bluuebunny/crossref_metadata_2025 huggingface dataset:
Thinking on Intelligent Design, Manufacture and Maintenance of Pressure Equipment in China
Authors: Chen Xuedong , Fan Zhichao , Chen Tao , Xu Shuangqing , Ou Guofu , Tang Xiaoying
Published: November 2019

This paper introduces briefly China’s development plan for intelligent manufacturing, and combining with the present situation of design, manufacture and maintenance of pressure equipment, puts forward the development directions for the digitization, networking and intelligentization of pressure equipment at present and in the next decade from three aspects. The first aspect is digital control of shape and performance of pressure equipment. Taking the furnace tube as an example, the Material Genome technology is recommended for establishing the relationship between the microstructure and macroscopic performance of its material and achieve the target macroscopic performance by the adjustment of composition, phase and microstructure; then the additive manufacturing (3D printing) technology can be used to control the resulting shape of certain special structures so as to achieve the integrated shape and performance and significant improvement of its service life. The second aspect is digitization and network-based interconnection of production factors such as materials, equipment and personnel in the pressure vessel production workshop to realize intelligent manufacturing. Taking the transportable pressure vessel for instance, the real-time identification, diagnosis and control of abnormal conditions can be realized by information and communication technology during the key production processes such as baiting, cutting, forming, welding, heat treatment, and non-destructive testing; and if necessary, the suitable manufacturing resources across different enterprises and regions can be organized to achieve the flexible production and collaborative manufacturing of the components such as heads and flanges, etc. The third aspect is to achieve the real-time online integrity assurance of pressure equipment in process industries (e.g., petrochemical and electric power, etc.) by digitization and networking of risk-based inspection (RBI), fitness-for-service (FFS) assessment technologies and their corresponding database, in combination with real-time monitoring technology based on the characteristic safety parameters. Taking the reactor effluent air cooler (REAC) system as an example, this technology would enable not only the safety warning of critical characteristic parameters, but also the self-limiting and self-prevention of the flow-induced corrosion failure by linking with the distributed control system (DCS).
A Study of Flexible Magnetic Camera for Welded Tubular Joint Inspection
Authors: Choe Eunho , Lee Hoyong , Lee Jinyi
Published: November 2019

Liquid penetrant testing (PT), magnetic particle testing (MT) and ultrasonic testing (UT) have been used as nondestructive testing methods for the welded tubular joints of reactor cooling systems. The PT and the MT that are applied to the surface test of the specimen have been experiencing problems such as specimen contamination, hazardous chemical exposure risk for the inspector, and the inspector’s extended time in the nuclear power plant due to the long testing time (increased risk of radiation exposure). This study is about the applicability of an alternative nondestructive examination (ANDE) method to solve the aforementioned problems. According to the requirements of ANDE, the NDE technology should be applied with the same or better sensitivity and shorter inspection time than the conventional inspection methods of PT and MT. In order to satisfy these requirements, a flexible-type multi-sensor array was developed in order to scan a certain welding area and complete the inspection in a short time. The static and time-varying magnetic fields were applied to the test specimen and the magnetic flux density distribution was measured by solid state magnetic sensors. Each sensor is arranged with a spatial resolution of less than 2 mm, and the shape can be varied according to the shape of the bead. By using the measured data, the magnetic flux density distribution according to the presence or absence of defects and shapes can be visualized in real time, and stored into the database.
Optimization of Expanding Gathering Pipeline Network in Gas Fields
Authors: Yuan Meng , Liang Yongtu , Wang Bohong
Published: November 2019

One major problem in the progressive development of gas field is the expanding of gas gathering pipeline network, especially when the existing gathering pipeline system cannot satisfy the production requirements of the new wells. How to design the expanding scheme of the new block, and how to determine the best linking between the new wells and the existing pipeline network can be challenging for designers due to the complexity of the coupling relationship of the variables and strong nonlinearity of the hydraulic characteristics. To our best knowledge, few studies have been done on this issue.

In this study, to expand a gathering pipeline network in a gas field, an optimal design method is proposed considering the hydraulic characteristics of the network with an objective function that maximizes the yearly profit. The connection scheme of the new production wells is obtained by employing a genetic algorithm (GA). This method is applied to a real case study of a gas gathering pipeline system in China. To find the optimal parameter combination in GA, three key parameters includes population size, crossover probability, and mutation probability are tested. Moreover, we also choose the method from previous research which using minimum pipeline length as objective, and apply it on the same example for comparison. The results show superiority of our method in fully utilizing the capacity of gas field while meeting the production requirements.
Effect of Hydrogen on Tensile and Fatigue Properties of SUS301 Austenitic Stainless Steel
Authors: Iijima Takashi , Enoki Hirotoshi , Yamabe Junichiro , Kimura Mitsuo , An Bai
Published: November 2019

SSRT and fatigue life tests of SUS301 austenitic stainless steel were performed to examine the effect of hydrogen on the mechanical properties. Ni content of SUS301, 6.00–8.00 mass%, is lower than that of SUS304 in JIS standard for austenitic stainless steels. In the case of SSRT tests, specimens with and without hydrogen charging were tested in laboratory air at room temperature (R.T.), −45 °C, and −80 °C. The 0.2% offset yield strength (Ys) of the hydrogen charged specimens was less than 300 MPa in the tested temperature range. The tensile strength (Ts) and total elongation (El) of hydrogen charged specimens decreased remarkably. With decreasing testing temperature, fracture surface facet of the hydrogen charged specimens became dominant. Therefore, the effect of hydrogen on the tensile properties of SUS301 is supposed to be large. Specimens with and without hydrogen charging were fatigued in laboratory air at R.T., and specimens without hydrogen charging were fatigued in 100 MPa hydrogen gas atmosphere at R.T. Number of cycles (Nf) at finite fatigue life region of the hydrogen charged specimens and of the specimens tested in hydrogen gas were two orders shorter than that of the specimens tested in air. However, the finite fatigue life region of the hydrogen charged specimens and the specimens tested in hydrogen gas showed a different profile. Additionally, ferrite equivalents of all fatigue tested specimens and fatigued fracture surface morphology suggested the fatigue fracture mechanism between the hydrogen charged specimens tested in air and the non-charged specimens tested in 100 MPa hydrogen gas seems to be different. Therefore, further investigations are required to clear this difference.
Finite Element Analysis of Printed Circuit Heat Exchanger Core for Creep and Creep-Fatigue Responses
Authors: Mahajan Heramb P. , Hassan Tasnim
Published: November 2019

Printed circuit heat exchangers (PCHEs) have a high heat transfer coefficient which makes them a suitable option for very high temperature reactors (VHTRs). ASME Section VIII design code provide PCHE design rules for non-nuclear applications. The PCHE design methodology for nuclear applications is yet to be established. Towards developing the ASME Section III code rules, this study started with the PCHE design as per section VIII. An experimental set up is developed to evaluate the designed PCHE for creep and creep-fatigue performances. This study performed pretest finite element analysis to estimate experimental responses and failure loads for setting up the experiments. Three dimensional isothermal analyses of the PCHE’s were conducted by using an advanced unified constitutive model to simulate the creep-fatigue interaction. The sub-modeling technique was used to analyze the channel scale response of the PCHE. Analysis results indicate that the failure may be governed by the channel corner responses, which is influenced by the creep-fatigue interaction. Analysis based creep-fatigue damage curve is plotted as per ASME code to evaluate the design of PCHEs for nuclear application.
Low-Cycle Fatigue of Base-Plate-to-Shell Connection in Uplifting Liquid Storage Tanks Under Seismic Loading
Authors: Chatzopoulou Giannoula , Karamanos Spyros A.
Published: November 2019

Unanchored steel tanks, subjected to strong seismic loading, may exhibit base plate uplifting. Under repeated uplifting, the welded connection of the tank base plate with the tank shell (a fillet-welded connection) is subjected to strong cyclic deformation, involving reverse plastic loading, and this could lead to failure of the welded connection in the form of low-cycle fatigue cracking. In the present paper, an experimental program is described, supported by numerical finite-element simulations. The tests are aimed at investigating the mechanical response of small-scale welded specimens, representing the connection of the base plate with the tank shell, subjected to uplifting loading conditions. The research has been partially supported by European research project INDUSE-2-SAFETY, on the seismic safety and resilience of critical components in industrial plants.
The Effect Mechanism of Hydrodynamic Factors on Naphthenic Acid Flow-Induced Corrosion
Authors: Lyu Yunrong
Published: November 2019

Hydrodynamic factors are the important factors affecting the flow-induced corrosion of naphthenic acid. The effect mechanisms of hydrodynamic factors such as flow velocity, flow pattern, erosion angle and multiphase flow, etc. on the flow-induced corrosion of naphthenic acid are analyzed comprehensively, and the effect mechanisms of critical hydrodynamic parameters such as surface shear stress and near-wall turbulence intensity, etc. on naphthenic acid corrosion are explained. It is pointed out that in the flow-induced corrosion system of naphthenic acid, hydrodynamic factors such as flow velocity, flow pattern, erosion angle and multiphase flow, etc. influence the erosion intensity and mass transfer process generally by changing the magnitude of surface shear stress and near-wall turbulence intensity, thus affecting the severity of corrosion.
A Proposed Framework for the Training and Qualification of Personnel Involved in Field Machining of Bolted Flanged Joints
Authors: Rodery Clay D. , Hamilton Scott , Ferguson Neil
Published: November 2019

One important element in the integrity of bolted flanged joints is the condition of the flange seating surfaces which contact the gasket. Just as the competence of the bolted joint assembler is a key element in the integrity of an otherwise properly designed and constructed bolted flanged joint assembly, when the decision is made to re-machine the gasket seating surfaces on the flange(s) the competence of the personnel who operate the field machining equipment can have an impact on those features of the flanges that affect alignment and surface finish. This paper outlines a proposed industry framework for the training and qualification of personnel who conduct field machining of flanges that is like what is currently in Appendix A of ASME PCC-1 for bolted joint assembly personnel.
Flow-Excited Acoustic Resonance Vibration Mitigation of Reactor Inlet Piping by a Perforated Annulus
Authors: Pontaza Juan P. , Pudwill Wesley K.
Published: November 2019

Piping vibration had been observed in one of our refinery’s reactor inlet piping for several decades. Vibration levels in inlet piping for reactor ‘D’ and ‘E’ were highest, relative to those in reactor ‘A’, ‘B’, and ‘C’. To cope with the vibration, design changes to small-bore branch connections had been implemented to reduce susceptibility to the vibration. A recent increase in production demand made the vibration levels more evident and a production constraint was imposed after an MOV gas seal failure.

Analysis identified the root-cause as flow-excited acoustic resonance of (almost) coaxial closed side branches in the flow path. The selected vibration mitigation solution involved installing a perforated annulus in the main line, in front of the mouth of the (almost) coaxial closed side branch acoustic resonator. Before fabricating and installing the perforated annulus, it was decided to evaluate its expected performance by means of computational fluid dynamics (CFD) and structural stress finite element analysis (FEA). This paper gives an account of the selection of the perforated annulus as the preferred vibration mitigation solution and its evaluation by means of high-performance computing CFD and FEA.

The CFD and FEA analysis showed that the perforated annulus would perform as intended and mitigate the piping vibration. The perforated annulus was fabricated and installed in the inlet piping for reactor ‘D’. Piping vibration was observed to be mitigated, even when flowing above the design rate. The perforated annulus vibration mitigation solution was replicated in the inlet piping for reactor ‘E’. The production constraint has since been lifted.
Failure Modes of Piping Systems Under Seismic Loading and Evaluation
Authors: Kai Satoru , Otani Akihito
Published: November 2019

Failure modes of piping systems under seismic motions were discussed for several decades if the fatigue failure is dominant or there is some possibility that the plastic collapse could occur. A handful of ratchet-buckling failure observed in Pipe Fittings Dynamic Reliability Program by EPRI was frequently taken up as the evidence of the plastic collapse, and inclusion of seismic response on structures into the Primary stress evaluation for piping systems in the code evaluation was considered to be conventionally justified. Although prevention of the plastic collapse type failure is the purpose of imposing the Primary stress evaluation, the other experimental tests conducted in several countries for decades were unable to represent the plastic collapse of piping components exposed to seismic loading and the discussion was abandoned for a while. However, the drastically increased design seismic motions for nuclear power plants due to several huge earthquake occurred in Japan reminded us of exploring the fact of the plastic collapse and the necessity of the Primary stress evaluation.

The load classification concept proposed by the authors introduces 3 conceptual force terms from the equation of motion to clarify the seismic loading from the aspect of the correlation of the said force terms. Based on the finding from the concept that the input force amplitude is to be evaluated for Primary stress, the gross-plastic deformation on a single cantilever with elastic-plastic analyses using multiple of single-cycle sinusoidal forcing functions was compared with the input force term. When the plastic collapse is defined as a gross-plastic deformation, the level of plastic collapse was found to be possibly anticipated with a static force evaluation that can be substitute for the conventional Primary stress evaluation with the dynamic response analysis.
A New Accurate Quantitative Inspection Technology to the Corrosion for the Offshore Erect Pipeline
Authors: Guangpei Cong , Yujiang Sun , Guanglei Lv , Lv Yunrong , Fu Shuxia
Published: November 2019

The erect pipe is a dangerous one with a special double concentric pipes, in which the inner pipe and outer pipe are both corroded on the offshore platform so that a effective corrosion inspection is needed to measure the thinning to the inner pipe and outer pipe at the same time. In addition, because of the narrow space in the offshore platform, it is difficult for the digital X-ray tangential photography (DR) to be implemented during the operation because of the larger X-ray dose that is enough to threaten the personal safety according to the standards in China. Hence, a special inspection tech is demanded to obtain the wall thicknesses of erect pipe which is the most important information to the corrosion management. In this article, A new measuring tech is proposed for the concentric multi-pipe structure to dissolve the bottleneck on the inspection of the offshore erect pipeline. Through the tangential scanning and a wall boundary identifying algorithm, the tech can accurately measure the wall thicknesses of erect pipe, and the ray dose can also be decreased about to the one thousandth of traditional DR, which can guarantee the safety of a inspection and monitoring during the operation in a narrow space as the offshore platform. Besides, the low dose of ray doesn’t influence the accuracy of the measurement which can still be kept into 0.2mm according to the theoretical analysis and experimental data.
Fracture Toughness Criteria of Irradiated Austenitic Stainless Steels for Structural Integrity Evaluation of BWR Internal Components
Authors: Hayashi Takahiro , Tanaka Shigeaki , Abe Tomonori , Sakuraya Seiji , Ooki Suguru , Kaminaga Takayuki
Published: November 2019

Continuous improvement of the structural integrity evaluation methodology in the plant life management (PLM) evaluations is of increasing importance for aged light water reactors. In PLM evaluations, structural integrity evaluations are required for degradation mechanisms considered in the subject equipment and components. Austenitic stainless steels used in reactor internal components are known to show decreases in ductility and fracture toughness due to accumulated neutron irradiation damage. In Japan, “Rules on Fitness-for-Service for Nuclear Power Plants of the Japan Society of Mechanical Engineers Code (JSME FFS Code)” provides fracture evaluation method and criterion, based on the linear elastic fracture mechanics, for irradiated stainless steels of boiling water reactor (BWR) internal components. The fracture toughness criterion, however, was developed with limited materials testing data and knowledge available at that time and it has not been revised since the code originally established.

In this study, fracture toughness criteria for structural integrity evaluation were discussed and developed with the latest database on fracture toughness of irradiated austenitic stainless steels, including additional material testing data obtained in this study for the neutron fluence range of interest from 1 to 3 dpa. First, the fracture toughness data of austenitic stainless steels irradiated in BWR conditions were compiled to evaluate the correlation between fracture toughness and neutron fluence. Material characteristics potentially affecting fracture toughness, such as chemical composition and specimen orientation, were also considered and discussed in the development of the fracture toughness criteria. Based on the results, the fracture toughness criteria for irradiated austenitic stainless steels were proposed for fracture evaluation of the BWR internal components.
Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 3 — Characteristics for Elements on Basis of Half-Scale Loading Tests
Authors: Somaki Takahiro , Fukasawa Tsuyoshi , Okamura Shigeki , Miyagawa Takayuki , Uchita Masato , Yamamoto Tomohiko , Watakabe Tomoyoshi , Fujita Satoshi
Published: November 2019

The authors have been developing the three-dimensional isolation system for a Sodium-cooled Fast Reactor, and reported the details of characteristics of disc springs and vertical oil dampers on the basis of full-scale loading tests [1].

To clarify the fundamental characteristics of the three-dimensional isolation system, the loading tests using a half-scale assembled specimen have been planned, which is composed of a rubber bearing, disc spring units, the horizontal supporting functions, the smoothly sliding elements, and the rotate restraint elements.

This paper describes each characteristic of the rubber bearings, disc springs and sliding element before assembling a half-scale specimen of the three-dimensional seismic isolation system by the static or dynamic loading. The applicability of design method, the scaling effect in disc springs, and the dependence on the friction coefficient of the sliding elements were investigated and confirmed. Additionally, the method of minimizing the variation of force-displacement relationships between four disc spring units, each of which has the three disc springs stacked in parallel and six disc springs stacked in series, was studied.

It should be noted that this paper is in series from Part 2 [1] held on 2018PVP.
Mode I Ductile Crack Growth of 1TCT Specimen Under Large Cyclic Loading: Part III
Authors: Hojo Kiminobu
Published: November 2019

Fitness for service rules and a calculation method for ductile crack growth under large scale plastic cyclic loading have not been established even for Mode I. In a paper presented at the PVP2018 conference the authors presented methods to establish how to determine the parameters of the combined hardening plasticity rule and applied it to simulate the ductile crack growth behavior of 1TCT specimens of the different load levels. Also, ΔJ calculations using the reference stress method, and a ΔJ-basis fatigue crack growth rate derived from that on ΔK-basis according to JSME rules for FFS were applied to estimate the crack growth under cyclic loading in excess of yield. Since in the 2018 paper identified some gaps were found between experiments and the predicted crack growth behavior, several equations of the reference stress method are evaluated in the present paper. Additionally, the prediction procedure using the ΔJ calculation by the reference stress method and the da/dN−ΔJ curve based on the JSME rules for FFS are applied to pipe fracture tests under cyclic loading. Their applicability is discussed for the case of an example piping system.
Technical Progress in Chinese Standard of Ultra-High Pressure Vessels
Authors: Chen Zhiwei , Li Tao , Yang Guoyi , Zheng Jinyang , Deng Guide
Published: November 2019

GB/T 34019-2017 “Ultra High Pressure Vessels” is the most important national standard that applies to pressure vessel which design pressure value is greater than or equal to 100MPa (14.5ksi). There is no standard for Ultra-high Pressure Vessel, Then this standard fills the gap in the standard system of pressure equipment in China. This paper mainly introduces the concept and main content of the new national standard, including the materials, design methods and nondestructive testing of ultra-high pressure vessel.
Ultrasonic Phased Array Inspection With Water Wedge for Butt Fusion Joints of Polyethylene Pipe
Authors: Miao Cunjian , Qin Yinkang , Guo Weican , An Chengmin , Ling Zhangwei , Chen Zhifa
Published: November 2019

Polyethylene pipe has been used widely in gas transportation and nuclear safety-related cooling water applications due to its exceptional resistance to corrosion and erosion. Butt fusion joint is one of the main welding forms for polyethylene pipes. Ultrasonic technique is a typical nondestructive examination technique. To overcome the coupling problems when inspecting butt fusion structures, an inspection technique of ultrasonic phased array using water wedge is proposed to solve the coupling matching and to increase the ultrasound amplitudes. The influences on the imaging of the parameters (such as the angle and height of the water wedge), the array element specifications, and the aperture, were investigated via simulations. The parameter optimization was conducted to establish a suitable detection process. After that, the related probe and a simulated water wedge were designed based on the results and manufactured, in which the simulated wedge as a specific probe holder could adjust its own incident angle and array height. Meanwhile, a typical DN315 pipe of PE 100 was made with some typical artificial defects in it. Experiments were conducted, and the results showed that the proposed water-wedged ultrasonic phased array technique is suitable for butt fusion joint inspection.
CFD Analysis and Structural Safety Assessment of a Bypass Mitigation Device Used During a Ti-SGTR Accidental Release From a MSSV
Authors: Wang Wung Jae , Yim Man Sung
Published: November 2019

In Nuclear power plants, Main steam safety valve (MSSV) is a barrier to prevent overpressure of steam flow by opening the secondary cycle to the atmosphere. Since MSSVs operate at condition of high temperature and pressure, they have possibility for stuck-open failure. If this accident occurs, large amount of steam or gases release through failed MSSV. It may lead Thermally-induced Steam generator tube rupture (TI-SGTR) due to sudden high gradient of temperature and pressure. With loss of electrical power, TI-SGTR occurs, Core will start to melt in 2–3hours after loss of electrical power. When TI-SGTR occurs with core melt, Leakage of radioactive material occurs through MSSV to environment. Though the probability of an accident is very low, the release of radioactive material can lead large cancer risk to the public. Therefore, many studies to mitigate the radioactive materials are in progress such as diversion to containment building or capturing with external mitigation system.

In this study, we are focusing on this capturing device. The objective of this study is to analyze integrity of mitigation device using fluid behavior from MSSV to capturing pipe. Hydraulic conditions at safety valve inlet were used from previous researches. Using commercial simulation software, computational fluid dynamics (CFD) analysis was performed for distribution of fluid temperature, pressure, velocity in MSSV and pipes. For structural safety assessment, 1-way Fluid-Structure interaction (FSI) method was used. CFD result was applied for load on structure surfaces to simulate transient structural analysis of mitigation device. As a result, stresses, strains of capturing pipe were calculated and integrity was discussed.
Further Investigation Into the Damage Tolerance of Different Coke Drum Support Skirt Designs
Authors: Kummari Seetha Ramudu , Prueter Phillip E. , Bifano Michael F. P. , Seijas Antonio J. , Hantz Benjamin F.
Published: November 2019

Evaluating the behavior of coke drums is challenging due to the randomness and uncertainties in typical cyclic loading conditions. Severe fluctuations in temperature and stress during the quench portion of the thermal cycle can often lead to distortion, fatigue damage, and ultimately, cracking. Since the evolution of damage in the coke drums is a cycle-dependent process, a snapshot of strain or distortion data generally has limited value in quantifying remaining life. Advanced fatigue methods and damage models are usually required to address the permanent irreversible damage and material degradation that is produced throughout multiple cycles. This paper represents an advanced finite element analysis (FEA)-based study that is a continuation of the work published in PVP2017-65807[1], with new coke drum support skirt geometries included in the comparisons. The thermal-mechanical behavior of five different support skirt designs; Egg-in-Cup, Tangential, Forged, Sliding, and Welded, are investigated, and relative fatigue life predictions are discussed for each type of design using consistent, idealized thermal transients.
The Use of Different Media in Leakage Tests
Authors: Schaaf Manfred , Herkert Frank , Arnett Adam
Published: November 2019

Previously, in Europe, in gasket tests mainly Nitrogen was used as the test medium. This medium was easy to handle, safe and cheap to buy. With increased sealing requirements on the sealing elements, however, a test medium had to be used, with which smaller leakage quantities can be reliably measured. In laboratory testing, Helium prevailed, with which in the vacuum method using a mass spectrometer these tightness requirements could be easily achieved. Other media, such as hydrogen or Methane, were not used in standard tests because of their hazard potential and detection limitation.

Particularly in performance tests, a practice-oriented medium has always been favored in sealing tests in the USA. Methane is the first choice as the smallest hydrocarbon molecule. In ASME B16.20, a new performance test has been introduced, in which the tightness requirement of spiral wound gaskets in a leakage test with Methane should be checked. And also in the valve test in ISO 15848-1, Methane is defined as an alternative test medium for Helium.

In this paper, the difference in the leakage test between Nitrogen, Helium and Methane in terms of handling, use in the test laboratory, the measurement of leakage rates and the detection limits between Nitrogen, Helium and Methane will be shown.
Evaluated Results of Seismic Design Approach Using Inelastic Dynamic Analysis for Equipment
Authors: Tamura Ichiro , Okubo Atsushi , Minakawa Yusuke , Iijima Tadashi , Namita Yoshio , Goshima Nobuyoshi , Amino Masanori , Okuda Yukihiko , Okuma Shunji
Published: November 2019

Securing adequate seismic safety margins has been important in safety reviews regarding the seismic design of equipment and piping systems in nuclear power plants, and there exists an increasing need for a more exact method for evaluating these margins. To this end, it is reasonable to take into account the reduction of seismic responses resulting from inelastic deformation. The authors studied this approach utilizing an elastic allowable limit in existing standard. The applicability of the proposed evaluation method was investigated by comparison with the conventional evaluation method. The proposed method consists of an inelastic dynamic analysis and an elastic-static analysis. The elastic-static analysis uses a load obtained from the inelastic dynamic analysis. For the investigation, the result obtained from the proposed method was compared with that obtained from the conventional elastic analysis to quantify the reduction in responses leading to seismic safety margins. For the comparison, the authors constructed three models that simulate a cantilever-type beam, four-legged tank, and core shroud and applied them to the analysis herein, and the applicability of our method was discussed for these models. In this paper, we present three topics. First, we present a scheme for developing the design approach of using inelastic analysis. Second, we report a sensitivity study of model parameters, such as yielding stress and second stiffness, done by analyzing the cantilever-type beam for the proposed method. Finally, we report the application of the method to the four-legged tank and core shroud.
Managing the Risks Associated With Operating a Hydrotreater Reactor With Possible High-Temperature Hydrogen Attack Damage
Authors: Prueter Phillip E. , Jones Ryan , Hess Jacki , DeLuca Joel
Published: November 2019

High-temperature hydrogen attack (HTHA) is a damage mechanism that can detrimentally affect the service life of carbon steel and low-chrome pressure equipment in the petroleum refining and related industries. HTHA involves the diffusion of hydrogen into steel, where it chemically reacts with free carbon at high temperatures to produce methane. This methane then gets trapped inside small cavities and other material defects. Over time, the rising methane pressure in these cavities can cause damage at the material grain boundaries. To this end, long-term exposure to high-temperature hydrogen environments can lead to volumetric damage that can diminish the load carrying capability of pressure equipment and accelerate the propagation of crack-like flaws. There have been several known industry failures attributed to HTHA damage as well.

This paper summarizes a case study of a detailed analytical evaluation of potential HTHA damage in a vintage C-0.5Mo hydrotreater reactor. The goal of this study is to quantify the severity of HTHA damage using methods developed as part of an ongoing, multi-year Joint Industry Project (JIP) to justify continued operation of the reactor until the earliest practical replacement opportunity. HTHA damage and crack growth predictions are carried out based on documented historical operating conditions. Additionally, sensitivity in predicted remaining life to anticipated future operating temperatures is considered. Furthermore, based on state-of-the-art non-destructive examination (NDE) methods, fracture mechanics-based minimum pressurization temperature (MPT) envelopes are generated to help guide start-up and shut-down procedures that mitigate the risk for brittle fracture. Practical recommendations are also provided to facilitate the interpretation of NDE findings and to implement on-going failure mitigation and risk management strategies, including the development of Integrity Operating Windows (IOWs), for the reactor until planned replacement.
Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 8 — Evaluation of Vibration Control Performance Using Experimental Design Method
Authors: Minagawa Keisuke , Aida Kiyoshi , Tanaka Go , Fujita Satoshi
Published: November 2019

After Great East Japan Earthquake, coal-fired thermal power generation is a very important power source in Japan. In addition, Hokkaido Eastern Iburi Earthquake occurred in Japan in 2018, and damage of coal-fired thermal power plants by this earthquake caused blackout in very wide area. Therefore improvement of the seismic performance of the thermal power plants is a very important issue. In general boilers of coal-fired power plants are suspended from the upper end of support structures in order to allow thermal expansion of the boilers. Therefore boilers are structures that easily sway by earthquakes. In order to suppress the vibration, stoppers made of steel are generally installed between boilers and their support structures. Although stoppers made of steel can suppress the vibration effectively and economically, further improvement of seismic performance is required from the viewpoint of abovementioned issue. Therefore authors have proposed and developed a vibration control damper for coal-fired power plants instead of the stopper made of steel. Construction of the damper is similar to oil dampers, but inner fluid is viscous fluid. In PVP 2017, the basic performance of the proposed damper was presented. In PVP 2018, influence of dispersion of damper properties was also investigated. In addition, seismic response analyses using various earthquakes that include long period and long duration earthquake waves were carried out. As a result of previous investigations, it was confirmed that the proposed damper has good performance in its lifetime. However, parameters of dampers were selected manually. Therefore, influence of parameters of dampers on the vibration control performance were evaluated theoretically by using the experimental design method in this paper. The experimental design method is one of the effective techniques for research such as investigation of the influence of the habitat environment on the growth of crops. The selection of damper parameters is complex optimization, because so many variables need to be optimized. Therefore the experimental design method is suitable technique for the evaluation of damper parameters. This paper will evaluate vibration control performance from the viewpoint of the experimental design method.
Prediction of Fracture Location in Tensile Test of Short-Fiber-Self-Reinforced Polyethylene Composite Plates
Authors: Tada Naoya , Jin Ming , Uemori Takeshi , Sakamoto Junji
Published: November 2019

Composite materials such as carbon-fiber-reinforced plastics (CFRP) and glass-fiber-reinforced plastics (GFRP) have been attracting much attention from the viewpoint of lightweight solution of automobiles and airplanes. However, the recyclability of these composite materials is not sufficient and the environmental load is large. Recently, self-reinforced polymer (SRP), in which similar polymer is used for reinforcing fibers and matrix, has been proposed. High-density polyethylene (HDPE) reinforced with ultra-high-molecular-weight polyethylene (UHMWPE) fibers, so-called self-reinforced PE (SRPE), is one of the promising thermoplastic composites. In this study, SRPE plates were made and the tensile tests were carried out. After the effect of reinforcement of UHMWPE fibers was evaluated on the basis of the tensile strength, the relationship between the distribution of UHMWPE fibers and the location of the final fracture line was examined. It was found from these experimental results that the fracture tends to occur along the regions with low area fraction of fibers or along those with low area fraction of fiber/matrix boundaries. This fact suggests that the fracture location of SRPs is predictable from the distribution of reinforcing fibers.
Evaluation of Fatigue Crack Propagation by ΔJ Approach
Authors: Li Jia , Ancelet Olivier , Double Alexandre , Chapuliot Stephane
Published: November 2019

An analysis of fatigue crack growth is required for large cast components to evaluate the possible defect evolution during the service life. These components are subjected to both mechanical loading and thermal loading. Due to their high thickness, temperature variations through the thickness can be significant. Thus, a conventional elastic analysis of fatigue crack propagation could be over conservative.

In order to take into account the effect of plasticity, the ΔJ approach of fatigue crack propagation evaluation is implemented in FE software SYSTUS [9]. The quarter of cycle method [11] (or twice-yield method in ASME code) will be used in this work to calculate ΔJ values under both thermal transient and mechanical loadings. Two strategies will be proposed to create the virtual monotonically increasing loading in 3D elastic–plastic FE calculations. The result in terms of numerical scheme will be validated by comparing with FE software CAST3M [10] and the RSE-M [3] simplified ΔKcp method.
Numerical Investigation on Strength of Tee Pipes Under In-Plane/Out-of-Plane Cyclic Loading
Authors: Nakamura Izumi
Published: November 2019

It is known that the expected failure mode of piping systems under excessive seismic motion would be the fatigue failure at elbows or tees. Although there are a lot of experimental and analytical investigations on the strength and the failure behavior of elbows under seismic loading, there are a few studies on tee pipe joints particularly in the inelastic range. To clarify the characteristics of the strength of tee pipes under elastic-plastic region, investigations by FEM analysis were conducted. In this analytical investigation, steel butt-welding type tee pipe joints were considered. Two kinds of parameters were considered; 1) the loading direction (in-plane bending / out-of-plane bending), 2) the branch size (equal tee / unequal tee).

From the analytical examination, the load-displacement relationship and the distribution of the accumulated plastic strain concentration position were obtained. The difference of the strength in the loading direction and the expected failure locations depending on the branch pipe size and the loading direction are discussed.
A Fluidelastic Model for the Nonlinear Dynamics of Two-Dimensional Inverted Flags
Authors: Tavallaeinejad Mohammad , Païdoussis Michael P. , Legrand Mathias , Kheiri Mojtaba
Published: November 2019

A nonlinear fluid-elastic model is proposed for the study of the dynamics of inverted flags. The quasi-steady version of Theodorsen’s unsteady aerodynamic theory is used for inviscid fluid-dynamic modelling of the deforming flag in axial flow. Polhamus’s leading edge suction analogy is employed to model flow separation effects from the free end at moderate angles of attack via a nonlinear vortex-lift force. The flag is modelled structurally via a geometrically-exact Euler-Bernoulli beam theory. Using the extended Hamilton’s principle, the nonlinear partial-integro-differential equation governing the dynamics of the inverted flag in terms of the angle of rotation of the flag is obtained. The equation of motion is discretised spatially via the Galerkin method and is integrated in time via Gear’s backward differentiation formula. The bifurcation diagrams are obtained using a time-integration method and pseudo-arclength continuation. It is shown that inverted flags undergo multiple bifurcations with respect to flow velocity, and they generally exhibit four dynamical states: (i) stretched-straight, (ii) buckled, (iii) deflected-flapping, and (iv) large-amplitude flapping. Also, flapping of inverted flags probably develops through fluid-elastic instabilities. Our findings suggest that the system dynamics is sensitive to the mass ratio. It is shown that the mass ratio parameter does not affect the stability of the stretched-straight state and the onset of divergence; however, it controls the possibility of a direct transition from static undeflected equilibrium to large-amplitude flapping motion and it affects the amplitude of large-amplitude flapping.
Influence of an Elevated Temperature Environment on the Tensile Mechanical Properties of a 3D Printed Thermoplastic Polymer
Authors: Torres Jose E. , Onwuzurike Otito N. , McClung Amber J. W. , Ocampo Juan D.
Published: November 2019

The purpose of this study is to examine the effects of the environment on 3D printed Polylactic Acid (PLA), a biodegradable thermoplastic polymer. The experimental program was specifically designed to explore the influence of print temperature and aging temperature on the mechanical performance of the printed material. Printing at the elevated temperatures (30–40°C) resulted in slight mechanical property changes. In order to understand which of the changes could also be caused by simply storing the materials at the elevated temperature, samples were printed at 25°C and subsequently aged (at 30–45°C) before mechanical testing. All mechanical testing was performed in standard laboratory temperature on an MTS Criterion. All of the mechanical properties were not greatly altered by printing or aging at elevated temperatures, suggesting that printing and using in extreme weather environments could be reasonable. The yield stress is not affected by storage at elevated temperatures, but is increased (or enhanced) by printing at elevated temperatures. The maximum stress is increased (or enhanced) by both aging and printing at elevated temperatures, but is accompanied by a large reduction in strain capacity. Changes that are observed in mechanical properties will be incorporated in future material models to accurately capture material behavior.
European Project ATLAS+: Evaluation of a Shear Modified Gurson Model by Comparison to Experimental Fracture Tests on SENT Fracture Specimens
Authors: Bolinder Tobias , Moinereau Dominique , Le Delliou Patrick , Dahl Anna , Besson Jacques
Published: November 2019

This paper will assess the capability of the shear modified Gurson model developed by Nahshon and Hutchinson which is used by Kiwa Inspecta within the ATLAS+ project. This is done by comparison to experimental results from SENT fracture tests performed by EDF and ARMINES. The procedure for parameter identification for the standard and shear modified Gurson model is also summarized.

The work presented in this paper is part of Work Package 3 within the ATLAS+ project. WP3 focus mainly on ductile tearing predictions for large defects in components. Models exists to accurately predict ductile tearing and to consider phenomena such as stress triaxiality effects. These advanced models include local approach coupled models or advanced energetic approaches. However, there is a need to validate these models for use in industrial applications. This will be done within the ATLAS+ project by predicting the results of the large scale component tests where input to the models are given from small size laboratory specimens.

Within the paper a description of the shear modified Gurson model is given, as developed by Nashson and Hutchinson [1]. Furthermore, the procedure in determining the material model parameters is discussed. To determine the material parameters for the shear modified Gurson model a uniaxial tensile test, a fracture test and shear tests are used. The material that is used is the ferritic steel WB 36 (15 NiCuMoNb 5) which will be used for the large scale component tests within the ATLAS+ project. The procedure is also evaluated by comparing predictions done with the shear modified Gurson model to experimental results from SENT specimens performed by EDF and ARMINES.

A comparison of the capability in predicting the ductile tearing in the SENT experiments between the standard Gurson model and the shear modified Gurson model is also presented within the paper.
High Temperature Performance of Bonded Composite Repairs for Pressure Vessels
Authors: Alnaser Ibrahim A. , Kiani Mahdi , Walker Roger , Keller Michael W.
Published: November 2019

Bonded composite repairs are commonly used as both a temporary and permanent repair method to restore damaged pressure vessels and pipelines. This repair approach is used in a wide variety of industries, including the oil and gas industry. Design and qualification of repair method have been standardized by the ASME post-construction codes. Significant literature has been generated to understand the behavior of these repairs under a variety of loading conditions, both static and dynamic. However, this repair type has typically only been investigated at or near room temperature. As the application possibilities for these repairs expand, higher service temperatures have become a focus for both repair manufacturers and operators. High temperatures (> 250°F) have a number of impacts on polymer composites, including reducing the elastic modulus of the repair material, which tends to reduce the repair strength. Therefore, it is critical to understand the effect of temperature on both the individual composite components, as well as the overall composite repair system. The research presented here studies the influence of temperature on bonded composite repair systems at service pressure (3000 psi) and high temperature conditions. This high temperature is generated using a heating element inside the repaired vessel while contained inside an insulated oven. Strain measurements of the repair are also investigated during a quasi-static testing.