bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmentally Assisted Fatigue Screening Process Application
Authors: Li Jia , De Baglion Laurent
Published: November 2022

In the frame of extension of nuclear plant operation life or new nuclear reactor construction, environmentally assisted fatigue (EAF) assessment is required by many regulators to be considered for pressure boundary components. The methodology of EAF assessment, through EAF cumulative usage factor (CUFen) calculations, has been integrated in RPP n°3 (Rule in Probationary Phase) of French RCC-M code [2]. This methodology is applicable to sentinel locations of Class 1 components made of austenitic SS that have been identified in advance.

In order to minimize final number of sentinel locations for considering EAF effects, EAF screening methods are presented in EPRI report [3], which allow to rank the CUFen values and give a list of sentinel locations that assume to cover other locations within each thermal zone. In particular, the EDF Screening method based on RCC-M code using Fenintegrated concept has been integrated in revision 1 of EPRI report.

The EDF Screening method [5] was built for the fourth ten-year visit of the 900 MWe plants, for which stress reports were updated and contain detailed information of fatigue analyses. It is not applicable for locations without an explicit fatigue analysis or without any pair loads information. In this paper, a new screening method is proposed based on Fenintegrated concept and RCC-M code for austenitic SS Class 1 components and piping. Environmental fatigue factor (Fen) is estimated by a simple process for each location. The CUFen is determined using Fen and Fenintegrated. For locations without an explicit cumulative usage factor (CUF) calculation, transient combinations will be estimated according to the analytical method described in B3600 of RCC-M for piping. Finally, the sentinel locations identified will be compared to those selected in EPRI report.
Flange Design for High Temperature - Material Selection, Functionality Challenges and Design Process Explained on Example
Authors: Lutkiewicz Przemyslaw
Published: November 2022

To use bolted flange connection is a common way to connect the piping system components in oil and power industry. In most of the cases the functionality, strength and tightness are assured by a proper flange type and material selection, followed by the existing design rules and hand calculation or FEA (Design by Analysis). In most cases the time dependent material properties are not considered, as the high temperature effects are minor. In this paper the author will focus on the high temperature applications, where time dependent material and flange properties need to be addressed. Shown on the Compact Flange example the design process and challenges related with high temperature conditions will be discussed. The definition of the critical temperature will be defined based on material creep properties. Design techniques used to predict long term connection behavior including bolt relaxation, flange material creep, loss of tightness and functionality within component lifetime will be presented. The design prediction based on hand calculation will be followed by a detailed time dependent FEA analysis of the connection, including thermal analysis. The influence of the thermal load conditions (steady state or transient) as well as thermal and structural loads fluctuation will be shown. The interaction between fatigue and creep will be shortly discussed. The industrial experience related with high temperature Compact Flange usage will be briefly presented.
Development of Life Estimation Method for Nozzle Welds in Large Scale Piping of Modified 9Cr-1Mo Steel -Part I: Experimental Study
Authors: Shigeyama Haruhisa , Takahashi Yukio , Tamura Koji , Yaguchi Masatsugu , Nishinoiri Satoshi
Published: November 2022

Type IV creep damage has been frequently reported in longitudinal welds and nozzle welds. Many studies have been conducted on the longitudinal welds, and the applicability of life evaluation by non-destructive testing and numerical analysis has been examined. On the other hand, there are few studies on the nozzle welds, and the applicability of the existing life evaluation method is not clear. In this study, internal pressure creep test and numerical analysis were carried out on a large diameter pipe specimen which has several welded nozzles in order to clarify the applicability of the creep life evaluation method for the nozzle welds.

This first report describes the experimental part. The internal pressure creep test at 650°C was performed on the large-diameter pipe specimen of modified 9Cr-1Mo (ASME P91) steel. The test was interrupted three times and nondestructive inspections were performed at each interruption. They included phased array ultrasonic testing, magnetic particle testing and replica observation. The test was completed when the test time reached about 20,000 hours and cross-sectional observations were performed after the specimen was cut into many pieces. Based on these efforts, the location and process of creep damage development in the nozzle welds and the effectiveness of non-destructive inspection were revealed.
Probabilistic Modular Tool to Assess Leak Before Break in Pipes
Authors: Brigante Francesco , Versteylen Casper , De Haan - De Wilde F. H. E.
Published: November 2022

This paper presents the probabilistic study for Leak Before Break (LBB) assessments. The research has been carried out with an in-house developed software that allows to perform both probabilistic and deterministic leak before break analyses for pressurized pipes. The study is based on the UK procedure for the assessment of the integrity of structures containing defects (R6). The procedure applied is the Detectable Leak Before Break (DLBB) that relies on the Failure Assessment Diagram (FAD) Option 1 assessment procedure. The calculations merge the plastic collapse assessment and the brittle failure mode of the pipe in the FAD. The first computed parameter for the LBB assessment is the Critical Crack Length (CCL) distribution density of the postulated through wall defect. The structural integrity assessment is then coupled with the Henry-Fauske two-phase critical flow model for the evaluation of the Leakage Rate (LR). With this coupling the Minimum Detectable Crack Length (MDCL) distribution density is calculated. This step sets the boundary conditions for the fracture mechanics assessment of the postulated defect. The main probabilistic outputs from the assessment are the probability of the structural failure and the probability that the defect does not leak a detectable amount of coolant. The probabilistic method used is the Latin Hypercube Sampling; the Monte Carlo method is applied for verification. These results are then compared with the deterministic output from the LBB procedure.
Demystifying the 1.1 Factor for Tensile Strength Above Room Temperature in Development of the Boiler Code Stress Tables
Authors: Ren Weiju
Published: November 2022

As the Boiler and Pressure Vessel Code continues to gain popularity worldwide, it is not uncommon that many users are mystified by the 1.1 factor used to establish the ultimate tensile strength above room temperature in developing the related design stresses of Section II Part D Stress Tables. Questions often arise about the origin and purpose of the factor, the reason for it not being applied to the yield strength, its due considerations regarding the tested tensile strength value of an alloy batch when accepting the batch for construction use, and more. Not having historic background or reliable sources for explicit explanations, some users tend to misinterpret the factor, abuse its application, incorrectly define alloy acceptance or qualification criteria, and mistakenly manipulate the safety margin in component design.

To help the Code users who struggle with these frequent and confusing issues, particularly those in the nuclear industry where rigorous criteria are required for component design and alloy acceptance or qualification, this paper is intended to demystify the 1.1 factor and facilitate knowledgeable interpretation and use of the Section II Part D Stress Tables as well as relevant Mandatory Appendices.

A brief review is first given on the background of the 1.1 factor, followed by a summary of its application in the Stress Tables. The provenance and purpose of the factor are then discussed in detail with graphic examples. Finally, current applicability and necessity of the factor are considered through a demonstration using example alloys.
How Data Point Numbers in Material Curve Affect Ansys Mechanical Simulation
Authors: Li Qi , Sulwinksi Rafal
Published: November 2022

Finite element analysis (FEA) plays a vital role in new product design. When designing components with a complex geometry and/or complex loading, the nonlinear elastic-plastic analysis method is recommended in the ASME Boiler and Pressure Vessel Code (BPVC). However, the true stress and true strain material curve must be calculated first before elastic-plastic analysis can be performed.

ASME BPVC has provided the method to calculate the material curve, but first, the user has to decide how many data points to use in Ansys. Next, the user needs to pick a plasticity model to generate the curve for simulation.

This paper describes how Ansys uses the data points in the material curve to calculate the stress and strain, specifically the sublayer or overlay model, in which the material is assumed to be composed of a number of sublayers or subvolumes. In addition, it includes case studies that evaluate the impact of data point numbers in the material curve on the Ansys simulation accuracy and solve time. It was discovered that the simulation accuracy was slightly affected by the data point numbers in the material curve; however, the data point numbers can have a significant effect on the solve time of each iteration: the more data point numbers, the more solve time for each iteration.
Towards a Probabilistic Analysis of Pressurized Thermal Shock
Authors: Versteylen C. D. , Siccama N. B. , Uitslag-Doolaard H. J. , Brigante F. , Pallaoro E. , De Haan - De Wilde F. H. E.
Published: November 2022

Pressurized thermal shock (PTS) in a reactor pressure vessel could lead to a sudden brittle and catastrophic cleavage fracture. The combination of radiation embrittlement, the thermal stresses, and low temperatures can cause severe conditions for the structures. Particularly thick-walled reactor pressure vessels, which contain weak spots such as welds and cracks.

In order to assess the probability for the initiation and propagation of a cleavage crack, a detailed image of the stress intensity and the temperature is needed. The critical stress intensity for brittle cleavage fracture depends on the ductile to brittle transition temperature. This complex combination of stresses, absolute temperatures and temperature gradients in combination with radiation damage requires an integral approach for the evaluation of the probability for the occurrence of cleavage fracture.

In order to get the most accurate image as possible of this problem, in previous work by the authors, simulations were performed with a combined CFD and FEM approach. Where a CFD model simulates the thermal mixing of the fluid and its effects on the reactor pressure vessel wall. The temperature profile on the reactor pressure wall is then used as input of a static structural model using FEM. Over the last few years the complexity of the models increased and different types of transients were investigated [1, 2]. Reducing the amount of modelling simplifications and assumptions should lead to the most complete picture of the risks of the accident scenario.

However in order to increase the speed of the calculations some simplifications are needed. In the coming years the simplifications will be added stepwise and their results will be checked against more complicated models. With a focus on verifying the stress intensity around a pre-existing crack, which leads directly to an increase on the probability of cleavage.

In order to correctly predict thermal mixing in the fluid, a computationally expensive 3D model is needed. However the full temperature distribution in the reactor pressure vessel at all times is not necessarily needed to determine the stress intensity. A finite element analysis has been performed on a small section of the reactor pressure vessel [3], speeding up the simulations significantly.

The largest amount of simulation time is spend on modelling the fluid using CFD. Other approaches to do this involve Thermal Hydraulic models, such as applied in the FAVOR code. The drawback of those codes is that they do not provide fluctuations which we can observe using CFD.

A first approach of a comprehensive model which features the heat transition during a transient and the resulting stress intensity. A comparison with the computationally more expensive methods is made. A significant calculation time reduction can be achieved, but more work is needed in order to perform sufficient simulations to account for a full probabilistic analysis.
Calibration and Verification of XFEM Model to Predict Ductile Fracture
Authors: Pereira Israel Cubas , Sarzosa Diego F. B.
Published: November 2022

The XFEM (Extended Finite Element Method) has emerged as a reliable tool for structural engineers to study fracture problems. This method was introduced in 1999 as an alternative to the solution of models with inclusions and discontinuities. As it is a recent method and despite being available in most of the commercial software, the modeling with XFEM lacks assessment on the sensitivity of the method in terms of mesh refinement and other parameters that need to be suitable for building the model. This experimental and numerical study explores the Extended Finite Element Method to predict ductile crack propagation of typical fracture specimens made of a pressure vessel ASTM A285 steel. First, a detailed parametric study is conducted to reproduce the load versus displacement curve obtained from a fracture toughness test using deep crack bend samples. Then, after calibrating the model parameters, the model is used to predict the response of specimens with different levels of crack-tip triaxiality. For this purpose, shallow crack bend specimens with and without side grooves are modeled and compared to experimental toughness tests. Overall, a good agreement between experimental and numerical responses was observed.
Real Time Mechanical Integrity for Pressure Vessels and Other Critical Assets
Authors: Sierra Simon , Wong Jerry , Dawson Kent , Podskarbi Mat , Knezevic David
Published: November 2022

There is a wall today in plant operations, maintenance, and reliability, where the integrity of assets is of critical importance to the health, safety, environmental and financial performance of plant operations. In many cases, the integrity of assets is only partially known, is informed by overly conservative assumptions or follows rules that have been established as part of historical approaches. The mechanical health of critical pressure vessels, piping and other assets is limited by the fidelity and model size of its finite element simulation. Operators must choose between speed, accuracy, and quality in setting up an asset health integrity system and legacy approaches provide partial answers at best and/or workflows that are not well suited for asset health integrity systems.

Industry has relied on finite element analysis to determine structural integrity during design, but new advances in numerical reduction methods and computational advances have been combined to dramatically decrease the time needed to solve high fidelity whole-asset structural simulations to visualize stress fields, accumulated fatigue life, and other structural/mechanical analysis in real-time.

This paper will address this problem through the lens of two real-world pressure vessels, demonstrate the limitations of legacy approaches, and discuss the benefits of running structural simulations in real time.
An Estimate of Spent Nuclear Fuel Mechanical Loads in the General 30 cm Package Drop Scenario
Authors: Klymyshyn Nicholas , Kadooka Kevin , Spitz Casey , Fitzpatrick James
Published: November 2022

The US Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program is performing research to determine the mechanical loading conditions applied to spent nuclear fuel (SNF) during normal conditions of transport to inform mechanical tests of SNF and close an important knowledge gap related to the practical disposition of SNF in the US. Researchers at Pacific Northwest National Laboratory (PNNL) have completed an extensive finite element study to characterize and estimate the potential mechanical loads on SNF during a hypothetical 30 cm drop of an SNF transportation package. This modeling study is validated with test data collected by the SFWST program during a physical test campaign that included one-third scale package drop tests and full-scale single fuel assembly drop tests. The test campaign was led by Sandia National Laboratories (SNL) and included international collaboration with Equipos Nucleares S.A, S.M.E (ENSA) and Bundesanstalt für Materialforschung und -prüfung (BAM).

The key contribution of the modeling study is to go beyond the limitations of the limited number of physical tests to estimate the impact response to variations in impact angle, initial gap conditions, fuel assembly design, burnup and other parameters that affect the mechanical loads. The methodology of this study included a classic parametric study to calculate the impact response of highly detailed fuel assemblies over many combinations of parameters. Models of a 17 × 17 pressurized water reactor fuel assembly and a generic 10 × 10 boiling water reactor fuel assembly were both used in this study to cover the major fuel assembly types in the US inventory. Over 2,000 impact responses were calculated. The results of the parametric study were evaluated using traditional methods and basic statistics. The results were also used to construct a damage model using multiple nonlinear regression techniques to predict the mechanical loads over the full range of all input parameters. The damage model was found to work very well for all impact angle cases where the cask came to rest on its side. It was concluded that end drop cases where the cask remained vertical (instead of tipping over onto its side) were not sufficiently characterized by the current set of parametric study cases to include in the damage model, but it was not a priority to fully investigate that range because the highest mechanical loads were observed in the broader range of side impact cases. This modeling work provides sufficient insight into the mechanical loads on SNF during a hypothetical 30 cm package drop that, when considered along with the physical test data collected by the SNL-led team, the SFSWT program can consider the knowledge gap closed.
Frame Structure Design of 40-Foot High Pressure and Large Capacity Hydrogen Storage Tube Bundle Container for Road Transportation
Authors: Liu Mengjie , Chen Zhiping , Cheng Zhi , Ou Haiyang
Published: November 2022

As a kind of clean energy with good prospect, the demand of trans-regional transportation of hydrogen is increasing rapidly. However, due to the difficulty and high cost of pipeline transportation, tube bundle containers are more used to transport hydrogen. As the fixing device of tube bundle container, the frame structure should not only ensure that the gas cylinder can be fixed, but also meet the requirements of stiffness and strength. In order to improve the efficiency of hydrogen transportation, a new frame structure of 40-foot high pressure and large capacity tube bundle container for road transportation was designed. There are two groups of tube bundles at the front and rear of the tube bundle container, carrying 18 hydrogen storage bottles. The total hydrogen storage capacity is more than 1000kg and the pressure is 52MPa. The design process is as follows: firstly, the stress analysis of the original frame structure under four inertia force conditions was carried out, and it was found that the structure was difficult to meet the strength requirements for road transportation. Then, the beam distribution of tube bundle container frame structure was preliminarily determined by using the method of topology optimization and the geometric model of the optimized frame structure was remodeled according to the topology optimization results. Finally, the static analysis of the frame structure under various driving inertia force loads was carried out by ANSYS Workbench finite element analysis software. The results show that the designed tube bundle container frame structure meets the requirements of strength. This work provides a reference for the design and safety evaluation of similar tube bundle container frame structure products.
The Impact of Perforation on the Fracture Propagation of Horizontal Well Multistage Fracturing in the Roof of Broken Soft Coal Seams
Authors: Li Xuejiao , Zhao Haifeng , Liu Changsong , Zhong Junbing , Wang Chaowei , He Yalong
Published: November 2022

Horizontal well multistage fracturing in the roof of low-permeability and broken soft coal seams has proven to be an effective technique to extract coalbed methane. However, fracture propagation behaviors under this technology vary significantly with different perforation patterns. Therefore, based on the 5# coal seam in Hancheng block of Ordos Basin in China, large-scale true triaxial hydraulic fracturing physical simulation experiments were performed using the “roof-coal-floor” similar material pouring model to optimize the perforation pattern. The fracture propagation behaviors and pressure curves characteristics of horizontal well multistage fracturing in the roof of coal seams with spiral perforation, double lateral downward perforation with a phase angle of 120° and vertically downward oriented perforation were investigated respectively. The experimental results show that a relatively simple fracture network covering half of the area of the coal seam was formed by spiral perforation fracturing. A 3D complex fracture network with good connectivity in the coal seam was generated by fracturing with double lateral downward perforation. A horizontal fracture with a small zone in the coal seam was induced by vertically downward oriented perforation fracturing. Finally, double lateral downward perforation with a phase angle of 120° is considered the optimal perforation pattern due to the desired fracturing effect and relatively low cost. The presented findings can provide references for the fracturing design of horizontal well multistage fracturing in the roof of low-permeability and broken soft coal seams.
Comparison of a Datum Temperature Calibration Method With Traditional Approach for Norton Power Law
Authors: Haque Mohammad Shafinul
Published: November 2022

Methods for minimum-creep-strain-rate prediction have evolved. Many models have been proposed, and different calibration techniques are used. Often the limitation of these models for accurate prediction arises due to a lack of long-range data incorporating both the low-stress and high-stress regions. This problem is more prominent for novel materials with very little data and may require long-term creep tests, delaying the material’s qualification. Model calibration against short-range data may lead to an inflection during extrapolation. In this study, a datum temperature (DT) calibration method derived from Parametric Numerical Isothermal Datum (P-NID) is compared with the traditional calibration approach for minimum-creep-strain-rate prediction using Norton power law. Minimum-creep-strain-rate data for Inconel 617 at five temperature levels (800 to 1000°C) and stress ranging from 11 to 122 MPa are used. Two different forms of the Norton power law are calibrated using the traditional approach and the most suitable form for Inconel 617 is selected. Next, the model is calibrated using the datum temperature calibration approach. In the datum temperature method, the data from different temperatures are transferred to a datum temperature creating a wide range of parametric data followed by model calibration against the transferred data at datum temperature. Finally, the model is transferred back to the original temperatures. The traditional approach and datum temperature method results are compared in terms of accuracy, calibration techniques, extrapolation, and limitations for Inconel 617. The datum temperature method is found to be accurate, like the traditional approach, however, requires comparatively less effort during calibration since the model is calibrated against a single temperature instead of multiple temperatures. Thus, the material constants are independent of temperature and stress resulting in stable, inflection-free, and reliable extrapolation over the traditional approach. A step-by-step procedure is provided to derive the datum temperature transformation equations and the calibration method. Finally, a general guideline is provided to apply the datum temperature method to any existing models.
Direct Method-Based Probabilistic Structural Integrity Assessment for High-Temperature Components Considering Uncertain Load Conditions
Authors: Wang Xiaoxiao , Ma Zhiyuan , Chen Haofeng , Luan Weiling
Published: November 2022

Excessive dependence on the safety factor of deterministic analysis leads to the conservative design of industrial components, resulting in conspicuous waste of manufacturing resources. The novel strategy for probabilistic assessments for structural integrity is proposed based on the direct method, Linear Matching Method (LMM) framework, a series of structural integrity analysis approaches, where the uncertain design conditions are taken into consideration. To address complicated failure modes under high-temperature, the probabilistic LMM (pLMM) framework consists of six modules, including shakedown analysis, ratcheting analysis, direct steady cycle analysis (DSCA), the unified procedure for fatigue and ratcheting analysis (UPFRA), creep rupture analysis and creep-fatigue analysis. Leveraging the load multiplier calculated by LMM, a general form of performance function is constructed that defines the limit state of different failure modes. Besides, the iteration algorithms of the first-order reliability method (FORM) is formulated to acquire the reliability index and failure probability. With different failure modes discussed, the numerical cases demonstrate the application of the proposed probabilistic structural integrity analysis, with corresponding failure risk and reliability index calculated. The pLMM-based reliability analysis can be introduced into the current structural integrity assessment procedures, which is conducive to replacing traditional safety factors, reducing risks and improving structural robustness.
A Review on the Effect of Heat Treatment for Thermoplastic Composites
Authors: Shang Ningtao , Yao Riwu , Wu Jinkui , Kong Zhiyong , Zheng Jinyang , Shi Jianfeng
Published: November 2022

Thermoplastic composites have recently attracted broad attention in aerospace, transportation, shipping, and other fields for their excellent mechanical properties and high recyclability. However, the properties of thermoplastic composites are unstable because of the problems such as microstructural differences and residual thermal stress after molding processing. Therefore, heat treatment, as a common method to modulate the microstructure and improve the properties of materials, is used to solve the problems. In this paper, the effects of different heat treatment methods were reviewed, including oven heating, microwave heating, and electric heating on the properties of various types of thermoplastic composites. The changes in material properties i.e., phase transformation, residual stress, interface bonding properties, etc. were discussed. Based on these investigations, electric heating experiments were carried out on the damaged samples of short carbon fiber reinforced polyethylene (SCFRPE) composites, and the mechanical properties of the samples before and after electric heating were analyzed. The results showed that the toughness increased, while the strength decreased after electric heating. These phenomena may be related to the changes of crystallinity and interfacial shear strength of the composites. This study can provide a reference for the manufacturing of SCFRPE based structures.
Numerical Study of Hydrogen Leakage and Explosion in Hydrogen Refueling Station With Large Volume Hydrogen Storage Vessels
Authors: Lu Chen , Hu Jieyi , Ye Sheng , Gu Chaohua , Hua Zhengli
Published: November 2022

Large volume multi-layered high pressure hydrogen storage vessel is one of the vital equipment in hydrogen refueling station. However, the possibility of leakage from container nozzles during service remains a safety concern. In this paper, a leakage model modified by the real gas equation of state and a three-dimensional (3D) computational fluid dynamics (CFD) model based on the real hydrogen refueling station layout are established to simulate the whole process of hydrogen diffusion and explosion after the large volume vessel leak. The influences of leakage direction, leakage height, hydrogen storage pressure and wind speed on the distribution of flammable hydrogen are studied, as well as the scope of overpressure harmful area is respectively predicted when the real hydrogen cloud is ignited at different times. Results indicate that the high-pressure hydrogen jet over 30MPa diffuses in a wide range near the surface under momentum control. And the smaller the leakage source height is, the more obvious the Coanda effect is. In addition, igniting after hydrogen leakage in a very short time (such as 0.5 s) will lead to higher maximum overpressure, and igniting after a long time will form a larger dangerous area. Compared with the seamless hydrogen storage cylinder group, the hydrogen explosion hazard of vertical large volume multi-layered hydrogen storage vessel is significantly alleviated after leakage. Also, setting a certain height of isolation walls outside the hydrogen storage area can effectively reduce the risk and consequences of accidents.
Numerical Analysis on the Blast Field From Gas Pipeline Burst Considering Fluid-Structure Interaction
Authors: Ren Yi , Du Yang , Zhou Fan
Published: November 2022

The blast wave propagates into the surrounding air when the high-pressure gas pipeline burst. Both temperature and pressure increase very rapidly. The generation of the blast wave and structural dynamic fracture are tightly coupled together during the burst of the high-pressure gas pipeline. However, fracture behavior and characteristics that influence blast waves’ intensity and spatial shape are rarely studied. This paper establishes a numerical model incorporating strain-based failure criteria for pipe material and fluid-structure coupling algorithm. The dynamic crack growth of the pipe and the outer blast wave propagation can be successfully captured in every timestep. The model is validated by comparing the simulated explosion pressure history and peak overpressure outside the pipeline with the experimental results. The blast wave intensity changes and the distribution of overpressure in the jet direction are clarified. Then some critical parameters of the resulting fracture and blast wave are examined, such as the pipe diameter and wall thickness. Specifically, the relationship between pipe fracture and the generated blast field is discussed, providing a deeper understanding of this highly transient and strong fluid-structure interaction problem. The results would benefit the prediction and accident investigation of high-pressure gas pipeline rupture.
Experimental Study of Fluid Forces on Direct-Acting Relief Valves
Authors: Li Qingye , Zong Chaoyong , Liu Fuwen , Zhou Weihao , Song Xueguan
Published: November 2022

Safety valves as the last barrier of the pressure vessel and piping system ensure the stability of the whole system. However, there are specific situations where valves may not operate properly, which can have a significant impact on the safety of the entire system. The reason for this is a lack of understanding of the dynamic characteristics of valves, of which fluid forces are the most critical factor. In this paper, a high-precision test rig was built to test steady-state fluid forces of a direct-acting relief valve, where proportional-integral-derivative control (PID) control was applied in order to obtain more accurate multi-stage flow rates adjustments. In addition, a adjustment mechanism has been designed to obtain a more accurate valve opening. Based on this test rig, the steady-state fluid force at different openings and different flow rates are conducted, the relationship between fluid forces, flow rates and pressure drop of the valve is analyzed from the test data, which provide an in-depth understanding of the dynamic characteristics of the valves.
First Large Scale Shaking Table
Authors: Minowa Chikahiro , Nakamura Izumi , Furuya Osamu
Published: November 2022

The large-scale shaking table in Tsukuba owned by National Research Center for Disaster Prevention, which was completed in 1970 after the 1964 Niigata Earthquake, will be closed in 2022. The table has an area of 15m × 15m and a exciting force of 360tons. The table was called as first large-scale shaking table. In 1970, the table was completed as one direction shaking table horizontal or vertical switching with stroke 60mm. In every year, several experiments were conducted. In 1988, the shaking table performance was improved. After Kobe Earthquake Damage, many shaking tables of high performance have been constructed. And it became clear that the seismic records exceeded 10m and 3m/s. Considering this situation, it must be said that the performance of the Tsukuba shaking table, which has been 50 years since its completion, has become difficult to meet the demands of the times.

In this paper, it will be described the process of determining the construction specifications for the Tsukuba Shaking Table and the results of the main experiments conducted over 50 years, and this is the final word.
Finite Element Numerical Simulation of Hydrogen Storage Vessel Under Dynamic Load Impact
Authors: Fang Zhou , Shi Puan , Wang Zhe , Wu Gang , Liu Qia , Wang Yongming
Published: November 2022

With the development of global society and the progress of technology, hydrogen energy is gradually becoming an emerging clean energy source. As a special high-pressure container for storing hydrogen, damage to the hydrogen storage vessel under the impact of dynamic load can cause serious accidents. In order to study the mechanical property changes of hydrogen storage vessel under dynamic load, this paper adopts the equivalent static method to numerically simulate the steel hydrogen storage vessel and analyze the effects of load size and impact location on the stress-strain of hydrogen storage vessel under dynamic load impact, so as to provide theoretical basis for the analysis, evaluation and design of hydrogen storage vessel’s crashworthiness.
Development of a Pressure Vessel Qualification Methodology and Testing - Proposal Enhancement to ASME BPVC Certification
Authors: Josodipuro Irawan
Published: November 2022

Pressure vessels play important roles in pressurized static equipment systems. In the oil and gas industry, for example, they are used to perform the process function, separation, filtration, and storage. Given the role of pressure vessel, which is subject to elevated pressure, temperature, and fatal accidents have occurred in the history of pressure vessel, it is important that pressure vessel end-users feel confident that the pressure vessel they procure meet the safety requirements. This paper presents a case study where there have been breakdowns in the qualification of pressure vessels being offered by pressure vessel suppliers to the industry that did not comply with industry standards which can adversely impact plant operations and personnel safety. The loss of pressure vessel supplier credibility is a concern that may rarely occur in mature economies but seem to be more prevalent in countries where qualification standards are either relatively new or non-existent. To address this issue, the author presents a systematic approach that can be used to ensure that pressure vessels supplied to end-users in oil and gas industries in emerging countries meet the design requirements and standards they are required to meet. The process used to control the manufacturers begins with a qualification plan which each supplier has to establish its product line. Following compliance with the qualification plan, a criticality matrix is introduced to the manufacturers that classify the criticality of each pressure vessel type in the system and the associated qualification program(s) that the manufacturers need to meet. The validation with an established program has shown some merit and could be applied to all manufacturers in emerging countries to ensure consistency. The details of the qualification program used and how the process is evaluated are covered in the body of the paper together with examples of how the process has worked.
Identification and Quantitative Analysis of Defect in Plates Based on Remote-Field Eddy Current Method
Authors: Zhang Hongsheng , Chang Jinpeng , Pan Wenjie , Sun Chencan , Guo Kai
Published: November 2022

Remote-field eddy current testing (RFECT) technology breaks through the limitation of skin effect. It has shown its advantages over the other electromagnetic non-destructive evaluation (ENDE) techniques in the detection and characterization of deeper defects. In this paper, a new RFEC transducer is designed for plate defect detection. The optimal sensor design scheme is obtained by comparing and analyzing the material and composition of the sensor shield structure through numerical simulation. Then, the identification and quantitative analysis of the detection signals is studied. The defect detection experiment is carried out to prove the effectiveness of the transducer. The results show that fitting relationship between the phase of the sensor detection signal and the defect depth are the quadratic function. The defect depth can be quantitatively analyzed by the phase of the detection signal. The new designed transducer is promising in online detection of buried defects in pressure vessels and pipes.
Study on Mitigation of Sliding Motion of Cask-Canister Coupled System Subjected to Seismic Excitation Using Highly Viscous Fluid
Authors: Shintani Atsuhiko , Nakagawa Chihiro , Ito Tomohiro
Published: November 2022

In this study, the suppression of the sliding motions of a coupled cask-canister system was investigated using a damping device consisting of two coaxial cylinders filled with a highly viscous liquid. An analytical model describing the coupled cask-canister system connected to a damping device is presented. The sliding behavior of the coupled cask-canister system when subjected to seismic excitations was studied both with and without a damping device. The displacement of the cask was found to be suppressed in most cases. By contrast, the displacement of the canister could not be mitigated completely. However, it was found that the acceleration response of the canister could be reduced significantly if its natural frequency is sufficiently different from the input frequency of the seismic waves.
Post-Irradiation Fracture Toughness Characterization of Generation II FeCrAl Alloys
Authors: Chen Xiang (Frank) , Field Kevin G. , Howard Richard , Massey Caleb P. , Nelson Andrew T.
Published: November 2022

FeCrAl alloys are promising candidate materials for the accident tolerant fuel (ATF) cladding application due to their exceptional resistance to oxidation in elevated temperature steam environments. Currently, limited fracture toughness data are available for the FeCrAl alloys, including the FeCrAl alloys newly developed at Oak Ridge National Laboratory (ORNL) under the U.S. Department of Energy’s Advanced Fuels Campaign (AFC) program. In this study, two Generation II candidate FeCrAl alloys, i.e., C06M (81.8Fe-10Cr-6Al-0.03Y-2Mo-0.2Si) and C36M (78.8Fe-13Cr-6Al-0.03Y-2Mo-0.2Si), were irradiated in the High Flux Isotope Reactor (HFIR) at ORNL to assess the fracture characteristics of these alloys after neutron irradiation. A total of six rabbit capsules were irradiated in HFIR at target temperatures of 200°C, 330°C, and 500°C up to target damage doses of 8 displacements per atom (dpa) and 16 dpa. Post-irradiation fracture toughness testing was performed following the Master Curve method in the ASTM E1921 standard. The main findings of this study are:

1) Both the C06M and C36M alloys exhibited a similar response to irradiation concerning irradiation hardening and embrittlement.

2) The irradiation temperature played different roles in terms of irradiation hardening and embrittlement for both C06M and C36M: after irradiation between 166°C and 204°C, both materials exhibited significant irradiation hardening and embrittlement; after irradiation between 315°C and 343°C, both materials showed small irradiation hardening without irradiation embrittlement. After irradiation between 501°C and 507°C, however, the irradiation softening without irradiation embrittlement was observed in both materials.

3) Comparing the microhardness and Master Curve reference temperature T0q before and after neutron irradiation, we did not observe a linear correlation between the two parameters for both C06M and C36M steels. This should be mainly due to a flat response of the Master Curve reference temperature T0q to the irradiations at 166–204°C and 315–343°C ranges

4) C06M showed a lower T0q, meaning better toughness, than C36M at the unirradiated condition, and such trend was kept even after neutron irradiation except for the 166–204°C irradiation after which both materials had similar T0q.

5) In terms of hardening and embrittlement, the irradiation effect on both C06M and C36M appeared to saturate after an irradiation dose of 7 dpa.
An Investigation on Vortex Induced Vibration and Wake Induced Galloping in Tandem Cylinders System
Authors: Guo Kai , Cheng Yuxuan , Fan Xiantao , Zhang Hongsheng , Tan Wei
Published: November 2022

The flow-induced vibration (FIV) of multi cylinders is a problem involving the safety of fluid engineering and energy harvesting. Due to the effect of wake galloping and vortex induced vibration (VIV), the mechanism of two tandem cylinders is more complex than that of a single cylinder. In this study, the vibration modes of two tandem cylinders with different spans (L/D = 1.5–4.0) are investigated at subcritical Reynolds number and high mass damping ratio through wind tunnel tests. In the experiment, the cylinders are free to vibrate in the transverse and in-flow direction. The characteristics of the vibration amplitude and vibration frequency response are discussed with the vibration mode. The results show that the vibration mode is related to the reduced pitches between the cylinders. The vibration of the two tandem cylinder system is combines results of vortex induced vibration and wake induced galloping (WIG). When the span is lower than 2.0, the galloping effect is more obvious than that of larger spans cylinders at the experiment mass damping parameters. The two cylinders turn to vibrate separately as the span grows larger.
Numerical Simulation on Hydrogen Induced Cracking Behavior of 4130X Hydrogen Storage Vessel With Defect
Authors: Wei Haotian , Xing Baihui , Cui Tiancheng , Shang Juan , Hua Zhengli , Gu Chaohua
Published: November 2022

This study aims to investigate the hydrogen-induced cracking behavior of the cylinder of 4130X hydrogen storage vessel in a 45 MPa high-pressure hydrogen environment under the synergistic influence of hydrogen and crack depth. Firstly, finite element analysis was performed via a modified hydrogen diffusion/plasticity coupled model to study the coupling behavior of hydrogen diffusion and plastic deformation in a hydrogen storage vessel with a crack. Then we used the modified hydrogen diffusion/plasticity coupled model to study the effect of crack depth on the hydrogen-induced cracking behavior in the hydrogen storage vessel. Results show that the hydrogen is mainly concentrated in the trap at the crack tip of the vessel, and the crack tip is always the position with the highest total hydrogen concentration. The distribution of plastic strain and trap hydrogen concentration on the crack surface is small along the axial direction of the cylinder, but large along the radial direction of the cylinder. With the increase of the initial crack depth, the pressure difference corresponding to the crack propagation from radial direction to unstable propagation and the depth of the crack propagation show a decreasing trend, and the hydrogen pressure of unstable propagation also decreases gradually. The greater the depth of cylinder crack, the more difficult it is to prevent cylinder failure.
Numerical Simulation Comparative Analysis of Pipe Soil Interaction in Buried Pipeline
Authors: Xu Feng , Xu Yongsheng , Song Jianfei , Suo Hongchao , Liu Xin
Published: November 2022

Aiming at the problem that there is no effective tool to quickly analyze the mechanical response of long-distance buried pipelines, this paper uses the APDL language of ANSYS to compile a rapid solution program for the mechanical response of buried pipelines based on the soil spring model. The program is used to establish the calculation model of 500 m long pipe, and analyze the mechanical response of the pipeline with and without medium and subsidence. The value are compared with those of ABAQUS based on PSI unit and solid contact model. The results show that the calculation value of these three methods are in good agreement. The program can realize rapid modeling and accurate analysis of long-distance buried pipelines, and has high engineering application value.
Numerical Simulation Research on Heat Transfer Characteristics of On-Board Type 4 Hydrogen Storage Cylinders Under Localized Fire
Authors: Song Jitian , Zhu Chaoyang , Li Xiang , Gu Chunlin , Huang Liang , Li Jiepu
Published: November 2022

Hydrogen energy and hydrogen fuel cell vehicles have become the key development directions of countries around the world, and high-pressure hydrogen storage technology is the most widely used hydrogen storage method in hydrogen fuel cell vehicles. The on-board Type 4 hydrogen storage cylinders are an important hydrogen storage component of hydrogen fuel cell vehicles, and the storage medium is flammable and explosive high-pressure hydrogen. Therefore, the on-board Type 4 hydrogen storage cylinders determine the safety of the hydrogen fuel cell vehicles. When a hydrogen fuel cell vehicle accidentally catches fire, the high-pressure hydrogen storage cylinder may be exposed to localized fire, and gas cylinders are at risk of explosion before the pressure relief device (TPRD) operates. In this paper, the computational fluid dynamics method was used to establish the numerical calculation model of the on-board Type 4 hydrogen storage cylinders under localized fire, and the accuracy of the numerical calculation model was verified by the fire test results. Using the established numerical calculation model, the heat transfer characteristics of the 35MPa on-board Type 4 hydrogen storage cylinders after localized fire for 600s was analyzed, the effect of different filling media on the heat transfer characteristics of Type 4 hydrogen storage cylinder was studied. The results show: The temperature of the burning area of gas cylinder was significantly higher than that of other areas. The temperature growth rate of the gas in cylinder remained basically unchanged, and the maximum temperature of the gas reached 353K at 600s. As the burning time goes on, the growth rate of the gas pressure increased continuously, and the gas pressure reached 36.3MPa at 600s. And different filling mediums have little effect on the heat transfer characteristics of on-board Type 4 hydrogen storage cylinders.