Pipeline operators’ utmost priority is to achieve high safety measures during the lifecycle of pipelines including effective management of integrity threats during excavation and repair processes. A single incident pertaining to a mechanical damage in a gas pipeline has been reported previously which resulted in one fatality and one injury during investigation. Some operators have reported leaking cracks while investigating rock induced dents. Excavation under full operating pressure can lead to changes in boundary conditions and unexpected loads, resulting in failure, injuries, or fatalities. In the meantime, lowering operating pressure during excavation can have a significant impact on production and operational availability. The situation poses two conflicting objectives; namely, maximizing safety and maximizing operational availability. Current pipeline regulations require that operators have to ensure safe working conditions by depressurizing the line to a level that will not cause a failure during the repair process. However, there are no detailed guidelines on how an operator should determine a safe excavation pressure (SEP) level, which could lead to engineering judgment and subjectivity in determining such safety level. While the pipeline industry relies on well-defined fitness for purpose analyses for threats such as crack and corrosion, there is a gap in defining a fitness for purpose for dents and dents associated with stress riser features in order to set an SEP. Stress and strain based assessment of dents can be used in this matter; however, it requires advanced techniques to account for geometric and material nonlinearity. Additionally, loading and unloading scenarios during excavation (e.g. removal of indenter, overburden pressure, etc.) drive a change in the boundary conditions of the pipe that could lead to leakage. Nevertheless, crack initiation or presence within a dent should be considered, which requires the incorporation of crack geometry and application of fracture mechanics in assessing a safe excavation pressure. Recently, there have been advancements in stress and strain based finite element analysis (FEA) of dents coupled with structural reliability analysis that can be utilized to assess SEP. This paper presents a reliability-based approach to determine a safe excavation pressure for dented liquid pipelines. The approach employs nonlinear FEA to model dents interacting with crack features coupled with uncertainties associated with pipe properties and in-line-inspection information. A fracture mechanics-based limit state is formulated to estimate the probability of failure of dents associated with cracks at different levels of operating pressure during excavation. The application of the developed approach is demonstrated through examples within limited scope. Recommended enhancements and future developments of the proposed approach are also discussed.
{"title":"Do We Need a Safe Excavation Pressure for Dented Pipelines: How Should it Be Defined?","authors":"Muntaseer Kainat, Doug Langer, S. Hassanien","doi":"10.1115/IPC2018-78376","DOIUrl":"https://doi.org/10.1115/IPC2018-78376","url":null,"abstract":"Pipeline operators’ utmost priority is to achieve high safety measures during the lifecycle of pipelines including effective management of integrity threats during excavation and repair processes. A single incident pertaining to a mechanical damage in a gas pipeline has been reported previously which resulted in one fatality and one injury during investigation. Some operators have reported leaking cracks while investigating rock induced dents. Excavation under full operating pressure can lead to changes in boundary conditions and unexpected loads, resulting in failure, injuries, or fatalities. In the meantime, lowering operating pressure during excavation can have a significant impact on production and operational availability. The situation poses two conflicting objectives; namely, maximizing safety and maximizing operational availability. Current pipeline regulations require that operators have to ensure safe working conditions by depressurizing the line to a level that will not cause a failure during the repair process. However, there are no detailed guidelines on how an operator should determine a safe excavation pressure (SEP) level, which could lead to engineering judgment and subjectivity in determining such safety level. While the pipeline industry relies on well-defined fitness for purpose analyses for threats such as crack and corrosion, there is a gap in defining a fitness for purpose for dents and dents associated with stress riser features in order to set an SEP. Stress and strain based assessment of dents can be used in this matter; however, it requires advanced techniques to account for geometric and material nonlinearity. Additionally, loading and unloading scenarios during excavation (e.g. removal of indenter, overburden pressure, etc.) drive a change in the boundary conditions of the pipe that could lead to leakage. Nevertheless, crack initiation or presence within a dent should be considered, which requires the incorporation of crack geometry and application of fracture mechanics in assessing a safe excavation pressure. Recently, there have been advancements in stress and strain based finite element analysis (FEA) of dents coupled with structural reliability analysis that can be utilized to assess SEP. This paper presents a reliability-based approach to determine a safe excavation pressure for dented liquid pipelines. The approach employs nonlinear FEA to model dents interacting with crack features coupled with uncertainties associated with pipe properties and in-line-inspection information. A fracture mechanics-based limit state is formulated to estimate the probability of failure of dents associated with cracks at different levels of operating pressure during excavation. The application of the developed approach is demonstrated through examples within limited scope. Recommended enhancements and future developments of the proposed approach are also discussed.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"168 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114523271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the pipeline industry, a widely accepted methodology for integrity crack management involves running ultrasonic In-Line Inspection (ILI) technologies. After an ILI tool run is completed, the performance of the tool is typically validated by excavating the pipeline and conducting in-the-ditch investigations. Ultrasonic Non-Destructive Evaluation (NDE) techniques are used in the field to characterize and measure crack-like features. These in-the-ditch measurements are compared back to ILI results in order to validate tool performance and drive continuous technology improvements. Since validation of the ILI tool relies on NDE measurements, acquiring accurate and representative data in the field is a critical step in this integrity crack management approach. Achieving an accurate field inspection comes with its challenges, some of which relate to complex long seam weld conditions present in older vintage pipelines including: weld misalignment, weld trim issues, and dense populations of manufacturing anomalies. In order to better understand the challenges associated with complex long seam weld conditions, an evaluation and comparison of the performance of NDE technologies currently available was conducted. In this study, a portion of a Canadian pipeline with complex long seam weld conditions was cut-out and removed from service. Multiple NDE crack inspection technologies and methods from three different vendors were used to assess the condition of the long seam weld. Conventional Ultrasonic Testing (UT), Phased Array Ultrasonic Testing (PAUT), Time of Flight Diffraction (TOFD), and variations of Full Matrix Capture Ultrasonic Testing (FMCUT) were used to assess the long seam weld and their results were compared. The performance of all NDE technologies is baselined by comparing them with destructive examination of sections of the long seam weld. The newer NDE assessment methodologies were shown to be consistently more accurate in characterizing long seam features.
{"title":"Ultrasonic NDE Technology Comparison for Measurement of Long Seam Weld Anomalies in Low Frequency Electric Resistance Welded Pipe","authors":"Luis A. Torres, M. Fowler, Jason Bergman","doi":"10.1115/IPC2018-78704","DOIUrl":"https://doi.org/10.1115/IPC2018-78704","url":null,"abstract":"In the pipeline industry, a widely accepted methodology for integrity crack management involves running ultrasonic In-Line Inspection (ILI) technologies. After an ILI tool run is completed, the performance of the tool is typically validated by excavating the pipeline and conducting in-the-ditch investigations. Ultrasonic Non-Destructive Evaluation (NDE) techniques are used in the field to characterize and measure crack-like features. These in-the-ditch measurements are compared back to ILI results in order to validate tool performance and drive continuous technology improvements. Since validation of the ILI tool relies on NDE measurements, acquiring accurate and representative data in the field is a critical step in this integrity crack management approach. Achieving an accurate field inspection comes with its challenges, some of which relate to complex long seam weld conditions present in older vintage pipelines including: weld misalignment, weld trim issues, and dense populations of manufacturing anomalies. In order to better understand the challenges associated with complex long seam weld conditions, an evaluation and comparison of the performance of NDE technologies currently available was conducted.\u0000 In this study, a portion of a Canadian pipeline with complex long seam weld conditions was cut-out and removed from service. Multiple NDE crack inspection technologies and methods from three different vendors were used to assess the condition of the long seam weld. Conventional Ultrasonic Testing (UT), Phased Array Ultrasonic Testing (PAUT), Time of Flight Diffraction (TOFD), and variations of Full Matrix Capture Ultrasonic Testing (FMCUT) were used to assess the long seam weld and their results were compared. The performance of all NDE technologies is baselined by comparing them with destructive examination of sections of the long seam weld. The newer NDE assessment methodologies were shown to be consistently more accurate in characterizing long seam features.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126963861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Bondurant, K. Farrag, H. Kannajosyula, M. Droessler, T. Mactutis
This paper presents the development and testing of an Electro-Magnetic Acoustic Transducer (EMAT) sensor prototype to detect and quantify longitudinal cracks in small diameter and difficult to inspect or unpiggable gas pipelines. The development of the system was a collaborative and jointly-funded work between Quest Integrated, Gas Technology Institute, Operations Technology Development, and US DOT, Pipeline Hazardous Material Safety Admin (PHMSA). The initial focus for the project was to inspect 8-inch (200 mm) diameter pipes with robotic or tethered towing, with the eventual goal of a free-swimming tool. A bench scale lab prototype has been successfully completed and tested in Phase 1 of the project in 2016. The prototype demonstrated the basic approach of a EMAT tool for crack detection and sizing that could be packaged into a single module, had reasonable flaw depth sensitivity, was bidirectional, and could negotiate a 1.5 D bend. Phase 2 focused on identifying and solving additional implementation issues, developing a more hardened tool for field pull testing, improving flaw sizing, and the necessary internal electronics and processing algorithms. The prototype recently developed in Phase 2 was tested in an extended length of 8-inch diameter steel pipe with pre-set and controlled longitudinal cracks. The results demonstrated the applicability of the integrated prototype in locating and sizing multiple flaws in the axial direction. This paper discusses the EMAT sensor development and results of the laboratory testing program.
{"title":"Advanced EMAT Crack Tool for Unpiggable Pipelines","authors":"P. Bondurant, K. Farrag, H. Kannajosyula, M. Droessler, T. Mactutis","doi":"10.1115/IPC2018-78421","DOIUrl":"https://doi.org/10.1115/IPC2018-78421","url":null,"abstract":"This paper presents the development and testing of an Electro-Magnetic Acoustic Transducer (EMAT) sensor prototype to detect and quantify longitudinal cracks in small diameter and difficult to inspect or unpiggable gas pipelines. The development of the system was a collaborative and jointly-funded work between Quest Integrated, Gas Technology Institute, Operations Technology Development, and US DOT, Pipeline Hazardous Material Safety Admin (PHMSA).\u0000 The initial focus for the project was to inspect 8-inch (200 mm) diameter pipes with robotic or tethered towing, with the eventual goal of a free-swimming tool. A bench scale lab prototype has been successfully completed and tested in Phase 1 of the project in 2016. The prototype demonstrated the basic approach of a EMAT tool for crack detection and sizing that could be packaged into a single module, had reasonable flaw depth sensitivity, was bidirectional, and could negotiate a 1.5 D bend.\u0000 Phase 2 focused on identifying and solving additional implementation issues, developing a more hardened tool for field pull testing, improving flaw sizing, and the necessary internal electronics and processing algorithms. The prototype recently developed in Phase 2 was tested in an extended length of 8-inch diameter steel pipe with pre-set and controlled longitudinal cracks. The results demonstrated the applicability of the integrated prototype in locating and sizing multiple flaws in the axial direction.\u0000 This paper discusses the EMAT sensor development and results of the laboratory testing program.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116093569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While In-line Inspection Magnetic Flux Leakage (MFL) tools have been used for many years to successfully manage corrosion related threats, small pinhole-sized metal-loss anomalies remain a significant concern to pipeline operators. These anomalies can grow undetected to develop leaks and cause significant consequences. The physical dimensions of these anomalies, their proximity to and/or interaction with other nearby anomalies can challenge MFL’s detection and sizing capabilities. Other factors such as tool speed, cleanliness of the line and incorrect assumptions have an impact as well. For pipeline operators to develop effective and efficient mitigation programs and to estimate risks to an asset, the underlying uncertainties in detection and sizing of pinholes need to be well understood. By using magnetic modeling software, the MFL response of metal-loss anomalies can be determined, and the effect of a number of factors such as radial position, wall thickness, depth profile, pipe cleanliness and tool speed on MFL response and reporting accuracy can be determined. This paper investigates these factors to determine the leading causes of uncertainties involved in the detection and sizing of pinhole corrosion. The understanding of these uncertainties should lead to improvements in integrity management of pinhole for pipeline operators. This paper first investigates the physical measurement methodology of MFL tools to understand the limitations of MFL technology. Then, comparisons of actual MFL data with field excavation results were studied, to understand the limitations of specific MFL technologies. Finally, recommendations are made on how to better use and assess MFL results.
{"title":"Development of Pinhole Corrosion Management Using MFL","authors":"G. Desjardins, J. Falk, V. Vorontsov","doi":"10.1115/IPC2018-78642","DOIUrl":"https://doi.org/10.1115/IPC2018-78642","url":null,"abstract":"While In-line Inspection Magnetic Flux Leakage (MFL) tools have been used for many years to successfully manage corrosion related threats, small pinhole-sized metal-loss anomalies remain a significant concern to pipeline operators. These anomalies can grow undetected to develop leaks and cause significant consequences. The physical dimensions of these anomalies, their proximity to and/or interaction with other nearby anomalies can challenge MFL’s detection and sizing capabilities. Other factors such as tool speed, cleanliness of the line and incorrect assumptions have an impact as well. For pipeline operators to develop effective and efficient mitigation programs and to estimate risks to an asset, the underlying uncertainties in detection and sizing of pinholes need to be well understood.\u0000 By using magnetic modeling software, the MFL response of metal-loss anomalies can be determined, and the effect of a number of factors such as radial position, wall thickness, depth profile, pipe cleanliness and tool speed on MFL response and reporting accuracy can be determined. This paper investigates these factors to determine the leading causes of uncertainties involved in the detection and sizing of pinhole corrosion. The understanding of these uncertainties should lead to improvements in integrity management of pinhole for pipeline operators.\u0000 This paper first investigates the physical measurement methodology of MFL tools to understand the limitations of MFL technology. Then, comparisons of actual MFL data with field excavation results were studied, to understand the limitations of specific MFL technologies. Finally, recommendations are made on how to better use and assess MFL results.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123793605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael Smith, Stefan Cronjaeger, N. Ershad, R. Nickle, Matthias Peussner
Effective integrity management of a corroded pipeline requires a significant quantity of data. Common data sources include in-line inspection (ILI), process monitoring, or external surveys. The key challenge for an integrity engineer is to leverage the data to understand the level of corrosion activity along the pipeline route, and make optimal decisions on future repair, mitigation and monitoring. This practice of gaining business insights from historical datasets is often referred to as ‘data analytics’. In this paper, a single application of data analytics is investigated — that of improving the estimation of corrosion growth rates (CGRs) from ILI data. When two or more sets of ILI data are available for the same pipeline, a process known as ‘box matching’ is typically used to estimate CGRs. Corresponding feature ‘boxes’ are linked between the two ILIs and a population of CGRs is generated based on changes in reported depth. While this is a well-established technique, there are uncertainties related to ILI sizing, detection limitations, and data censoring. Great care is required if these uncertain CGRs are used to predict future pipeline integrity. A superior technique is ‘signal matching’, which involves the direct alignment, normalization and comparison of magnetic flux leakage (MFL) signals. This delivers CGRs with a higher accuracy than box matching. However, signal matching is not always feasible (e.g. when conducting a cross-vendor or cross-technology comparison). When box matching is the only option for a pipeline, there is great value in understanding how the box matching CGRs can be improved in order to more closely resemble those from signal matching. This limits the extent to which uncertainties are propagated into any subsequent analyses, such as repair plan generation or remaining life assessment. Given their relative accuracy, signal matching CGRs can be utilized as a ‘ground truth’ against which box matching results can be validated. This is analogous to the ILI verification process, where in-field measurements (e.g. with laser scan) are used to validate feature depths reported by an ILI. By extension, a model to estimate CGRs following a box matching analysis can be trained with CGRs from a signal matching analysis, using supervised machine learning. The outcome is an enhanced output from box matching, which more closely resembles the true state of corrosion growth in a pipeline. Through testing on real pipeline data, it is shown that this new technique has the potential to improve pipeline integrity management decisions and support economical, safe and compliant operation.
{"title":"Pipeline Data Analytics: Enhanced Corrosion Growth Assessment Through Machine Learning","authors":"Michael Smith, Stefan Cronjaeger, N. Ershad, R. Nickle, Matthias Peussner","doi":"10.1115/IPC2018-78364","DOIUrl":"https://doi.org/10.1115/IPC2018-78364","url":null,"abstract":"Effective integrity management of a corroded pipeline requires a significant quantity of data. Common data sources include in-line inspection (ILI), process monitoring, or external surveys. The key challenge for an integrity engineer is to leverage the data to understand the level of corrosion activity along the pipeline route, and make optimal decisions on future repair, mitigation and monitoring. This practice of gaining business insights from historical datasets is often referred to as ‘data analytics’.\u0000 In this paper, a single application of data analytics is investigated — that of improving the estimation of corrosion growth rates (CGRs) from ILI data. When two or more sets of ILI data are available for the same pipeline, a process known as ‘box matching’ is typically used to estimate CGRs. Corresponding feature ‘boxes’ are linked between the two ILIs and a population of CGRs is generated based on changes in reported depth. While this is a well-established technique, there are uncertainties related to ILI sizing, detection limitations, and data censoring. Great care is required if these uncertain CGRs are used to predict future pipeline integrity.\u0000 A superior technique is ‘signal matching’, which involves the direct alignment, normalization and comparison of magnetic flux leakage (MFL) signals. This delivers CGRs with a higher accuracy than box matching. However, signal matching is not always feasible (e.g. when conducting a cross-vendor or cross-technology comparison). When box matching is the only option for a pipeline, there is great value in understanding how the box matching CGRs can be improved in order to more closely resemble those from signal matching. This limits the extent to which uncertainties are propagated into any subsequent analyses, such as repair plan generation or remaining life assessment.\u0000 Given their relative accuracy, signal matching CGRs can be utilized as a ‘ground truth’ against which box matching results can be validated. This is analogous to the ILI verification process, where in-field measurements (e.g. with laser scan) are used to validate feature depths reported by an ILI. By extension, a model to estimate CGRs following a box matching analysis can be trained with CGRs from a signal matching analysis, using supervised machine learning. The outcome is an enhanced output from box matching, which more closely resembles the true state of corrosion growth in a pipeline.\u0000 Through testing on real pipeline data, it is shown that this new technique has the potential to improve pipeline integrity management decisions and support economical, safe and compliant operation.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125338342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Colonial pipeline’s asset data management team maintains large volumes of data, CAD facility drawings, and historical records. Organizing and encapsulating this data has been a historical challenge. Frequent requests for data relevant to individual projects was time-consuming and laborious. Colonial Scout was designed to be a simple self-help tool that allows employees to locate data quickly. Further, it was constructed to provide a one-stop shop for accessing Colonial data in its most current and up to date forms. Design of the Colonial Scout application took approximately six months to complete. The final result is an intuitive web map application connected to a versioned enterprise geodatabase. Within the application, relevant tools interact with live data, providing immediate access to Colonial’s most up to date information. Integration with FME server, adept document management and Esri’s ArcGIS enterprise have advanced colonial scout’s efficiency in locating data. These software products enhance colonial scout’s power as a help-yourself product for accessing current information through means of helpful data visualization. Colonial Scout is the go to source for alignment sheets, CAD drawings, property and easement records, locating tank assets, and Colonial’s 5,500 miles of pipeline assets. Users also have the ability to download data in a variety of file formats for project specific analysis and reports. Colonial Scout has significantly reduced the number of work orders related to searching for data, drawings and records. Employees are better informed by acquiring the latest information and no longer rely on outdated paper hardcopies. Colonial Scout is an innovative and expandable solution for Colonial’s ever-growing data needs.
{"title":"Colonial Scout: A Powerful Web Map Solution Designed As the Data Messenger for Colonial Pipeline Company","authors":"Eric H. James","doi":"10.1115/IPC2018-78646","DOIUrl":"https://doi.org/10.1115/IPC2018-78646","url":null,"abstract":"Colonial pipeline’s asset data management team maintains large volumes of data, CAD facility drawings, and historical records. Organizing and encapsulating this data has been a historical challenge. Frequent requests for data relevant to individual projects was time-consuming and laborious. Colonial Scout was designed to be a simple self-help tool that allows employees to locate data quickly. Further, it was constructed to provide a one-stop shop for accessing Colonial data in its most current and up to date forms. Design of the Colonial Scout application took approximately six months to complete. The final result is an intuitive web map application connected to a versioned enterprise geodatabase. Within the application, relevant tools interact with live data, providing immediate access to Colonial’s most up to date information. Integration with FME server, adept document management and Esri’s ArcGIS enterprise have advanced colonial scout’s efficiency in locating data. These software products enhance colonial scout’s power as a help-yourself product for accessing current information through means of helpful data visualization. Colonial Scout is the go to source for alignment sheets, CAD drawings, property and easement records, locating tank assets, and Colonial’s 5,500 miles of pipeline assets. Users also have the ability to download data in a variety of file formats for project specific analysis and reports. Colonial Scout has significantly reduced the number of work orders related to searching for data, drawings and records. Employees are better informed by acquiring the latest information and no longer rely on outdated paper hardcopies. Colonial Scout is an innovative and expandable solution for Colonial’s ever-growing data needs.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115169109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High pH Stress Corrosion Cracking (HpHSCC) is a significant threat to the buried pipelines, which are protected through simultaneous coating and cathodic protection strategies. In the past decades, extensive research has been devoted to assessing the influence of environmental and metallurgical factors on the susceptibility to HpHSCC. With reference to mechanical factors, previous studies employed either slow strain rate or constant amplitude testing methods. However, the pressure fluctuation data extracted from pipeline operations has indicated that pipelines experience highly variable amplitude loading conditions during their service. Accordingly, an important consideration in managing HpHSCC is load interaction. Statistics show a higher probability of HpHSCC failures within the 30 km downstream from pump/compressor stations where the pipeline steels experience elevated service temperatures, with incipient higher susceptibility to HpHSCC. However, the pipeline sections within the 30 km downstream from pump/compressor stations also experience the underload-type of pressure fluctuations that feature a maximum pressure close to the design limit, frequent and large amplitudes of depressurization, resulting in low stress ratio, R (minimum stress/maximum stress), and many smaller pressure fluctuations (minor cycles) with R ratio closer to +1.0. It has been well characterized that the underload-minor-cycle-type of pressure fluctuations has the significant acceleration effect on crack growth rates in near-neutral pH (NNpH) environments. However, the effect of the underload-type of pressure schemes on HpHSCC crack growth has not been well developed. In this research work, a cathodically protected X65 steel specimen in the developed high pH solution, composed of 1N Na2CO3 and 1N NaHCO3, was subjected to different loading conditions. These loading waveforms simulate underload cycles (R = 0.5), minor cycles (R = 0.9) and variable amplitudes consisting of both underload and minor cycles, respectively. The HpHSCC test results showed that the highest and lowest crack growth rates were obtained in high and low R ratio constant amplitude loading conditions, respectively. Furthermore, an intermediate crack growth rate was obtained under variable amplitude loading condition. These results indicate that the underload cycles retard crack growth rate in high pH environments.
{"title":"High pH Crack Growth Sensitivity to Underload-Type of Pressure Fluctuations","authors":"H. Niazi, Hao Zhang, K. Korol, Weixing Chen","doi":"10.1115/IPC2018-78394","DOIUrl":"https://doi.org/10.1115/IPC2018-78394","url":null,"abstract":"High pH Stress Corrosion Cracking (HpHSCC) is a significant threat to the buried pipelines, which are protected through simultaneous coating and cathodic protection strategies. In the past decades, extensive research has been devoted to assessing the influence of environmental and metallurgical factors on the susceptibility to HpHSCC. With reference to mechanical factors, previous studies employed either slow strain rate or constant amplitude testing methods. However, the pressure fluctuation data extracted from pipeline operations has indicated that pipelines experience highly variable amplitude loading conditions during their service. Accordingly, an important consideration in managing HpHSCC is load interaction. Statistics show a higher probability of HpHSCC failures within the 30 km downstream from pump/compressor stations where the pipeline steels experience elevated service temperatures, with incipient higher susceptibility to HpHSCC. However, the pipeline sections within the 30 km downstream from pump/compressor stations also experience the underload-type of pressure fluctuations that feature a maximum pressure close to the design limit, frequent and large amplitudes of depressurization, resulting in low stress ratio, R (minimum stress/maximum stress), and many smaller pressure fluctuations (minor cycles) with R ratio closer to +1.0. It has been well characterized that the underload-minor-cycle-type of pressure fluctuations has the significant acceleration effect on crack growth rates in near-neutral pH (NNpH) environments. However, the effect of the underload-type of pressure schemes on HpHSCC crack growth has not been well developed. In this research work, a cathodically protected X65 steel specimen in the developed high pH solution, composed of 1N Na2CO3 and 1N NaHCO3, was subjected to different loading conditions. These loading waveforms simulate underload cycles (R = 0.5), minor cycles (R = 0.9) and variable amplitudes consisting of both underload and minor cycles, respectively. The HpHSCC test results showed that the highest and lowest crack growth rates were obtained in high and low R ratio constant amplitude loading conditions, respectively. Furthermore, an intermediate crack growth rate was obtained under variable amplitude loading condition. These results indicate that the underload cycles retard crack growth rate in high pH environments.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123297040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is generally accepted that hot induction bending (HIB) results in a decrease in strength and an increase in fracture toughness in bend area, heat affected zone (HAZ) and weld metal (WM). As the result, Post bend heat treatment (PBHT) is not considered to be a requirement and could be waived for saving money and time. This research work raises the concern that factual verification of proper microstructure and no localized brittle zone is vitally necessary prior to waving PBHT. Evaluation of the steel microstructure and mechanical properties as the result of various pipe chemistries during pipe bending has been verified in this experimental work. It is emphasized that knowledge and control of prior steel pipe chemistry, control of temperature, cooling rate and bending speed assures the reliability and repeatability of induction bends, especially in critical environments such as low temperature application. In the present work, qualitative and quantitative microstructural analysis, hardness and impact test performed and evaluated on samples from X70 line pipe with 3 different steel chemistries. The samples prepared from different locations on body, weld and HAZ in the as received and as bent condition. It was found that the final microstructure and mechanical properties in the as bent condition is dependent on the chemistry, steel cleanliness and microstructural uniformity. It was observed that small localized brittle zone with traces of upper Bainite and Martensite islands could be transformed in the microstructure with rich chemistry containing non-homogenous central segregation. It is concluded that factual verification of proper microstructure with no localized hard zone is required prior to waving PBHT.
{"title":"An Investigation on Microstructural Evolution of X70 Steel Pipe During Hot Induction Bending","authors":"M. Meschian, A. Duncan, M. Yarmuch, Fred Myschuk","doi":"10.1115/IPC2018-78018","DOIUrl":"https://doi.org/10.1115/IPC2018-78018","url":null,"abstract":"It is generally accepted that hot induction bending (HIB) results in a decrease in strength and an increase in fracture toughness in bend area, heat affected zone (HAZ) and weld metal (WM). As the result, Post bend heat treatment (PBHT) is not considered to be a requirement and could be waived for saving money and time. This research work raises the concern that factual verification of proper microstructure and no localized brittle zone is vitally necessary prior to waving PBHT.\u0000 Evaluation of the steel microstructure and mechanical properties as the result of various pipe chemistries during pipe bending has been verified in this experimental work. It is emphasized that knowledge and control of prior steel pipe chemistry, control of temperature, cooling rate and bending speed assures the reliability and repeatability of induction bends, especially in critical environments such as low temperature application.\u0000 In the present work, qualitative and quantitative microstructural analysis, hardness and impact test performed and evaluated on samples from X70 line pipe with 3 different steel chemistries. The samples prepared from different locations on body, weld and HAZ in the as received and as bent condition. It was found that the final microstructure and mechanical properties in the as bent condition is dependent on the chemistry, steel cleanliness and microstructural uniformity. It was observed that small localized brittle zone with traces of upper Bainite and Martensite islands could be transformed in the microstructure with rich chemistry containing non-homogenous central segregation. It is concluded that factual verification of proper microstructure with no localized hard zone is required prior to waving PBHT.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124827810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matthew A. Ellinger, Andrew R. Lutz, T. Bubenik, Tara McMahan
The Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a Notice of Proposed Rulemaking (NPRM)1 on April 8, 2016 that is expected to have an impact on the pipeline industry’s approach to crack growth analyses. Specifically, the NPRM defines values for pipe toughness that should be used in analyzing crack anomalies that are subjected to fatigue growth for instances in which known or measured pipe toughness values are not available. Pipeline Operators conduct these types of analyses to derive remaining life values which can in turn be utilized to establish pipeline integrity reassessment intervals. Thus, the impacts of this NPRM are felt by all pipeline operators who own assets in which cracking is considered a threat. The goal of this paper is to quantify the effects of using the NPRM defined toughness values in pressure test assessments for scenarios where pipe toughness values are unavailable.
{"title":"A Sensitivity Study: Effects of Toughness Values on Fatigue Crack Growth Analysis of Just-Survived Flaws Following a Pressure Test","authors":"Matthew A. Ellinger, Andrew R. Lutz, T. Bubenik, Tara McMahan","doi":"10.1115/IPC2018-78554","DOIUrl":"https://doi.org/10.1115/IPC2018-78554","url":null,"abstract":"The Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a Notice of Proposed Rulemaking (NPRM)1 on April 8, 2016 that is expected to have an impact on the pipeline industry’s approach to crack growth analyses. Specifically, the NPRM defines values for pipe toughness that should be used in analyzing crack anomalies that are subjected to fatigue growth for instances in which known or measured pipe toughness values are not available. Pipeline Operators conduct these types of analyses to derive remaining life values which can in turn be utilized to establish pipeline integrity reassessment intervals. Thus, the impacts of this NPRM are felt by all pipeline operators who own assets in which cracking is considered a threat. The goal of this paper is to quantify the effects of using the NPRM defined toughness values in pressure test assessments for scenarios where pipe toughness values are unavailable.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123910235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the last 10 years, technical and economical efforts have been made to improve pipeline integrity management. Those efforts focus on developing “searching tools”, capable of identifying pipe mechanical damage due to slow landslides. We identified two main tools: geohazard mapping and inline inspection (OCP is using caliper with inertial navigation system INS). The INS system generates a substantial amount of information about pipe’s geometry and deformation, reported as pitch, yaw and distance cover for each run. Since the caliper has been used for years, the pipeline’s path of evolution over the years is already available. The INS data was merged with pipeline field inspections to develop an assessment tool based on Machine Learning Technology. This tool was applied to the complete path of the pipeline, analyzing each girth weld, thus obtaining a so called “criticality level” for each weld. Two models were evaluated, which differ on the size of the vicinity considered for each girth weld: 250m and 500m. The highest precision model was found with 250m, which already has allowed improvements in field inspections. This paper will describe this technique, capable of improving OCP’s pipeline integrity management.
{"title":"Criticality Level Assessment From ILI Data","authors":"P. Jaya, R. Köck","doi":"10.1115/IPC2018-78750","DOIUrl":"https://doi.org/10.1115/IPC2018-78750","url":null,"abstract":"In the last 10 years, technical and economical efforts have been made to improve pipeline integrity management. Those efforts focus on developing “searching tools”, capable of identifying pipe mechanical damage due to slow landslides.\u0000 We identified two main tools: geohazard mapping and inline inspection (OCP is using caliper with inertial navigation system INS). The INS system generates a substantial amount of information about pipe’s geometry and deformation, reported as pitch, yaw and distance cover for each run. Since the caliper has been used for years, the pipeline’s path of evolution over the years is already available.\u0000 The INS data was merged with pipeline field inspections to develop an assessment tool based on Machine Learning Technology.\u0000 This tool was applied to the complete path of the pipeline, analyzing each girth weld, thus obtaining a so called “criticality level” for each weld. Two models were evaluated, which differ on the size of the vicinity considered for each girth weld: 250m and 500m. The highest precision model was found with 250m, which already has allowed improvements in field inspections.\u0000 This paper will describe this technique, capable of improving OCP’s pipeline integrity management.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129569849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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