bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Shock Testing and Analysis of IN617 and Super 304H Samples
Authors: Shingledecker J. P. , Carter P. , Battiste R. L.
Published: August 2009

The DOE/OCDO sponsored Ultrasupercritical (USC) Steam Boiler Consortium is conducting thermal shock tests on austenitic and nickel-based materials to assess their use in thick-section boiler components. This paper describes the tests on CCA617 (a controlled chemistry version of IN617) and Super 304H thick-walled tubes. Details are given of the metallurgical analyses of the observed cracking in the bore and on the OD of the samples, and of the thermal-mechanical analyses to explain the results. Elastic-plastic and elastic-plastic-creep analyses are used to calculate damage based on rupture life and creep strain accumulation. Fatigue calculations are performed. The results of the metallurgical and mechanical analyses are compared and conclusions drawn as to the accuracy and effectiveness of available high temperature life prediction techniques.
Properties and Experience of High Cr Austenitic Stainless Steel for Boiler Tubes
Authors: Minami Yusuke , Fukui Toshihiko
Published: August 2009

Recent boilers for thermal power generation are designed for higher temperature and pressure than in the past, and substantial efforts are being made worldwide to establish technology for ultra super critical power plants. Such boilers will require the use of steels having higher strength and better corrosion resistance than conventional 18-8 austenitic stainless steels. High chromium austenitic stainless steel (22Cr-15Ni-Nb-N) has been developed as a candidate material, and creep rupture strength is more than 50% higher than ASME SA-213 Grade TP347H at 700°C. The hot corrosion and steam oxidation resistance of this steel are also superior to 18-8 stainless steels due to higher Cr content. Thirteen years practical service as superheater tubing in a power plant characterized by high pressure (35MPa) and high temperature (615&°C) has revealed that the mechanical properties and environmental resistance of this steel are sufficient for high temperature boiler tube applications.
High-Temperature Creep-Fatigue of Alloy 617 Base Metal and Weldments
Authors: Totemeier Terry C.
Published: August 2009

Creep-fatigue testing of nickel alloy 617 base metal and fusion weldments was performed at temperatures of 800 and 1000°C in air in support of ASME BPV Sec III code qualification of alloy 617 for the Next-Generation Nuclear Plant. Cyclic loading was performed in strain control with a trapezoidal waveform and was fully reversed. Creep was introduced into the fatigue cycle by a hold period at maximum tensile strain which varied from 18 to 9000 seconds. Base metal specimens were machined from 20 mm thick rolled plate; weldment specimens were machined from GTAW butt-welded plate such that the loading direction was oriented transverse to the welding direction. Weld metal, heat-affected zone, and base metal were present in the reduced section of weldment specimens. Creep-fatigue lives decreased with increasing hold time for both base metal and weldments; lives of weldments were reduced relative to those of base metal. Creep-fatigue cracking in weldment specimens initiated in the weld metal.
Region Splitting Analysis on Creep Strength Enhanced Ferritic Steels
Authors: Kimura Kazuhiro , Kushima Hideaki , Sawada Kota , Toda Yoshiaki
Published: August 2009

Overestimation of long-term creep strength of creep strength enhanced ferritic steels is caused by inflection of a relation between stress and time to rupture. Creep rupture strength of those steels has been re-evaluated by a region splitting analysis and allowable tensile stress of some steels regulated in METI (Ministry of Economy, Trade and Industry) Thermal Power Standard Code in Japan has been reduced. A region splitting analysis method evaluates creep rupture strength in the short- and the long-term individually, which is separated by 50% of 0.2% offset yield stress. Inflection of stress vs. time to rupture curve is attributable to longer creep rupture life with a stabilized microstructure of creep strength enhanced ferritic steels, since tensile strength property, which determines short-term creep rupture strength, remains the same level. Accuracy of creep rupture strength evaluation is improved by region splitting analysis. Delta ferrite produces concentration gap due to difference in equilibrium composition of austenite and ferrite at the normalizing temperature. It increases driving force for diffusion and promotes recovery of tempered martensite adjacent to delta-ferrite. Concentration gap may be produced also in heat affected zone (HAZ), especially in fine grain HAZ similar to that in dual phase steel, and it has possibilities to promote recovery and, therefore, to decrease creep strength.
Ultrasmart: Developments in Ultrasonic Flaw Detection and Monitoring for High Temperature Plant Applications
Authors: Atkinson Ian , Gregory Chris , Kelly Stephen P. , Kirk Katherine J.
Published: August 2009

Plant in the power generation, petrochemical and metals processing industries is subject to increasingly onerous operational and regulatory requirements. Where plant that operates at high temperature is involved, the costs associated with shutdown for planned or unplanned inspection to meet these requirements can be particularly high. The ability to perform condition monitoring or flaw detection at on-line plant temperatures would enable plant to remain in operation for longer periods, reduce the risk of damage from thermal cycling associated with periodic shutdowns and allow shutdowns to be completed more quickly. The associated minimizing of the loss of revenue caused by frequent and lengthy shutdowns is a highly attractive proposition to the plant operators. This paper reports on progress in the Ultrasmart Project, which is being undertaken by a consortium of UK companies and aims to address the problems associated with performing ultrasonic inspection on pressure vessels and piping at temperatures exceeding ∼350°C. A brief review of the state of current industry capabilities is given and then details of the developments investigated within Ultrasmart are reported and discussed. These include: • Liquid cooled transducers and automated scanning mechanisms suitable for deployment on components with surface temperatures up to ∼500°C. • Permanently mounted piezoelectric transducers suitable for long term flaw growth or component thickness monitoring at temperatures up to ∼750°C. • Techniques, procedures and protocols necessary to achieve reliable and quantifiable inspection capability at high temperatures. • Use of a novel non-resonant thin film Aluminum Nitride (AlN) transducer for in-situ component monitoring.
Eddy Current Techniques to Detect Incipient Creep Damage of Stainless Steel Boiler Tubes
Authors: Sablik Martin J. , Augustyniak Boleslaw , Augustyniak Marek , Chmielewski M.
Published: August 2009

As creep damage degradation proceeds in 304, 321, and 347 grade stainless steel boiler tubes, the tubes develop a ferro-magnetic component depending on length of service. Incipient creep damage occurs inside the steel, involving precipitation inside the grains, with precipitates getting larger and forming mostly at or near grain boundaries as degradation continues. This incipient creep damage eventually leads further to the development of cavities at grain boundaries, which in turn lead eventually to microcracking and cracking. The amount of ferromagnetic component has been correlated (albeit in a relatively small number of exploited specimens) to the amount of incipient creep damage. The ferromagnetic component appears to be primarily associated with the formation of ferromagnetic hard oxide scale on the outer surface of the boiler tube. The ferromagnetic part of the scale has been identified, using x-rays, as magnetite. This ferromagnetic oxide surface can be easily inspected in power plants using eddy current techniques. Because of the correlation with incipient creep damage, the suggestion is that measurement of the amount of ferromagnetic component can be used to nondestructively monitor the development of incipient creep damage in austenitic steel at stages of development well before cavitation and microcracking. We have found that a processed signal can be extracted from eddy current measurements, which is directly related to the amount of ferromagnetic component. We have shown mathematically why the signal behaves as it does. This same signal has been simulated using finite element modeling (FEM). Its linear dependence on the amount of ferromagnetic component is verified experimentally, mathematically, and by FEM. In addition, we also demonstrate a way in which frequency dependence of the eddy current signal can be used to separate out effects of conductivity from effects of change in permeability due to the ferromagnetic component, thereby reducing effects of experimental error in evaluating the amount of ferromagnetic component at low amounts of degradation. In the present year, the technique is now being tested via measurements at several power plant sites.
Virtual Methods in Creep Crack Growth Predictions in 316H Stainless Steels
Authors: Yatomi Masataka , Nikbin Kamran M.
Published: August 2009

The paper discusses numerically based virtual techniques of creep crack growth predictions in a fracture mechanics component. The material properties used are for 316H stainless steels and the constitutive behaviour of the steel is described by a power law creep model. A damage-based approach is used to predict the crack propagation rate in compact tension (C(T)) specimens and the data are correlated against an independently determined C* parameter. Elastic-plastic-creep analyses are performed using two different crack growth criteria to predict crack extension under plane stress and plane strain conditions. The NSW and NSW-MOD strain exhaustion models are applied to compare to the experimental data and FE predictions. The plane strain crack growth rate predicted from the numerical analysis is found to be less conservative than the plane strain NSW model but more conservative than plane strain NSW-MOD model, for values of C* within the limits of the present creep crack growth testing standards. At higher loads and C* values, the plane strain crack growth rates, predicted using an elastic-plastic-creep material response, approach is considered and compared to the plane strain NSW-MOD model.
Effect of Microscopic Inhomogeneity on Creep-Fatigue Crack Propagation of Transversally Loaded Directionally Solidified Superalloy
Authors: Yamamoto Masato , Kitamura Takayuki , Ogata Takashi
Published: August 2009

Directionally solidified superalloy, which has elongated large grains, is used for a gas-turbine blade because of its high creep strength. Since the grain size is not small enough in comparison with the size of component and crack, the inhomogeneous microstructure strongly affects the crack propagation behavior. The aim of this research is to clarify the microstructural effect in the creep-fatigue under a transverse load. The experiment reveals characteristic crack path and fluctuation of crack propagation rate in detail. Several intergranular sub-cracks initiated ahead of the tip of main crack occasionally connect with each other and form a complicated crack path. The deformation near the crack tip during a loading cycle is highly dependent on the local grain boundary network, grain shape, and crack shape. The magnitude of da/dN is correlated fairly well with that of local deformation in the vicinity of crack tip. This suggests that the stress field near the crack tip governs the crack propagation.
Effect of Service Exposure on Material Properties of Austenitic Boiler Steels
Authors: Masuyama Fujimitsu , Boyles Peter R.
Published: August 2009

A long-term field exposure test of austenitic stainless steels developed through the early 1980s was conducted at Eddystone Power Station Unit No.1, which has highest steam parameters worldwide to date. The experimental lengths include TP347 chromized, Tempaloy A-1, TP347HFG and 17-14CuMo/310S coextruded, and were service-exposed in the final superheater operated at steam conditions of 1170°F (632°C) and 4550 psig (31MPa) for about ten years. The test lengths were removed from the final superheater at operating duration points of about 20,000 and 50,000 hours. In this paper the post-service creep rupture properties and changes in mechanical properties are presented and discussed through comparative study with unused materials. Steam oxidation scale growth behavior of the test steels during high-temperature superheater service is also reported.
Evaluation of Creep Deformation Mechanism of Heat Resistant Steel by Stress Change Test
Authors: Hayakawa Hiroyuki , Nakashima Satoshi , Kusumoto Junichi , Kanaya Akihiro , Terada Daisuke , Yoshida Fuyuki , Nakashima Hideharu
Published: August 2009

In order to evaluate creep deformation mechanism of heat resistant steels, stress change tests were conducted during creep tests. In this study, it was confirmed that the dislocation behavior during the creep tests was in viscous manner, because no instantaneous plastic strain was observed at stress increments. Transient behavior was observed after stress changes for all kinds of steel in this work. Mobility of dislocation was evaluated by the observed backward creep behavior after stress reduction. Internal stress was evaluated by the change of creep rate in stress increment, and mobile dislocation density was evaluated with the estimated mobility of dislocation and the change of creep rate in stress increment. It was found that the variation of mobile dislocation density during creep deformation showed the same tendency as the variation of creep rate. Therefore mobile dislocation density is the dominant factor that influences the creep rate variation in creep deformation of heat resistant steels investigated in this work. The mobility of dislocation showed a good correlation with 1/T and it is related with the amount of solute Mo that is a solution strengthening element. Microstructure of crept specimens was observed by TEM to discuss the validation of these results.
Considerations to the An-Isothermal Creep-Fatigue Assessment of Steam Turbine Rotor Steels
Authors: Reigl Martin , Dave Harish N.
Published: August 2009

The high creep-fatigue loading of fast starting steam turbines is investigated. Based on real turbine operation, but assuming worse conditions like increased notch factors, typical stress-strain cycles of the rotor are calculated. These an-isothermal cycles consists of phases of different start-types (cold start, warm start and hot start), of steady-state operation, shut-down and stand-still. Experiments, performed with these cycles, are evaluated with different methods. For the LCF fraction of the lifetime consumption, several reference temperatures are compared, whereby the so-called ‘corner temperature’ is preferably incorporated, which is the temperature at the end of the compression phase. The creep fraction of the lifetime consumption is firstly assessed with the time fraction rule, either considering the midlife cycles only or considering each individual cycle, either considering all phases of the cycles or the steady state operation phase only. Then, the ductility exhaustion method for the creep damage is applied, after defining the ductility for several experiments.
Cold Bending of Boiler Tubes in New Grades
Authors: Gabrel Jean , Bendick Walter , Zakine Carine , Vandenberghe Bruno
Published: August 2009

New high creep resistant steels have to be bent according to specific procedures in order to preserve parent tube properties. Cold bending of tubing can lead to an important level of deformation in extrados and intrados areas depending on the bending radius and the process used. Fabrication codes allow bending without any heat treatment in case of small deformation. However in case of larger deformation they may require a stress relieving treatment (SRT) in order to eliminate the brittleness of severely cold worked areas. In addition the bends often undergo a post weld heat treatment (PWHT) due to welds in boiler components. A softening effect can occur on these cold worked areas during heat treatment (SRT or PWHT) or service depending on the operation conditions. This softening effect resulting from recrystallization or recovery phenomena can be detrimental to the creep properties. This conference paper focuses on the creep behavior of several new steel grades such as T23, T24, T92 and VM12 after cold bending followed by different heat treatments. The results are compared with the well-known T91 grade, taken as a reference. Recommendations for cold bending are proposed to define the best fabrication routes for these new steels and compared with fabrication codes, mainly with the recent ASME proposal for T91 steel.
Evaluation of a New Low Thermal Expansion Creep Resistant Nickel-Based Alloy
Authors: Jablonski Paul D. , Schrems Karol K.
Published: August 2009

For many large-scale systems such as land-based power generation and chemical processing facilities, stresses due to thermal expansion can become a significant consideration in system design. Additionally, differential thermal stresses result from materials such as ferritic steels used in conjunction with nickel-based superalloys. An experimental nickel-based alloy designed for low CTE (Coefficient of Thermal Expansion) has been evaluated for creep performance and is compared to other low CTE nickel-based alloys. The creep results of this new alloy compare favorably to other low CTE nickel-based alloys.
Fatigue Strength Evaluation of Perforated Plate at Elevated Temperature Using Stress Redistribution Locus Method
Authors: Watanabe Osamu , Bubphachot Bopit , Kawasaki Nobuchika , Kasahara Naoto
Published: August 2009

This study reports the experimental results carried out at the elevated temperature of 550°C on fatigue strength of the perforated plate. Stress Redistribution Locus (abbreviated as SRL hereafter) Method is applied to predict fatigue life for the specimens having stress concentration. The specimens made of SUS304 stainless steel have through holes with different number and different diameter, accordingly leading to the different stress concentration condition. The inelastic local strain is estimated by the SRL method or the other previous Neuber’s rule, and compared to the experimental results on the crack initiation life at the edge of the hole using the concentrated local strain obtained by these methods. The obtained result is that the SRL method is best used with the onset of failure or crack initiation.
Creep-Fatigue Strength Evaluation of Perforated Plate at Elevated Temperature Using Stress Redistribution Locus Method
Authors: Bubphachot Bopit , Watanabe Osamu , Kawasaki Nobuchika , Kasahara Naoto
Published: August 2009

This study investigates the effects of creep behavior on fatigue strength of the perforated plate at elevated temperature, when Stress Redistribution Locus (abbreviated as SRL) method is applied for the perforated plate. The creep-fatigue test is carried out by using the specimens made of SUS304 stainless steel at the temperature of 550°C. The trapezoidal wave having tensile hold time at peak strain is assumed. The geometry of the perforated plate specimens are changed in the same manner as the fatigue test by varying number or diameter-size of through holes. The linear damage rule for fatigue and creep is assumed, and the comparison between the experimental results, namely the SRL method evaluation at the Campbell’s diagram will be made. Both of the load and displacement are measured in all the cyclic history of the loadings to clarify the relation between crack initiation or propagation and the load decrease from the viewpoint of direct observation of crack at the holes side.
Characteristic of Crack Growth Life for W Added 9Cr Ferritic Heat Resistant Steel Under the Conditions of High Temperature Creep-Fatigue Multiplication Based on Non-Equilibrium Science
Authors: Yokobori A. T. , Sugiura R. , Yoshino D. , Tabuchi M. , Hasegawa Y.
Published: August 2009

The W added 9Cr ferritic heat resistant steel ASME grade P92, developed as a boiler tube material, is used under the conditions of creep-fatigue multiplication. In this paper, using P92 steel, crack growth tests under the conditions of creep-fatigue multiplication were conducted and the effects of cycle-dependent and time-dependent mechanisms on the crack growth life tf were investigated. Furthermore, on the basis of the concept of non-equilibrium science, the multiple effects of creep and fatigue on the crack growth life tf were clarified.
Creep Properties of Nitrogen-Alloyed Type 316L Stainless Steel
Authors: Mathew M. D. , Shastry C. Girish , Latha S. , Bhanu Sankara Rao K.
Published: August 2009

Type 316L stainless steel (SS) alloyed with 0.06–0.08 wt% nitrogen is the principal structural material for the sodium circuit components of India’s Prototype Fast Breeder Reactor. Carbon in the range of 0.045–0.055 wt% and nitrogen in the range of 0.06–0.10 wt% have been specified for the welding consumable to provide weld joints with creep strength as close as possible to that of the base metal. Design of the components is based on RCC-MR fast reactor code. Creep properties of the plates and the welding consumables, which were produced by the Indian industry, have been studied at 873 and 923 K. Creep rupture strength of the weld joint was found to be comparable with that of the base metal, implying a weld strength reduction factor close to unity. Creep rupture strength of the weld metal was found to be lower than that of the weld joint at 923 K whereas it was comparable to that of the weld joint at 873 K. The creep failure location shifted from the base metal to the weld metal with increase in test temperature from 873 K to 923 K. The base metal and the weld joint satisfied the average strength requirements specified by RCC-MR code. Addition of nitrogen was found to increase rupture strength by about 35% as compared to that of 316 SS. Rupture elongation decreased in the order base metal > weld joint > weld metal. Phenomenological observations on creep behaviour have been rationalized based on the mechanistic aspects of deformation and damage and microstructural changes.
Creep Deformation Behavior and Microstructural Degradation During Creep of Pre-Strained 25Cr-20Ni-Nb-N Steel
Authors: Saito Nobuhiko , Komai Nobuyoshi
Published: August 2009

The purpose of this study is to clarify the creep deformation behavior and microstructural degradation during creep of pre-strained 25Cr-20Ni-Nb-N steel (TP310HCbN), which has the highest creep strength among austenite stainless steels used for boiler tubes. The creep rupture strengths of the 20% pre-strained materials tested at 650°C under 210 MPa and 180 MPa were higher than those of solution-treated materials. However, the long time creep rupture strengths of the 20% pre-strained materials tested at 700°C and 750°C were lower than those of solution-treated materials. Thus, the creep strengths of the prestrained materials depend on test temperature and stress. Furthermore, the minimum creep rate of the 20% pre-strained materials and re-solution-treated materials tested at 650°C under 300MPa were 1.2 × 10−9 and 1.6 × 10−8 s−1, respectively. Thus, the minimum creep rate of the 20% pre-strained materials was lower than for re-solution-treated materials. The creep strengthening mechanism of the pre-strained materials at 650°C was considered to be that high-density dislocations were maintained until the late stage of creep. On the other hand, the creep rupture strengths of the 20% pre-strained materials were lower than those of solution-treated materials tested at over 700°C because of agglomeration and coarsening of precipitates and the recovery of dislocations.
Effect of Boron Addition on Creep Strength in 9Cr-3W-3Co-V-Nb Steels
Authors: Komai Nobuyoshi , Masuyama Fujimitsu
Published: August 2009

Recently, boron is being added to high-strength steels for boilers and turbines in order to raise creep strength. However, there are various points that are not yet fully understood with regard to the creep-strengthening mechanism of boron addition. In order to investigate the influence of boron addition on creep strength, varying the amounts of boron and nitrogen were added in 9Cr-3W-3Co-V-Nb steels tempered two different conditions and investigated. Although creep strengths of all materials converged to become similar in the low-stress region, the materials tempering at 780°C with boron addition which exhibited the lowest strength on the high-stress region is seen to have slightly greater strength on the low-stress region. In analysis of the precipitates and grain boundary of creepruptured material conducted using TEM-EDS and Auger diffraction analysis equipment, the presence of boron could not be detected.
The ECCC Approach to Creep Data Assessment
Authors: Holdsworth Stuart R.
Published: August 2009

The ECCC (European Creep Collaborative Committee) approach to creep data assessment has now been established for almost 10 years. The methodology covers the analysis of rupture strength and ductility, creep strain and stress relaxation data, for a range of material conditions. This paper reviews the concepts and procedures involved. The original approach was devised to determine Data Sheets for use by committees responsible for the preparation of National and International Design and Product Standards, and the methods developed for data quality evaluation and data analysis were therefore intentionally rigorous. The focus was clearly on the determination of long time property values from the largest possible datasets involving a significant number of observations in the mechanism regime for which predictions were required. More recently, the emphasis has changed. There is now an increasing requirement for full property descriptions from very short times to very long, and hence the need for much more flexible model representations than were previously required. There continues to be a requirement for reliable long time predictions from relatively small datasets comprising relatively short duration tests, in particular to exploit new alloy developments at the earliest practical opportunity. In such circumstances, it is not feasible to apply the same degree of rigour adopted for large dataset assessment. Current developments are reviewed.
U.S. Program on Materials Technology for Ultrasupercritical Coal-Fired Steam Power Plants
Authors: Viswanathan R. , Purgert Robert
Published: August 2009

One of the pathways for achieving the goal of utilizing the available large quantities of indigenous coal, at the same time reducing emissions, is by increasing the efficiency of power plants by utilizing much higher steam conditions. The US Ultra-Supercritical Steam (USC) Project funded by US Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) promises to increase the efficiency of pulverized coal-fired power plants by as much as nine percentage points, with an associated reduction of CO2 emissions by about 22% compared to current subcritical steam power plants, by increasing the operating temperature and pressure to 760°C (1400°F) and 35 MPa (5000 psi), respectively. Preliminary analysis has shown such a plant to be economically viable. The current project primarily focuses on developing the materials technology needed to achieve these conditions in the boiler. The scope of the materials evaluation includes mechanical properties, steam-side oxidation and fireside corrosion studies, weldability and fabricability evaluations, and review of applicable design codes and standards. These evaluations are nearly completed and are providing the confidence that currently-available materials can meet the challenge.
Remnant Life Assessment of Platformer Heater T9 Tubes Using API 579 Omega Method
Authors: Kwon Ohgeon , Thomas Charles , Knowles David , Saunders-Tack Andrew
Published: August 2009

Tubes operated in furnaces are known to suffer from damage as a result of time dependent strain, i.e. creep. As such there is a need to predict remaining life. The MPC Omega Method has been adopted by API (API 579 “Fitness for Service”) as the standard method of life assessment and has been used to perform a remnant life assessment on a platformer furnace. Samples of T9 tubes were removed from the heater based on site inspection to determine the levels of strain. This inspection was undertaken after 224,000 hours operation at a process gas outlet temperature of 540°C. The uncertainty caused by the difference in life based either on minimum and mean material properties, indicates the necessity of proceeding to a Level 3 assessment in order to determine the actual material properties. The results of this approach using the API 579 Omega method demonstrated that the hot face material had properties within the scatter band, mid-way between the mean and minimum data lines and provided confidence as to the remaining life. The Omega approach successfully allowed the impact of variations in future operating conditions to be explored providing information to set the operational envelope and define inspection and replacement strategies.
Field Testing of a Load Reducing Bushing Assembly for Valve Position Indicators
Authors: Reich Alton , Doherty Steve , Vogt Michael , Williams Keith
Published: August 2009

The Arnold Engineering Development Center (AEDC) testing complex includes more than 50 wind tunnels, test cells, arc heaters, and other specialized test facilities. Of these, 27 units have capabilities that are unmatched in the United States, and 14 are unmatched in the world. These unique facilities create equally unique operating environments for instrumentation used for monitoring and control of test conditions. Several high flow-rate, supersonic wind tunnels utilize off-the-shelf angular displacement transducers (ADTs) for monitoring the position of 90° valves (i.e. butterfly valves) used to control the air flow-rate, operating pressure, and temperature during testing. There are significant structural vibrations in the wind tunnels to which the ADTs are subject. These ADTs have experienced an unacceptably high rate of failure during testing. These failures increase maintenance costs, and in some cases can require test operations be suspended while the faulty ADT is replaced; leading to significant cost and schedule impacts associated with the down-time. This paper will discuss an effort to design a bushing assembly to reduce the loads experienced by the ADTs. The bushing assembly redirects vibrational energy from the valves into supporting structure, rather than into the ADT where it could cause bearing wear and ultimately failure. The paper will focus on the efforts to develop a meaningful field test arrangement for the bushing assemblies on one of the wind tunnels at AEDC, and an instrumentation package that monitored and recorded data relative to the performance of the bushing assembly during normal wind tunnel operations. Key results of this test program will be highlighted.
Thermal Testing of Prototype General Purpose Fissile Packages Using a Furnace
Authors: Smith Allen C. , Gelder Lawrence F. , Blanton Paul S. , Lutz Rex N.
Published: August 2009

The 9977 / 9978 General Purpose Fissile Package (GPFP) was designed by SRNL to replace the DOT 6M Specification Package and ship Plutonium and Uranium metals and oxides. Urethane foam was used for the overpack to ensure the package would withstand the 10CFR71.73(c)(2) crush test, which is a severe test for drum-type packages. In addition, it was necessary to confirm that the urethane foam configuration provided adequate thermal protection for the containment vessel during the subsequent 10CFR71.73(c)(4) thermal test. Development tests were performed on early prototype test specimens of different diameter overpacks and a range of urethane foam densities. The thermal test was performed using an industrial furnace. Test results were used to optimize the selection of package diameter and foam density, and provided the basis for design enhancements incorporated into the final package design.
Velocity Limits for Rigid Body Penetrators With Ogive Noses
Authors: Torres Karen L. , Stoltz Brian C. , Hankins Melissa D. , Jones Stanley E.
Published: August 2009

In this paper, the authors use recent results for predicting the onset of lateral instability to discuss the limitations on rigid body penetration. An analysis of lateral instability was proposed in [1] and verified experimentally for laboratory-scale projectiles [2]. After the onset of lateral instability, declining performance was observed even though the projectile does not catastrophically fail. The authors utilized an analysis to estimate the critical velocity at which the penetrator becomes laterally unstable. With this estimate, a maximum penetration depth for each penetrator aspect ratio is predicted. The objective of the analysis is to determine the velocity limits to achieve the maximize penetration depth. The results are supported by a limited set of experimental data.
On the Effect of External Bending Loads in Bolted Flange Joints
Authors: Bouzid Abdel-Hakim , Birembaut Yves , Lejeune Hubert
Published: August 2009

Most current flange design methods use an equivalent pressure to treat bolted flange connections subjected to external bending loads. This oversimplified approach together with the lack of a proper assessment of the actual affected tightness make these methods inadequate for modern flange design. The substitution of the external applied moment by an equivalent pressure is excessively conservative and not realistic since it assumes that the achieved tightness is that of a gasket unloaded entirely to a minimum stress whereas in reality only a small section of it is, the rest of it is actually at a much higher stress. The successfulness of a valid analytical approach in yielding to an acceptable solution resides in its ability to account for the circumferential distribution of the gasket contact stress and its effect on leakage. This paper presents an analytical model based on the flexibility of the flange to treat flanges subjected to bending loads such as those produced by external moments and misalignments and capable of integrating leakage around the gasket circumference. The bolted joint sealing performance in the presence of such loads is evaluated using the new PVRC gasket constants Gb, a and Gs obtained from ROTT tests. The analytical results including leakage predictions are validated by comparison to those obtained numerically by FEA and experimentally on different size flanges. The over-conservatism of the equivalent pressure is demonstrated.
Pre-Qualification of a Typical Annular Tank
Authors: Hari Yogeshwar
Published: August 2009

The objective of this paper is to develop the vessel design pre-qualification for a typical annular tank. The pressures and pressure combinations being considered are first combined maximum working internal pressure plus static pressure second combined maximum accidental internal pressure plus static pressure and third combined internal working pressure plus static pressure plus seismic. The FEA modeling method is used to determine if the Annular Tank’s deflection remain within the criticality deflection tolerance and ASME Code stresses are not exceeded. If the tank’s deflection and/or stresses are exceeded, tank original design is modified and new analysis is performed. This process is repeated until the Annular Tank’s design is within the acceptable range of ASME Code stresses and deflection.
Thermal Testing of 9977 General Purpose Fissile Package Using a Pool Fire
Authors: Gelder Lawrence F. , Malloy John , May Cecil G. , Abramczyk Glenn A. , Smith Allen C.
Published: August 2009

The 9977 / 9978 General Purpose Fissile Package (GPFP), has been designed as a cost-effective, user-friendly replacement for the DOT 6M Specification Package for transporting Plutonium and Uranium metals and oxides. To ensure the capability of the 9977 GPFP to withstand the regulatory crush test, urethane foam was chosen for the impact absorbing overpack. As part of the package development it was necessary to confirm that the urethane foam overpack would provide the required protection for the containment vessel during the thermal test portion of the Hypothetical Accident Conditions Sequential Tests. Development tests of early prototypes were performed using a furnace. Based on the results of the development tests, detailed design enhancements were incorporated into the final design. Examples of the definitive 9977 design configuration were subjected to an all-engulfing pool fire test, as part of the HAC Sequential Tests, to support the application for certification. Testing has confirmed the package’s ability to withstand the HAC thermal tests.
The Mode I Elastic Stress Distribution Near the Root of a Deep Notch With a Parabolic Root Profile
Authors: Smith E.
Published: August 2009

The basis of a fracture mechanics type methodology for fracture initiation at a blunt notch is the elastic stress distribution immediately ahead of a notch root. Earlier work, presented at the 2006 ASME PVP Conference [7], for the Mode III deformation of a deep notch with a parabolic root profile, has shown that the shear stress σ(x) at a distance x ahead of the root is uniquely defined by the peak stress σp, x and ρ (the notch root radius of curvature), when x and ρ are both small compared with the notch depth, irrespective of the loading characteristics and the notch shape away from the root. This paper is concerned with the corresponding Mode I deformation situation, with the objective of providing support for the viability of a similar conclusion for Mode I deformation.
The Effective Opening Area of a Uniform Stress Process Zone at Fracture Initiation
Authors: Smith E.
Published: August 2009

The paper derives an expression for the effective opening area of a uniform stress process zone at fracture initiation. The expression relates this area to the area that is appropriate to the idealized case of a semi-infinite crack in an infinite solid, and is a two term expansion in terms of the ratio of the square root of this area to a characteristic structural dimension.
Application of Instrumented Indentation Technique for Small Scale Testing
Authors: Kim Kug-Hwan , Lee Kyung-Woo , Kim Ju-Young , Kwon Dongil , Kim Kwang-Ho
Published: August 2009

Instrumented indentation technique (IIT) is a novel tool to estimate mechanical properties such as tensile properties, residual stress and fracture toughness by analyzing indentation load-depth curve measured during loading-unloading of indentation. It can be applied directly in small-scale and localized sections of pressure vessel and pipeline since the preparation of specimen is very easy and the experimental procedure is feasible and nondestructive. We present the principles developed for measuring mechanical properties using IIT; the tensile properties by defining the representative stress and strain underneath a spherical indenter, the residual stress near the weldments using the stress-insensitive contact hardness model, and the fracture toughness of ductile metal based on critical indentation energy model. The experimental results from IIT were verified by comparing the results from the conventional methods such as uniaxial tensile test for tensile properties, mechanical saw-cutting and hole-drilling methods for residual stress, and CTOD test for fracture toughness. In particular, the applications of IIT in small scale materials and localized sections of the pressure vessel and pipeline in-use and in-fields are presented.
Stress State Investigations for a Tube in the Contact Area With Rigid Saddle
Authors: Blyukher Boris , Szurgott Piotr , Malachowski Jerzy
Published: August 2009

Results of numerical analyses of pipe section subjected to a three-point bending test enable numerical evaluation of deformation and analysis of the state of stress in both the contact area and that with imperfections. In the analysed instances plastic deformations of the object under examination is what we have to deal with. In the engineering practice such states could occur where the pipe contacts some other object(s) or when one pipe lies upon the other one. What happens is local loss of stability of the pipe’s cross-section. In consequence, effected are any kinds of folds or concavities.
Regulatory Guidance for Risk-Informed In-Service Inspection of Nuclear Power Plants in Bulgaria
Authors: Toft Adam , Lidbury David , Miteva Rossitza , Vasilev Dimitar
Published: August 2009

Risk-Informed In-Service Inspection (RI-ISI) aims to integrate service experience, plant and operating conditions, other deterministic information, and risk insights in developing augmented in-service inspection (ISI) programmes for Nuclear Power Plant (NPP). RI-ISI is a developing methodology which is increasingly being adopted world-wide, and is seen as having the potential to make ISI programmes more effective and efficient in terms of both nuclear safety and the economical operation of nuclear plant. The Nuclear Regulatory Agency (NRA) bears responsibility for regulating nuclear facilities in Bulgaria. In anticipation of a forthcoming application by Kozloduy NPP to adopt an RI-ISI programme for selected systems in WWER-1000 plant, the NRA required a suitable regulatory guidance document to help assess such an application. The UK Department of Trade and Industry-funded Project NSP/04-B23 “Assistance with the Regulatory Aspects of Risk-informed In-Service Inspection (RI-ISI)” has enabled the development of a guidance document, the initial draft of which was produced by Serco Assurance in close consultation with the NRA and other Bulgarian stakeholders. This paper presents a description of how current international best practice has been tailored to Bulgarian NPP, and provides a summary of the draft guidance document produced as the principal output of Project NSP/04-B23.
Ultrasonic Sensors for Health Monitoring of Pressure Vessels: A Survey
Authors: Tittmann B. R.
Published: August 2009

Ageing pressure vessels are potentially dangerous in that when not properly monitored they can lead to catastrophic failure. This report surveys some novel sensor techniques for monitoring the health of gas pressure vessels. They emphasize non-invasive techniques such as provided by ultrasonic inspection. They range from acoustic emission, to resonance acoustic gas pressure measurement, to crack imaging by acoustic microscopy, to ultrasonic position indication.
NULIFE: European Network Dedicated to Nuclear Plant Life Management
Authors: Rintamaa Rauno , Aho-Mantila Irina , Taylor Nigel
Published: August 2009

The European Network of Excellence NULIFE (Nuclear Plant Life Prediction) has been launched with a clear focus on integrating safety-oriented research on materials, structures and systems and exploiting the results of this integration through the production of harmonised lifetime assessment methods. NULIFE will help provide a better common understanding of, and information on, the factors affecting the lifetime of nuclear power plants which, together with associated management methods, will help facilitate extensions to the safe and economic lifetime of existing nuclear power plants. In addition, NULIFE will help in the development of design criteria for future generations of nuclear power plant. Led by VTT (Technical Research Centre of Finland), the five-year project has a total budget in excess of EUR 8 millions, with partners drawn from leading research institutions, technical support organisations, power companies and manufacturers throughout Europe.
Further Analysis of Multiple Co-Planar Flaws Under Cleavage Failure Conditions
Authors: Sharples J. K. , Wilkes M. A. , Beardsmore D. W. , Melvin G. T. , Sherry A. H. , Goldthorpe M. R. , Watson C. T.
Published: August 2009

In assessing the integrity of structures, complex multiple flaws located in close proximity to each other are generally characterised as one, larger, single flaw. Guidance for the characterisation of multiple flaws is provided in codes such as R6 and BS 7910, which are routinely used in the UK and elsewhere in the structural integrity assessment of structures and components. Recent studies have shown that the current characterisation rules may be non-conservative under some circumstances. A combined experimental and analytical programme of work is underway within the UK in order to further investigate this potential non-conservatism for situations where the possibility of cleavage failure may have to be taken into account when assessing structures or components containing multiple flaws. Details of early stages of the analytical programme were reported at the 2006 ASME PVP Conference and comprised a number of finite element analyses to evaluate cleavage failure probability, via a master-curve based approach, for interacting twin flaws and the corresponding characterised single flaw under an applied tensile load. These analyses considered surface-breaking semi-elliptical flaws of the same depth but three values of aspect ratio and a range of separations. It was found that non-conservatism was indicated for flaws of high aspect ratio in contact. This paper describes further analytical work that has been undertaken to extend the results previously reported. The further work described has been centred on: • extending the three aspect ratios (a/c = 0.2, 0.44 and 0.8) for the twin surface flaws previously considered to a/c = 1. • extending the study to include an applied bending load. • extending the study on surface breaking flaws to include embedded flaws (for a/c = 0.8 and tensile loading only). The paper also includes results of the experimental work completed to-date.
Load and Crack History Effects on Fracture
Authors: Sharples J. K. , James P. M. , Higham L. A. , Wood P. M. , Teng H. , Beardsmore D. W. , Goldthorpe M. R. , Sherry A. H. , Watson C. T.
Published: August 2009

Assessments of the integrity of structures containing defects or cracks require estimates to be made of the elastic-plastic crack driving force (CDF) parameter J. This is the characterising parameter that controls the intensity of the fields of stress and strain close to the tip of a crack. Such estimates of J are inherently made in assessment procedures such as R6, Revision 4 [1]. Engineering components are typically subjected to load cycles, often with significant variations in magnitude. Normal operation cycles or overload (by a proof pressure test for example) may cause a re-distribution of weld residual stresses. A defect can be present at fabrication or develop during operation due to a sub-critical process such as fatigue or stress corrosion cracking. In these two cases, it is reasonable to suppose that the actual crack driving forces are different; since the development of a defect in a region of weld residual stress, in conjunction with additional primary loading, can cause significant non-proportional loading of the crack tip. The objective of the work described in this paper is to provide more accurate estimates of the crack driving force parameter for defects subjected to combined primary and secondary stresses, taking into account the effects of loading hisotory. The eventual aim is to reduce uncertainty in assessments of plant integrity, and to clarify advantage that can be taken from a reduction in crack driving forces due to weld residual stress resulting from overload, operational cycles and the progressive introduction of sub-critical defects. Finite element analyses and R6 calculations are undertaken and compared to examine the effects of inserting a crack at different times during the life of an engineering structure.