Stress Analysis of Lifting and Lowering-In Process

2014 ◽  
Author(s):  
Fan Zhang ◽  
Ming Liu ◽  
Yong-Yi Wang ◽  
William A. Bruce
Keyword(s):  
Vertical Plane ◽  
Ground Movement ◽  
Lateral Movement ◽  
Combined Stress ◽  
Acceptance Criteria ◽  
Element Analysis ◽  
Bending Stresses ◽  
Cross Country ◽  
Potential Damage

For typical cross-country pipelines not expected to experience ground movement hazards, the longitudinal stresses experienced during lifting and lowering-in are typically the highest that they experience in their entire service life. Vertical bending stresses are produced by the curvature created from the upward lifting forces of the sidebooms and the downward force of the pipe weight. Horizontal bending stresses are produced due to the lateral movement of the pipe when the pipe string is moved from its support position on the side of trench to the center of the trench. It is critical to limit the stresses during lifting and lowering-in so that potential damage to the pipeline is avoided. For pipelines constructed using an engineering critical assessment (ECA) based flaw acceptance criteria, stresses must be controlled below the limit established during the development of the flaw acceptance criteria. However, there is little in the way of formal guidance in current codes and standards for controlling stresses during the lifting and lowering-in process. This paper is part of a long-term effort being sponsored primarily by Pipeline Research Council International (PRCI) to develop general construction guidelines that can be used to manage lifting and lowering-in stresses during pipeline construction. In this paper, the stresses during lifting and lowering-in on normally flat terrain were studied. The component of stress due to bending in the horizontal plane was determined through an analytical method. The component of stress due to the bending in the vertical plane was studied by finite element analysis (FEA). The FEA determined the stresses under various profiles. Recommended lifting profiles in the format of lifting height ranges were developed. The combined stress was then determined from the two components. In addition, FEA was used to simulate the lifting and lowering-in process of a pipe string including a field side bend. The results show that the side bend produces a very slight increase in the stress level. More work is being performed to investigate various other scenarios of field and pipe string conditions.

Rational Limits of High-Low Misalignment in Girth Welds

2020 ◽  
Author(s):  
Banglin Liu ◽  
Yong-Yi Wang ◽  
Dan Jia ◽  
Steve Rapp
Keyword(s):  
Pipe Wall ◽  
Safety Margin ◽  
Bending Stress ◽  
Test Program ◽  
Acceptance Criteria ◽  
Element Analysis ◽  
Wide Range ◽  
Capacity Reduction ◽  
Girth Welds

Abstract High-low misalignment in girth welds introduces local bending stress and thus can potentially have detrimental effects on the stress capacity of girth welds. However, long-term pipeline service experience demonstrates that high levels of high-low misalignment do not always lead to reductions in the safety and integrity of pipelines. This paper discusses a PRCI-funded work that aimed to understand the impacts of misalignment on the integrity of girth welds and develop rational limits for misalignment for incorporation into existing standards. Two sets of recommendations were developed: (1) recommendations on the incorporation of rational limits for misalignment into workmanship criteria, and (2) recommendations on rational limits for misalignment for application in alternative flaw acceptance criteria, such that those in API 1104 Annex A and CSA Z662 Annex K. The recommendations for the workmanship criteria utilize extra weld reinforcement to compensate for stress capacity reduction due to misalignment. The recommendations consist of minimum values for key weld dimensions for a wide range of pipe wall thicknesses. The recommendations were developed based on a cross-weld tensile (CWT) test program and were validated using targeted finite element analysis (FEA). The recommendations for the application of the engineering critical assessment (ECA) procedures provide a maximum permissible misalignment level, up to which the ECA procedures produce sufficiently conservative flaw acceptance criteria without needing to correct for misalignment. The maximum permissible misalignment was based on comparisons between FEA and the API 1104 Annex A ECA procedures. A concept of a safety margin was introduced to quantify the conservatism built into the Annex A procedures and to derive a maximum allowable misalignment value.

Influence of Permeability on the Compressive Property of Articular Cartilage: A Scaffold-Free, Stem Cell-Based Therapy for Cartilage Repair

2011 ◽  
Author(s):  
Tomoya Susa ◽  
Ryosuke Nansai ◽  
Norimasa Nakamura ◽  
Hiromichi Fujie
Keyword(s):  
Articular Cartilage ◽  
Superficial Layer ◽  
Cell Delivery ◽  
Compressive Property ◽  
Chondral Defect ◽  
Element Analysis ◽  
Normal Cartilage ◽  
Cell Based Therapy ◽  
Immunological Effects

Since the healing capacity of articular cartilage is limited, it is important to develop cell-based therapies for the repair of cartilage. Although synthetic or animal-derived scaffolds are frequently used for effective cell delivery long-term safety and efficiency of such scaffolds still remain unclear. We have been studying on a scaffold-free tissue engineered construct (TEC) bio-synthesized from synovium-derived mesenchymal stem cells (MSCs) [1]. As the TEC specimen is composed of cells with their native extracellular matrix, we believe that it is free from concern regarding long term immunological effects. our previous studies indicated that a porcine partial thickness chondral defect was successfully repaired with TEC but that the compressive property of the TEC-treated cartilage-like repaired tissue was different from normal cartilage in both immature and mature animals. Imura et al. found that the permeability of the immature porcine cartilage-like tissues repaired with TEC recovered to normal level for 6 months except the superficial layer [2]. Therefore, the present study was performed to determine the depth-dependent permeability of mature porcine cartilage-like tissue repaired with TEC. Moreover, we investigated the effect of difference of permeability on the compressive property of articular cartilage using a finite element analysis (FEM).

scholarly journals Long-Term Incidence of Atrial Fibrillation and Stroke Among Cross-Country Skiers: Cohort Study of Endurance-Trained Male and Female Athletes

Circulation ◽  
2019 ◽  
Author(s):  
Niclas Svedberg ◽  
Johan Sundström ◽  
Stefan James ◽  
Ulf Hållmarker ◽  
Kristina Hambraeus ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cohort Study ◽  
Female Athletes ◽  
Male And Female ◽  
Cross Country

Pipeline Geohazard Assessment: Bridging the Gap Between Integrity Management and Construction Safety Contexts

2018 ◽  
Author(s):  
Rodney S. Read
Keyword(s):  
Construction Safety ◽  
Worker Safety ◽  
Ground Movement ◽  
Pipeline Construction ◽  
Probability Estimates ◽  
Subject Matter Expertise ◽  
Management Context ◽  
Integrity Management ◽  
Geohazard Assessment

Geohazards are threats of a geological, geotechnical, hydrological, or seismic/tectonic nature that may negatively affect people, infrastructure and/or the environment. In a pipeline integrity management context, geohazards are considered under the time-independent threat category of Weather-related and Outside Force in the American standard ASME B31.8S. Geotechnical failure of pipelines due to ground movement is addressed in Annex H and elsewhere in the Canadian standard CSA-Z662. Both of these standards allow flexibility in terms of geohazard assessment as part of pipeline integrity management. As a result of this flexibility, many systems for identifying, characterizing, analyzing and managing geohazards have been developed by operators and geotechnical engineering practitioners. The evolution of these systems, and general expectations regarding geohazard assessment, toward quantitative geohazard frequency assessment is a trend in recent pipeline hearings and regulatory filings in Canada. While this trend is intended to frame geohazard assessment in an objective and repeatable manner, partitioning the assessment into a series of conditional probability estimates, the reality is that there is always an element of subjectivity in assigning these conditional probabilities, requiring subject matter expertise and expert judgment to make informed and defensible decisions. Defining a specific risk context (typically loss of containment from a pipeline) and communicating uncertainty are important aspects of applying these types of systems. Adoption of these approaches for alternate risk contexts, such as worker safety during pipeline construction, is challenging in that the specific geohazards and threat scenarios considered for long-term pipeline integrity may or may not adequately represent all credible threats during pipeline construction. This paper explores the commonalities and differences in short- and long-term framing of geohazard assessment, and offers guidance for extending geohazard assessment for long-term pipeline integrity to other contexts such as construction safety.

scholarly journals Analysis of Non-Uniform Shrinkage Effect in Box Girder Sections for Long-Span Continuous Rigid Frame Bridge

2018 ◽  
Vol 13 (2) ◽  
pp. 146-155 ◽  
Author(s):  
Zhuoya Yuan ◽  
Pui-Lam Ng ◽  
Darius Bačinskas ◽  
Jinsheng Du
Keyword(s):  
Finite Element ◽  
General Purpose ◽  
Element Analysis ◽  
Box Girder ◽  
Finite Element Program ◽  
Continuous Rigid Frame Bridge ◽  
Rigid Frame ◽  
Shrinkage Effect ◽  
Rigid Frame Bridge

To consider the effect of non-uniform shrinkage of box girder sections on the long-term deformations of continuous rigid frame bridges, and to improve the prediction accuracy of analysis in the design phase, this paper proposes a new simulation technique for use with general-purpose finite element program. The non-uniform shrinkage effect of the box girder is transformed to an equivalent temperature gradient and then applied as external load onto the beam elements in the finite element analysis. Comparative analysis of the difference in deflections between uniform shrinkage and nonuniform shrinkage of the main girder was made for a vehicular bridge in reality using the proposed technique. The results indicate that the maximum deflection of box girder under the action of non-uniform shrinkage is much greater than that under the action of uniform shrinkage. The maximum downward deflection of the bridge girder caused by uniform shrinkage is 5.6 mm at 20 years after completion of bridge deck construction, whereas the maximum downward deflection caused by non-uniform shrinkage is 21.6 mm, which is 3.8 times larger. This study shows that the non-uniform shrinkage effect of the girder sections has a significant impact on the long-term deflection of continuous rigid frame bridge, and it can be accurately simulated by the proposed transformation technique.

scholarly journals A Novel Method for Tooth Bending Stress Calculation of Gears With Asymmetric Teeth

2021 ◽  
Author(s):  
Oguz DOGAN ◽  
Celalettin YUCE ◽  
Fatih KARPAT
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Bending Stress ◽  
Element Analysis ◽  
Stress Calculation ◽  
Bending Stresses ◽  
New Equation ◽  
Asymmetric Factor

Abstract Today, gear designs with asymmetric tooth profiles offer essential solutions in reducing tooth root stresses of gears. Although numerical, analytical, and experimental studies are carried out to calculate the bending stresses in gears with asymmetric tooth profiles a standard or a simplified equation or empirical statement has not been encountered in the literature. In this study, a novel bending stress calculation procedure for gears with asymmetric tooth profiles is developed using both the DIN3990 standard and the finite element method. The bending stresses of gears with symmetrical profile were determined by the developed finite element model and was verified by comparing the results with the DIN 3990 standard. Using the verified finite element model, by changing the drive side pressure angle between 20° and 30° and the number of teeth between 18 and 100, 66 different cases were examined and the bending stresses in gears with asymmetric profile were determined. As a result of the analysis, a new asymmetric factor was derived. By adding the obtained asymmetric factor to the DIN 3390 formula, a new equation has been derived to be used in tooth bending stresses of gears with asymmetric profile. Thanks to this equation, designers will be able to calculate tooth bending stresses with high precision in gears with asymmetric tooth profile without the need for finite element analysis.

scholarly journals Topology Optimization of Spiral Bevel Gear for Differential

2020 ◽  
Vol 9 (3) ◽  
pp. 1205-1209
Keyword(s):  
Taguchi Method ◽  
Optimal Parameter ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Element Analysis ◽  
Differential Gear ◽  
Bending Stresses ◽  
Spiral Bevel ◽  
Time Required ◽  
Sufficient Strength

The Spiral Bevel gear used in differential should be enough stiff to resist the vibrations and stresses encountered during its operation. The gear must also have sufficient strength to bear the bending stresses occurring in the differential assembly in its course of operation. This research is typically focused in designing a differential gear with least weight and minimal stresses. The model of the gear is designed in the Solidworks version 2015 while its analysis is carried in ANSYS 14.5. The number of parameters and levels involved in designing are more; the number of probable models is too many. To choose the optimal parameter among the list of choices, TAGUCHI method along with Finite Element Analysis (FEA) is used. By application of TAGUCHI method, not only the time required to design all the probable models is reduced, but also the time required to analyze all the models is cut down. Orthogonal Array has been incorporated to change the parameters necessary for reducing the weight of the gear. To get the best possible model of gear, FEA is then performed on the designed models. This process not only saves production time, but also prevents material wastage and production cost.

Quantification of ESG Regulations: A Cross-Country Benchmarking Analysis

2021 ◽  
pp. 097226292110541
Author(s):  
Monica Singhania ◽  
Neha Saini
Keyword(s):  
South Africa ◽  
Sustainable Development ◽  
Early Stage ◽  
Well Being ◽  
Financial Information ◽  
Social Awareness ◽  
Financial Disclosures ◽  
Cross Country ◽  
Economic Choices

Environmental, social and governance (ESG) criteria mean investment in economic choices which, without interference with the environment, are intended to promote long-term economic and social well-being. Due to high environmental and social awareness, customers expect companies to devote time and efforts to such sustainable practices. This attitude has led to an overall rise in ESG disclosures and reporting instruments globally with a focus on influence of ESG disclosures on financial performance of companies. Many European countries have already introduced mandatory disclosure of non-financial information. This transition from voluntary to mandatory motivated other countries to adopt mandatory ESG disclosure practices for sustainable development. The practice of reporting non-financial disclosures has been rising due to several reasons, such as increasing visibility, informing customers, avoiding the risk associated with firm performance and achieving sustainability. Countries in the early stages of ESG disclosure need to understand the benchmark practices used by countries with a well-developed ESG system. For preparing the ESG disclosure index and benchmarking based on disclosure score, this study considers a set of developed and developing countries with their ESG disclosures. On the basis of ESG disclosures, the countries have been classified into four different categories. We found Norway, Sweden, Denmark, Finland, United Kingdom, Belgium and France, to have high ESG scores and have been classified as Countries with Well-Developed ESG Framework. Germany, Italy, USA, Australia, Switzerland, Canada, Japan, Brazil and South Africa have medium to high ESG scores and fall under the category Rapidly improving ESG framework. While Singapore, India, China, Philippines, Malaysia and Argentina are categorized as countries with ESG framework at developing stage, Russia, Indonesia, Thailand, Nigeria and Vietnam are classified as Countries with early-stage framework due to low ESG scores.

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