bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering Critical Assessment (ECA) of Onshore Natural Gas Pipelines Using Partial Safety Factors (PSFs)
Authors: Kagita Gurumurthy , S. K. Pottem Penchala , Gupta Deepak , G. S. Achary Gudimella , V. R. Sripada Subramanyam 
Published: November 2022

Abstract
Pipeline design codes recognize the potential risks posed by gas pipelines by relating the factors which affect the probability of failure to consequences in particular locations. To maintain more or less uniform risk level, ASME B31.8 Code adopted risk based concepts indirectly through location classifications by specifying different design factors (DFs). Engineering Critical Assessment (ECA) of onshore natural gas pipelines in accordance with pipeline-specific methods such as API 1104 allow much deeper defects in higher class pipe, which is in contrary to the basic design concept. This is due to the lack of consideration for the higher consequences in the higher classes even though they were considered at the design stage. To ensure the failure probability within a target value, generic fitness for service standards such as API 579-1/ASME FFS-1 and BS 7910 recommend partial safety factors (PSFs) to key variables. However, there is no correlation between the design factors used during the pipeline design stage and the PSFs used for the ECA. To achieve the basic intent of design code i.e., to maintain risk level as per location classifications, this paper proposes to use PSFs based on class location. Few case studies are presented to demonstrate the proposed methodology.
Fugitive Emission for Different Seals and Flange Designs – Test Results and Design Prediction
Authors: Wellings Stuart , Lutkiewicz Przemyslaw , Robertson David 
Published: November 2022

Abstract
In today’s environment, the functionality of a sealing solution is highly valued. The ability to provide a solution with high sealing integrity and low fugitive emissions follows the industry trend for developing a more environmentally friendly solution. There are some existing standards and methodologies that provide a basis for practical testing activities. Other methodologies, such as FEA and hand calculations, are available to evaluate the seal tightness on a theoretical basis during the design stage and predict fugitive emissions values. Test measurement for fugitive emissions is subject to the design of the flange and seal components, the quality of those components, and the test set-up methods employed. This paper will focus on the comparison of different flange designs currently available in the market, as well as a comparison of various metal to metal seal types. The scope of this paper covers flanges designed to ASME B16.5, API 6A, non-standard flanges (e.g. compact flanges) as well as clamp connectors. For metal seals, this paper will cover HX, BX and Techlok seal rings. Test methodologies and set up will be detailed and the test results listed, with the theoretical predicted fugitive emissions values also provided for comparison. Results for previous compact flange analysis are also included for reference.
Environmentally Assisted Fatigue Screening Process Application
Authors: Li Jia , De Baglion Laurent 
Published: November 2022

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.