An Approach for Evaluating the Integrity of Plain Dents Reported by In-Line Inspection Tools

2012 ◽  
Author(s):  
Joseph P. Bratton ◽  
Tom Alexander ◽  
Thomas A. Bubenik ◽  
Shane Finneran ◽  
Hans Olav Heggen
Keyword(s):  
Dynamic Pressure ◽  
Equivalent Stress ◽  
The United States ◽  
Peak Strain ◽  
Maximum Strain ◽  
Element Analysis ◽  
Pressure Cycling ◽  
Pressure Cycle ◽  
Integrity Management ◽  
Rainflow Cycle Counting

Current federal regulations in the U.S. require excavation of plain dents identified through in-line inspection surveys based primarily on depth. Industry experience, and previous research, has shown that the depth of the dent, alone, is not sufficient to assess dent severity and that releases could occur at dents below the excavation threshold (Dawson, 2006). Canada’s National Energy Board released a safety advisory on June 18, 2010, to all companies under their jurisdiction regarding two incidents involving shallow dents. The safety advisory stated that all integrity management programs should be reviewed and updated where appropriate to address the threat posed by shallow dents. Similar incidents have raised awareness in the United States and elsewhere around the world. This paper focuses on the fitness for service of dents identified by in-line inspection surveys. The fitness for service assessment provides an estimated remaining life of a dent based on the geometry of the dent and current pressure cycling of the pipeline. Dynamic pressure cycling at each dent location is estimated using the upstream and downstream pressure cycle data, elevation, and distance along the pipe. The dynamic pressure cycle data at each dent is then converted into equivalent stress cycles based on the results of rainflow cycle counting. Maximum strain levels of the dents are calculated based on the geometry of the dent as determined by radial sensor measurements from the in-line inspection survey. The combination of assessment methods provides estimates of remaining fatigue life and peak strain which can be used for prioritizing the investigation and remediation of plain dents in pipelines. Finite element analysis (FEA) is performed for one dent to calculate the maximum strain levels and identify stress concentration areas. These results are compared with the values applied during the fitness for service assessment to validate the accuracy and conservatism of the calculation methods used. An idealized dent will be analyzed to investigate the strain calculations in ASME B31.8 and localize maximum strain values.

Fitness for Service of Dents Associated With Metal Loss due to Corrosion

2014 ◽  
Author(s):  
Hans Olav Heggen ◽  
Joe Bratton ◽  
David Kemp ◽  
Jun Liu ◽  
Jason Austin
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Maximum Stress ◽  
Dynamic Pressure ◽  
Equivalent Stress ◽  
Metal Loss ◽  
General Effect ◽  
Element Analysis ◽  
Pressure Cycling ◽  
Pressure Cycle

Current federal regulations in the U.S. require excavation of all dents associated with metal loss due to corrosion identified through in line inspection surveys. Once a dent has been found to be associated with metal loss through excavation, there is little guidance to determine the serviceability of the anomaly. Past research has provided methodologies to assess the fatigue life of plain dents, considering the shape of the dent, but there are no widely accepted assessment methodologies to predict the effect of associated metal loss due to corrosion on the fatigue life of dents. This paper focuses on the fitness for service of dents associated with metal loss, particularly corrosion in dents. Currently, fitness for service assessments of plain dents provide an estimated remaining life of a dent based on the geometry of the dent and current pressure cycling of the pipeline. Dynamic pressure cycling at each dent location is estimated using the upstream and downstream pressure cycle data, elevation, and distance along the pipe. The dynamic pressure cycle data at each dent is then converted into equivalent stress cycles based on the results of rainflow cycle counting. Finite element analysis (FEA) of a dent without metal loss and with metal loss is performed to compare the maximum stress concentration areas. The FEA program Abaqus is used with solid elements to model the dents. The differences between maximum stress concentration areas is compared for a matrix of extent of metal loss, and orientation of metal loss to analyze the general effect of metal loss and the interaction of metal loss in a dent. The stress concentration areas of dents without metal loss and with metal loss are then applied to current fatigue assessment methodologies provided in API 579 to analyze the effect of metal loss on the fatigue life of dents.

Fitness-for-Service of Unconstrained Shallow Dents

2014 ◽  
Author(s):  
Joseph P. Bratton ◽  
Mitch Glass ◽  
Edgar Cote ◽  
Andy Gallagher ◽  
William V. Harper
Keyword(s):  
United States ◽  
The United States ◽  
Federal Regulations ◽  
Maximum Strain ◽  
Service Program ◽  
Remaining Service Life ◽  
The World ◽  
Integrity Management ◽  
Industry Experience ◽  
The U.S

Current federal regulations in the U.S. require excavation of plain dents identified through in line inspection surveys based primarily on depth. Industry experience, and previous research, has shown that the depth of the dent, alone, is not sufficient to assess dent severity and that releases could occur at dents below the excavation threshold (Dawson, 2006). Canada’s National Energy Board released a safety advisory on June 18, 2010, to all companies under their jurisdiction regarding two incidents involving shallow dents. The safety advisory stated that all integrity management programs should be reviewed and updated where appropriate to address the threat posed by shallow dents. Similar incidents have raised awareness in the United States and elsewhere around the world. This paper focuses on an extensive multi-year effort to analyze the fitness for service of unconstrained shallow dents on multiple pipeline systems. Fatigue and strain analyses were performed to determine the serviceability and estimate the remaining service life. The dents in this study included both topside dents and bottomside dents that were previously evaluated through excavation to be unconstrained. Results of the fatigue and strain assessments are presented, along with field results of dents that were chosen for excavation. Comparison of the fitness for service results and subsequent excavation findings were performed to improve an ongoing campaign to prioritize several hundred in-service unconstrained dents. Maximum strain levels of the dents were calculated based on the geometry of the dent as determined by radial sensor measurements from in line inspection surveys. The results of the in-line inspection and field measurement comparisons were analyzed to determine the accuracy and possible adjustments of strain assessments for the ongoing fitness-for-service program.

Live-Load Girder Distribution Factors for Bridges Subjected to Wide Trucks

2000 ◽  
Vol 1696 (1) ◽  
pp. 144-149 ◽  
Author(s):  
Sami W. Tabsh ◽  
Muna Tabatabai
Keyword(s):  
Finite Element ◽  
The United States ◽  
Live Load ◽  
Wheel Load ◽  
Element Analysis ◽  
Load Effect ◽  
Design Specifications ◽  
Girder Bridges ◽  
Girder Distribution Factors ◽  
Modification Factor

An important problem facing engineers and officials in the United States is the constraint imposed on transportation due to limitations of bridges. These limitations typically constrain vehicles to minimum heights and widths, to minimum and maximum lengths, and to a maximum allowable weight. However, with current demands of society and industry, there are times when a truck must carry a load that exceeds the size and weight of the legal limit. In this situation, the trucking company requests from the state departments of transportation an overload permit. For a truck with a wheel gauge larger than 1.8 m (6 ft), the process of issuing a permit for an overload truck requires a tremendous amount of engineering efforts. This is because the wheel load girder distribution factors (GDFs) in the design specifications cannot be used to estimate the live-load effect in the girders. In some cases, an expensive and time-consuming finite element analysis may be needed to check the safety of the structure. In this study, the finite element method is used to develop a modification factor for the GDF in AASHTO’s LRFD Bridge Design Specifications to account for oversized trucks with a wheel gauge larger than 1.8 m. To develop this factor, nine bridges were considered with various numbers of girders, span lengths, girder spacings, and deck slab thicknesses. The results indicated that use of the proposed modification factor with the GDF in the design specifications can help increase the allowable load on slab-on-girder bridges.

Pressure Cycling Monitoring Helps Ensure the Integrity of Energy Pipelines

2010 ◽  
Author(s):  
Peter Song ◽  
Doug Lawrence ◽  
Sean Keane ◽  
Scott Ironside ◽  
Aaron Sutton
Keyword(s):  
Fatigue Life ◽  
Pipeline System ◽  
Outer Diameter ◽  
Operating Pressure ◽  
Potential Growth ◽  
Integrity Assessment ◽  
Pressure Cycling ◽  
Pressure Cycle ◽  
Primary Focus ◽  
Pump Stations

Liquids pipelines undergo pressure cycling as part of normal operations. The source of these fluctuations can be complex, but can include line start-stop during normal pipeline operations, batch pigs by-passing pump stations, product injection or delivery, and unexpected line shut-down events. One of the factors that govern potential growth of flaws by pressure cycle induced fatigue is operational pressure cycles. The severity of these pressure cycles can affect both the need and timing for an integrity assessment. A Pressure Cycling Monitoring (PCM) program was initiated at Enbridge Pipelines Inc. (Enbridge) to monitor the Pressure Cycling Severity (PCS) change with time during line operations. The PCM program has many purposes, but primary focus is to ensure the continued validity of the integrity assessment interval and for early identification of notable changes in operations resulting in fatigue damage. In conducting the PCM program, an estimated fatigue life based on one month or one quarter period of operations is plotted on the PCM graph. The estimated fatigue life is obtained by conducting fatigue analysis using Paris Law equation, a flaw with dimensions proportional to the pipe wall thickness and the outer diameter, and the operating pressure data queried from Enbridge SCADA system. This standardized estimated fatigue life calculation is a measure of the PCS. Trends in PCS overtime can potentially indicate the crack threat susceptibility the integrity assessment interval should be updated. Two examples observed on pipeline segments within Enbridge pipeline system are provided that show the PCS change over time. Conclusions are drawn for the PCM program thereafter.

High-Frequency Vibration Response of Metal Honeycomb Sandwich Structure

2009 ◽  
Vol 79-82 ◽  
pp. 1727-1730 ◽  
Author(s):  
Xiao Dong He ◽  
Xiang Hao Kong ◽  
Li Ping Shi ◽  
Ming Wei Li
Keyword(s):  
High Frequency ◽  
Sandwich Structure ◽  
Dynamic Pressure ◽  
Vibration Response ◽  
Element Analysis ◽  
High Frequency Vibration ◽  
Honeycomb Sandwich ◽  
Vibration Experiment ◽  
Aerial Vehicle ◽  
Honeycomb Sandwich Structure

ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction. So the active environment of metal honeycomb sandwich structure is very formidable. We have to discuss any extreme situation, for reason of making sure aerial vehicle is safe. And high-frequency vibration is one of active environment. In this paper we have analyzed high-frequency vibration response of metal honeycomb sandwich structure. We processed high-frequency vibration experiment by simulating true aerial environment. Sequentially we operated high-frequency vibration experiment of metal honeycomb sandwich structure with cracks, notches and holes. Then finite-element analysis was performed by way of validating the experiment results. Haynes214 is a good high temperature alloy material of both face sheet and core at present, so we choose it in this paper.

Effect of Temperature, Reeling Speed and Pipe Tension on the Performance of Field Joint Coating During Reeling of Offshore Pipelines

2021 ◽  
Author(s):  
Rajaram Dhole ◽  
Ismael Ripoll ◽  
Sabesan Rajaratnam ◽  
Celine Jablonski
Keyword(s):  
Influential Factors ◽  
Influential Factor ◽  
Effect Of Temperature ◽  
Mechanical And Thermal Properties ◽  
Peak Strain ◽  
Element Analysis ◽  
Novel Approach ◽  
Laboratory Test Results ◽  
Coating Design ◽  
Highly Strained

Abstract Pipelines are coated with insulating material that minimizes heat losses to the environment. Reeled pipe can experience nominal bending strain in the order of 1% to 2%. Thick coating on the pipe is inherently more highly strained, because of concentrations that occur at the interface between parent coating and field joint coating. Occasionally, contractors who specialize in pipe-lay using the reeling method have experienced difficulties relating to unexpected disbondment and cracks in coating at these interfaces. Any disbonded coating is routinely identified and repaired, but it is important to understand the influential factors that could lead to this type of coating disbondment. It is known in the industry that parameters such as temperature, reeling speed and pipe tension are influential but the relative influence of the factors is not well understood. In addition, there is currently no industry code or recommended practice that proposes the strain levels that the coating could safely withstand prior to cracking. This paper addresses thermo-mechanical aspects of coating design and presents a novel approach to quantify which parameters have the largest influence. In the presented assessments, coating strain was assessed using finite element analysis. Material input was selected from a combination of typical values and specific laboratory test results for polypropylene (PP) and injection molded polypropylene (IMPP). An essential aspect was that the mechanical and thermal properties of the PP were related to temperature and strain rate. Strain rates in the coating during reeling operations were obtained from global FE models. Detailed local FE models incorporated all the material and load inputs and temperature conditions that are necessary to determine peak strain values in the coating; the peak strain values would indicate the locations of potential coating disbondment. The study is purely a strain assessment and excludes any potential for defects or delamination in the coating that could result from its manufacturing process. This strain-based study revealed that coating temperature during reeling is the most influential factor on strain level in the coating. Reeling speed and pipe tension are parameters providing secondary influences.

Optimization design of titanium alloy connecting rod based on structural topology optimization

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bin Zheng ◽  
Yi Cai ◽  
Kelun Tang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Topology Optimization ◽  
Optimization Design ◽  
Equivalent Stress ◽  
Connecting Rod ◽  
Element Analysis ◽  
Content Type ◽  
The Finite Element Analysis ◽  
Maximum Equivalent Stress

Purpose The purpose of this paper is to realize the lightweight of connecting rod and meet the requirements of low energy consumption and vibration. Based on the structural design of the original connecting rod, the finite element analysis was conducted to reduce the weight and increase the natural frequencies, so as to reduce materials consumption and improve the energy efficiency of internal combustion engine. Design/methodology/approach The finite element analysis, structural optimization design and topology optimization of the connecting rod are applied. Efficient hybrid method is deployed: static and modal analysis; and structure re-design of the connecting rod based on topology optimization. Findings After the optimization of the connecting rod, the weight is reduced from 1.7907 to 1.4875 kg, with a reduction of 16.93%. The maximum equivalent stress of the optimized connecting rod is 183.97 MPa and that of the original structure is 217.18 MPa, with the reduction of 15.62%. The first, second and third natural frequencies of the optimized connecting rod are increased by 8.89%, 8.85% and 11.09%, respectively. Through the finite element analysis and based on the lightweight, the maximum equivalent stress is reduced and the low-order natural frequency is increased. Originality/value This paper presents an optimization method on the connecting rod structure. Based on the statics and modal analysis of the connecting rod and combined with the topology optimization, the size of the connecting rod is improved, and the static and dynamic characteristics of the optimized connecting rod are improved.

scholarly journals Researches regarding the modernizing of hydro-technical designing through assisted designing

2021 ◽  
Vol 11 (5) ◽  
pp. 78-84
Author(s):  
Marin Silviu Nan ◽  
Iosif Kovacs ◽  
Aurelian Horia Nicola ◽  
Daniel Cosmin Vitan
Keyword(s):  
Hydrostatic Pressure ◽  
Dynamic Pressure ◽  
Mechanical Action ◽  
Simulation Software ◽  
Water Pipe ◽  
Inclined Plane ◽  
Element Analysis ◽  
Main Stress ◽  
Physical Chemical ◽  
Technical Construction

Hydro-technical works differ from the other engineering constructions due to the fact that they are subject to water influence. In nature, water exerts mechanical, physical, chemical and biological actions. Water’s mechanical action is expressed by hydrostatic pressure and dynamic pressure. Hydrostatic pressure represents the main stress, which generally determines the form and size of hydro- technical construction. As a rule, dynamic pressure is exerted by water in motion upon the elements it enters into contact. The present paper present with the dimensioning of the pipe segments, focusing on the joining of these and the simulation in conditions as close as possible to reality, of the water pipe, within the help of finite element analysis, but also with specialized simulation software. After analysis, verification and fabrication of the pipe segments, they must be transported and mounted on the inclined plane. The constructive solution of the transport sleigh for the pipes transported on the inclined plane is also verified at requests with the help of the Solid Work software, in order to be able to use it in safe conditions.

Improved Semi-Quantitative Reliability-Based Method for Assessment of Pipeline Dents With Stress Risers

2020 ◽  
Author(s):  
Amandeep Singh Virk ◽  
Doug Langer ◽  
Janine Woo ◽  
Nader Yoosef-Ghodsi ◽  
Muntaseer Kainat
Keyword(s):  
The United States ◽  
Radius Of Curvature ◽  
Pressure Cycling ◽  
Stress Risers ◽  
Fitting Method ◽  
Quantitative Analysis Method ◽  
Comprehensive Reliability ◽  
Reported Data ◽  
Improved Model ◽  
Integrity Analysis

Abstract Dents, especially those interacting with stress risers, can pose integrity threats to pipeline systems. Regulations in Canada and the United States mandate the repair of dents based on depth and interaction with stress risers, however, there have been cases in the past where dents that have passed these criteria have ended up in loss of containment. Recent industry’s recommendations regarding dent integrity analysis are predominantly based on strain, and the dent-fatigue models have been proven to be limited in their application. Additionally, these models or methodologies are generally deterministic which may not fully account for uncertainties associated with pipe properties and in-line inspection (ILI) tool measurement. Enbridge Liquid Pipelines Inc. had previously presented a framework to support system wide dent assessment with an efficient probabilistic-based calibrated semi-quantitative analysis method for dents (SQuAD), which elicits potentially injurious features from thousands of features within a system in a reasonable analysis timeframe. This paper expands on the authors’ previous work and presents several improvements that have since been made to the SQuAD model to address the limitations in the initial version of the model. The previous version of SQuAD was strain-based and did not explicitly account for pressure-cycling induced, fatigue-based failure quantitatively. An approximate circle fitting method was adopted for estimating the dent’s radii of curvature in order to calculate strains. In the improved model, filtering techniques have been employed to reduce the noise in the ILI-reported data while preserving the dent shape. Furthermore, a simplified FEA process has been developed to calculate the stresses within a dent due to pressure cycles, thus the fatigue-based Probability of Failure (PoF) of a dent can now be estimated using S-N approach. The filtered data allows for better accuracy in quantifying the radius of curvature of dents as reported by ILI tools, which are used for calculating dent strain as recommended in the updated version of ASME B31.8, Appendix R. Finally, the feasibility of applying this improved SQuAD model is discussed from an operator’s perspective. The improvements allow the enhanced SQuAD model to be used as an effective screening tool on a system-wide basis as part of a comprehensive, reliability-based dent assessment framework.

scholarly journals The Wall Apposition Evaluation for a Mechanical Embolus Retrieval Device

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Xuelian Gu ◽  
Yongxiang Qi ◽  
Arthur G. Erdman
Keyword(s):  
Close Contact ◽  
Peak Strain ◽  
Element Analysis ◽  
Evaluation Approach ◽  
Intracranial Vessel ◽  
Computational Evaluation ◽  
Unit Cells ◽  
Wall Apposition ◽  
System Migration ◽  
Retrieval Device

A computational evaluation approach to the wall apposition of a cerebral mechanical emboli retrieval device (MERD) is presented. The typical enclosed multilattice structure, manufactured from the thin-walled Nitinol tube, consists of repeated “V”-shaped unit cells. During interventional thrombectomy, the MERD system is delivered inside an artery stenosis segment to capture emboli and restore cerebral blood flow. The wall apposition, which deteriorates during embolus capture, occurs during system migration along the tortuous intracranial vessel. The commercial finite element analysis (FEA) solver ABAQUS 6.10 Standard and user subroutine (UMAT/Nitinol) are utilized to study the ability to remain in close contact with the curved vessel wall during migration. In this numerical analysis, the influence of the contacting interference loadings on structure deformation and strain field distribution is obtained and analyzed. The results indicate that the middle segment of the MERD seriously contracts or collapses inside the curved vessel. In addition, the peak strain is in the apex flow-prone region and maintains at the safe range.

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