bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Products Pipeline Accident Infiltration Process in Surface Soil Condition
Authors: Wang Xiao , Liang Yongtu , Liu Shengli , Wu Mengyu
Published: November 2019

The most common way of transportation for refined oil is long-distance pipeline. Pipeline accidents occur frequently due to corrosion, equipment failure, external forces destruction. Aiming at predicting the contaminated area in soil caused by products pipeline accidents, this experimental study was conducted to examine the relationship between the light non-aqueous phase liquids (LNAPL) accumulative infiltrate volume and the time of infiltration process in homogeneous and layered soils. The soil’s hydraulic parameters were obtained by basic experiments and RETC software. Compared with traditional infiltration mathematical model, Green-Ampt model is the most common mathematical model to calculate the infiltration process in the unsaturated soil. In this study, a modified Green-Ampt model was developed to describe water and diesel infiltration through a 100-cm-long and layered soil column. In the modified Green-Ampt model, an infiltration reduction ratio was introduced to describe the effect of the hydraulic conductivity of the layered position. To evaluate the proposed method in the effect of the layers position infiltration permeability, eight constant water head layered column infiltration experiment were conducted to record the different infiltration fluid and different constant water head infiltration process. Compared the experiment results with traditional mathematical traditional Green-Ampt model (average R2 = 0.976) and Hydrus-1D software (average R2 = 0.988) The modified Green-Ampt model had relatively higher precision in accumulative infiltrate volume (average R2 = 0.992) and the wetting front velocity in infiltration process (average R2 = 0.997). Thus, the modified mathematical model was applied an effective upscaling scheme in layered formations. The experimental result also demonstrated that soil layering affected the infiltration process. With the increase of soil depth and density, the infiltration speed of the layered soil column decreased. Additionally, the infiltrate speed of wetting front decreases slowly at the layered surface. The experiment’s fitting results showed that the modified mathematical model about infiltrate time and liquid contaminant accumulative infiltrate volume, wetting front infiltrate velocity can highly effective approach to simulate water and light non-aqueous phase liquids (LNAPL) infiltration process in layered soils.
Assessing Low-Constraint Fracture Toughness Test Methods Using Clamped SENT Specimens
Authors: Zhu Xian-Kui , McGaughy Tom
Published: November 2019

The low-constraint fracture toughness can be measured using a single edge-notched tension (SENT) specimen in the clamped-end conditions. The SENT specimen has been used in the oil and gas industry in the strain-based design and the crack assessment for transmission pipelines. Since 2006 when DNV published the first SENT test practice, many investigations have been done, and various SENT test methods were developed, including CANMET and ExxonMobil methods in terms of the J-integral and CTOD. The effort led to the first SENT test standard BS 8571 being published in 2014. However, the experimental evaluation methods remain in developing, and different methods may determine inconsistent results. For this reason, the present paper gives a brief review on SENT fracture testing and assesses the available test methods, including progresses on study of stress intensity factor, geometric eta factors, elastic compliance equation, and constraint m factor as well. The difference between J-converted CTOD and double clip gage measured CTOD is also discussed. On those bases, agreements and challenges in SENT testing are identified. The results provide a direction for further investigation to improve the current SENT test methods.
Recent Improvements in Toughness Prediction of Cast Duplex Stainless Steel Components
Authors: Le Delliou Patrick , Saillet Sébastien
Published: November 2019

Thermal ageing of cast duplex stainless steel components is a concern for long-term operation of EDF nuclear power plants. The thermal ageing embrittlement results from the microstructural evolution of the ferrite phase (spinodal decomposition), and can reduce the fracture toughness properties of the steel. In addition, it is necessary to consider manufacturing quality and the possible occurrence of casting defects such as shrinkage cavities. In a context of life extension, it is important to assess the safety margins to crack initiation and crack propagation instability. One major input of the assessment methodology is the toughness value of the thermally aged component. Recent work conducted at EDF R&D to improve the accuracy and the conservativeness of the toughness prediction has led to the development of new prediction formulae.

The toughness prediction relies on three steps:

• estimation of the Charpy impact test values at 20 and 320°C using the chemical composition of the steel and the aging conditions (temperature and duration),

• estimation of the J-R curve at 20 and 320°C - defined by a power law J = CΔan - thanks to correlations between n and C and the Charpy impact test values,

• estimation of the J-R curve at any temperature between 20 and 320°C thanks to interpolation formulae.

The paper presents the experimental data used to develop the formulae, the formulae themselves and some elements of validation.
Technical Basis and Strategy for Consolidation of ASME Boiler and Pressure Vessel Code, Section III, Subsection NC (Class 2) and Subsection ND (Class 3) Into a Single Subsection
Authors: Wen Jie , Keating Robert , Adams Timothy M.
Published: November 2019

ASME Boiler Pressure Vessel Code, Section III, Division 1, Subsection NC, Class 2 components, and Subsection ND, Class 3 components, have significant technical and administrative similarities. The ASME BPV III Standards Committee has a long-standing goal of combining these two subsections (NC and ND). Consolidating Subsections NC and ND will simplify, reduce repetitions and make the Code easier to use. Additionally, a combined Subsection NC/ND will simplify Code maintenance. To facilitate this consolidation, the Subgroup on Component Design, under the BPV III Standards Committee assigned a Task Group to develop a strategy to combine the two subsections into a single subsection while maintaining both Class 2 and Class 3 as separate classes of construction.

Both Subsections NC and ND of the Code have been completely reviewed, compared and the technical bases for the differences have been established. The conclusion of this review is that there are only a few major technical differences between the two code class rules; however, there are a significant number of editorial differences. Based on the review, the Task Group developed a strategy that completes the consolidation within two publishing cycles of Code edition. For the Code Edition 2019, two separate Subsections NC and ND books will be published to resolve editorial differences and otherwise align the two subsections. For the Code Edition 2021, a single merged subsection will be published. This paper provides the background for the proposed code change, discusses the detailed result of the NC/ND comparison, and provides the basis for the major technical differences. The paper will also update the status of the project and code actions needed to consolidate to a single subsection.
Fitness-for-Service Strategies for Impulsively Loaded Vessels
Authors: Duffey Thomas A. , Fehlmann Kevin R.
Published: November 2019

High-explosive containment vessels are most commonly designed for repeated use, implying predominately elastic material behavior. Each explosive test imparts an impulse to the vessel wall. The vessel subsequently vibrates as a result of the internal blast loading, with amplitude diminishing exponentially in time due to structural damping. Flaws present in the vessel could potentially grow by fatigue during these vibrations. Subsequent explosive tests result in new sequences of vibrations, providing further opportunity for existing flaws to grow by fatigue. The obvious question is, ‘How many explosive experiments can be performed before flaws potentially grow to unsafe limits?’ The evaluation of remaining life and fitness-forservice of explosive containment vessels draws upon three interrelated codes and standards: Section VIII, Division 3 of the ASME Boiler and Pressure Vessel Code; API-579/ASME FFS-1; and ASME Code Case 2564. The paper discusses their implementation in determining the remaining life of dynamically loaded vessels that have seen service and are potentially damaged. In this paper, results of a representative explosive containment vessel are presented using actual flaw data for both embedded weld flaws and fragment damage. Because of the potentially large number of flaws that can be detected by modern non-destructive inspection methods, simplifying procedures are also presented for conservatively eliminating from further consideration the vast majority of the flaws that possess considerable remaining life.
Investigation on the Protection of the End Cover of the Cylindrical Containment Vessel
Authors: Zhang Liucheng , Dong Qi , Yang Sha , Feng Jiahe , Hu Rongxi
Published: November 2019

The cover of a cylindrical explosion containment vessel would suffer an extremely intense impact because the shock wave and blast products would converge at the cover area. To reduce the impact of shock waves to the cover, cases with aluminum foam placed at the end of the vessel and in the interior of the cylindrical portion are studied by numerical simulation and experiment. The result shows that aluminum foam located at the end of the vessel can have a great effect on the protection of the cover because it can absorb the energy of the shock wave that has spread to the end of the vessel. Aluminum foam located in the interior of the cylindrical portion would have a negative effect on the protection of the cover because it would reduce the distance between the charge and the cylindrical portion, the effect of which is more significant than the effect of energy absorption. These results can contribute to the design of cylindrical explosion containment vessels.
Experimental and Analytical Study on Local Failure of Structure Subjected to High Temperature and Pressure
Authors: Tsunemoto Yoshiki , Sakaguchi Takashi , Sato Takuya , Kasahara Naoto
Published: November 2019

In our past paper, the new fracture surface was proposed considering the effects of hydrostatic stress in an elastic-plastic region and in a creep region. In this paper, the mechanism the dominant factors of local failure were studied in an elastic-plastic region. Experimental and analytical study were made using circular plate specimens with a nozzle. The material was a lead alloy (99% Pb-1% Sb). The fracture test was performed in an elastic-plastic region at room temperature. Both ductile fracture and local failure were observed at structural discontinuities, based on the stiffness differences between attached nozzles and plates. In this study, the proposed fracture surface in an elastic-plastic region showed the fracture location accurately, for the both failure modes. It was concluded that the proposed fracture surface is available and useful in order to predict the failure mode and the failure location.
Elastic-Plastic Analysis of Pipe Structure by Transfer Matrix Method
Authors: Arai Masayuki , Kuroda Shoichi , Ito Kiyohiro
Published: November 2019

Pipe systems have been widely used in industrial plants such as power stations. In these systems, it is often required to predict the displacement and stress distribution. Analytical and numerical methods such as the finite element method (FEM), boundary element method (BEM), and frame structure method (FSM) are typically adopted to predict the displacement and stress distribution. The analytical methods are solved based on the Timoshenko beam theory, but the problem that can be solved is limited to simple geometry under simple boundary conditions. Both FEM and BEM can be applied to more complicated problems, although this usually involves a large number of degrees of freedom in a stiffness matrix. The structure is modeled by a beam element in FSM. However, the stiffness matrix still becomes large, as does the matrix size constructed in FEM and BEM. In this study, the transfer matrix method (TMM) is studied to effectively solve complicated problems such as a pipe structure under a small size of the stiffness matrix. The fundamental formula is extended to apply to an elastic-plastic problem. The efficiency and simplicity of this method is demonstrated to solve a space-curved pipe system that involves elbows. The results are compared with those obtained by FEM to verify this method.
Effect of Internal Pressure on Gasket Stress and Leakage Rate of Bolted Flanged Joint During the Long Term Service at High Temperature
Authors: Xue Jilin , Chen Xuedong , Fan Zhichao , Wang Lu
Published: November 2019

Bolted flange joints (BFJs) are very common in the process industries, and they play an important role in equipment connection. A lot of BFJs are working at high temperature. The temperature and internal pressure will lead to gasket stress redistribution, and then affect time-dependent leakage rate of BFJs. In this paper, the effect of internal pressure on gasket stress and leakage rate of BFJ during the long term service at high temperature was discussed. The time-dependent gasket stresses of BFJ during the long term service at high temperature under two tightness levels and three internal pressures were calculated by using the finite element method. And then, based on the leakage rate prediction model of BFJ during the long term service at high temperature proposed, the corresponding time-dependent leakage rates of BFJ during the long term service at high temperature were acquired. The results showed that the internal pressure had a significant impact on the time-dependent gasket stresses and time-dependent leakage rates of BFJ during the long term service at high temperature. This research will help the engineers and technicians to understand the role of the internal pressure on the time-dependent gasket stresses and time-dependent leakage rates of BFJ during the long term service at high temperature.
Failure Assessment Using XFEM for the Austenitic Stainless Steel Pipe With the Circumferential Crack Subjected to Bending and Torque
Authors: Ono Yohei , Sakai Michiya
Published: November 2019

Failure assessment of a pipe with a circumferential crack in a nuclear power plant has to conform to the Rules on Fitness for Service for Nuclear Power Plants published by JSME (The Japan Society of Mechanical Engineering) [1] in Japan. Based on the rules, the applied stresses considered in the failure assessment of the pipe using limit load assessment are membrane, bending, and thermal stresses. The failure assessment focuses only on mode I. In actual plants, depending on the piping system, there is a possibility that torsional stress [2] is applied to the pipe, in addition to membrane, bending, and thermal stresses. Under such a load condition, the crack opening mode will be mixed-mode. In ASME Boiler & Pressure Vessel Code section XI, the bending and torsional moment are considered in failure assessment of the pipe. Therefore, it is important to establish the failure assessment method for the pipe with the crack under mixed-mode. In this study, the XFEM (extended Finite Element Method) [3][4] was applied to assess failure of the austenitic stainless steel pipe (Type 304) with a circumferential crack subjected to bending and torsional moment. XFEM does not require elemental division considering the crack shape and its propagation path. Therefore, the time and cost for developing the analysis model can be reduced compared with conventional FEA (Finite Element Analysis). Fracture test results conducted under two conditions were used the analysis (Specimen No. TP1 and TP2) for determining the energy release rate for crack propagation and verifying the analysis results. The difference between the two tests was the ratio of torsional moment to bending moment. The ratios in TP1 and TP 2 were 0.6 and 1.2, respectively. A parametric analysis was conducted to determine the critical equivalent strain energy release rate required for crack initiation and propagation by comparison with TP1 results. The determined critical equivalent strain energy release rate was verified by comparison with TP2 results. In response to the above considerations, the decreasing load due to crack propagation in the fracture tests under mixed-mode condition was simulated by XFEM, and the maximum load, bending moment, and torsional moment were predicted within the margin of error of 6.1%.
Unsteady Fluid Force and Random Excitation Force Measurement of Triangular Array Tube Bundle in Steam-Water Two Phase Flow
Authors: Nishida Shingo , Kawakami Ryoichi , Hirota Kazuo , Morita Hideyuki , Kondo Yoshiyuki , Utsumi Seiho
Published: November 2019

The in-plane (stream-wise) fluid-elastic instability of triangular tube arrays caused tube-to-tube wear indications as observed in the U-bend regions of tube the bundles of San Onofre Unit-3 steam generators. To understand the in-plane FEI characteristics, stability analysis using unsteady fluid forces is quite helpful. However, taking measurements of unsteady fluid forces in the in-plane direction is quite challenging as the fluid coupling forces of the surrounding tubes must be measured simultaneously for the in-plane stability analysis. In particular, taking measurements under a high pressure and high temperature steam-water conditions, similar to an SG operating condition, is extremely difficult. Recently we have been able to successfully measure unsteady fluid force using a specially designed test equipment. In the meantime, random excitation forces acting on heat transfer tubes were also measured. We calculated the stability boundary of the in-plane FEI using the unsteady fluid force measurement with this special equipment.
Model and Experimental Analysis of the Fiber-Reinforced Pultrusion Composite Under Tension and Shear
Authors: Zhang Qian , Zhang Yanting , Jiang Wenchun
Published: November 2019

This paper proposed a homogenization model, and compiled a VUMAT subroutine to simulate the tension and shear of fiber-reinforced pultrusion composite (FRPC). Experiments were also performed to verify the accuracy of the homogenization model. The results show that, the simulation results agree well with the experiment data. The stiffness and strength increase with the increase of the diameter of the carbon composite part. The limit shear load and the horizontal shear strength decrease with the increase of the span. When FRPC is under shear with smaller span, the matrix tensile damage initiates first and it is the dominate failure mode, then the matrix and fiber compression damage occur at where the indenters contact. However, with the increase of the span, the delamination damage between the wound glass-fiber reinforced composite and pultrusion glass-fiber reinforced composite occurs and becomes the dominate failure mode for FRPC shear.
Evaluation of the Transportable Detonation Chamber for Processing Recovered Munitions
Authors: Tribble Megan K. , Stofleth Jerome H.
Published: November 2019

Sandia National Laboratories was tasked by the United States Army Recovered Chemical Materiel Directorate with evaluating the fitness of the Transportable Detonation Chamber for use in demilitarization of chemical munitions. The chamber was instrumented with strain, pressure, and acceleration sensors to study its behavior during explosive tests ranging from 1.25 to 20 lb of explosive charge weight. The structural response of the chamber and techniques recommended by the manufacturer — use of water bags and sand-filled walls — were assessed. Through this testing, it was found that the two techniques did not significantly affect the chamber’s response. It was also discovered that the structural integrity of the chamber (and, therefore, its suitability for use with chemical agents) was compromised, as some welds failed. Sandia does not recommend using this vessel for chemical munition demilitarization. This chamber is suitable, however, for demilitarization of conventional munitions, in which fragments and overpressure are the primary concern.
Development of Creep Test Method for Thermoplastic Fiber-Reinforced Polymer Composite Tubes Under Pure Hoop Loading Condition
Authors: Doan Hai G. M. , Ashrafizadeh Hossein , Mertiny Pierre
Published: November 2019

Piping made from thermoplastic fiber reinforced polymer composites (TP-FRPCs) is receiving increasing attention in the oil and gas industry. Creep and time-dependent behavior is one of the main factors defining the service life of TP-FRPC structures. The lifetime and time-dependent behavior of TP-FRPC structures can be predicted using simulation tools, such as finite element analysis, to aid in the design optimization by modeling the long-term behavior of the material. Composite material time-dependent properties are required inputs for such models. While there is previous research available on creep testing of TP-FRPCs in laminate geometry, such tests may not enable accurate determination of the composite properties due to edge effects. On the other hand, coupons with tubular geometry not only provide improved load distribution between the fibers and matrix with minimal end effects, they also enable certain loading conditions experienced during typical piping operations such as internal pressure. In this study, a testing method to capture the creep behavior of tubular TP-FRPC specimens subjected to multi-axial loading conditions was developed. Tubular coupons were prototyped by an automated tape placement process. Strain was measure using digital image correlation technique and strain gauges. The development of the test setup forms the foundation for further testing of tubular TP-FRPC coupons at different multi-axial loading conditions. As a preliminary test, the creep behavior of a TP-FRPC tube subjected to pure hoop stress condition was evaluated using the developed testing process.
Resilience Calculation of Process Plants Under Seismic Loading: A Case Study
Authors: Kalemi Bledar , Caputo Antonio C. , Paolacci Fabrizio
Published: November 2019

Earthquakes causes approximately 8% of total accidents in industrial facilities. Although there are several researches in literature pertaining to industrial resilience, none of them provides a modelling framework to quantify the seismic resilience of process plants. This paper presents a methodology for providing a quantitative measure of resilience and business economic losses for the process plants in case of a seismic event. The two main parameters which have utmost influence on the resilience of a process plant are operational capacity and recovery time, so they must be evaluated in proper way. Plant mapping and components vulnerability are the key modelling parameters of plant operational capacity. Exact recovery step functions are introduced based on General Reconstruction Activity Network (GRAN), considering interdependencies between plant components. In order to illustrate the discussed method, a nitric acid plant is set up as a case study. “PRIAMUS” software is used to generate the most probable damage scenarios, assuming the plant is located in seismic region of South Italy, Sicily. Ultimately, recovery curves are constructed for each damaged scenario, and business economic losses are calculated according to direct cost and business interruption. In short, this methodology provides a good estimation of the most critical components and economic losses of a process plant in case of a seismic event.
Re-Evaluation of Stress Rupture Factors for Grade 91 Weldments Based on the Extended Database With the Data Collected in Japan
Authors: Kimura Kazuhiro , Yaguchi Masatsugu
Published: November 2019

Stress rupture factors and weld strength reduction factors for Grade 91 steel weldments in the codes and literatures have been reviewed. Stress rupture factors for weld metals proposed for Code Case N-47 in the mid 1980’s was defined as a ratio of average rupture strength of the deposited filler metal to the average rupture strength of the base metal. Remarkable drop in creep rupture strength of weldments is significant issue of Grade 91, especially in the low-stress and long-term regime. A premature failure of Grade 91 steel weldments in the long-term, however, is caused by Type IV failure which takes place in the fine grain heat affected zone (FG-HAZ), rather than fracture in the deposited weld metal. The stress rupture factor of the Grade 91 steel, therefore, was based on the creep rupture strength of cross weld test specimens. Creep rupture data of Grade 91 steel weldments reported in the publication of ASME STP-PT-077 was incorporated in the creep database collected in Japan which was used for the previous study. Time and temperature dependent stress rupture factors for Grade 91 steel have been re-evaluated based on the extended database as a ratio of average creep rupture strength of cross weld test specimen to the average creep rupture strength of base metal.
Vibration Suppression in Frame-Structural Tower With Fluid Viscous Dampers
Authors: Fan Xiantao , Du Yian , Tan Wei
Published: November 2019

Flexible and skyscraping frame-structural tower is sensitive to dynamic loads, that might oscillate intensely under seismic and wind loads. Thus, vibration suppression system is required and fluid viscous damper (FVD) is implemented to suppress such vibration in this study. The vibration behavior of frame-structural tower with FVD (F-FVD) is investigated by an equivalent model combined with experiment under seismic and wind loads, respectively, and the vibration suppression effect is evaluated by the displacement and energy distribution. The equivalent model of the frame-structural tower with FVD is primarily established, of which FVD is considered through Kelvin model. The parameters of FVD are supplemented to the damping term through a time-dependent damping matrix based in Rayleigh damping, and to the stiffness term through a stiffness matrix based in stiffness-equivalent simply-supported beam. Van der Pol wake oscillator is considered as the wind force term. Several conventional numerical integration methods for solving the equivalent model which belongs to the nonlinear system are compared and Newmark-β algorithm is adopted. The vibration suppression regularity of normalized stiffness coefficient Kr, damping coefficient Cr and velocity exponent α is analyzed via the equivalent model. There is a balance between the stiffness effect and energy dissipation effect of FVD, and the sensitiveness to α depends on excitation and stiffness of F-FVD system. The optimal parameters of fluid viscous damper, Kr = 1.30∼2.0, Cr = 1.65∼3.30 and α = 0.4∼0.8, are obtained eventually. It is indicated that the vibration suppression by fluid viscous damper is effective. And this study can be conducive to vibration suppression design of such flexible and skyscraping frame-structural tower.
Estimation of Impact Energy for Seat Seals in Spring-Operated Pressure Relief Valves During the Reseating Process Under Compressible Fluid Service Conditions
Authors: Schimanowski Alex , Schlattmann Josef
Published: November 2019

Spring operated pressure relief valves (SOPRVs) are used in many industrial fields for hazardous applications in order to protect people and environment as well as to reduce the risks of containment loss. Since SOPRVs are essential elements of safety systems, they are subject to strict functional and reliability requirements, which demand not only a proper disk lift but also give regulations concerning the maximum allowable valve tightness. However, despite the high practical importance of SOPRVs tightness through the whole life cycle, only initial tightness is considered in the literature and regulations. Therefore, in the present contribution we make an attempt to quantify the impact energy of the valve disk during the reseating of the valve, which is assumed to be the most relevant factor for repeated valve tightness. First, we present three different methods of increasing complexity for disk impact energy estimation. Subsequently, we demonstrate the application of these methods on the example of a SOPRV Type API 526 1E2 and discuss the findings. Finally, we consider a set of selected common used soft sealing materials and give implications for their usage within a range of set pressures and maximum disk lifts based on findings for the presented use case.
Investigation on Fluidelastic Instability Accompanied by Wake Shedding With a Time-Domain Model
Authors: Guo Kai , Wang Yipeng , Su Tong , Liu Liyan , Jia Zhanbin , Tan Wei
Published: November 2019

As the most dangerous flow-induced vibration (FIV) mechanism, fluid-elastic instability is always accompanied by the wake shedding. If both of the two FIV mechanisms are considered, fluid forces in this condition can be quite complex. In this paper, a time-domain model based on unsteady flow theory was used to investigate the fluid-elastic instability in a rotated triangular tube array. The vortex shedding forces were simplified as harmonic forces. Computational fluid dynamics (CFD) was used to get the fluid force coefficients with vortex shedding. The model was established by a finite element code with MATLAB software and simulation results agreed with the experiment results. The results showed the critical instability velocity can be influenced by vortex shedding forces, and double peaks can be found in the frequency spectrum of displacements of tubes. The time-domain displacements showed the phases had been impacted by the shedding and periodic characteristic was found in the displacements results. The model can also be adopted in fluid-elastic instability analysis in other tube arrangements and flow conditions.
Mechanical Enhancement and Strain Sensing of Electrofusion Joint With Carbon-Fiber-Reinforced Polyethylene
Authors: Yao Riwu , Shi Jianfeng , Zheng Jinyang
Published: November 2019

Electrofusion (EF) technology is widely used for connecting plastic pipes or composite pipes. For these pipes used in natural gas transportation and nuclear power plant, the higher and higher operation pressure makes the strength of EF joint a limitation in the pressure pipeline systems. In this paper, high density polyethylene (HDPE) filled with different contents of short-cut carbon fiber (CF) was prepared by melt mixing and injection molding. Scanning electron microscopy imagines indicated a good dispersion of CF in HDPE matrix. Experiments were carried out to evaluate the mechanical and electrical properties of the HDPE-CF composite. The addition of CF improved the elastic modulus and yield stress of the composite compared with neat HDPE. The enhanced mechanical properties of HDPE-CF composite can improve the strength of EF joints, and bursting tests revealed a burst pressure of 8.11 MPa, which is 41.8% higher than that of neat HDPE EF joint. Based on the improved electrical conductivity, the electrical resistance of EF joint induced by the strain under internal pressure can be monitored for structural health monitoring of the pipeline. Thus, the combination of mechanical enhancement and strain sensing of EF joint with carbon-fiber-reinforced polyethylene can improve the strength and reliability of pressure pipeline.
Fitness for Service Assessment of Carbon Steel Vessel With Localized Deformation During PWHT
Authors: Shah Utkarsh , Prasad Piyush
Published: November 2019

Post weld heat treatment (PWHT) is applied to welded pressure vessels and piping to relieve residual stress built up during welding. During the PWHT, pressure vessel made of carbon steel is heated up to a minimum temperature of 595 °C for a holding period as required based on the thickness (Refer ASME Section VIII, Division 1, UCS 56) [1]. However, for equipment susceptible to carbonate stress corrosion cracking, PWHT is required irrespective of thickness at a temperature range of 649 °C to 663 °C as per WRC 452 [2].

A process column built in 1983 and operating in carbonate stress corrosion cracking environment was observed to have widespread corrosion under insulation at reboiler supports. Material of construction for the column was SM41B (Japanese Industry Standards Carbon Steel). Four Insert plates of various sizes were welded at same circumferential band during turnaround. The insert plate repair sizes were relatively large. Local PWHT was required to be performed with the equipment in vertical condition. Due to risk of uneven temperature distribution and resultant local thermal stresses, spot PWHT or Bulls-eye method of PWHT was not considered. Full circumferential local PWHT was considered for this equipment. During the actual PWHT process, localized overheating occurred, and some areas of deformation were observed in the equipment.

A multi discipline review was performed to understand the root cause of the localized overheating and subsequent deformation. This paper describes the methodology and results of the fitness-for-service (FFS) assessments that were performed based on API 579-1/ ASME FFS-1, 2016 [3] to assess the integrity of the column. Based on the assessment performed, the equipment was found to be fit for service and continued safe operations.
Seismic Test Results of Air-Operated Valve Actuators for Nuclear Power Plants (Air-Operated Globe Valve (Cylinder Type))
Authors: Kubota Ryo , Tsutsumi Yoshitaka , Matsubara Yoshinao , Suzuki Shigeki , Kumagai Shin
Published: November 2019

It is believed that air-operated globe valves are able to operate during and after earthquakes, leading to maximum accelerations beyond the existing allowable acceleration for nuclear power plants in Japan (6 × 9.8 m/s2). In this work, this assumption is verified using a resonance shaking table for seismic testing at acceleration levels of 20 × 9.8 m/s2 (see Ref. [1]). Results show that the active components used in existing air-operated globe valve designs remain operable at 22 × 9.8 m/s2 (horizontal (X and Y) and vertical (Z) directions).
Evaluation of Bolt Strength Characteristics in Bolted Joints Using an Optical Fiber Sensor System
Authors: Shirakawa Atsushi , Sawa Toshiyuki
Published: November 2019

Bolted joints are used in many industrial products such as mechanical structures, automobiles, airplanes, chemical plants, and so on. In many cases, after the design of new products is finished, various tests on the bolt and bolted joints are carried out using actual parts to prevent accidents due to bolt loosening and fracture. At the same time, in the strength tests, external force measurement, axial bolt force measurement and so on are included. However, there are no advanced tests in which axial bolt strain distribution or bolt elongation in actual parts and so on are measured. Therefore, in this research, a new method for evaluating bolt strength characteristics using an optical fiber sensor system capable of measuring actual parts is demonstrated. First, a tensile strength test using an optical fiber sensor is carried out to measure strain distribution in a bolt, and a maximum strain value position in the measured clamp load-strain curve is shown. Then, the elongation at each part of the bolt is shown. Next, yield clamp bolt force is found using this sensor system in torque/clamp force testing. In addition, the measured yield clamp bolt force is compared with the values in the conventional measurement method and in the estimation formula. Also, discussed is the effective cross section area by which the stress at the engaged threads is calculated under tensile load. Finally, another case where an optical fiber sensor system is used for bolt fastening evaluation is discussed.
A Co-Reliability-Target-Based Fatigue Failure Probability Model for Implementing the New ASME Boiler and Pressure Vessel Section XI Division 2 Reliability and Integrity Management Code: A Technical Brief
Authors: Fong Jeffrey T. , Heckert N. A. , Filliben J. J. , Freiman Stephen W.
Published: November 2019

ASME Pressure Vessel and Piping Code (BPVC) Section XI Committee Division 2 has recently completed the development of a proposed new code named the “Reliability and Integrity Management (RIM).” RIM was developed using the system-based code (SBC) concept proposed by the Japanese Society of Mechanical Engineers (JSME) in 2012. Key to the SBC concept is the requirement for the establishment of a co-reliability target (or, reliability-index target by JSME terminology). Such target is usually in the low probability ranges such as 1.0 E−8 to 1.0 E−3. In a paper presented at the 2018 International Symposium on Structural Integrity (ISSI2018), Nov. 2–5, 2018, Nanjing, China, we developed a new theory of fatigue and creep rupture life modeling for metal alloys at room and elevated temperatures such that the co-reliability target can be estimated from fatigue and creep tupture test data. To illustrate an application of this new modeling approach, we included two numerical examples using (a) the fatigue failure data of six AISI 4340 steel specimens at room temperature (Dowling, N. E., 1973) and (b) the creep rupture time data of 37 specimens of 1.3Mn-0.5Mo-0.5Ni steel plates at 500 C (NRIM, 1987). Since the ASME BPVC Section XI Div. 2 RIM Code has just been developed, and the information in that yet-to-be-published ISSI2018 Proceedings is critical to the implementation of that RIM Code, it is, therefore, of interest to the engineering community to have a preview of that information in the form of a technical brief as described in this PVP2019 conference paper.
Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 7 — Evaluation of Lifetime Using Experimental Design Method
Authors: Aida Kiyoshi , Minagawa Keisuke , Tanaka Go , Fujita Satoshi
Published: November 2019

In 2011, Great East Japan Earthquake that was the largest earthquake in Japanese history occurred. The earthquake had large acceleration, long duration and a lot of aftershocks, and coal-fired thermal power plants were damaged by the earthquake. Boiler structures in coal-fired thermal power plants are generally high-rise structures, and boilers are simply suspended from the top of the support structures in order not to restrict thermal expansion. Therefore boilers are easy to vibrate. In order to suppress vibration of boilers during earthquakes, stoppers are generally set between boilers and support structures. The stoppers are made of steel, and dissipate vibration energy by plastic deformation. However aseismic requirements for thermal power plants have been increased as a result of the Great East Japan Earthquake. Thus authors have developed a vibration control damper for coal-fired power plants. The damper is set instead of conventional stopper. 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 lifetime 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 evaluates lifetime of dampers from the viewpoint of the experimental design method.
Application of the Incremental Step Loading Technique to Small Punch Tests in Hydrogen Embrittlement
Authors: Arroyo B. , González P. , Andrea L. , Álvarez J. A. , Lacalle R.
Published: November 2019

In this work, the incremental step loading technique to measure hydrogen embrittlement threshold in steels from ASTM F1624 standard is applied to the Small Punch test technique. For the experimental program, a medium strength steel is employed, simulating the hydrogen embrittlement environment by a cathodic polarization of 5 mA/cm2 in an acid electrolyte mainly consisting of 1N H2SO4 in H2O. Regular standard tests on cylindrical tensile specimens were carried out under the same environment following the ASTM F1624 standard, observing the same trends in both cases, which validates the methodology proposed.

In order to adapt the aforementioned standard to small punch testing, the duration of the loading steps had to be modified, proposing much shorter ones according to the Small Punch specimen dimensions and the punch rate taking place in these scenarios, which is pointed in bibliography. This proposal allows to obtain a threshold load by using at least 3 specimens in a total time of around a week.
Simple Calculations of J-Integral for Through-Wall Crack in Welded Pipes Based on Failure Assessment Diagram
Authors: Park Jun-Geun , Jeon Da-Som , Huh Nam-Su , Lee Sang-Min , Kim Ye-Ji
Published: November 2019

In the present study, simple J-integral estimations of welded pipes with a circumferential through-wall crack (TWC) in weld zone were proposed based on the failure assessment diagram (FAD) concept using scaling factor that is defined as a ratio of plastic limit load of welded pipe to that of base metal pipe. For this purpose, the detailed 3-dimensional (3-D) finite element (FE) limit analyses for welded pipes with a circumferential TWC have been systematically carried out considering various thickness of pipe, circumferential crack lengths, strength mismatches between base and weld metal, widths of weldment and locations of TWC (weld center and interface between the weld metal and the base metal). As for loading conditions, axial tension and global bending were considered in the FE analyses.

Based on the present FE results, numerical expressions on scaling factors representing the ratio of plastic limit loads of welded pipes to those of base metal pipes were derived. Finally, the new FAD-based J-estimations based on option 1 concept was proposed to predict J-integrals of welded pipes incorporating the present scaling factors, i.e. ratio of plastic limit load. Moreover, the proposed J estimations were validated by comparing with FE results using actual properties.
Effect of Plasticity on Creep Deformation in Type 316H Stainless Steel
Authors: Mamun Abdullah Al , Simpson Chris , Erinosho Tomiwa , Agius Dylan , Reinhard Christina , Mostafavi Mahmoud , Knowles David
Published: November 2019

The creep life and deformation behaviour of high-temperature steels can be significantly affected by the prior plastic loading. This effect is partly due to the generation of intergranular strains from the grain-scale elastic and plastic anisotropic deformation during plastic loading. This paper investigates the effect of these plasticity generated intergranular strains on the subsequent creep strain accumulation behavior in type 316H stainless steel. An in-situ synchrotron diffraction experiment was conducted at 550°C, where the sample was loaded incrementally to different magnitudes of plastic strain, followed by a displacement-controlled stress relaxation dwell at each of this stage. The lattice strains of 4 grain families were measured during these stages. It was found that the intergranular strains generated during the plastic deformation significantly affect the relative magnitude of creep strain accumulation in different grain families. A subtle but significant difference has been observed between the creep intergranular strain accumulation behavior and the plastic intergranular strain accumulation behavior in different grain families which can be used to interrogate the validity of any micromechanical models’ formulation for creep and plastic deformation. The macroscopic stress relaxations measured from the experiment were compared with the prediction from a novel crystal plasticity based micromechanical model developed in our group. A good overall match was found between the experiment and the model regarding the magnitude of stress relaxation after various level of plasticity. The experiments have demonstrated that the model requires further development to accurately predict the rate of stress relaxation and the micro scale lattice strain evolution during creep.
Heat Treatment of Fabricated Components and the Effect on Properties of Materials
Authors: Gopalakrishnan Shyam , Mathkar Ameya
Published: November 2019

Most of the heavy thickness boiler and pressure vessel components require heat treatment — in the form of post weld heat treatment (PWHT) and sometimes coupled with local PWHT. It is also a common practice to apply post heating/ intermediate stress relieving/ dehydrogenation heat treatment in case of alloy steels.

The heat treatment applied during the various manufacturing stages of boiler and pressure vessel have varying effects on the type of material that is used in fabrication. It is essential to understand the effect of time and temperature on the properties (like tensile and yield strength/ impact/ hardness, etc.) of the materials that are used for fabrication.

Considering the temperature gradients involved during the welding operation a thorough understanding of the time-temperature effect is essential. Heat treatments are generally done at varying time and temperatures depending on the governing thickness and the type of materials. The structural effects on the materials or the properties of the materials tends to vary based on the heat treatment. All boiler and pressure vessel Code require that the properties of the material should be intact and meet the minimum Code specification requirements after all the heat treatment operations are completed.

ASME Code(s) like Sec I, Section VIII Division 1 and Division 2 and API recommended practices like API 934 calls for simulation heat treatment of test specimen of the material used in fabrication to ascertain whether the intended material used in construction meets the required properties after all heat treatment operations are completed.

The work reported in this paper — “Heat treatment of fabricated components and the effect on properties of materials” is an attempt to review the heat treatment and the effect on the properties of materials that are commonly used in construction of boiler and pressure vessel. For this study, simulation heat treatment for PWHT of test specimen for CS/ LAS plate and forging material was carried out as specified in ASME Section VIII Div 1, Div 2 and API 934-C. The results of heat treatment on material properties are plotted and compared. In conclusion recommendations are made which purchaser/ manufacturer may consider for simulation heat treatment of test specimen.