bluuebunny/crossref_metadata_2025 huggingface dataset:
Unprevented or prevented dispensing incidents: which outcome to use in dispensing error research?
Authors: James K Lynette , Barlow Dave , Burfield Robin , Hiom Sarah , Roberts Dave , Whittlesea Cate
Published: January 2011

Objectives

To compare the rate, error type, causes and clinical significance of unprevented and prevented dispensing incidents reported by Welsh National Health Service (NHS) hospital pharmacies.

Methods

Details of all unprevented and prevented dispensing incidents occurring over 3 months (September–December 2005) at five district general hospitals across Wales were reported and analysed using a validated method. Rates of unprevented and prevented dispensing incidents were compared using Mann–Whitney U test. Reported error types, contributory factors and clinical significance of unprevented and prevented incidents were compared using Fisher's exact test.

Key findings

Thirty-five unprevented and 291 prevented dispensing incidents were reported amongst 221 670 items. The rate of unprevented (16/100 000 items) and prevented dispensing incidents (131/100 000 items; P = 0.04) was significantly different. There was a significant difference in the proportions of prevented and unprevented dispensing incidents involving the wrong directions/warnings on the label (prevented, n = 100, 29%; unprevented, n = 4, 10%; P = 0.02) and the wrong drug details on the label (prevented, n = 15, 4%; unprevented, n = 6, 14%; P = 0.01). There was a significant difference in the proportions of prevented and unprevented dispensing incidents involving supply of the wrong strength (prevented, n = 46, 14%; unprevented, n = 2, 5%; P = 0.02) and issue of expired medicines (prevented, n = 3, 1%; unprevented, n = 5, 12%; P = 0.002).

Conclusion

The use of prevented dispensing incidents as a surrogate marker for unprevented incidents is questionable. There were significant differences between unprevented and prevented dispensing incidents in terms of rate and error types. This is consistent with the medication error iceberg. Care must be exercised when extrapolating prevented dispensing incident data on error types to unprevented dispensing incidents.
An assessment of dispensing practices in private pharmacies in Dar-es-Salaam, Tanzania
Authors: Kagashe Godeliver A B , Minzi Omary , Matowe Lloyd
Published: January 2011

Objectives

To assess medicine dispensing practices in private pharmacies in Dar-es-Salaam, Tanzania and recommend interventions to improve practice.

Methods

A cross-sectional survey and observational study of dispensing practices among 70 pharmacies in metropolitan Dar-es-Salaam, Tanzania.

Key findings

There were 1479 dispensing encounters recorded across the 70 pharmacies. This translated to 1573 medicines dispensed. Of the medicines dispensed, 16% were anti-infectives; 45% of the dispensed medicines were requested by the client, 32% were recommended by the dispenser and only 23% were on prescriptions. The main reasons for pharmacy consultations were coughs (62%), general pain (62%) and 'flu and colds. Malaria constituted 21% of the private pharmacy visits. Of the cough encounters, 30% received antibiotics. In addition, oral antibiotics were given to 81% of the clients with diarrhoea and to 95% of those with eye and ear problems. Of the 628 clients who requested specific medicines without a prescription, only 29% were asked questions on why the medicines were required. Of the clients who bought antibiotics, 20% bought incomplete doses. In total, 1180 clients were interviewed. Of these, 35% could not repeat the instructions given to them by the dispenser. Of the 70 dispensers who gave dosage instructions, only 20% gave them according to guidelines.

Conclusion

In Tanzania, an overwhelming proportion of medicines sold in pharmacies are dispensed without a prescription. The majority of medicines dispensed without a prescription are either requested by the client or recommended by the dispenser. When dispensing medicines, dispensers seldom give dosage instructions; when they do, the instructions are often not consistent with guidelines. A high proportion of clients seeking management of coughs and colds or for diarrhoea from private pharmacies receive antibiotics. Interventions that build the capacity of dispensers, improve the rational use of antibiotics and the management of diarrhoea in private pharmacies in Tanzania are necessary to provide consistent quality services to a populace that relies heavily on the private sector for their medications needs.
Diesel Engine Operation Using Ammonia as a Carbon-Free Fuel
Authors: Reiter Aaron J. , Kong Song-Charng
Published: January 2011

Ammonia combustion does not produce carbon dioxide and thus can be regarded as a carbon-free fuel. Ammonia was used as a fuel in a compression-ignition engine in this study. Vapor ammonia was introduced into the engine intake port, and diesel fuel was injected directly into the cylinder to initiate combustion. This dual-fuel approach was chosen because ammonia has a high resistance to autoignition. A liquid ammonia tank was used for fuel storage and a high pressure relief valve regulated the ammonia flow rate, and ignition was controlled by diesel fuel injection. Ammonia was used as an energy replacement for diesel fuel. The results showed that the peak engine torque could be achieved by using different combinations of diesel fuel and ammonia. During testing, a maximum energy replacement of 95% was measured. It should be noted that, if more ammonia is added, a higher than rated power can be achieved depending on engine load conditions. It was also shown that CO2 emissions were reduced monotonically for the same engine torque output as the amount of the ammonia in the fuel mixture increased. Additionally, burning ammonia in engines does not necessarily increase NOx emissions despite the fuel-bound nitrogen. Lower levels of NOx emissions were obtained as long as energy substitution by ammonia did not exceed 60%. This is thought to occur because of the lower combustion temperature of ammonia.
Optimization of the Performance and Emissions of Soy Biodiesel Blends in a Modern Diesel Engine
Authors: Bunce Mike , Snyder David , Adi Gayatri , Hall Carrie , Shaver Gregory
Published: January 2011

As the world is faced with continued petroleum demand, the need for alternative fuels which are renewable and domestically available is becoming apparent. Biodiesel is one such attractive alternative fuel which has physical and chemical properties similar to, and miscible with conventional diesel. While biodiesel does have many advantages, due to fuel property differences including oxygenation and a lower calorific value than diesel fuel, biodiesel combustion often results in higher fuel consumption and higher nitrogen oxide (NOx) emissions than diesel combustion. Stock diesel engine design and decision making target optimal performance with conventional diesel fuel, leading to suboptimal results for biodiesel. This study aimed to determine the appropriate engine decision making for the air/fuel ratio (AFR), exhaust gas recirculation (EGR) fraction, injection (rail) pressure, and start of main fuel injection (SOI) in a modern common rail diesel engine using variable geometry turbo-charging and operating with varying blend ratios of diesel and soy-based biodiesel fuel mixtures to minimize brake-specific fuel consumption (BSFC) and adhere to strict combustion noise, NOx and particulate matter (PM) emission constraints. When operating with the stock engine decision making, biodiesel blend combustion resulted in increases in NOx of up to 39% and fuel consumption increases up to 20% higher than the nominal diesel levels but also had substantial reductions in PM. Through modulation of the AFR, EGR fracton, rail pressure, and SOI at several operating points, it was demonstrated that the optimal engine decision-making for biodiesel shifted to lower AFRs and higher EGR fractions in order to reduce NOx, and shifted to more advanced timings in order to mitigate the observed increases in fuel consumption at the nominal settings. The optimal parameter combinations for B5 (5% biodiesel and 95% diesel), B20 (20% biodiesel and 80% diesel) and B100 (100% biodiesel) still maintained substantial PM reductions but resulted in NOx and noise levels below nominal diesel levels. However, these parameter combinations had little impact on reducing the biodiesel fuel consumption penalty but did improve the thermal efficiency of biodiesel blend combustion.
Mineral-Metal, Multi-Phase Coatings to Protect Combustion Chamber Components Against Hot-Gas Corrosion and Thermal Loading
Authors: Verlotski Vadim , Stanglmaier Rudolf H. , Moormann Gu¨nter , Geraets Ralph
Published: January 2011

Many marine and stationary engines operate on fuels that contain corrosive elements, with the result that some highly-loaded combustion chamber components must be replaced frequently. MWH has pioneered the development of mineral-metal, multi-phase coatings to protect valves and other highly-loaded engine components against hot-gas corrosion. Mineral-metal, multi-phase coatings are a unique and innovative approach to improving hot-gas corrosion resistance in a cost-effective manner. In general, these coatings combine the beneficial chemical and thermal attributes of ceramic coatings with the mechanical properties and substrate adhesion characteristics of a metal. Extensive laboratory and field trials have proven that MWH CrystalCoat protects HFO engine exhaust valves against hot-gas corrosion. It is projected that the newest coating formulation (CrystalCoat HT) will protect 4-stroke HFO exhaust valves against hot-gas corrosion over their entire service life.
Development of Engine Bearing Solutions for New High Output Automotive Engines
Authors: Saxton David , Kantola Troy , Adam Achim , Wilhelm Maik , Lindner Karl-Heinz
Published: January 2011

With the development of advanced engine technologies, which includes direct injected, turbo-charged, variable valve timed, flex-fuel, hybrid start-stop cycles and a general downsizing of engine architectures, bearing surface areas have decreased and connecting rod loading has increased. As a result, modern bearings experience decreased oil film thickness, more frequent non-hydrodynamic lubrication periods and higher surface sliding speeds. Subsequently, bearing applications demand an increase in fatigue and scuffing resistance. In response to this, two new complementary material developments are documented: one a new aluminum based lining material, the other a polymeric surface layer. The new lining material, called A-650, was developed to have improved fatigue strength relative to existing Al engine bearing lining options. Results for rig testing of fatigue and seizure resistance properties are provided, along with engine test evaluations using multiple fuels. The polymeric surface layer, a polyamideimide based resin called IROX™, is intended as a durable surface coating providing exceptional wear and seizure resistance under high sliding speed and start-stop conditions. Furthermore, an increase of the specific load capacity is achieved with aluminum based substrates. A description of the material, with test results, is included.
New Approaches on Material Design for High-Performance 2-Stroke Engine Bearings
Authors: Mergen Robert , Langbein Falko , Harreither Leopold
Published: January 2011

When looking at the performance criteria of bearings for the application in Two-Stroke engines, properties like emergency running capabilities, embedability and the fatigue properties are vital to the performance of these engines. The typical approach is to use materials with a soft Tin matrix and hard intermetallic phases commonly known as “Babbitt” alloys. In a second, more recent approach, Aluminium alloys with elevated Tin content are more and more often chosen. Babbitts outmatch any bearing alloys by their outstanding tribological performance but have very limited mechanical properties. Oppositely, the Aluminium alloys have substantial higher strength but leak somehow with regard to emergency running properties. Whereas the poorer running properties of Aluminium Alloys can be overcome by using suitable running-in coatings, the strength increase of the Tin matrices of Babbitts is rigorously limited by the production technology of spin casting and the ban of hazardous alloying elements such as Cadmium. In order to satisfy the needs of engines manufacturers for a material which combines the advantages of Aluminium- and Tin-base alloys, a new approach which combines both metallurgical alloy development and process technology redesign is necessary. By a fundamental process analysis, the limiting effect with regard to alloy tuning of the existing production technology for steel-babbitt bearing shells will be shown in this paper. Further more, new process routings with the effect of enabling the production of Babbitt bearings with never practized alloy compositions with enhanced mechanical properties are presented.
Engine Oils for Landfill Service: Requirements and Proof of Performance
Authors: Girshick Frederick W.
Published: January 2011

This paper presents the results of a field test comparing four engine oil formulations in commercial landfill service for 16 months. The major differences among the oils were combustion chamber deposit control and oil consumption control, whose mechanism is likely to be control of liner deposits. Control of these deposits led to extension of the time between top-end overhauls. Control of used oil parameters, such as acid and base numbers, was achieved, allowing extended oil drain intervals. The requirements for engine oils in reciprocating internal combustion engines in landfill service will be reviewed briefly. The development of a new generation of engine oils for landfill service will be presented, including deployment of detergent chemistry previously unused in this application. The theoretical justification and preliminary screener testing of this chemistry justified the full scale field testing which is shown. This chemistry has since been commercialized by several oil companies. The operational benefits of engine oils specifically designed for this service will be discussed.
Three-Dimensional CFD Analysis of a Spring-Loaded Pressure Safety Valve From Opening to Re-Closure
Authors: Song Xue Guan , Cui Lei , Park Young Chul
Published: January 2011

We describe the dynamic analysis of a spring-loaded pressure safety valve (PSV) using a moving mesh technique and transient analysis in computational fluid dynamics (CFD). Multiple domains containing pure structural meshes are generated to ensure that the correlative mesh could change properly without negative volumes. With a geometrically accurate CFD model including the PSV and vessel rather than only the PSV, the entire process from valve opening to valve re-closure is presented. A detailed picture of the compressible fluid flowing through the PSV is obtained, including flow features in the very small seat region. In addition, the forces on the disc and its motion are monitored. Results from the model were very useful in investigating the dynamic and fluid characteristics of the PSV. Our practical CFD model has the potential to reduce the costs and risks associated with the development of new pressure safety valve designs. Future work will focus on improving the spring stiffness and seat region to eliminate or reduce vibration during the re-closure process.
High Velocity Uniaxial Strain Response of ERG Aerospace Aluminum Foam
Authors: Maines Warren R. , Chhabildas Lalit , Reinhart William D. , Thornhill Tom F.
Published: January 2011

We report the results of uniaxial strain experiments of ERG Aerospace aluminum foam, at 50% relative density up to 10 GPa. The reverse ballistic plate reverberation technique was used to obtain shock compression states of the material. In these tests, 6061 T-6 aluminum, oxygen free homogenous copper (OFHC), and tantalum were used as standard material targets and were shocked by an aluminum foam projectile traversing up to 2.0 km/s. The response of the target plates were monitored by three different velocity interferometers positioned at three different locations on the witness plate. This provided us with the compaction behavior of the foam material in three discrete locations per sample, due to the presence of porosity in the foam material.
Probabilistic Fracture Mechanics Application for Alloy 82/182 Welds in PWRS
Authors: Hong Jong-Dae , Jang Changheui
Published: January 2011

In operating PWRs (Pressurized Water Reactors), incidents of Alloy 82/182 cracking increased the concern for structural integrity of butt weld locations recently, because of high weld residual stresses. Studies on PWSCC (Primary Water Stress Corrosion Cracking) have been mainly performed using deterministic approaches by controlling parameters, but a quantitative evaluation is difficult because of large uncertainties in each parameter and test results. The purposes of this paper are to provide a probabilistic fracture mechanics (PFM) analysis methodology and quantify failure probabilities for Alloy 82/182 welds in primary piping systems of nuclear power plants. To calculate failure probabilities, Monte Carlo simulation technique was used. To estimate the time to crack initiation, material susceptibility was quantified considering the effects of various processing, grain boundary carbide coverage, water chemistry including zinc addition, and so on. In crack growth analysis, crack orientation and the effects of water chemistry including dissolved hydrogen concentration were considered. And the effects of weld repair were evaluated.
Failure Probability of Degraded Pipes Based on Probabilistic Fracture Mechanics for Seismic Safety Margin Assessment on NPP
Authors: Li Yinsheng , Nakagawa Masaki , Ebisawa Katsumi , Yoshimura Shinobu , Kameda Hiroyuki
Published: January 2011

The Niigata-ken Chuetsu-oki Earthquake happened in July 2007. Although the observed seismic ground motions of Kashiwazaki-Kariwa nuclear power plants greatly exceeded their design values, the important functions of the plants such as “shutdown”, “cooling”, and “confinement” were successfully ensured. Therefore, assessment of the seismic safety margin of nuclear power plants, both their systems and their components, becomes a very important issue. In this paper, failure probability of cracked pipes in existing nuclear power plants is analyzed by employing an improved probabilistic fracture mechanical analysis code and considering stress corrosion cracking and fatigue. Based on the analysis results of the failure probability and the definitions of the seismic safety margin, the seismic safety margin of degraded pipes in existing nuclear power plants is investigated.
Application of the ASME Code SEC III Pressure Design Requirements on Locally Thinned Tight Radius Pipe Bends
Authors: Abdelsalam Usama
Published: January 2011

This paper addresses the primary stress requirements for the pressure loading of tight radius pipe bends according to the ASME Code SEC III NB-3200 (Design by Analysis). Solid FEA models are constructed to represent a tight radius pipe bend with general and local internal wall thinning. The wall thickness variation is considered using uniform and non-uniform axial and circumferential profiles. It is demonstrated that for a tight radius bend with wall thickness equal to the pressure based thickness of the corresponding straight pipe, the linear elastic criteria of NB-3221 are significantly exceeded. Results are presented to show the minimum acceptable wall thickness using uniform thickness distributions. The allowable wall thickness criterion of the ASME Code SEC XI Code Case N-597-2 is examined using a finite element model implementing the recommended thickness distribution along the circumferential direction. It is demonstrated that this distribution achieves a uniform stress intensity over the entire bend (uniform strength). A local thin area (LTA) centered at the intrados of the bend is super-imposed on a general thinned area and the axial and circumferential extents are varied. FEA results are presented to demonstrate Code compliance and its dependency on the axial and circumferential extents of the LTA and the thickness of the surrounding material.
A Review of Alloy 800H for Applications in the Gen IV Nuclear Energy Systems
Authors: Ren Weiju , Swindeman Robert
Published: January 2011

Alloy 800H is currently under consideration for applications in the Next Generation Nuclear Plant at operational temperatures above 750°C. To provide supporting information in this paper at the attempt to facilitate the consideration, service requirements of the nuclear system for structural materials is first described; and then an extensive review of Alloy 800H is given on its codification with respect to development and research history, mechanical behavior and design allowables, metallurgical aging resistance, environmental effect considerations, data requirements and availability, weldments, as well as many other aspects relevant to the intended nuclear application; an finally further research and development activities to support the materials qualification are suggested.
Conception and Current Progress of China In-Service Pressure Equipment Inspection and Assessment Regulation and Standard System
Authors: Jia Guodong , Shou Binan , Wang Hui , Shi Jin , Xie Guoshan , Jiang Haiyi , Chen Yanze , Chen Zhaohe
Published: January 2011

Based on the analysis of the current status of China inservice pressure equipment inspection and assessment regulation and standard system, the China RBI application is overviewed in this paper. The conception of in-service pressure equipment inspection and assessment system of China is presented and feature of this system and its current progress is introduced.
The Effects of Classification of Misalignment-Induced Stresses in Engineering Critical Assessments of Welded Joints With Some Misalignment
Authors: Wei Liwu
Published: January 2011

In the ECA of a structure or component such as a pipeline girth weld, the bending stress component arising from misalignment across the weld is often classified as primary, partly because standards such as BS 7910 and API 579-1/ASME FFS-1 do not give definitive guidance on this subject. This approach may be over-conservative as the σmis is localised. In order to obtain a more realistic assessment of the structural integrity of structures containing misalignment, it is necessary to understand the conservatism or non-conservatism in an ECA associated with the classification of σmis. To address the above concerns, systematic investigations were carried out of surface cracks in a plate butt-weld including some misalignment, external circumferential surface cracks and external fully circumferential cracks in a misaligned pipe connection. FEA of these cracked welded joints with some misalignment (typically from 1mm to 2mm) was performed to calculate crack driving force and plastic limit load. The results from FEA were compared with the existing solutions of KI and σref in BS 7910 generated by assuming three options of treating the σmis. The three options were: (1) classification of σmis wholly as primary stress; (2) 15% of σmis as primary and 85% of σmis as secondary stress; and (3) classification of σmis wholly as secondary stress. Variations in parameters (eg misalignment, crack size, loading, weld overmatch and base material properties) were taken into account in order to determine the effects of these parameters on plastic limit load and crack driving force. The implication of different classifications of σmis in terms of ECAs of misaligned welded joints was revealed by conducting BS 7910 Level 2B assessments with the use of a FAD. It was found in this work that for the cases examined, use of the σmis as entirely primary bending in an ECA was over-conservative, and even treatment of σmis as entirely secondary bending was generally shown to be still conservative, when compared with the assessments based on FEA solutions. Furthermore, caution should be exercised in using the solutions of KI and σref given in the existing BS 7910 for crack-containing structures subjected to a bi-axial or tri-axial stress state. A non-conservative estimate may result from the use of these solutions which have been derived based on a uniaxial stress condition.
Evaluating the Use of Ultrasonic Testing in Lieu of Radiography for Inspecting Welds in Nuclear Power Plants
Authors: Moran Traci L. , Ramuhalli Pradeep , Pardini Allan F. , Doctor Steven R. , Anderson Michael T.
Published: January 2011

The nuclear power industry has recently proposed using ultrasonic testing (UT) in lieu of radiographic testing (RT) on new construction welds and on the repairs of operating reactor component welds. Advantages of UT include a reduction in inspection time, costs, and plant personnel exposure to radiation fields. The replacement of one nondestructive testing method with another, however, requires a detailed analysis of the capabilities of the replacement method as compared to the existing method. Capabilities of interest in this context include detection reliability, false call rates, flaw characterization and sizing accuracy, human factors, data recording capabilities, and cost. The interchangeability of UT and RT has been studied by several institutions, but the evidence found to date in a literature search is not conclusive and therefore requires further investigation to assess the ability of UT to meet nuclear power industry fabrication and pre-service inspection standards. This paper reviews relevant literature on the interchangeability of UT and RT, and identifies potential gaps that may need to be addressed in this area.
Integrity Assessment of Pressure Vessels Subjected to Hydrogen Induced Damages
Authors: Al-Mithin Abdul Wahab , Sardesai Vinayak , Al-Ajmi Ghassab , Hannan Abdul Sattar A.
Published: January 2011

Hydrogen damage to pressure vessels in a Crude Oil Production facility is not uncommon. The intriguing question is about the decision to continue affected vessels in safe operation if such decision is supported by an accurate engineering assessment of the damage and the impending risk. Engineering assessments of the vessels instill confidence for safe operation and help in minimizing production loss & capital expenditure. This paper presents the integrity assessment undertaken during the years 2004–2005 for pressure vessels of an upstream oil production facility (Gathering Centre) of Kuwait Oil Company (KOC), where high H2S (hydrogen Sulfide) levels in the process streams have made the pressure vessels susceptible to hydrogen induced damages. These carbon steel pressure vessels were manufactured to ASME Section VIII Div 1 during the years 1961–1968. As part of elaborate Inspection Program of the pressure vessels in the Gathering Centre, ultrasonic testing was conducted on all the hydrocarbon pressure vessels. Several vessels were found with significant embedded flaws including hydrogen induced crack-like defects & blisters. These defects were further evaluated by Automated Ultrasonic Testing (AUT) which comprised of C-Scan and Time-of-Flight Diffraction (ToFD) techniques. AUT was used for the precise detection & sizing of the embedded flaws which is important for Fitness-For-Service (FFS) Evaluation. Subsequently, the affected vessels with critical flaws were evaluated by FFS assessment as per API-579. While some vessels were found unfit for further safe operation, others were retained in operation with periodic monitoring.
Technical Basis of Material Toughness Requirements in the ASME B&PV Code, Section VIII, Division 2
Authors: Osage David A. , Prager Martin
Published: January 2011

The development of new toughness requirements was a major part of the effort to re-write the ASME B&PV Code, Section VIII, Division 2. The new toughness rules in this code were established using the fracture mechanics assessment procedures in API 579-1/ASME FFS-1 Fitness-For-Service, Part 9. The major changes in the toughness rules when compared to older editions of Section VIII, Division 2 and the current edition of Section VIII, Division 1 are for carbon and low alloy steel materials excluding bolting. The new toughness rules in Section VIII, Division 2 are based on a Charpy V-Notch impact requirement of 20 ft-lbs (27 Joules) consistent with European practice and the beneficial effects of post weld heat treatment are included consistent with the procedures in API 579-1/ASME FFS-1. This paper provides a technical background to the new toughness rules including the development of material toughness requirements and the development of impact test exemption rules.
Effect of Gauge Volume on the Residual Stress Measurement Using Deep Hole Drilling Technique
Authors: Mahmoudi Amir H. , Smith David J. , Truman Chris E. , Pavier Martyn J.
Published: January 2011

Accurate evaluation of residual stress is essential if is to be taken into account in structural integrity assessments. For thick components, many non-destructive residual stress measurement techniques cannot be used since they are unable to measure the stresses deep within the component. Measurement techniques which involve mechanical strain relief through material removal are the only alternative. Recently, it has been found that these techniques may fail to measure the stresses correctly when highly triaxial stresses are present because plastic redistribution can occur when the material removal is carried out. The Deep Hole Drilling technique is a very powerful method to measure the stresses within very thick engineering components. However, it can suffer from high levels of plasticity and lead to inaccurate results. It is shown in the present research that the effect of plasticity on the measured stresses can be eliminated. In the present work, the effect of gauge volume on the plasticity effect is investigated.
Inspection of Piping Wall Loss With Flow Accelerated Corrosion Accelerated Simulation Test
Authors: Ryu Kyung Ha , Kim Ji Hak , Hwang Il Soon
Published: January 2011

Flow accelerated corrosion (FAC) is a major issue for aging of carbon steel piping system such as secondary sides of NPPs. An equipotential switching direct current potential drop (ES-DCPD) method was developed to monitor the thickness of piping that covers area instead of points unlike ultrasonic technique (UT). Hence it covers wide range of piping at one time and takes less monitoring time. In this paper, two accelerated FAC phenomenon; 23.7% thinning in 216.7 hrs and 51.4% thinning in 795 hrs are discussed. These were monitored by both ES-DCPD as well as UT. To accelerate FAC process water chemistry parameters were controlled and monitored. As sensitive factors on FAC, temperature and pH were changed during the test, the wall loss monitored results successfully reflected these changes. These results were also found in agreement with predication model.
Thick Plates in Grade 91 for Fourth Generation Nuclear Reactors
Authors: Pillot Sylvain , Zhao Zhao , Corre Ste´phanie , Chauvy Ce´dric , Coudreuse Lionel , Toussaint Patrick
Published: January 2011

To face the future challenge of global energy supply, taking into account the depletion of fossil fuels and global warming issues, the main nuclear energy users are strongly involved in a research program to fourth-generation reactor technology. This new generation will work at high temperatures between about 450 °C and 550 °C. Extensive studies have been launched worldwide to assess steel grades able to meet these new operating conditions. One of the candidates is Vanadium enhanced 9% Chromium steel grade (EN 10028-2 X11CrMoVNb 9-1 – ASTM A387 grade 91 class 2 – ASME SA387 grade 91 class 2). To meet the future needs in nuclear energy, Industeel improved its conventional 9Cr1MoVNb steel devoted to the fabrication of steam lines in thermal power plants. Preliminary studies revealed the feasibility of thick plates in this enhanced grade. Thick plates, 140 and 210 mm thick, have been hot rolled from a 82 metric tons ingot. Welded joints have then been prepared. Tests performed on both base metal and welded zones proved the excellent mechanical properties of the grade, especially regarding toughness property. This work demonstrated the industrial feasibility of very thick plates made of grade 91 for nuclear applications. This contribution is a review of the work done as well as the results obtained on the plates.
Codification of 316LN in RCC-MR Code: Experience and Prospective Projects
Authors: Bonne D. , Dubiez-LeGoff S. , Drubay B.
Published: January 2011

The 316L with controlled nitrogen austenitic stainless steel is widely used in nuclear construction. The main components of Superphenix (SPX) as the main vessel, internals, intermediate heat exchangers and piping loops operating at high temperature, have been made using this grade. The RCC-MR code has gathered the feedback from the SPX construction. Later the results of European Fast Reactor R&D Programs have been integrated also in the code. Creep strain laws, cyclic and fatigue curves, and fatigue-creep interaction diagram are available in the RCC-MR database, but also it can be found specific filler metal for welding, and dedicated Reference Procurement Specifications. Today, this material, referred to as “316L with controlled nitrogen”, tabulated in RCC-MR is still relevant for current reactor projects. The Indian Fast Breeder Reactor (PFBR) uses this austenitic stainless steel and ITER has selected this alloy for the Vacuum Vessel, with a few additional requirements to comply with its own technical constraints — 316L(N) ITER Grade —. In France, the Sodium Fast Reactor Project (SFR) keeps using the 316L with controlled nitrogen for its major components in sodium with a new challenge regarding the extension of design life to 60 years and confirming its ability to be manufactured using new technologies (large forgings, automatic welding…). In this way, studies are carried out either to validate the current rules or to propose new ones. In particular, the validation of the negligible irradiation curve and the determination of a suitable thermal ageing coefficient, are under consideration, for base metal and for weldments too. Future edition of RCC-MR will include the conclusion of these works. The objective of this paper is to recall the main current data available for 316L with controlled nitrogen and to discuss the approach adopted to take into account for this grade the extension of design life.
Evolution in the Italian Standard for Creep-Operated Pressure Equipment
Authors: Grisolia Ottaviano , Delle Site Corrado
Published: January 2011

The directives of the Italian legislation, specifically the Ministry Decree N. 329, have changed the scope of regulations on creep-operated equipment. The UNI/ISPESL specification will replace the technical procedure (TP) N. 48/2003 [2] of the Italian Certification Agency (ISPESL); meanwhile, the UNI specification will cover the guideline (GL) to the TP and the application of metallographic methods by replication. This new standardization will include a more thorough approach for the determination of the creep threshold, introducing the effect of operation time on creep temperature. An example will show the application of the risk-based inspection (RBI) procedure to a furnace.
Modelling the Complex Manufacturing History of a Pipework Joint and Assessment of Its Through Life Creep-Fatigue Damage Using Finite Element Based Methods
Authors: Bray D. P. , Dennis R. J. , Bradford R. A. W.
Published: January 2011

The work reported in this paper investigates the complex manufacture and through-life operation of a pipework joint in a UK AGR boiler. Residual stresses resulting from the fabrication process can be a key driver for creep and creep-fatigue damage. The calculation of creep-fatigue damage for assessment purposes is typically undertaken within the framework of an appropriate assessment code (such as British Energy’s R5). The standard assessment approach usually requires the undertaking of elastic finite element analysis followed by Neuber construction to convert elastic stress ranges into elastic-plastic stress and strain ranges prior to the calculation of creep-fatigue damage. A combination of explicit and implicit finite element methods are employed in order to simulate a range of manufacturing processes which influence the material state for a branched pipework joint. The solution is effectively obtained within one finite element model, with re-meshing performed where necessary. This solution then feeds into a finite element based structural integrity assessment. The methods utilise the principles outlined in the British Energy R5 assessment code but utilise the inelastic strains calculated directly from analysis. The methods are based around the general purpose finite-element code Abaqus enhanced by the use of user-defined subroutines CREEP and UVARM. This paper describes analyses performed to simulate the complex manufacturing history of a branched pipework component, and to estimate its subsequent in service creep-fatigue damage using finite element based methods.
Simulation of Ductile Tearing in a Dissimilar Material Weld up to Pipe Wall Break-Through
Authors: Gilles Philippe , Brosse Alexandre , Pignol Moi¨se
Published: January 2011

This paper presents ductile initiation calculations and growth simulations of a surface crack up to pipe wall breakthrough. For validation purpose, one of the two BIMET configurations is selected. The EC program BIMET has been carried out to analyze the ductile tearing behavior of DMWs through experiments and computational analyses. In the mock-up, the initial defect is an external circumferential defect located close to the weld-ferritic interface, with a depth of one third of the wall thickness. During the test, the crack extended up to two third of the pipe wall thickness. The aim of the study is to simulate the crack initiation and growth, to compare the results with the experimental records and to continue the ductile crack growth up to pipe wall break-through.
Alternate Flaw Acceptance Criterial for Flaws in Ferritic Steel Vessels Operating in the Upper Shelf Range
Authors: Gustin H. L. , Cipolla R. C. , Scarth D. A.
Published: January 2011

The ASME Section XI flaw evaluation rules for ferritic vessels (IWB-3610/3620 plus Appendix A) are based on Linear Elastic Fracture Mechanics (LEFM) techniques and were developed primarily for the irradiated RPV beltline region and other low temperature carbon and low-alloy steel applications in which the material exhibits limited or no ductility prior to failure. There are situations in which ferritic steel components operate at the upper shelf region and therefore exhibit ample ductility and increased flaw tolerance. Application of LEFM techniques to these cases is very conservative. In order to address flaw evaluation of ferritic materials exhibiting upper shelf toughness and high ductility, the ASME Section XI draft Code Case N-749 was developed and is currently under committee review. This proposed Code Case requires alternate acceptance criteria for situations in which the component is operating in the upper shelf temperature region and therefore possesses adequate ductility to allow the use of Elastic Plastic Fracture Mechanics (EPFM) techniques.
Vibration-Induced Loosening Performance of Preloaded Threaded Fasteners
Authors: Yang Xianjie , Nassar Sayed
Published: January 2011

In an effort to establish a theoretical outline of a criterion for preventing the vibration-induced loosening of preloaded threaded fasteners, this paper provides an experimental and analytical insight into the effect of the initial bolt preload and the excitation amplitude on the self loosening performance of cap screw fastener. A nonlinear model is used for predicting the clamp load loss caused by the vibration-induced loosening of cap screw fasteners under cyclic transverse loading. Experimental verification was conducted on the twisting torque variation and the effect of the preload level and transverse displacement amplitude. Comparison of the experimental and analytical results on the clamp load loss with the number of cycles verifies that the proposed model accurately predicts self-loosening performance.
Experimental Investigations of Fatigue Crack Propagation for Pipe Under Torsional Loading
Authors: Nakane Motoki , Kanno Satoshi , Hashimoto Shota , Watanabe Takayuki , Takahashi Yukio
Published: January 2011

This study discusses methods for evaluating fatigue crack propagation under torsional loading for pipes. To achieve this objective, fatigue crack propagation tests were carried out on both stainless steel and carbon steel used in piping systems of nuclear power plants. Two different kinds of pipes were tested in this study. These pipes had the same shape but the diameter and thickness of the larger pipe were twice those of the smaller pipe. The nominal shear stress amplitudes applied to the specimen were set between 50 and 100 MPa depending on the dimension of the specimen and desired crack growth rates. All fatigue tests were conducted under pure torsional loading with stress ratio R = −1 and at room temperature. The geometrical correction factors for the specimen were derived from elastic J-integral calculated by the FEM. The fatigue crack propagation tests results show that the crack growth rates estimated by the elastic stress intensity factor with the geometrical correction factor were much faster than curves prescribed in The Japan Society of Mechanical Engineers (JSME) codes. These results suggest that elastic plastic fracture parameters should be considered into the stress intensity factor because yield stresses for torsional loading would be smaller than those of uniaxial loading. The plastic zone correction method and modified reference stress method were examined as alternative methods. The crack growth rates estimated by the proposed methods almost totally correspond to the JSME curves. The two proposed methods were found to be quite effective at correctly evaluating the crack growth rates under torsional loading.
Evaluation of Tensile Properties Profile of Weld Zone Using Instrumented Indentation
Authors: Kang Seung-Kyun , Kim Young-Cheon , Park Chan-Pyoung , Kwon Dongil
Published: January 2011

Understanding the property distribution in the weld zone is very important for structural safety, since deformation and fracture begin at the weakest point. However, conventional tensile tests can measure only average material properties because they require large specimens. Small-scale tests are being extensively researched to remove this limitation, among such tests, instrumented indentation test (IIT) are of great interest because of their simple procedures. Here we describe the evaluation of tensile properties using IIT and a representative stress-strain approach. The representative stressstrain method, introduced in 2008 in ISO/TR29381, directly correlates the stress and strain under the indenter to the true stress and strain of tensile testing by defining representative functions. Using this technique, we successfully estimate the yield strength and tensile strength of structural metallic materials and also obtain profiles of the weld-zone tensile properties.
An Investigation on Stress Concentration of Local Wall Thinning in Feeder Elbow Pipe
Authors: Kim Jong Sung , Seo Jae Seok
Published: January 2011

Feeder pipes that connect the inlet and outlet headers with the in-reactor fuel channels in CANDU nuclear power plants are considered as safety Class 1 piping items. Therefore, fatigue of feeder pipes should be assessed at design stage in order to verify structural integrity during design lifetime. In accordance with the fatigue assessment result, cumulative usage factors of some feeder pipes have significant values. The feeder pipes made of SA-106 Grade B carbon steel have some elbows and bends. An active degradation mechanism for the carbon steel outlet feeder piping is local wall thinning due to flow-accelerated corrosion. Inspection results from plants and metallurgical examinations of removed feeders indicated the presence of localized thinning. This local wall thinning can cause increase of peak stress due to stress concentration by notch effect. The increase of peak stress results in increase of cumulative usage factor. However, present fatigue assessment doesn’t consider the stress concentration due to local wall thinning. Therefore, it is necessary to assess the effect of local wall thinning on stress concentration. This study investigates the effect of local wall thinning geometry on stress concentration by performing finite element elastic stress analysis.
The Impact of Key Simulation Variables on Predicted Residual Stresses in Pressuriser Nozzle Dissimilar Metal Weld Mock-Ups: Part 1—Simulation
Authors: Smith Michael C. , Mura´nsky Ondrej , Bendeich Philip J. , Edwards Lyndon
Published: January 2011

British Energy (BE) has funded a large work programme to assess the possible impact of primary water stress corrosion cracking on dissimilar metal welds in the primary circuit of the Sizewell ‘B’ pressurised water reactor. This effort has included the design and manufacture of representative pressuriser safety/relief valve nozzle welds both with and without a full structural weld overlay, multiple residual stress measurements on both mock-ups using the deep hole and incremental deep hole methods, and a number of finite element weld residual stress simulations of both the mock-ups and equivalent plant welds. Three organisations have performed simulations of the safety/relief valve nozzle configuration: Westinghouse, Engineering Mechanics Corporation of Columbus (EMC2) and the Australian Nuclear Science and Technology Organisation (ANSTO). The simulations employ different welding heat input idealisations, make different assumptions about manufacturing history, and use a variety of different material constitutive models, ranging from simple bilinear kinematic hardening to a full mixed isotropic-kinematic formulation. The availability of both high quality measurements from well characterised mock-ups, and a large matrix of simulations, offers the opportunity for a “mini-round-robin” examining both the accuracy and key solution variables of dissimilar metal weld finite element simulations. This paper is one of a series at this conference that examine various aspects of the BE work programme. It describes the detailed finite element simulation of the mock-ups performed by BE and ANSTO. This makes use of the extensive mock-up manufacturing records to perform a detailed pass-bypass simulation of the entire manufacturing process from initial nozzle buttering through to completion of the safe end to pipe weld. The thermal simulation makes use of a dedicated welding heat source modelling tool to derive Gaussian volumetric heat source parameters from the welding records, and the mechanical simulation employs isotropic, kinematic and mixed isotropic-kinematic material constitutive models. Additional sensitivity studies examine sensitivity to manufacturing history and physical properties such as expansion coefficient mismatch.
Considerations in Using FEA for Layered Vessel Construction
Authors: Seipp Trevor G. , Stonehouse Mark , Ormsbee Charles
Published: January 2011

This paper will examine some of the considerations for using finite element analysis when evaluating pressure vessels constructed using the layered-shell construction. Since the layers of the shell interact through contact and at the circumferential welds, these particular aspects are discussed. Special attention is paid to the proper selection of the initial gap between the layers. The use of an elastic-plastic stress-strain curve is also discussed. Since the material model is non-linear, the path-dependency of the loading sequence is demonstrated, including the inclusion of the initial hydrostatic test. The techniques presented will be demonstrated using an example of a typical layered shell pressure vessel. Since the evaluation of this type of vessel is usually undertaken in a fitness-for-service sense, and fatigue is often the primary damage mechanism, the remaining fatigue life of this typical pressure vessel is calculated.