3. Saravanan, M., Vishnuvardhan, S., Pukazhendi, D. M. and Raghava G., Sahu, M. K., Chattopadhyay, J., Dutta, B. K. and Vaze, K. K. (2011). Fracture studies on carbon steel piping components at elevated temperatures. International conference, SMiRT21, New Delhi. 4. Singh, P. K., Chattopadhyay, J., Kushwaha H. S., Tarafder S. and Ranganath V. R. (1998). “Tensile and fracture properties evaluation of PHT system piping material of PHWR,” Int. J. Pressure Vessels and Piping, 75, 271-280.
In Japan, large earthquakes exceed design earthquake occurred sometimes, such as Pacific Coast of Tohoku earthquake in 2011. It is important to confirm failure modes and safety margin until ultimate strength of piping components from the point of view of seismic safety. Many dynamic failure tests of the thick-wall piping components for Light Water Reactors (LWRs) have been performed [1-5]. According to these studies, it was shown that almost of the thick-wall piping failure mode under seismic loading were low cycle fatigue. However, there are little dynamic failure test data of the thin-wall pipe for Fast Breeder Reactors (FBRs).
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To investigate several unresolved issues and to improve upon the existing equations for integrity assessment of piping components, a comprehensive Component Integrity Test Program (CITP) was initiated at BARC, India. As a part of this program, several fracture tests have been conducted on straight pipes and pipe bends, which forms a valuable data base. Simultaneously, analytical work have been undertaken to propose the improvements in the existing equations for optimized and more accurate integrity assessment of piping components. As an outcome of this analytical investigations, generalized equation of η pl and γ have been proposed to evaluate J-R curve, study of
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In this study, external diameter turning method and press processing method for the piping components including 90 degrees elbow are proposed to manufacture the precise scale model. Scaling laws by geometric similitude are also provided relationship between a prototype and its small scale model. The experimental results indicate that piping scale models can be used to accurately predict aspects of prototype behaviour under static loading. However, the straight pipe length to reflect the ovalization effect of the section and welding imperfections must be considered before manufacturing the piping. ACKNOWLEDGMENTS
In order to study the fracture behavior of piping components used in Primary Heat Transport (PHT) piping system at elevated temperature, experimental investigations were carried out on two carbon steel pipes and one elbow at an elevated temperature of 300°C. The pipes and elbow were made of SA 333 Gr.6 steel. Out of the two pipe specimens, one pipe specimen had 219 mm outer diameter (OD) and the other 406 mm OD. The nominal thicknesses of these pipe specimens were 15.1 mm and 26.9 mm, respectively. The pipe specimens had circumferential part-through notch at the centre. The initial notch angles of the pipe specimens were 34.1° and 37.8°, respectively. The elbow specimen had 219 mm OD and 14.8 mm thickness. The part-through axial notch in the elbow was located at intrados and the initial notch length was 64 mm. Prior to the fracture tests, all the pipes and elbow specimens were fatigue pre-cracked. The pipes and elbow were tested under four point bending and in-plane opening moment respectively. No significant crack growth was observed during the fracture tests on both the pipes and elbow.
Copyright © 2005 by SMiRT18 Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing the effectiveness and reliability of novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the utility, effectiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the inservice ultrasonic inspection of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and results from assessments of three different NDE approaches including ultrasonic phased array inspection techniques, eddy current testing for surface-breaking flaws, and a low-frequency ultrasonic inspection methodology coupled with a synthetic aperture focusing technique (SAFT). Westinghouse Owner’s Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank spool pieces were used for assessing the inspection methods. Eddy current studies were conducted on the inner diameter (ID) surface of piping specimens while the ultrasonic inspection methods were applied from the outer diameter (OD) surface of the specimens. The eddy current technique employed a Zetec MIZ-27SI Eddy Current instrument and a Zetec Z0000857-1 cross point spot probe with an operating frequency of 250 kHz. In order to reduce noise effects, degaussing of a subset of the samples resulted in noticeable improvements. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1 MHz, providing composite volumetric images of the samples. The low-frequency ultrasonic method employs a zone-focused, multi-incident angle inspection protocol (operating at 250-500 kHz) coupled with SAFT for improved signal-to-noise and advanced imaging capabilities. A variety of dual-element, custom designed low-frequency probes (fixed-wedge and variable angle configurations) were employed in laboratory trials. Results from laboratory studies for assessing detection, localization and length sizing effectiveness are discussed. This work was sponsored by the U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RLO 1830; NRC JCN Y6604; Mr. Wallace Norris, Program Monitor.
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The first step of the R-Book routine is to extract data from the event database, i.e. OPDE Light. For each system the database is filtered with respect to plant type (BWR or PWR), Completeness Index 1 (CI 3 is discarded) and the relevant degradation mechanisms. Queries are then defined to intersect the resulting tables with respect to pipe dimensions, piping components and material, counting the failures in each intersection. In principle a set of calculation cases are to be defined for each combination of degradation mechanism and component type.
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In order to maintain the structural integrity of safety related components, it is required to determine the fracture behaviour of materials at component level at different operating conditions. J-resistance curves are conventionally used for characterizing the elasto-plastic fracture behaviour of metallic components. They are usually derived from ASTM standard specimens. However, there is a problem in transferring the specimen J- resistance curves to the components because of the existence of stress triaxiality. The micro-mechanical models are used to overcome this problem and these models help in predicting the fracture behaviour of any component with any geometry and loading conditions. In this work, the Gurson-Tvergaard-Needleman (GTN) damage mechanics model is used for the crack growth analysis of real life reactor piping components. The paper also addresses the challenges involved in such analyses. In the present work, some of the selected components have been analyzed numerically by using parallel in-house finite element code ‘MADAM’ with GTN constitutive model. The strength of the micro mechanical models has been demonstrated by comparing the numerical results like load v/s. load-line displacements, J-R curves with the experimental data.
Numerous manufacturing processes induce residual stresses and distortions in piping components and associated welds: quenching of cast pipings, machining and welding. In Pressurized Water Reactors, most of the components have a large thickness for sustaining pressure and distortions are a minor source of concern. This is not the case for residual stresses which may have a strong influence on several type of damage such as fatigue, corrosion, brittle fracture. In low toughness components, residual stress fields may contribute to ductile tearing initiation. These potential damages are mitigated after welding by stress relief heat treatment, which is applied in a systematic manner to ferritic components of the primary system in nuclear reactors. This treatment is not applied on austenitic piping for which the heat treatment temperature is limited due to the risk of sensitization and residual stresses are difficult to eliminate completely.
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From the experiments on steel elbow pipes and specimens made of Pb / Pb-Sb alloys, the possible failure modes under excessive seismic loads are mainly thought to be 1) fatigue failure, 2) ratchet-collapse, and 3) ductile fracture in the case of low ductile materials. The most likely failure mode is the fatigue failure both in the pipe component tests and the fundamental plate tests. In some cases of the excitation tests on the specimens made of Pb, the ratchet-collapse failure mode was observed both on the plate-type test pieces and the pipe elbow specimens. This failure mode was observed under the condition that the specimen was a top-heavy configuration, and was excited by a high-level pulse like sinusoidal wave. Once a lean deformation occurs on the top-heavy configuration specimen, the collapse failure would be accelerated by the gravity effect. The ductile failure was obtained in one case in the fundamental plate tests on the test piece with a notch made of Pb90%-Sb10% alloy. From these results, the relation between the intensity of the input motion and the strength of the piping specimen is of course one important factor, furthermore it seems that other factors, such as the configuration of the specimen, the material property, the existing stress concentration part and so on also affect the occurrence of a specified failure mode. In the next step, the effect of the relation between the frequency of the input motion and the natural frequency of the specimen, the effective numbers of cycles in the input motion to cause the fatigue failure, the failure mode by the random wave such as seismic motions, etc., are still necessary to investigate to clarify the failure mechanism under excessive seismic loads.
Step 1: Develop an effective component level model based on experimental test data. To conduct a full-scale system analysis, an experimentally validated component model such as a nonlinear moment-rotational model for the T-joint has been reconciled with component level test data. Laboratory tests were conducted by the University at Buffalo, State University of New York (UB) as a part of the NEES Grand Challenge Project “Simulation of the Seismic Performance of Nonstructural Systems” on various kinds of T-joint components in branch lines of sprinkler piping systems (Tian et al., 2010). The behaviors of T-joint connections for each component were modeled by the computational models in the Open System for Earthquake Engineering Simulation (Open Sees, 2010). Step 2: Characterize the failure limit of components in terms of piping performance based on experimental test data. Seismic performance levels for structural or nonstructural systems are achieved if the member forces or deformations on each element in a structural analysis do not exceed predefined limits (SEAOC, 1995; FEMA 273, 1997). ASME Boiler & Pressure Vessel Code (ASME, 2007) specifies the limit load criteria that prevent the gross plastic deformation and large displacement of ductile materials. Using similar approach, the limit criterion of rotations in a piping component can be defined by the moment corresponding to the intersection of the moment-rotation curve and a collapse limit line with twice an angle of the elastic angle from the moment- axis.
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The tensile specimens have been machined from the piping material (SA333Gr6 Carbon Steel). The true stress-strain curves derived from the uni-axial test is shown in Fig. 4. Table 3 summarizes the material properties . The uni-axial true stress-strain curve is modeled in multi linear fashion as indicated in Fig. 4. The data is given up to the ultimate tensile stress level (20% of strain). Ramberg Osgood equation is fit up to ultimate stress and for further points the curve is extrapolated.
PROST is a probabilistic fracture mechanics computer code written in Java++ for personal computers and UNIX systems to evaluate leak and failure probabilities of piping systems in nuclear power plants. A graphical user interface supports the necessary data input. In the actual version 2.0 leak and break probabilities from pre-existing semi elliptical shaped inner surface cracks subjected to cyclic or static loading conditions can be estimated. The calculation of the subcritical crack growth and the final instability are based on deterministic fracture mechanics principles. The probabilistic nature is determined by the uncertainties of the input data entering the deterministic routines. The deterministic fatigue crack growth rate da/dN (in mm/cycle) is calculated by the following modified Paris law:
Fatigue crack growth based on the Paris Law has been studied extensively using compact tension or three point bend specimens following ASTM E647 . The ASME Boiler and Pressure Vessel Code Section XI also gives the fatigue crack growth rate curve for air environments for austenitic stainless steels  based on small specimens. In this paper the curve corresponding to air environment has been referred to for comparison purposes for the material (SS 304LN) under study. The effects of stress ratio on the fatigue crack growth behaviour are widely available for standard specimens . These crack growth data obtained from CT specimens are used conveniently for prediction of crack growth in surface flawed components with assumptions such as surface flaw assumes semi elliptical shape during growth, crack growth rate is independent of direction and stress state etc. Few researchers [5- 9] have carried out fatigue crack growth studies on full scale piping components. Shimakawa et al  performed studies on surface cracked pipes to establish a method based on non-linear fracture mechanics.
Operating temperature and pressure increases so that ASA B31 code is developed for pressure piping. During the 1950s, the code was developed for different segments piping industry such as power, gas transmission and petrochemical companies. The 1960s and 1970s is development period of requirements, methodologies and standard concepts. Standards and codes are developed to provide manufacturing methods reporting and listing design data .
ultimately motivated by the need to check an EPP feature on the Subject in Spec(TP). Note that in the derived tree above, the subject of the clause, er, lies directly on a line of specifiers from Spec(TP) to the specifier of the lowest vP (i.e. Spec(Spec(PartP))). This is not coincidental to the derivation, but following Biberauer (2003b), it is in fact the motivation for all of the movement that derives the correct ordering of verbs in German: the subject has moved to Spec(TP) in order to satisfy the EPP and to check nominative Case, and in doing so, it has pied-piped the maximum amount of structure with it. (Actually, to be more precise, the maximum amount of structure has been pied-piped by the end of the derivation. In fact, the first move up the tree by the subject only pied-pipes the vP projection of which it is a specifier, i.e., the projection immediately dominating it, as is usual for pied-piping. Then the second move up the tree pied-pipes one more projection, and so on until the structure in 5 is formed. In this way, pied-piping remains local to one projection up on each move). Thus, vP movement to Spec(TP) in a language like German checks the same EPP and Case features as the movement of subjects to Spec(TP) in English, though English differs from German in that the subject moves alone to Spec(TP). The difference between English, German, and, as I will show in the next section, Dutch, lies in the extent to which additional structure is pied-piped along with the subject to Spec(TP) and to each of the subject’s intermediate landing sites on its way up the tree to Spec(TP).
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Though intentionality may have to do with aboutness, inquiring as to whether a plover should be credited with intentionality may invoke many different ways of understanding the question. While the piping plover BWD behavior has been discussed in terms of emotion (Stieg 2007), I intend the notion of intentionality here to be more general. One possible understanding is whether one ought to treat the plover as an intentional system (i.e. as having beliefs, desires, hopes, etc. which play some role in its cognitive and behavioral activities) regardless of whether it really has these intentional states or not. On this view, “treating” the plover in this manner involves, among other things, predicting its behavior by considering the bird to be a creature that acts as if it were rational and acting on the basis of its beliefs, desires, etc. Another way of approaching this question might be to treat the plover as an intentional system, though it is not clear whether they are or not, in an effort to design and create experiments that might shed light on whether the birds actually have beliefs and desires. This seems to be the sort of approach that Ristau takes in her discussion of plovers.
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Abstract. Natural gas is transported to customer via gas pipeline. Any damage in the piping system will bring difficulties and even danger to public as well as the appropriate company. Therefore, the purpose of this study is to carry out stress analysis and displacement magnitude of natural gas piping system at Gas System Laboratory of University Technology Malaysia, as well as the capability of the supports to hold the whole piping system once it operated. In addition, modification of pipe supports location will be discovered in this study too. This study will focus on the stresses for natural gas piping system at Gas System Laboratory of UTM only and the piping system is designed by Gas Piping Design Group of Faculty of Chemical and Natural Resources (FKKKSA), UTM. In order to conduct this project, a Computer Aided Engineering Simulator will be used throughout this study. Only sustained loads and thermal expansion are considered in this study. The simulation results show the sum of these factors is 181.76 MPa where it is less than the allowables (241.3MPa). This performs that the design piping system is well-restrained. Modification of the supports location is done to reduce the stresses that act on the piping system. The result shows the sum of sustained loads and thermal expansion is reduced to 181.75 MPa. In conclusion, the pipe stress analysis software proposed is able to compute the stress for the piping system in this study. In addition, modification of the supports location can be considered to ensure the system is adequate for public safety once it operates.
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ontwerpopgave, maar met het nieuwe ontwerp instrumentarium wisten we niet hoe we dat moesten aanpakken. Bij piping kwamen er namelijk zulke grote tekorten uit, dat we er zo erg aan twijfelde dat we het vooruit hebben geschoven. We hebben ervoor gekozen om voor piping niet hele grote grondbermen aan te leggen, wat we vroeger altijd deden. Maar we lossen het op met een verticale voorziening, we zitten nu in de planuitwerkingsfase waar we een ontwerpteam hebben samen met een aannemers combinatie en een inginieursbureau. We hebben nu dus heel veel knappe koppen bij elkaar om dit probleem eens goed vast te pakken. Wat we nu eigenlijk eerst zijn gaan doen is meer grond onderzoek met nieuwe technieken om te kijken zit er nou echt een piping opgave. We verwachten dat we daar al een reductie van minimaal 50% van de totale opgave krijgen. En van die overige 50% proberen we meer duidelijk te krijgen wat hebben we nou tekort. Als je het over duurzaamheid hebt dan is dat wat mij betreft de duurzaamste methode.
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This paper describes a round-robin effort conducted as part of the on-going Battelle Integrity of Nuclear Piping (BINP) Program to characterize the piping system restraint effects on the crack-opening displacement for different pipe diameters, crack lengths, pipe radius-to-thickness ratios, and distances from the crack plane to the restraining boundary location (both symmetric and non-symmetric restraint lengths). These efforts are leading to an analytical correction to the existing crack-opening displacement analyses for improved LBB analyses.