are designed with high thermal gradients to operate at high temperature environments and they are subject to cyclic strains that are produced thermally and mechanically and under these cyclic temperatures and strains, thermo-mechanical fatigue (TMF) damage occurs which will lead to the initiation of cracking and subsequent crack growth. In this paper a novel sensitivity analysis of the damage parameters c1, c2, c3 and c4 on hysteresis loops has been used based on Taguchi method in conjunction with the numerical and experimental investigation of low cycle fatigue life of 9Cr steel to predict the damage under low cycle fatigue.
The 2011 Forum on Appropriate Criteria and Methods for Seismic Design of Nuclear Piping
Authors: Slagis Gerry C.
Published: August 2013

A summary of The 2011 SEC Forum on Appropriate Criteria and Methods for Seismic Design of Nuclear Piping is provided. This forum session was the fifteenth in a series that was started in 1992. In the 2011 forum, the main topic of discussion was “Seismic Response Behavior of Piping”. The ASME Section III code for design of nuclear piping allows significant material plasticity at the Level D (SSE) limits. Test results from the EPRI/NRC Piping and Fitting Dynamic Reliability Program were reviewed including the failure modes of collapse versus fatigue. The Section III seismic stress limits were reviewed. The main discussion was on predicting fatigue life for an SSE including the effect of ratchet strains on fatigue life.
Effect of Undermatched Weld on Deformation and Brittle Fracture Behaviors in High-Tensile Strength Steel Plate Welded Joint
Authors: Mochizuki Masahito , Kawabata Tomoya
Published: August 2013

High tensile strength steel such as 950 MPa class is used in hydropower plant components due to its lower cost and higher reliability. This steel is already used for penstocks in the Kanna-gawa and Omaru-gawa hydropower plants in Japan. Proper welding is one of the most critical factors to ensure integrity of the plant components against brittle fracture from weld defects. For example, preheat- and interpass-temperature controls are essential to avoid weld defects and to ensure strength, since the weld process induces residual stress and possible weld deformations such as angular distortion or unevenness. Undermatching (lower strength in weld metal than in the base plate) makes high strength steel plate become easier to use for welding because restrictions in the welding process can be reduced by using softer welding consumables. Tensile strength in welded joints increases near the base plate when the undermatched zone is not much wider than the thickness. When the appropriate welding conditions for assuring strength and preventing brittle fracture are clarified, it becomes clear to be possible to use undermatched joints for penstock.

In this paper, numerical simulation of stress-strain behavior during the weld process is performed by considering the microstructural effect due to phase transformation. Phase transformation data is obtained from measured dilatometric curves in continuous cooling transformation (CCT) diagrams. Phase transformation data involves many parameters, including not only the maximum temperature, cooling rate and heat input, but also the superposition of multi heat cycles. Then, the characteristics of deformation and strength in a welded joint of 950 MPa class steel plate for penstock with undermatched region, which is equivalent to using weld material with lower strength level, are discussed to expand the allowable welding conditions in penstock fabrication. Finally, brittle fracture behaviors are discussed by using standard crack-tip opening displacement (CTOD) tests and wide plate tests with through-thickness notch by the welded joint.
Seismic Capacity of Threaded, Brazed and Grooved Fire Protection Pipe Joints
Authors: Gutierrez Brent , Antaki George
Published: August 2013

A series of static and shake table tests were conducted on pressurized threaded, brazed and mechanical, i.e., grooved pipe joints, commonly used in fire protection systems. The objective of the tests was to understand the behavior and failure modes of these common types of joints under seismic and static lateral loads. The paper presents the measured loads and deflections of the joints up to the point of failure. It also describes the joints’ static and dynamic failure modes. While this information may be limited it can be used to model the joint flexibility under large lateral loads, determine their capacity, and help understand the leak and rupture characteristics of threaded, brazed and clamped joints.
Examination of Power Supply of the Rice Powder Making Device With the Pressure Vessel Having the Clear Window Using Underwater Shock Wave
Authors: Matsubara R. , Higa O. , Matsui T. , Higa K. , Shimojima K. , Miyafuji Y. , Naha K. , Tanaka S. , Itoh S.
Published: August 2013

We have developed the rice powder production device using the underwater shock wave. The spark by a high-voltage power supply was used for generating of a shock wave. We developed two types of the high voltage power supplies, the CR circuit using transformer, Cockcroft-Walton circuit (CW circuit). We developed the vessel having the window for observation of shock wave. Generated pressure and velocity of the shock wave are evaluated using shadowgraph method used two power supplies (CR circuit and CW circuit).
Pu/SS Eutectic Assessment in 9975 Packagings in a Storage Facility During Extended Fire
Authors: Gupta Narendra K.
Published: August 2013

In a radioactive material (RAM) packaging, the formation of eutectic at the Pu/SS (plutonium/stainless steel) interface is a serious concern and must be avoided to prevent of leakage of fissile material to the environment. The eutectic temperature for the Pu/SS is rather low (410°C) and could seriously impact the structural integrity of the containment vessel under accident conditions involving fire. The 9975 packaging is used for long term storage of Pu bearing materials in the DOE complex where the Pu comes in contact with the stainless steel containment vessel. Due to the serious consequences of the containment breach at the eutectic site, the Pu/SS interface temperature is kept well below the eutectic formation temperature of 410°C. This paper discusses the thermal models and the results for the extended fire conditions (1500°F for 86 minutes) that exist in a long term storage facility and concludes that the 9975 packaging Pu/SS interface temperature is well below the eutectic temperature.
Advanced NDE Techniques and Their Deployment on High Pressure Equipment
Authors: Milligan Jeffrey P. , Peters Daniel T. , Van Velsor Jason K.
Published: August 2013

Many advances in Non-Destructive Examination (NDE) have occurred in recent years. Some of these are becoming common in typical industry applications and are slowly migrating their way into niche industries, such as high-pressure applications. These advanced NDE techniques include the use of Linear Phased Array (LPA) ultrasonic examination for volumetric examination and Eddy Current Array (ECA) technology for surface examination. Advancements in ultrasonic Guided Wave Testing (GWT) also show promise for the examination of long tubes, such as in tubular low density polyethylene (LDPE) reactors. Effective deployment and delivery of these advanced techniques is critical to the collection and analysis of the inspection data.

Common challenges found in high-pressure equipment include access issues such as small diameter deep bores, large and thick section components, weld overlays and examination of thick section welds, complex geometries, and small crack sizes required for detection due to materials and design.

Applying these modern techniques in new designs and updating of in-service inspection plans for this high-pressure equipment can lead to a more accurate assessment of the equipment’s fitness for continued service, reduced maintenance costs, proper asset management of key capital equipment, and reduced turn-around time.
Experiences Gained During the Development of the License Renewal Application for Unit 1 of Paks NPP
Authors: Ratkai Sandor , Katona Tamas Janos
Published: August 2013

Operational license of the four VVER-440/213 units at Paks NPP, Hungary is limited to the design lifetime of 30 years. Extension by an additional 20 years of the original license is one of the main goals of the plant owner. In 2008 a programme for long-term operation (LTO) was developed and submitted to the Hungarian Atomic Energy Authority. The LTO Programme defines the activities for ensuring the extension of the operational lifetime and contains the justification of the safe LTO. The LTO Programme has to be implemented and comprehensive justification of the safe LTO has to be provided in the formal License Renewal Applications unit by unit. This work has been completed by the end of 2011, and the application has been submitted for approval for the Unit 1. The authority review and the approval of the License Renewal Application for Unit 1 should be finished before the expiration of the original design lifetime in 2012. In line with the regulations and supporting the License Renewal Application, a large number of engineering tasks have been performed. In this paper the entire project will be reported. The issues will be discussed, which have been arisen during the development of the application as well as the difficulties generated by the Hungarian technical and regulatory peculiarities will be presented.