S. Tiku, M. Ghovanlou, A. Dinovitzer, M. Piazza, T. A. Jones
While the general fracture mechanics principles and methodologies for calculating fatigue lives are well documented and validated, their application in the prediction of pipeline system fatigue lives differed from field experience. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates are an important element when establishing integrity management programs. Of particular interest are the fatigue life estimates used in integrity management programs for electric resistance welded (ERW) pipeline systems that may have pipe seam anomalies oriented along the pipe axis. BMT Canada Ltd (BMT) was contracted by Pipeline Research Council International (PRCI) to develop a pipeline material fatigue crack growth database and conduct full scale cyclic pressure fatigue tests to develop improved crack growth rate parameters. A pipeline material fatigue crack growth database was developed using 185 fatigue crack growth rate tests on 45 pipeline materials ranging in grade from X46 to X70 and in vintage from 1937 to 2014. The database included fatigue crack growth rate tests on 18 pipe body base materials (BM) and 27 ERW weld seam materials at two different, stress ratios (R), of R-ratio = 0.1 and R-ratio = 0.6. The sampled crack growth rates observed in the pipeline steels, tested in the project were 2 to 3 times lower than the crack growth rates recommended in BS 7910. This paper presents the proposed power (Paris) law fatigue crack growth equation parameters, C and m, developed in the study. Two full-scale cyclic pressure tests were carried out to validate the use of recommended crack growth rate parameters. Axial flaws were machined in the pipe body and weld center line (WCL). Fifty-one (51) flaws of different lengths and depths were machined. The crack growth rates were monitored during the cyclic pressure tests by recording crack mouth opening displacement (CMOD). The calibration curves for correlating CMODs with crack depths were developed and validated against finite element (FE) analysis. The fatigue crack growth rates observed in the full-scale tests were then compared with existing BS 7910 and API 579 formulations. The comparison confirmed that the BS 7910 approach results in very conservative estimates of fatigue crack growth rates for axial flaws. The BS 7910 stress intensity factor formulation overestimated the bulging correction for axially oriented flaws. The API 579 fracture mechanics-based fatigue crack growth formulation combined with crack growth rate parameters developed in this program provided improved estimates for fatigue life. The fatigue crack growth rates for line pipe and ERW weld seams developed in this project were shown to be less conservative and better predictors for fatigue crack growth and represent a valuable tool for pipeline integrity management. The use of this information will enable pipeline operators to focus remedial actions on features that have the lowest estimated fatigue li
{"title":"Full Scale Test Validation of Fatigue Crack Growth Rate of Flaws in ERW Pipe","authors":"S. Tiku, M. Ghovanlou, A. Dinovitzer, M. Piazza, T. A. Jones","doi":"10.1115/IPC2020-9705","DOIUrl":"https://doi.org/10.1115/IPC2020-9705","url":null,"abstract":"\u0000 While the general fracture mechanics principles and methodologies for calculating fatigue lives are well documented and validated, their application in the prediction of pipeline system fatigue lives differed from field experience. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates are an important element when establishing integrity management programs. Of particular interest are the fatigue life estimates used in integrity management programs for electric resistance welded (ERW) pipeline systems that may have pipe seam anomalies oriented along the pipe axis. BMT Canada Ltd (BMT) was contracted by Pipeline Research Council International (PRCI) to develop a pipeline material fatigue crack growth database and conduct full scale cyclic pressure fatigue tests to develop improved crack growth rate parameters.\u0000 A pipeline material fatigue crack growth database was developed using 185 fatigue crack growth rate tests on 45 pipeline materials ranging in grade from X46 to X70 and in vintage from 1937 to 2014. The database included fatigue crack growth rate tests on 18 pipe body base materials (BM) and 27 ERW weld seam materials at two different, stress ratios (R), of R-ratio = 0.1 and R-ratio = 0.6. The sampled crack growth rates observed in the pipeline steels, tested in the project were 2 to 3 times lower than the crack growth rates recommended in BS 7910. This paper presents the proposed power (Paris) law fatigue crack growth equation parameters, C and m, developed in the study.\u0000 Two full-scale cyclic pressure tests were carried out to validate the use of recommended crack growth rate parameters. Axial flaws were machined in the pipe body and weld center line (WCL). Fifty-one (51) flaws of different lengths and depths were machined. The crack growth rates were monitored during the cyclic pressure tests by recording crack mouth opening displacement (CMOD). The calibration curves for correlating CMODs with crack depths were developed and validated against finite element (FE) analysis. The fatigue crack growth rates observed in the full-scale tests were then compared with existing BS 7910 and API 579 formulations.\u0000 The comparison confirmed that the BS 7910 approach results in very conservative estimates of fatigue crack growth rates for axial flaws. The BS 7910 stress intensity factor formulation overestimated the bulging correction for axially oriented flaws. The API 579 fracture mechanics-based fatigue crack growth formulation combined with crack growth rate parameters developed in this program provided improved estimates for fatigue life. The fatigue crack growth rates for line pipe and ERW weld seams developed in this project were shown to be less conservative and better predictors for fatigue crack growth and represent a valuable tool for pipeline integrity management. The use of this information will enable pipeline operators to focus remedial actions on features that have the lowest estimated fatigue li","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121934323","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}
A Bayesian methodology was applied to use data from multiple inline inspection (ILI) runs and field measurements with non-destructive examination (NDE) tools to increase confidence in crack size estimates. Multiple crack depth measurements were used in two different ways — namely, to improve the characterization of ILI sizing error bias and to update the maximum depth distribution of individual crack features. This methodology was applied to selected datasets from an industrywide database for crack ILI data collected over a series of Pipeline Research Council International (PRCI) projects. The results of the approach are presented for two datasets, showing reduced variance in sizing error bias and improved confidence in crack depth estimates. In addition to the PRCI datasets, an additional dataset was collected and used to investigate the effect of multiple ILI runs on estimates of rate of detection and depth distribution of undetected features. The results of this analysis are also summarized.
{"title":"A Bayesian Approach for Effective Use of Multiple Measurements of Crack Depths","authors":"S. Koduru, M. Nessim, S. Bott, M. Al-Amin","doi":"10.1115/IPC2020-9307","DOIUrl":"https://doi.org/10.1115/IPC2020-9307","url":null,"abstract":"\u0000 A Bayesian methodology was applied to use data from multiple inline inspection (ILI) runs and field measurements with non-destructive examination (NDE) tools to increase confidence in crack size estimates. Multiple crack depth measurements were used in two different ways — namely, to improve the characterization of ILI sizing error bias and to update the maximum depth distribution of individual crack features. This methodology was applied to selected datasets from an industrywide database for crack ILI data collected over a series of Pipeline Research Council International (PRCI) projects. The results of the approach are presented for two datasets, showing reduced variance in sizing error bias and improved confidence in crack depth estimates. In addition to the PRCI datasets, an additional dataset was collected and used to investigate the effect of multiple ILI runs on estimates of rate of detection and depth distribution of undetected features. The results of this analysis are also summarized.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125072253","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 2014, Enbridge published a request for proposals to develop and provide a solution on a specific type of long seam cracks in a 26” pipeline. In-line inspection technologies available at the time were not able to consistently and accurately characterize the crack threat, although the line was successfully hydrostatically tested in 2015. During the early stages of the project, NDT Global analyzed in detail Enbridge’s requirements, including the specific challenges, spool type, seam weld characteristics etc. and provided different proposals to Enbridge. In 2016, both parties signed a development contract to develop and build a 26” Next Generation Crack Inspection Platform (Proton). The project was divided into various stages to support a successful project that met performance requirements based both on pump tests and a field trial supported by investigative digs and coupon cutouts. The robot developed is a highly versatile crack inspection platform: it allows to be set up in a configuration optimized for the given threat, pipeline conditions, inspection speed and medium characteristics. This optimization of the configuration allows choosing the optimum measurement modes for flaws in the base material and in the seam weld independently. Additionally, the local wall thickness even in the seam weld is measured accurately. These capabilities allow the operator to collect the best data for each situation. Feeding the information into the crack management program allows Enbridge to maintain the target reliability of the asset. The robot was utilized successfully in the 26” pipeline. Processing, data analysis and reporting were performed within pre-agreed periods. Initial field findings and lab tests show high correlation of ILI and real flaws and proof the stated accuracy of the new service. The authors will present in detail some of the specific challenges of the pipeline system and limitations of available crack inspection technologies. Validation results from in-the-ditch non-destructive examination and destructive freeze breaks including cross sections from flaws with complex morphologies will be shown. Performance statistics and comparison to previous inspection results will be used to demonstrate that the new robot can be used as part of an effective crack management program.
{"title":"At the Forefront of In-Line Crack Inspection Services: A Highly Versatile Crack Inspection Platform for Complex Flaw Morphologies and Absolute Depth Sizing","authors":"S. Bott, R. MacKenzie, M. Hill, T. Hennig","doi":"10.1115/IPC2020-9386","DOIUrl":"https://doi.org/10.1115/IPC2020-9386","url":null,"abstract":"\u0000 In 2014, Enbridge published a request for proposals to develop and provide a solution on a specific type of long seam cracks in a 26” pipeline. In-line inspection technologies available at the time were not able to consistently and accurately characterize the crack threat, although the line was successfully hydrostatically tested in 2015. During the early stages of the project, NDT Global analyzed in detail Enbridge’s requirements, including the specific challenges, spool type, seam weld characteristics etc. and provided different proposals to Enbridge. In 2016, both parties signed a development contract to develop and build a 26” Next Generation Crack Inspection Platform (Proton). The project was divided into various stages to support a successful project that met performance requirements based both on pump tests and a field trial supported by investigative digs and coupon cutouts.\u0000 The robot developed is a highly versatile crack inspection platform: it allows to be set up in a configuration optimized for the given threat, pipeline conditions, inspection speed and medium characteristics. This optimization of the configuration allows choosing the optimum measurement modes for flaws in the base material and in the seam weld independently. Additionally, the local wall thickness even in the seam weld is measured accurately. These capabilities allow the operator to collect the best data for each situation. Feeding the information into the crack management program allows Enbridge to maintain the target reliability of the asset.\u0000 The robot was utilized successfully in the 26” pipeline. Processing, data analysis and reporting were performed within pre-agreed periods. Initial field findings and lab tests show high correlation of ILI and real flaws and proof the stated accuracy of the new service.\u0000 The authors will present in detail some of the specific challenges of the pipeline system and limitations of available crack inspection technologies. Validation results from in-the-ditch non-destructive examination and destructive freeze breaks including cross sections from flaws with complex morphologies will be shown. Performance statistics and comparison to previous inspection results will be used to demonstrate that the new robot can be used as part of an effective crack management program.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116019459","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}
An enhanced corrosion assessment model has been developed by TC Energy. The new model is called the “Plausible Profiles Model for Corrosion Assessment” or “Psqr” for short and is described in three IPC 2020 papers1,2,3. The Psqr model uses a probabilistic approach for creating a number of plausible profiles along a corroded area. The predicted failure pressure for each plausible profile is calculated using RSTRENG, resulting in a probabilistic distribution of predicted failure pressures. The predicted failure pressure for the corroded area is taken to be the lower 5th percentile value of the distribution. TC Energy requested that PRCI sponsor an independent review of the Psqr model by subject matter experts (SMEs). The PRCI Corrosion Technical Committee and TC Energy jointly selected a team of SMEs to conduct the review. The team was comprised of the following individuals: • Maher Nessim — C-FER Technologies • Ming Gao — Blade Energy Partners • Ravi Krishnamurthy — Blade Energy Partners • Phil Hopkins — Independent Consultant • Andrew Cosham — Ninth Planet Engineering • Michael Rosenfeld — RSI Pipeline Solutions • Bruce Nestleroth — Kiefner and Associates, Inc. • John Kiefner — RSI Pipeline Solutions This paper describes the work carried out by the SMEs and presents their findings and conclusions. Basically, they found that the model is more accurate and exhibits less scatter than existing models such as RSTRENG, B31G, and Modified B31G4. They recommended that the Psqr Model be implemented in conjunction with a high-quality corrosion management plan such as that outlined in TC Energy’s technical report5, and they recommended specific minimum Psqr-predicted failure stress levels for use on pipelines being operated at maximum stress levels ranging from 40% of SMYS to 80% of SMYS.
{"title":"Peer Review of the Plausible Profiles Corrosion Assessment Model","authors":"J. Kiefner","doi":"10.1115/IPC2020-9254","DOIUrl":"https://doi.org/10.1115/IPC2020-9254","url":null,"abstract":"\u0000 An enhanced corrosion assessment model has been developed by TC Energy. The new model is called the “Plausible Profiles Model for Corrosion Assessment” or “Psqr” for short and is described in three IPC 2020 papers1,2,3. The Psqr model uses a probabilistic approach for creating a number of plausible profiles along a corroded area. The predicted failure pressure for each plausible profile is calculated using RSTRENG, resulting in a probabilistic distribution of predicted failure pressures. The predicted failure pressure for the corroded area is taken to be the lower 5th percentile value of the distribution.\u0000 TC Energy requested that PRCI sponsor an independent review of the Psqr model by subject matter experts (SMEs). The PRCI Corrosion Technical Committee and TC Energy jointly selected a team of SMEs to conduct the review. The team was comprised of the following individuals:\u0000 • Maher Nessim — C-FER Technologies\u0000 • Ming Gao — Blade Energy Partners\u0000 • Ravi Krishnamurthy — Blade Energy Partners\u0000 • Phil Hopkins — Independent Consultant\u0000 • Andrew Cosham — Ninth Planet Engineering\u0000 • Michael Rosenfeld — RSI Pipeline Solutions\u0000 • Bruce Nestleroth — Kiefner and Associates, Inc.\u0000 • John Kiefner — RSI Pipeline Solutions\u0000 This paper describes the work carried out by the SMEs and presents their findings and conclusions. Basically, they found that the model is more accurate and exhibits less scatter than existing models such as RSTRENG, B31G, and Modified B31G4. They recommended that the Psqr Model be implemented in conjunction with a high-quality corrosion management plan such as that outlined in TC Energy’s technical report5, and they recommended specific minimum Psqr-predicted failure stress levels for use on pipelines being operated at maximum stress levels ranging from 40% of SMYS to 80% of SMYS.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"67 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130876614","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}
Udayasankar Arumugam, M. Gao, R. Krishnamurthy, M. Zaréa
Dents containing crack fields (colonies) were often observed in liquid pipelines. A recent PRCI research “Study of the Mechanism for Cracking in Dents in a Crude Oil Pipeline” showed evidence of corrosion fatigue cracking mechanism in dents and estimated the crack growth rate as a function of stress intensity factor using the measured spacings of fatigue striations from fracture surfaces based on the assumption that the formation of fatigue striations on a cycle-by-cycle basis. However, due to the lack of full-scale fatigue crack growth data, the success was limited in this study. This gap prompted PRCI to launch a full-scale experimental investigation of cracks-indents under cyclic pressure load in the simulated groundwater (NS4 solution) environment. The objective of the study is to determine the crack growth rate in dent as a function of stress intensity factor, the number of cycles to failure, and the failure modes of crack-in-dent. The investigation is aimed at establishing a framework for the remaining fatigue life prediction of cracks-in-dents in liquid pipelines. This framework would benefit liquid pipeline operators to manage the integrity of dents associated with corrosion fatigue cracking exposed to groundwater in a timely manner. A total of six pipe samples containing cracks in shallow dents excavated from a 24-inch diameter liquid transmission pipeline were selected for full-scale fatigue tests. The test system developed under the project consisted of (1) a computer-controlled hydraulic pressure cycling system, (2) an environment chamber containing NS4 solution mounted on the dent region to provide a simulated field environment condition, (3) real-time crack growth monitoring systems including direct current potential drop (DCPD) system, Clip gage, and Strain gage, and (4) a data acquisition system. The cyclic pressure range used in the fatigue test was between 78 psig (7.2%SMYS, minimum) and 780 psig (72%SMYS, maximum) with R = 0.1, which was based on historical operational pressure fluctuation data. A constant frequency of 0.0526 Hz was selected for the testing to ensure the frequency requirement for corrosion fatigue was met. In this paper, the objective, along with the background of this research, is discussed first. Then, the pipe sample preparation, experimental setup, and test results are presented. The fatigue crack growth rate as a function of the stress intensity factor is then discussed. Following this, the fatigue crack growth coefficients were estimated using the full-scale test data and FEA. Finally, the fatigue test results are summarized and presented the framework for the life prediction of corrosion fatigue cracks in shallow dents.
{"title":"Full-Scale Fatigue Testing of Crack-in-Dent and Framework Development for Life Prediction","authors":"Udayasankar Arumugam, M. Gao, R. Krishnamurthy, M. Zaréa","doi":"10.1115/IPC2020-9709","DOIUrl":"https://doi.org/10.1115/IPC2020-9709","url":null,"abstract":"\u0000 Dents containing crack fields (colonies) were often observed in liquid pipelines. A recent PRCI research “Study of the Mechanism for Cracking in Dents in a Crude Oil Pipeline” showed evidence of corrosion fatigue cracking mechanism in dents and estimated the crack growth rate as a function of stress intensity factor using the measured spacings of fatigue striations from fracture surfaces based on the assumption that the formation of fatigue striations on a cycle-by-cycle basis. However, due to the lack of full-scale fatigue crack growth data, the success was limited in this study. This gap prompted PRCI to launch a full-scale experimental investigation of cracks-indents under cyclic pressure load in the simulated groundwater (NS4 solution) environment. The objective of the study is to determine the crack growth rate in dent as a function of stress intensity factor, the number of cycles to failure, and the failure modes of crack-in-dent. The investigation is aimed at establishing a framework for the remaining fatigue life prediction of cracks-in-dents in liquid pipelines. This framework would benefit liquid pipeline operators to manage the integrity of dents associated with corrosion fatigue cracking exposed to groundwater in a timely manner.\u0000 A total of six pipe samples containing cracks in shallow dents excavated from a 24-inch diameter liquid transmission pipeline were selected for full-scale fatigue tests. The test system developed under the project consisted of (1) a computer-controlled hydraulic pressure cycling system, (2) an environment chamber containing NS4 solution mounted on the dent region to provide a simulated field environment condition, (3) real-time crack growth monitoring systems including direct current potential drop (DCPD) system, Clip gage, and Strain gage, and (4) a data acquisition system. The cyclic pressure range used in the fatigue test was between 78 psig (7.2%SMYS, minimum) and 780 psig (72%SMYS, maximum) with R = 0.1, which was based on historical operational pressure fluctuation data. A constant frequency of 0.0526 Hz was selected for the testing to ensure the frequency requirement for corrosion fatigue was met.\u0000 In this paper, the objective, along with the background of this research, is discussed first. Then, the pipe sample preparation, experimental setup, and test results are presented. The fatigue crack growth rate as a function of the stress intensity factor is then discussed. Following this, the fatigue crack growth coefficients were estimated using the full-scale test data and FEA. Finally, the fatigue test results are summarized and presented the framework for the life prediction of corrosion fatigue cracks in shallow dents.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115480490","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}
A. Virk, Doug Langer, Janine Woo, N. Yoosef-Ghodsi, Muntaseer Kainat
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.
{"title":"Improved Semi-Quantitative Reliability-Based Method for Assessment of Pipeline Dents With Stress Risers","authors":"A. Virk, Doug Langer, Janine Woo, N. Yoosef-Ghodsi, Muntaseer Kainat","doi":"10.1115/IPC2020-9472","DOIUrl":"https://doi.org/10.1115/IPC2020-9472","url":null,"abstract":"\u0000 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.\u0000 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.\u0000 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.\u0000 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.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115623637","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}
A. Naderi, Ruoqi Deng, Deli Yu, R. Kania, LePing Li
During a pipeline excavation, additional pipe stress and deflection can be produced due to altered soil support beneath the exposed pipe, which might bring in additional integrity concerns for the pipe under assessment. Classical beam theories and soil-spring modeling are inadequate for the complex pipe-soil interactions and boundary conditions. The objective of the present study was to develop a computational model that can be used to predict pipe stress and deflection during an integrity dig. The pipe-soil interaction was modeled with 3D elements using surface-to-surface contact approximation in ABAQUS. The pipe was assumed to be initially buried, then exposed for 12, 20, 30 and 34 m subsequently to mimic a buried pipeline under step-by-step excavation. The results indicated that the depth of soil support is a dominant factor for the pipe stress and deflection during an integrity excavation, which has not been previously investigated. Significant axial stress and strain in the longitudinal direction were produced by excavation, which may increase the risk of failure for the pipe that is suspected of circumferential defects. Furthermore, nonuniform soil support could cause substantial pipe deflections and stresses that may trigger an integrity dig. The model may be used to estimate the pipe stress and deflection prior to an integrity dig based on the soil conditions.
{"title":"Pipe Stress and Deflection During an Integrity Dig","authors":"A. Naderi, Ruoqi Deng, Deli Yu, R. Kania, LePing Li","doi":"10.1115/IPC2020-9269","DOIUrl":"https://doi.org/10.1115/IPC2020-9269","url":null,"abstract":"\u0000 During a pipeline excavation, additional pipe stress and deflection can be produced due to altered soil support beneath the exposed pipe, which might bring in additional integrity concerns for the pipe under assessment. Classical beam theories and soil-spring modeling are inadequate for the complex pipe-soil interactions and boundary conditions. The objective of the present study was to develop a computational model that can be used to predict pipe stress and deflection during an integrity dig. The pipe-soil interaction was modeled with 3D elements using surface-to-surface contact approximation in ABAQUS. The pipe was assumed to be initially buried, then exposed for 12, 20, 30 and 34 m subsequently to mimic a buried pipeline under step-by-step excavation. The results indicated that the depth of soil support is a dominant factor for the pipe stress and deflection during an integrity excavation, which has not been previously investigated. Significant axial stress and strain in the longitudinal direction were produced by excavation, which may increase the risk of failure for the pipe that is suspected of circumferential defects. Furthermore, nonuniform soil support could cause substantial pipe deflections and stresses that may trigger an integrity dig. The model may be used to estimate the pipe stress and deflection prior to an integrity dig based on the soil conditions.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116235575","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}
M. Al-Amin, Shenwei Zhang, S. Kariyawasam, Jason Yan, Tammie Matchim
Pipeline operators assess metal-loss corrosion anomalies identified on pipelines to determine whether such anomalies require remediation. The assessment of metal-loss anomalies can be performed using deterministic or probabilistic approach. In deterministic method, the failure pressure ratio (FPR) for a metal-loss corrosion anomaly is evaluated against a predetermined safety factor, where FPR is defined as the predicted burst pressure of the anomaly divided by the maximum allowable operating pressure (MAOP) or maximum operating pressure (MOP). Conservative characteristic values are used for the variables such as measurements of metal-loss, pipe geometry, material properties, operating pressure and assessment model in calculating FPR. Safety factors in deterministic assessment are used to account for residual uncertainties, human error and consequence levels. Safety factors are established in various codes and standards in North America. However, those safety factors are not consistent across codes and standards as demonstrated in this paper. This paper describes the fundamentals of how appropriate safety can be assured for pipelines containing metal-loss anomalies by selecting appropriate safety factors. The effect of using different safety factors on the reliability level of the pipeline system is examined in this study. A set of new safety factors to ensure consistent safety level for pipelines containing metal-loss corrosion are proposed in this paper. The impact of the proposed safety factors on the integrity decisions are also demonstrated.
{"title":"Achieving Consistent Safety by Using Appropriate Safety Factors in Corrosion Management Program","authors":"M. Al-Amin, Shenwei Zhang, S. Kariyawasam, Jason Yan, Tammie Matchim","doi":"10.1115/IPC2020-9470","DOIUrl":"https://doi.org/10.1115/IPC2020-9470","url":null,"abstract":"\u0000 Pipeline operators assess metal-loss corrosion anomalies identified on pipelines to determine whether such anomalies require remediation. The assessment of metal-loss anomalies can be performed using deterministic or probabilistic approach. In deterministic method, the failure pressure ratio (FPR) for a metal-loss corrosion anomaly is evaluated against a predetermined safety factor, where FPR is defined as the predicted burst pressure of the anomaly divided by the maximum allowable operating pressure (MAOP) or maximum operating pressure (MOP). Conservative characteristic values are used for the variables such as measurements of metal-loss, pipe geometry, material properties, operating pressure and assessment model in calculating FPR. Safety factors in deterministic assessment are used to account for residual uncertainties, human error and consequence levels. Safety factors are established in various codes and standards in North America. However, those safety factors are not consistent across codes and standards as demonstrated in this paper. This paper describes the fundamentals of how appropriate safety can be assured for pipelines containing metal-loss anomalies by selecting appropriate safety factors. The effect of using different safety factors on the reliability level of the pipeline system is examined in this study. A set of new safety factors to ensure consistent safety level for pipelines containing metal-loss corrosion are proposed in this paper. The impact of the proposed safety factors on the integrity decisions are also demonstrated.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128477303","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}
D. Bonner, A. Greig, H. Lindner, Johannes Becker, B. Roulston
As part of a major pipeline expansion, two deactivated 24″ diameter pipeline segments with a combined length of 192 kilometres will be assessed and upgraded to operational status. These line segments include a 42 kilometre section within the North Thompson valley of British Columbia, and a 150 kilometre segment through the Rocky Mountains of Alberta and British Columbia. Reactivating the lines to operational condition is a multi-staged process, which will be partially guided by a National Energy Board Condition requiring the issuance of a certificate from an independent certifying body that the system is fit for service and meets all applicable requirements of CSA Z662, Oil and Gas Pipeline Systems. This certificate must be unconditional and remain in effect for a period of 5 years. The need for unconditional certification of fitness for service drives the need for a comprehensive assessment of the pipeline condition using a broad slate of inline inspection technologies. Tools were selected for the assessment of deformations, metal loss, manufacturing anomalies and cracking. The lines were maintained with a low pressure nitrogen blanket for between 9 and 13 years prior to the start of the reactivation work and it was therefore not possible to run the tools using service fluid. Several options were considered for propelling the inline inspection tools including nitrogen, compressed air and water slugs in compressed nitrogen or air. Each method has advantages and disadvantages and modelling was carried out to simulate the transport of the tools through each segment. The modelling needed to account for pipe elevation changes, wall thickness changes, valves, tool drive friction, acceptable tool velocity, and the pressure of the drive medium in the pipeline. The modelling focused on the following constraints: i. Ensure ILI data quality ii. Ensure safety considering the potential presence of defects in the lines iii. Minimize risk iv. Minimize overall cost These constraints guided a flow modelling/feasibility study for inspecting the lines with the 4 tools. The objective of the study was to determine the optimum configuration of propellant, inspection tools, and line segmentation while ensuring a safe, economical operation resulting in optimal data collection. The paper will provide some background on the line segments being reactivated and pressure limitations that were adopted for ILI runs. The majority of the content will focus on the determination of tool drive technique, how simulation occurred and how the actual execution of the runs compared. Details regarding the challenges and troubleshooting required to successfully complete the integrity surveys will also be discussed in depth.
{"title":"Reactivating a Legacy Pipeline: Simulating ILI Run Behavior, Operation Optimization, and Project Challenges","authors":"D. Bonner, A. Greig, H. Lindner, Johannes Becker, B. Roulston","doi":"10.1115/IPC2018-78158","DOIUrl":"https://doi.org/10.1115/IPC2018-78158","url":null,"abstract":"As part of a major pipeline expansion, two deactivated 24″ diameter pipeline segments with a combined length of 192 kilometres will be assessed and upgraded to operational status. These line segments include a 42 kilometre section within the North Thompson valley of British Columbia, and a 150 kilometre segment through the Rocky Mountains of Alberta and British Columbia.\u0000 Reactivating the lines to operational condition is a multi-staged process, which will be partially guided by a National Energy Board Condition requiring the issuance of a certificate from an independent certifying body that the system is fit for service and meets all applicable requirements of CSA Z662, Oil and Gas Pipeline Systems. This certificate must be unconditional and remain in effect for a period of 5 years.\u0000 The need for unconditional certification of fitness for service drives the need for a comprehensive assessment of the pipeline condition using a broad slate of inline inspection technologies. Tools were selected for the assessment of deformations, metal loss, manufacturing anomalies and cracking. The lines were maintained with a low pressure nitrogen blanket for between 9 and 13 years prior to the start of the reactivation work and it was therefore not possible to run the tools using service fluid.\u0000 Several options were considered for propelling the inline inspection tools including nitrogen, compressed air and water slugs in compressed nitrogen or air. Each method has advantages and disadvantages and modelling was carried out to simulate the transport of the tools through each segment. The modelling needed to account for pipe elevation changes, wall thickness changes, valves, tool drive friction, acceptable tool velocity, and the pressure of the drive medium in the pipeline.\u0000 The modelling focused on the following constraints:\u0000 i. Ensure ILI data quality\u0000 ii. Ensure safety considering the potential presence of defects in the lines\u0000 iii. Minimize risk\u0000 iv. Minimize overall cost\u0000 These constraints guided a flow modelling/feasibility study for inspecting the lines with the 4 tools. The objective of the study was to determine the optimum configuration of propellant, inspection tools, and line segmentation while ensuring a safe, economical operation resulting in optimal data collection.\u0000 The paper will provide some background on the line segments being reactivated and pressure limitations that were adopted for ILI runs. The majority of the content will focus on the determination of tool drive technique, how simulation occurred and how the actual execution of the runs compared. Details regarding the challenges and troubleshooting required to successfully complete the integrity surveys will also be discussed in depth.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"10 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":"125572997","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}
J. J. Trujillo-Tadeo, J. González-Velázquez, D. Rivas-López
This work proposes an assessment procedure for the determination of the remaining strength in pressure vessels with pitting type metal loss, trough the developed of integrity diagrams according to the pitting density, pitting depths and the internal pressure of the component using Finite Element Analysis simulations. The simulations results indicate that the pitting density and depths according to the Gumbel Max Distribution, are the main factors that determine the mechanical integrity of the component; where 45% damaged area by pitting generates a stress concentration that multiplies at least ten times the stress compared with components without defects, since these variables present a synergistic behavior in the stress state. The proposed assessment procedure facilitates the evaluation of the components that present pitting corrosion damage, due to the geometric and population effect of the pitting is considered in the finite element simulation.
{"title":"Remaining Strength in Pressure Vessels With Pitting Type Metal Loss: Part 1","authors":"J. J. Trujillo-Tadeo, J. González-Velázquez, D. Rivas-López","doi":"10.1115/IPC2018-78425","DOIUrl":"https://doi.org/10.1115/IPC2018-78425","url":null,"abstract":"This work proposes an assessment procedure for the determination of the remaining strength in pressure vessels with pitting type metal loss, trough the developed of integrity diagrams according to the pitting density, pitting depths and the internal pressure of the component using Finite Element Analysis simulations.\u0000 The simulations results indicate that the pitting density and depths according to the Gumbel Max Distribution, are the main factors that determine the mechanical integrity of the component; where 45% damaged area by pitting generates a stress concentration that multiplies at least ten times the stress compared with components without defects, since these variables present a synergistic behavior in the stress state.\u0000 The proposed assessment procedure facilitates the evaluation of the components that present pitting corrosion damage, due to the geometric and population effect of the pitting is considered in the finite element simulation.","PeriodicalId":273758,"journal":{"name":"Volume 1: Pipeline and Facilities Integrity","volume":"186 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":"116385383","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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