bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of mitochondria in modulation of spontaneous Ca2+ waves in freshly dispersed interstitial cells of Cajal from the rabbit urethra
Authors: Sergeant Gerard P. , Bradley Eamonn , Thornbury Keith D. , McHale Noel G. , Hollywood Mark A.
Published: August 2008

Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit pacemaker activity that results from spontaneous Ca2+ waves. The purpose of this study was to investigate if this activity was influenced by Ca2+ uptake into mitochondria. Spontaneous Ca2+ waves were recorded using a Nipkow spinning disk confocal microscope and spontaneous transient inward currents (STICs) were recorded using the whole‐cell patch clamp technique. Disruption of the mitochondrial membrane potential with the electron transport chain inhibitors rotenone (10 μm) and antimycin A (5 μm) abolished Ca2+ waves and increased basal Ca2+ levels. Similar results were achieved when mitochondria membrane potential was collapsed using the protonophores FCCP (0.2 μm) and CCCP (1 μm). Spontaneous Ca2+ waves were not inhibited by the ATP synthase inhibitor oligomycin (1 μm), suggesting that these effects were not attributable to an effect on ATP levels. STICs recorded under voltage clamp at −60 mV were also inhibited by CCCP and antimycin A. Dialysis of cells with the mitochondrial uniporter inhibitor RU360 (10 μm) also inhibited STICS. Stimulation of Ca2+ uptake into mitochondria using the plant flavonoid kaempferol (10 μm) induced a series of propagating Ca2+ waves. The kaempferol‐induced activity was inhibited by application of caffeine (10 mm) or removal of extracellular Ca2+, but was not significantly affected by the IP3 receptor blocker 2‐APB (100 μm). These data suggest that spontaneous Ca2+ waves in urethral ICC are regulated by buffering of cytoplasmic Ca2+ by mitochondria.
Two-Phase Flow Simulation of Mist Film Cooling on Turbine Blades With Conjugate Internal Cooling
Authors: Li Xianchang , Wang Ting
Published: August 2008

Effective cooling of gas turbine combustor liners, combustor transition pieces, turbine vanes (nozzles), and blades (buckets) is a critical task to protect these components from the flue gas at extremely high temperature. Air film cooling has been successfully used to cool these hot sections for the past half century. However, the net benefits from the traditional methods seem to be incremental, but the temperature of working gas is continuously increasing to achieve high thermal efficiency. Therefore, new cooling techniques need to be developed. One of the promising techniques is to enhance film cooling with mist injection. While the previous study reported the effect of mist on the cooling effectiveness with an adiabatic wall, this paper focuses on the effect of mist injection on heat transfer of film cooling with a nonadiabatic flat wall, using the commercial computational fluid dynamics software package FLUENT. Both 2D and 3D cases are considered with a 2D slot and diffusive compound-angle holes. Modeling of the interaction of a droplet with a uniformly cooled wall as well as conjugate heat conduction inside the solid base are conducted. Different mist droplet sizes and mist concentrations are adopted. Conditions both in a gas turbine operating environment (15 atm and 1561 K) and in a laboratory environment (1 atm and 450 K) are considered. Results show that injecting 2–10% mist reduces the heat transfer coefficient and the wall temperature. Especially, mist has the prolonged effect of cooling the region downstream for 15 jet hole diameters, where conventional air film cooling is not effective.
Buoyancy Dominated He–O2 Separated Jet Mixing in a Tubular Reactor
Authors: Bordoloi Ankur Deep , Panigrahi P. K.
Published: August 2008

Mixing of two variable-density jets, one of which is essentially a negatively buoyant jet (He) and the other a nonbuoyant jet (O2) is studied experimentally using digital particle image velocimetry technique for separated nozzle geometry. Two jets are separated from each other, i.e., He jet exit plane is located upstream of the O2 jet exit plane. Experiments were carried out keeping the nonbuoyant O2 jet at constant Reynolds number (Re2=245) and varying the Richardson number (Ri1=1.8,4.7,16.4) of the buoyant He jet. The interaction between two jets as a function of buoyancy strength of helium jet is investigated. The flow visualization images clearly demonstrate the growth and shape of buoyant jet as a function of Richardson number. Mean velocity and vorticity field results provide quantitative picture about the mixing and interaction between the two jets. The stream trace results show the flow structures, i.e., recirculation zone and foci of vortex structures as a function of Richardson number. The mixing between two jets takes place at far downstream region for low Richardson number (Ri1=1.8). At high Richardson number (Ri1=16.4), the buoyant He jet is located near its exit plane without any direct interaction with the O2 jet. At the intermediate Richardson number (Ri1=4.7), the buoyant jet encroaches the nonbuoyant O2 jet at a favorable penetration distance and a good amount of mixing between the two jets take place. The jet growth results based on the y0.5-location development in the streamwise direction clearly demonstrate the interaction between the He and O2 jets in the interjet region. The entrainment coefficient, vorticity magnitude, and turbulent kinetic energy magnitude are maximum at the intermediate Richardson number (Ri1=4.7) demonstrating direct relationship among each other. The mixing between buoyant He jet and nonbuoyant O2 jet is a function of both shear between the two jets and the strength of buoyant plume.
Advanced Gasket Testing Methodology: The New Situation in the European Standardization
Authors: Hahn R. , Kockelmann H. , Zerres H. , Gue´rout Y.
Published: August 2008

Great progress was observed in the European standardization in the last years in the field of the design of floating type bolted flange connections. New design rules were developed (EN 1591) which include new definitions of gasket characteristics for the calculation of floating type flanged joints. In addition a new gasket testing standard was drafted (prEN 13555) which assures a comprehensive characterization of gaskets for bolted flanged joints. This draft standard contains some new features which were examined and validated within a still running European research project PERL (Pressure Equipment - Reduction of Leak Rate). The gasket testing strategy layed down in prEN 13555 is presented in this paper. Some testing results highlighten the measuring procedures and the evaluation of the gasket characteristics.
Evolution of a High Temperature Sealing Material Technology
Authors: Hoyes John
Published: August 2008

This paper discusses the shortcomings at high temperature of the existing sealing materials and introduces a novel, evolving, high temperature sealing material technology based upon the use chemically exfoliated vermiculite as an inorganic binder. The general properties of the materials developed on the basis of this technology are discussed and test data for sheet, spiral wound and covered serrated metal cored gaskets is presented. Service experience is also discussed.
Simulation of the Pressure Equipment Behavior Under Thermal Loading Sealing Application
Authors: Scliffet Laurent , Toumbas Dimitri , Henry Guillaume , Zerres Hildegard , Gue´rout Yann
Published: August 2008

The performances of calculator and Finite Elements codes enable nowadays to perform low cost and very accurate 3D simulations of thermo-mechanical behavior of pressure equipment. It enables an accurate analysis of the leak-tightness problems. In this paper, we describe flanges, heat exchangers, and valves modeling as examples. Then we present the economical interest of the application of such approach.
Compact Flanged Connections for High Temperature Applications
Authors: Lassesen Sjur , Woll Frank
Published: August 2008

The Steelproducts Offshore Compact Flange System (SPO CFS) has proven to be an exceptionally good flange design for the oil and gas industry with service temperatures normally ranging from −100°C to +250°C. High reliability, small size and low weight are properties the offshore industry has appreciated. The design relies on a high bolt pre-tension in order to obtain the double sealing capability and the static behavior. For limited temperatures, the high pre-tension can be applied without any risk of loosing the pre-tension when the operating temperature is reached. For high temperatures, the temperature dependent material properties in flange and bolt need to be carefully evaluated and taken into account when designing the connection. Finite element analysis simulating all relevant phases from flange make-up to process start up and shut down have been performed in order to study flange behavior such as bolt tension, flange stresses, and seal contact. Relatively simple analytical equations have been used in order to predict the flange behavior and hence been basis for choosing bolting material, prestress and flange face angle. For process industry dealing with temperatures up to 720°C, it is now possible to use compact flanges. The use of compact flanged connection will first of all increase the reliability of the flanged connection, reducing the need for maintenance.
Mechanical Analysis of Glass Reinforced Plastics Bolt Flanged Connection With Elastomeric Seals
Authors: Mallard Hubert , Landry Charlotte , Birembaut Yves
Published: August 2008

The pressure vessel industry can now propose piping networks made of Glass Reinforced Plastics. This technology has advantages, lesser weight, resistance to corrosion… The most important drawback problem is the lack of industrial references, standards, sizing of these structures needs an approach different from that used for more conventional steel structures and has to be put in a specific part of a code linked to standard steel codes re´f. 1. The sizing can use conventional numerical tools like the finite element analysis but needs a good knowledge of the materials as well as an adapted calculation Code. In Europe, projects try to give theorica, tests data, design consideration, informations to be able to build standards, for example “Design of GRP Flanges and Tests to Verify the Design and to Determine Long-Term Properties of GRP Pipes”. This paper shows examples of such mechanical analysis done on GRP flanges.
Finite Element Simulation of the Disassembly Process of Pipe Flange Connections
Authors: Fukuoka Toshimichi , Takaki Tomohiro
Published: August 2008

Elastic interaction between bolts occurs in pipe flange connections during not only the bolt assembly process but also the disassembly process. In this study, the mechanical behaviors of pipe flange connections during the disassembly process have been systematically examined by using finite element analysis. As a result, it is shown that the increase in the rating class and nominal size of pipe flange increases the maximum value of bolt loads occurred during the bolt removing process. The effects of the bolt removing sequence are also analyzed in order to estimate the redistributions of bolt loads and the variations of contact pressure distributions on the gasket bearing surface. Furthermore, it is simulated how a pipe flange connection behaves when the clamping forces of some bolts are lost due to failure or loosening.
The Effect of Steady State Thermal Loading on the Deflections of a Flanged Joint With a Cover Plate
Authors: Bouzid Abdel-Hakim , Nechache Akli , Brown Warren
Published: August 2008

It is well recognized that bolted flange joints operating at high temperature are often very difficult to seal. The existing flange design methods including that of the ASME code do not address thermal effects other than the variation of flange and bolt material mechanical properties with temperature. It is possible to include the effects of temperature loading in the flexibility analysis of the joint. However, the temperature profile to be known to determine the radial and axial thermal expansion displacements of the joint elements to be used in the analysis. This paper outlines the theoretical analysis used for the determination of the steady state operating temperature profile, the thermal expansion displacements of the joint components and the bolt load changes for the case of a flange joint with a blind cover. The results from the proposed analytical model are verified by comparison to finite element results of three different sizes of bolted joints.
NORSOK L-005 — Compact Flanged Connections (CFC): The New Flange Standard
Authors: Lassesen Sjur , Eriksen Tor , Teller Finn
Published: August 2008

The SPO Compact Flange System (SPO CFS) has for more than 10 years proven its ability to fulfil the most severe operational conditions in the North Sea. In view of the good experiences and desire for a wider market application for Compact Flanged Connections (CFC), an agreement for the right to use the patented SPO compact flange was negotiated between SPO and the two Norwegian oil companies, Statoil and Norsk Hydro, in 2001. The agreement also includes the right to establish a Norwegian petroleum industry NORSOK standard for CFC where the dimensional standard is based on the SPO compact flange design. The fact that this compact flange system fully comply with ASME codes and standards, also the ASME B 16.34 valve design standard, may create a significant market for this new standard. This paper describes the new NORSOK standard, which is expected to be published in 2002, and it outlines the advantages of the CFC and the field experience so far.
Fracture Assessment of a Clad Steel Using the SINTAP Defect Assessment Procedure
Authors: Motarjemi A. K. , Koc¸ak M.
Published: August 2008

In many critical industries such as nuclear, chemical and petrochemical industries, bi-material components in the form of clad plates are used due to their superior environmental and mechanical properties. During the service life of these bi-material components, cracks or crack-like defects may develop in the clad layer and penetrate into the substrate. The assessment of the integrity of such a cracked as well as complex structure would be an important task. Hence, this study is aimed at applying the recently developed European Structural Integrity Assessment Procedure (SINTAP) to a through thickness centre cracked clad steel wide plate to validate the procedure for this type of bi-material structure. Based on the available input data, various assessment levels as well as two different assessment routes, namely crack driving force (CDF) and failure assessment diagram (FAD), can be used for predicting the failure loads. In principle both routes should provide similar results and this has been verified by having very similar results for both SINTAP routes. Furthermore, the degree of conservatism has been reduced by using higher analysis levels of SINTAP.
Measurement of Residual Stresses in Steel Nozzle Intersections Containing Repair Welds
Authors: Thomas A. , Ehrlich R. , Kingston E. , Smith D. J.
Published: August 2008

As part of a programme to explore the influence of weld repairs on the life of high temperature power plant systems, partial weld repairs were introduced into steel welded T-sections. Each T-section, extracted from ex-service steam pipes, consisted of a nozzle welded to a cylinder. The surface and through thickness residual stresses were measured using incremental centre hole and deep hole drilling methods. Two types of partial weld repairs were examined, one “pwr1”, where the top 50% of the original weld was removed and repaired and a second, “pwr2”, where only one original heat affected zone was removed and repaired. The surface residual stress distributions within each weld repair were distinctly different, although were found to be similar in adjacent parent material. Distributions of the through thickness residual stresses in the new heat affected zone adjacent to the original parent material were found to be very similar. The results are compared with earlier measurements in other welded steel components.
Consistent Treatment of Weld Residual Stresses in Fracture Assessment
Authors: Dong P. , Hong J. K.
Published: August 2008

Over the last decade, as more in-depth understanding of weld residual stresses is being achieved, particularly of their characteristic distributions in pressure vessel and piping components, the residual stress effects on stress intensities at welds are becoming better understood. In this paper, some of the important residual stress characteristics are first identified in the form of either “bending” dominated or “self-equilibrating” dominated types for girth welds. The applicability in other joint configurations in welded structures is then discussed, with a collection of validated residual stress distributions. The characterization of both “bending” and “self-equilibrating” types in residual stress distributions provides a consistent framework for stress intensity factor considerations in either fracture and fatigue assessment. The contribution of weld residual stresses to stress intensities at welds are shown to be in the form of K solutions under displacement controlled conditions. The “bending” type residual stresses provide a longer range of influence than “self-equilibrating” type in K solutions. The contribution of “self-equilibrating” type residual stresses to stress intensities is shown to be dominant when crack size is small, while the contribution of the “bending” type dominant for crack size up to a much large size with respect to wall thickness.
Predicting How Crack Tip Residual Stresses Influence Brittle Fracture
Authors: Hadidimoud Saeid , Mirzaee-Sisan Ali , Truman Chris E. , Smith David J.
Published: August 2008

A probability distribution model, based on the local approach to fracture, has been developed and used for estimating cleavage fracture following prior loading (or warm pre-stressing) in two ferritic steels. Although there are many experimental studies it is not clear from these studies whether the generation of local residual stress and/or crack tip blunting as a result of prior loading contribute to the enhancement in toughness. We first identify the Weibull parameters required to match the experimental scatter in lower shelf toughness of the candidate steels. Second we use these parameters in finite element simulations of prior loading on the upper shelf followed by unloading and cooling to lower shelf temperatures to determine the probability of failure. The predictions are consistent with experimental scatter in toughness following WPS and provide a means of determining the relative importance of the crack tip residual stresses and crack tip blunting. We demonstrate that for our steels the crack tip residual stress is the pivotal feature in improving the fracture toughness following WPS. The paper finally discusses these results in the context of the non-uniqueness and the sensitivity of the Weibull parameters.
Influence of the Cutting Parameters on the Cutting Forces of Carbon Steel
Authors: Cassier Zulay , Mun˜oz-Escanola Patricia , Sa´nchez Rolda´n
Published: August 2008

Plain carbon steels and alloy steels have a great application in the manufacturing process especially due to their characteristic of high machinability and low cost. The machining of these materials, the study of the cutting forces, and the power required for the cutting process is one of the most important parameters to be evaluated. The relationship between this parameter and the other cutting variables process is crucial for the optimization of the machining process. The results of this research are empirical expressions, obtained from the cutting parameters (tool nose radius, feed rate and depth of cut) and the influence of these parameters on the cutting forces for each carbon steel studied (AISI 1020, AISI 1045 and AISI 4340), as well as a general expression which includes the mechanical properties of these carbon steels. These results enable the user to predict cutting forces when using a turning process.
Effect of Plastic Constraint and Strain Rate on Characteristics of Strength and Fracture in Undermatched Joints
Authors: Mochizuki Masahito , An Gyu-Baek , Toyoda Masao
Published: August 2008

Welded joint generally has heterogeneity of strength, material, and fracture toughness. It is important to understand the characteristics of material strength and fracture in welded joint considering plastic constraint effect due to material heterogeneity. Furthermore, the material behavior becomes more complicated when welded joint receives dynamic loading like as earthquake. In this paper, the characteristics of strength and fracture in undermatched joints with strength heterogeneity under dynamic loading were studied by round-bar tension tests and thermal elastic-plastic analysis. These strength and fracture in undermatched joints are evaluated by considering the effects of strain rate and temperature including temperature rise due to rapid plastic deformation. The differences of fracture characteristics such as ductile-to-brittle transition behavior are considered from the plastic constraint effect and strain rate effect, and they are precisely explained in terms of the stress-strain distribution obtained by numerical analysis.
Internal Damage in a High Pressure Process System by Thermal Hydraulic Forces: A Case History
Authors: Brown Sam , LeMay Iain , Moody Fred
Published: August 2008

Unanticipated internal system conditions which may seem minor can lead to hazardous conditions that can result in severe, costly internal system damage consequences. This paper examines the effects of a number of events that caused thermal hydraulic pressure waves in the pressure system of a High Pressure process facility. Some equipment effects on thermal hydraulic forces examined are: compressor surge, compressor impeller failure, pipe failure, valve operation, compressor diaphragm failure as well as design, allowable defects, material specification, fabrication, operation/use, maintenance, inspection, protection. This paper discusses how the risk of damages could have been eliminated or reduced by a risk analysis system design and protective system design. References are provided regarding the process description and damages, as well as the failure modes and mechanisms.
A Case Study of a Valve Failure Due to Condensation-Induced Waterhammer
Authors: Harling Henry E.
Published: August 2008

In preparation for a power reduction at a Pressurized Water Reactor (PWR) power plant, the Moisture Separator Drain Tanks (MSDT) were being transitioned from pumping to a flash tank to dumping to the Condenser. This evolution includes initially transitioning to pressure feeding to a lower pressure flash tank first. As soon as the MSDT Pump was tripped, a waterhammer occurred in the 6″ line that contained a valve that isolated the flow path to the lower pressure flash tank. The waterhammer caused the operator of this valve to fail due to a fracture of the yoke on the actuator. Several thermal-hydraulic mechanisms were evaluated and it was postulated that the failure mechanism was a bubble collapse in a 6″ horizontal line upstream of the failed isolation valve leading to the lower pressure (a.k.a., “D”) flash tank. A prerequisite for this mechanism is that the isolation valve leading to the “D” flash tank is “tight” such that line is “cold.” As the valve opens the initial flow regime would be annular before transitioning to a dispersed regime. The vapor and cold water interacted leading to the collapse of an assumed 1″ diameter “trapped” bubble. The collapse of the postulated bubble yielded an unbalanced impulse force of 6000 lbs. for approximately 5 – 10 milliseconds. The pressure spike that generated the unbalanced force was estimated at 208 psid. The initial acceleration of the pipe was estimated to have been as high as 21 g, which was greater than the 11 g estimated necessary to fail the valve actuator.
Farley Main Steam Flow-Induced Vibration Investigation
Authors: Zysk Gregory , Oliver Michael
Published: August 2008

Piping vibration had been observed in the Farley Unit 2 main steam system since plant start-up. Hanger damage occurred in several portions of the system, including inside containment, in the Main Steam Valve Room (MSVR), and in the turbine building. A program was undertaken to determine the cause of the failures in the main steam supports. This program included the installation of diagnostic equipment, data analysis, and acoustic and structural modeling in an effort to determine the root cause of the piping vibration. The program also addressed a modified system support scheme, which included the addition of vibration absorbing and dampening devices. Recommendations were also provided to resolve the vibration issue.
Evaluation of Shutdown Cooling Transients Using Simplified Models
Authors: Zysk Gregory
Published: August 2008

A shutdown cooling (SDC) system was observed to have pressure spikes that lifted relief valves upon alignment with the Reactor Coolant System (RCS) hot leg. Investigations showed that gas could accumulate at several local high points of the system. An evaluation was conducted with the primary objective of determining if the accumulated gas could lift the relief valve and the secondary objective of increased understanding of how the gas affected the system. Modeling was performed to evaluate the effect of various gas pocket sizes on the over pressurization. Pressure data from operation of the LPSI pumps was used to test the model. This investigation determined that pressure magnitudes produced during the alignment of the SDC system would be limited by the acceleration of the fluid mass for small bubbles and by compressibility of the gas pocket for large bubbles. The study results showed that pressure was maximized for small to medium sized gas bubbles at locations outside of containment.
An Investigation of High Pressure Coolant Injection (HPCI) Line Dynamic Transient at Dresden Nuclear Generating Station
Authors: Drowley Jeff , Ramsden Kevin
Published: August 2008

The purpose of this paper is to discuss the thermal hydraulic behavior and related dynamic response of the Dresden Unit 3 HPCI (High Pressure Coolant Injection) Injection piping. A hydraulic transient occurred on the HPCI injection line piping, that resulted in damge to piping support, pulling the anchors out of the wall. The ensuing investigation following the discovery of the failed support suspected a possible waterhammer event, but walkdowns of the system did not provide much evidence of a propagating disturbance in the system. A review of plant data subsequent to the July 5, 2001 trip showed that during an automatic HPCI injection initiation, a pressure transient occurred, with the potential to produce loads on the piping and supports in excess of their designed capacity. The ensuing investigation determined that non-condensable was present at two locations within the system. It was also determined that the temperatures of the piping downstream of the HPCI injection valve were sufficiently high to introduce some amount of steam to the upper portions of the HPCI line during the time interval between the injection valve opening and the HPCI pump reaching pressure. This paper will discuss the analytical work performed to investigate this transient, along with the piping forces calculated for various scenarios considered.
Modelling and Simulation of the Three-Dimensional Hydrodynamic Problem
Authors: Tourbier Matthieu , Peseux Bernard , Donguy Bundi , Gornet Laurent
Published: August 2008

This paper deals with slamming phenomenon (impact between bow ship and water free surface). Slamming loads on ship may be sufficiently important so as to create plastic deformations of the hull external structure. In extreme cases, they have been recognised for being responsible for the loss of ships. The problem to solve is transient and highly non-linear due to the character of the flow. In the present paper, the three-dimensional Wagner problem is solved numerically using a variational formulation together with a Finite Element Method. Three-dimensional results for simple rigid bodies such as a cone and an ellipsoid are successfully compared with analytical results. Results for deformable structure will be presented.
An Experimental Study of Slip Behavior of Large Scale Model Tank
Authors: Tazuke Hideyuki , Yamaguchi Satoru , Akiyama Hiroshi , Sakurai Tomoki , Chiba Toshio
Published: August 2008

We recognized the importance of the seismic capability against earthquakes of the thermal power plant on the occurrence of the Hyogoken-Nanbu Earthquake in 1995. In this respect, seismic proving tests on the equipment of the thermal power plant had been planned and carried out. Vibration tests and FEM analysis were performed to demonstrate the seismic capability of the equipment. LNG tank was selected as one of the subjects. One of the remarkable nonlinear phenomena was lateral slip for an actual large tank. To investigate the slip behavior of the tank, vibration test of the large scale model tank and FEM analysis of actual tank were conducted. We estimated the slip behavior of the tank under severe seismic excitation. As the results, we confirmed that lateral slipping was mainly partial slip and total slip did not occur at severe seismic excitation.
Chimney Walls Behavior When Submitted to an Internal Explosion
Authors: Autrusson B. , Milcent G.
Published: August 2008

The nuclear fuel reprocessing or fabrication and power plants must be assessed for a set of various normal and accidental situations including explosions due to either operation hazards or malevolent acts. In order to evaluate the consequences of such an aggression in terms of damage to the plants and of radiological release in the environment, IRSN has launched a program including experiments and development of numerical models concerning the behavior concrete walls which are parts of plants. The purpose of this document is to present numerical simulations of chimney wall behavior when submitted to an internal explosion. The simulation uses a three dimensional model with a finite element code. The wave propagation is estimated including the reflection on the wall (the combination between the incident wave and the reflected waves, the attenuation). The detonation simulation is done in considering the walls at rest. The dynamic response of the structure is an estimation relating the time sequence in which the pressure is applied on the surrounding walls. The concrete and iron reinforcements have been taken into account. The stresses, strains and the percentage of cracks in wall are estimated.
An Estimate for Mass Loss From High Velocity Steel Penetrators
Authors: Jones S. E. , Foster J. C. , Toness O. A. , DeAngelis R. J. , Rule William K.
Published: August 2008

Analytical models of the penetration process focus on estimating depth of penetration based on target density, target strength (sometimes associated with the unconfined compressive strength of the target for geological targets), the areal density of the penetrator (W/A), and the impact velocity. In this paper, an expression for work is used in conjunction with thermodynamic considerations to devise a simple estimate for mass lost by a high velocity projectile during the penetration process. The result shows that the mass loss is directly proportional to the tunnel length and the target shear strength. The constant of proportionality is not easy to deduce, however, in that it contains an unusual factor from the work analysis. A method for estimating target shear under high pressure from penetration experiments is introduced.
Recent Advances in High Pressure Food Processing Equipment and Equipment Requirements to Meet New Process Needs
Authors: Farkas Daniel F. , Kapp Joseph A.
Published: August 2008

Foods preserved by high pressure processes (HPP) are sold in Japan, the United States, and Europe. HPP technology is used to pasteurize low acid solid and liquid foods such as oysters, hams, and guacamole and to extend refrigerated shelf-life. HPP technology can commercially sterilize liquid and solid acid products such as fruit juices, salsa, and cut tomatoes. Product sales have reached millions of pounds per year. New processes have been developed to sterilize low acid foods using a combination of heat and pressure. Foods at temperatures of 90 to 1000C can be compressed to 600 to 700 MPa for one or more cycles and thus heated uniformly by compression heating in the range of 111 to 121 0C. Decompression brings the product back to its starting temperature for final cooling. This application provides a high-temperature-short-time sterilization process for low acid foods and thus preserves fresh product quality. Commercial HPP foods require rapid cycling of equipment and maximum use of the pressure vessel volume. These requirements have been met in commercial, semi-continuous, liquid food treatment systems. A single 25 liter pressure vessel can cycle 15 times per hour with a three minute product hold at a pressure of 580 MPa. This vessel operating 5000 hours per year can treat over four million pounds of liquid food. Batch equipment designed to cycle over 12 times per hour with a three minute product hold at 680 MPa is under construction. All units manufactured for the HPP treatment of foods use stainless steel contacting parts, potable water as the compression fluid, and are designed to have a safe cycle life of over 100,000 cycles at 580 MPa. Equipment used for the HPP treatment of food must have an up-time in excess of 90% and must be capable of repair and maintenance by food process line technicians. Ease of access and ease of seal and wear part replacement is required. Equipment must meet cleaning and sanitation requirements of the FDA and the USDA if used to treat meat containing products. Pressure chamber volume use in batch systems must be optimized. Even one additional package per cycle at 12 cycles per hour and 5000 hours per year can yield 60,000 additional packages. High cycle rates require automatic package handling systems for loading packages into carriers and for loading and unloading carriers at the pressure vessel. The operation of high pressure food processing equipment must integrate with a specified food packaging and package handling system as it is desirable to have the high pressure processing system as an integral part of the total food processing and packaging system.
From Test Pilot to 20th Century High Pressure Entrepreneur
Authors: Walkup N. Wayne
Published: August 2008

This paper tells the story of Joseph McCartney, and his high pressure engineering and equipment company. The evolution of the company and its equipment are examined, leading up to the present day when the McCartney Division of Ingersoll-Rand is recognized as a leader in the high pressure technology field.
The Influence of Finite Three Dimensional Multiple Axial Erosions on the Fatigue Life of Partially Autofrettaged Pressurized Cylinders
Authors: Levy C. , Perl M. , Ma Q.
Published: August 2008

Erosion geometry effects on the mode I stress intensity factor (SIF) for a crack emanating from the farthest erosion’s deepest point in a finitely or fully multiply eroded, partially autofrettaged, pressurized, thick-walled cylinder is investigated. The problem is solved via the FEM method. Autofrettage, based on von Mises yield criterion, is simulated by thermal loading and SIFs are determined by the nodal displacement method. SIFs were evaluated for a variety of relative crack depths, a/t = 0.01 – 0.30 and crack ellipticities, a/c = 0.5 – 1.5 emanating from the tip of the erosion of various geometries, namely, a) semi-circular erosions of relative depths of 1–10% of the cylinder’s wall thickness, t; b) arc erosions for several dimensionless radii of curvature, r′/t = 0.05 – 0.3; and C) semi-elliptical erosions with ellipticities of d/h = 0.5 – 1.5. In the cases of finite erosions, the semi-erosion length to the semicrack length, Le/c, was between 2 and 10, erosion angular spacing, α, was between 7 and 120 degrees, whereas autofrettage effects investigated were for 30%, 60% and 100% autofrettage. The normalized SIFs and the normalized effective SIFs of a crack emanating from the farthest finite erosion are found to rise sharply for values of Le/c < 3. Both the normalized SIF and normalized effective SIF values are mitigated as the amount of partial autofrettage increases with the most rapid decrease occurring between 0–60% autofrettage. The purpose of this study is to detail these findings.
Fatigue Life of Commercial High Pressure Tubing
Authors: Mann Michael D.
Published: August 2008

Design guidance for high pressure components, has undergone a dramatic change with the release of ASME Section VIII division 3 pressure vessel code. For the first time, a thorough design criteria is available for design of thick wall pressure vessels. The most critical components of a design are safety and reliability. Ultra high-pressure vessels, in most cases, do not have an “infinite” life. The design must therefore be “leak before break” and a design cycle life must be specified. This paper looks at the effects of fatigue on commercial high-pressure tubing under tri-axial fatigue. The tubing investigated is 316 stainless steel 9/16″ and 3/8″ diameter 4100 bar (60,000 psi) tubing. The testing was performed using a tri-axial fatigue machine originally designed by Dr. B. Crossland, Dr. J. L. M. Morrison and Dr. J. S. C. Perry in 1960 and upgraded by the Author. This investigation compares the fatigue life prediction per KD3 in the ASME pressure vessel code Section VIII division 3 and actual test results from the fatigue machine. This verification gives important reliability data for commercial hardware used in high-pressure piping.
Improving Availability of Hypercompressors
Authors: Giacomelli E. , Pratesi S. , Fani R. , Gimignani L.
Published: August 2008

Always growing capacities and performance requirements, renew the continuous challenge for designers. Plant feedback and Service engineering tremendously improve safety, reliability, availability, and maintainability of the machines, with operating economical benefits. A suitable machine design, system engineering, operation and maintenance critically affect a successful plant exploitation. Innovative methods of simulation, modeling, technologies, diagnostic systems with the use of special features, optimize maintenance and improve efficiency, allowing to reach high availability factors.
A Simplified Method for Calculating Crack Opening Area
Authors: Smith E.
Published: August 2008

In the context of the formulation of a leak-before-break case for a component in a pressurized system, this paper is concerned with the quantification of the crack opening area associated with a two-dimensional crack that is subjected to tensile stresses. We present a simple method, based on the strip yield representation of plastic deformation, for calculating the area. The method is validated against the known result for the ease of an isolated crack in a uniformly stressed infinite solid. It is then used for a general stress distribution, as might arise from a combination of pressure induced and weld residual tensile stresses, with the considerations being focussed on the case where plastic deformation is limited, as is usually appropriate for normal operating situations; application of the method is then especially simple.
Inspection and Evaluation Guidelines for Light Water Reactor Core Internals in Japan
Authors: Takeuchi Kimihito , Iizuka Naoto , Kameyama Masashi , Fujimori Haruo , Motora Yuichi , Koyama Koji
Published: August 2008

There have been many cracking experiences of light water reactor (LWR) core internals worldwide in the past. Thermal and Nuclear Power Engineering Society in Japan (TENPES) has organized a committee to prepare technically reasonable and appropriate inspection and evaluation guidelines (I&E guidelines) for core internals. This committee consists of scholars and representatives from electric utilities and nuclear plant vendors in Japan. I&E guidelines, which cover a rational inspection plan, structural integrity assessment and repair methods, have been developed considering nuclear safety function and structural strength of each core internal component. For BWR reactors, the development of I&E guidelines cover major core internal components like shroud support, core shroud, top guide, core plate, ICM and CRD housing, core spray piping and sparger, jet pump etc. For PWR reactors, the development of I&E guidelines cover baffle former bolts, barrel former bolts, core barrel weld, bottom mounted instrumentation, etc. The I&E guidelines will be completed by the end of March 2002. The basic concept of the guidelines, and a guideline for shroud support of a BWR as an example, are shown in this paper.
Validation of Constraint Based Methodology in Structural Integrity – VOCALIST: Analytical Programme
Authors: Keim Elisabeth , Bass Richard , McAfee Wallace , Bhandari Surender , Gilles Philippe , Marie Ste´phane , Wadier Yves , Lidbury David , Sherry Andrew , Eisele Ulrich , Keinanen Heikki , Wallin Kim
Published: August 2008

The aim of the EC project VOCALIST (Validation of Constraint-Based Assessment Methodology in Structural Integrity) is to develop and validate innovative procedures for assessing the level of, and possible changes to, constraint-based safety margins in ageing nuclear pressure boundary components. An iterative process of experiment and analysis will address this overall objective. The analytical investigations within VOCALIST cover all three ferritic materials used in the experimental program. Two of the three materials are investigated in the brittle to transition regime and the third material will be tested in the ductile regime. The main effort is to predict the results of the large-scale tests in terms of constraint effects. All participants use constraint based methods, which are in a first step calibrated to the behaviour of well-known specimens and then applied to the features or the large scale tests of each material. ORNL has developed a very promising method for the prediction of cleavage fracture using the local approach based on a three-parameter Weibull model. This model has been successfully used to predict the biaxial effects on fracture toughness during the HSST program. It could be further developed and used to predict the structural behaviour of a component containing a shallow flaw and loaded biaxially by using the results of standard fracture toughness specimen with deep notches and loaded uniaxially. In this contribution the first steps of the analytical program of VOCALIST are introduced. The specimens and components under investigation are highlighted with respect to modelling aspects and the first results are presented.
A Comparison of 3-D Finite Element and Simplified Estimates of J Under Thermal and Mechanical Loads
Authors: Lei Yuebao
Published: August 2008

Elastic and elastic-plastic finite element (FE) analyses have been performed for semi-elliptical surface cracks in plates under combined thermal and mechanical loading. J values obtained from the FE analyses have been compared with predictions using methods described in the R6 assessment procedure and its underlying reference stress based J-estimation scheme. The results show that the predictions of the reference stress method and therefore the R6 method for the treatment of the combined load are conservative for all cases considered in this work. The results also show that the accuracy of the R6 methods for determining the effective stress intensity factor (SIF) for the secondary stresses, KJS, depends on the ratio λ = (KIS)max/(σyπa¯). Here (KIS)max is the maximum elastic SIF along the crack front due to the secondary stress, σy is the yield or 0.2% proof stress and a¯ is a geometry parameter for the cracked body. For λ ≤ 1, the methods in R6 give good predictions of KJS, for both the deepest and the plate surface points along the crack front. For λ > 1, the detailed inelastic R6 method under-estimates KJS for all positions along the crack front except for the point at the plate surface, whereas the method based on a small scale yielding correction to KIS over-estimates KJS for all positions along the crack front and KIS provides the best approximation to KJS.
Application of Local Approach Concept of Cleavage Fracture to VVER Materials
Authors: Margolin B. Z. , Karzov G. P. , Shvetsova V. A. , Keim E. , Chaouadi R.
Published: August 2008

The Prometey local approach of cleavage fracture has been applied within the TACIS R2.06/96 project: “Surveillance Program for VVER 1000 Reactors”, sponsored by the European Commission. The main tasks are: • perform special experiments on smooth cylindrical and pre-cracked Charpy (PCC) specimens for VVER 1000 RPV material in initial, embrittled and irradiated state; • perform fracture toughness tests on 2T-CT specimens for RPV steel in initial and embrittled state; • predict the KJC(T) curves by this model; • compare the calculated and experimental results with the Master Curve results. The local approach of cleavage fracture is applied to predict KJC(T) curves in the transition regime of RPV materials in the initial state, embrittled by thermal heat treatment and irradiated, samples in the latter cases taken from surveillance capsules of a VVER 1000 NPP. The test data of large fracture mechanics specimens (2T-CT) could be well described over a wide temperature range for the initial state and the embrittled material, when the test results of PCC specimens at one temperature are used for the calibration of the model parameters. It is recommended for future application cases to use PCC specimens for the calibration of the parameters. A comparison of the Prometey local approach with the Master Curve approach lead to a good agreement for all investigated materials apart from the thermally embrittled material which has a very high embrittlement level (DBTT shift). The KJC(T) curves of VVER1000 RPV steels with low and moderate embrittlement level could be well predicted by both methods. Because the Master Curve method is already accepted as an international standard, it might be easier to apply in more routine cases. The Prometey probabilistic model may be also used for the prediction of KJC(T) curves of RPV steels with a high embrittlement level.
Limit Load Solutions for Surface Cracks in Plates Under Different Loading Types
Authors: Dillstro¨m Peter , Sattari-Far Iradj
Published: August 2008

Limit load solutions of plates containing surface cracks are determined using non-linear finite element analysis. The study covers both shallow and deep cracks with different crack length/crack depth ratios under different loading types. The crack configurations consist of semi-elliptical surface cracks with a/t = 0.20, 0.40, 0.60, 0.80 and l/a = 2, 5, 10. Also studied are plates containing infinite surface cracks with a/t = 0.00, 0.20, 0.40, 0.60, 0.80. The cracked plates are subjected to pure tension, pure bending and combined tension and bending. The finite element results obtained from this study are compared with some published limit load solutions in the literature. It is shown that the exiting solutions are in general overly conservative.
Root Cause Evaluation and Repair of Alloy 82/182 J-Groove Weld Cracking of Reactor Vessel Head Penetrations at North Anna Unit 2
Authors: Bennetch J. I. , Modzelewski G. E. , Spain L. L. , Rao G. V.
Published: August 2008

In the fall of 2001, North Anna Unit 2 conducted a visual inspection of the outer surface of its reactor vessel head (RVH), looking for evidence of leakage. Three of 69 control rod drive mechanism (CRDM) penetrations were identified as suspect, based on the presence of boric acid crystals encircling the three penetrations. Supplemental inspections from underneath the ferritic steel RVH revealed crack-like indications in the vicinity of the J-groove weld/butter region of each of the three penetration attachment welds. To characterize the flaws, a representative portion of one of the welds was removed for metallographic analysis. The results of the analysis formed the technical basis for a root cause evaluation (RCE), conducted to determine the origin of cracking. This report summarizes the findings of that RCE. It also briefly discusses the inspection/repair strategy implemented by Dominion to comply with US Nuclear Regulatory Commission Bulletin 2001–01.