bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Stress-Activated Creep at Axial Cracks in Pipelines
Authors: Leis Brian N. , Zhu Xian-Kui , Cosham Andrew 
Published: January 2021

Abstract
The failure of a pipeline that had just passed a proof-pressure test as it was being re-pressurized for its return to service (a so-called pressure reversal) reflects the stable growth due to stress-activated creep of a near-critical anomaly that had remained stable as the proof test ended. In the same way that stable growth of a near-critical anomaly can lead to a pressure reversal, stable tearing (cracking) can occur and remain stable at the pressure first imposed upon the pipeline’s return to service, and so pose concern for in-service failure. Ductile failures that are absent evidence of time-dependent degradation mechanisms, like corrosion, and show the traits of stable tearing have been termed time-delayed failures. As time passed, the reasons for time-delayed failures became clear, and criteria to prevent such failures through a pressure reduction were established.
The advent of much tougher steels opened to the potential for crack initiation and stable tearing at service pressures under circumstances that differed from that for the early line pipe steels. The 2004 incident at Ghislenghien involving a modern high-toughness X70 pipeline raised the need to better understand how to manage time-delayed failures in such steels.
This paper develops a model to quantify stable tearing and possible instability at axial part-through-wall defects as a function of the steel, the length and depth of the defect, and the operating pressure. The theoretical basis for this nonlinear fracture mechanics (NLFM) model is outlined first. Case-specific finite-element analysis were used to benchmark NLFM Handbook results, which extended the use of predictive technology developed previously for lower toughness steels. As before, this solution is recast for time-marching analysis that is coupled with isochronous stress-strain response and NLFM resistance curves. Finally, the model is used to make blind predictions of cracking and instability in step-load and hold testing, and found to be viable in that context. Companion papers at this conference present the details of related work.
An Onshore Pipeline Failure due to Hydrogen Assisted Cracking Induced by Cathodic Protection Operated at Near -1200 mV CSE: A Case Study
Authors: Cazenave Pablo , Gao Ming , Moneta Andrea , Cruzado Juan , Hryciuk Pedro 
Published: January 2021

Abstract
A 22-inch onshore natural gas transmission pipeline experienced an in-service rupture in January of 2018. The rupture was caused by an axial crack that occurred 150 Km (93 miles) downstream of the closest compression station.
While the root cause analysis of the rupture was in progress, excavations of indications reported by a Hard Spot In-Line Inspection (ILI) were undertaken starting approximately 42 km (26 miles) downstream of the rupture. These excavations discovered predominantly circumferential crack colonies, with a number of through-wall cracks being leak.
The root cause analysis concluded that both the axial and circumferential external surface cracks are consistent with hydrogen environment assisted cracking generated by the impressed-current cathodic protection system, operated near the pipe-to-soil recommended potential limit of −1200 mV as measured with respect to a saturated copper/copper sulfate reference electrode (CSE).
Transportadora de Gas del Norte (TGN) implemented a series of preventive and corrective measures that included pressure testing, cathodic protection improvement, coating rehabilitation programs and In-Line Inspection programs among others.
This paper presents the background and approach used in the root cause analysis, summarizes the methodology, results and findings, and discusses their implications in the management of the Pipeline Integrity of the pipeline system operated by TGN.
Effect of Cooling Process on Microstructure Especially Precipitation Behavior of High-Strength Pipeline Steel
Authors: Hesong Zheng , Tao Niu , Fei Li 
Published: January 2021

Abstract
The effect of different cooling processes on microstructure especially precipitation behavior and properties of high grade pipeline steel was investigated in this paper. The results showed that: By two stage controlled cooling process, ferrite-bainite phase was obtained in X80 pipeline steel with high deformability, the average size of Martensite and Austenitic islands (M/A) was approximately 1μm, the Uniform Elongation (UEl) was 10%. Whereas granular bainite was obtained after conventional laminar cooling process and fine M/A of 1∼2μm size dispersed in grains or along grain boundaries. Compared with conventional pipeline steel, high deformability pipeline steel through two stage controlled cooling process had higher Elongation (El), impact toughness and lower yield ratio, due to the existence of ferrie+bainite phase structure which reduced yield strength (YS) and enhanced deformation performance and fracture toughness. Additionally, the effect of precipitation strengthening of high grade pipeline steel produced by Ultra-fast cooling (UFC) process was superior to that produced by conventional laminar cooling process. A significant amount of nano particles precipitated with the size of 1nm to 5nm were obtained through the UFC process. The application of UFC made the precipitation process avoid the nose temperature of precipitation temperature time (PTT) curve, thus the size of nano particles were smaller and the distribution of precipitation was more dispersive.
Full-Scale Step-Load-Hold Tests on X65 and X70 Line Pipe Steels
Authors: Cosham Andrew , Leis Brian N. , Zarèa Mures , Orth Fabian , Linton Valerie 
Published: January 2021

Abstract
A time-delayed failure due to stress-activated creep (cold-creep) will occur if the applied load is held constant at a level above the threshold. The results of small and full-scale tests on line pipe steels conducted by the Battelle Memorial Institute and the British Gas Corporation in the 1960s and 70s indicated that the (empirical) threshold for a time-delayed failure was approximately 85–95% SAPF (straight-away-pressure-to-failure). The line pipe steels were Grades X52 or X60, and the full-size equivalent Charpy V-notch impact energy (where reported) did not exceed 35 J.
The strength and toughness of line pipe steels has significantly increased over the decades due to developments in steel-making and processing. The question then is whether an empirical threshold based on tests on lower strength and lower toughness steels is applicable to higher strength and higher toughness steels.
A Tripartite Project was established to answer this question. The Australian Pipelines and Gas Association (APGA), the European Pipeline Research Group (EPRG) and the Pipeline Research Council International (PRCI) collaborated in conducting six full-scale step-load-hold tests on higher strength and higher toughness steels. Companion papers present the other aspects of this multi-year project. The line pipe supplied for testing is summarised below.
• Identifier — Dimensions and Grade — f.s.e. Charpy V-notch impact energy at 0 C
• APGA [A] — 457.0 × 9.1 mm, Grade X70M, ERW — 263 J
• EPRG [E] — 1016.0 × 13.6 mm, Grade X70M, SAWL — 165 J
• PRCI [P] — 609.6 × 6.4 mm, Grade X65, SAWL — 160 J
Six step-load-hold tests, each with four part-through-wall defects, were conducted. Test Nos. APGA 1 and 2, and Nos. EPRG 1 and 2 were conducted at Engie, France. Test Nos. PRCI 1 and 2 were conducted at EWI, USA. The full-scale tests, and associated small-scale testing, are described and discussed.
A time-delayed failure due to stress-activated creep occurred in each of the step-load-hold tests. The failures occurred during a hold-period at 93.7–104.4% SAPF, after a hold of approximately 1.0–13.9 hours. The results of the six step-load-hold tests are consistent with a threshold for a time-delayed failure of approximately 90% SAPF.
Plausible Profile (Psqr) Corrosion Assessment Model: Refinement, Validation and Operationalization
Authors: Zhang Shenwei , Yan Jason , Kariyawasam Shahani , Huang Terry , Al-Amin Mohammad 
Published: January 2021

Abstract
This paper presents the refinement, validation, and operationalization of Plausible Profiles (Psqr) corrosion assessment model that TC Energy (TCE) published in IPC 2018.
Metal-loss corrosion continues to be a major integrity threat to oil and gas pipelines. Inline inspection (ILI) based corrosion management, where ILI measured anomalies are assessed and mitigated, has proven to be the best way to manage corrosion. The assessment model used to estimate the burst pressure of pipelines has the most significant impact on integrity decisions. These decisions include (1) which anomalies to excavate based on In-line inspection (ILI); (2) pressure reduction (i.e. derate) required to maintain safety until repairs are completed, and (3) repair decisions during the excavation. Consequently, TCE focused on improving the shape factor of the Modified B31G effective area technique and published an overview of the improvement in IPC 2018 paper titled “A More Accurate and Precise Method for Large Metal Loss Corrosion Assessment”. From 2018 TCE refined the model using further testing, validation, internal review, and external review.
In 2019, the model was reviewed by eight industry experts through Pipeline Research Council International (PRCI) project “EC-2-9 Peer Review of the Plausible Profile (Psqr) Corrosion Assessment Model”. The project outcome recommended Psqr as an improved corrosion assessment model. The comments and recommendations provided by the reviewers will be reported in IPC 2020 in a companion paper. Validation results show the Psqr model is safe, and more accurate and precise than RSTRENG. The resulting magnitude of reduction in unnecessary activities depends on the corrosion morphology.
Statistical Analysis of Dig Operations Leading to Productive Repairs
Authors: Petrov Yevgeniy , Dubuc Jordan , Murray Michael H. , Edward Tim 
Published: January 2021

Abstract
Inline inspection data from several runs spanning many years is available for individual pipeline segments, but compilation of this data into a comprehensive picture of pipeline integrity necessarily relies on computational tools. A critical advantage of modern data storage, analysis, and visualization techniques is the relative ease of performing statistical assessments of integrity operations. Data from a single user of OneBridge Solution’s software may comprise over 1,000 in-line inspections (ILI) runs, hundreds of pipe segments, several million aligned anomalies, and thousands of repair records. Automated alignment of ILI data allows a single physical anomaly to be reliably tracked through many years of growth and repeated measurement and then correlated to repair records.
We present a study of cases where ILI anomaly measurements warranted a dig operation in which repair actions were either performed or found to be unnecessary. The fraction of dig operations leading to a productive repair varies with the condition triggering the dig and discretionary choices about dig condition parameters. The analysis is done through the exploration of different methods of corrosion growth forecasting in use by operators and how they compare. The measures that have been taken into consideration for the purpose of this study include half-life vs. pit-to-pit where the effectiveness of identifying and mitigating fast-growing anomalies is compared across models. Further exploration of how forecasting and building a dig program based on pit-to-pit alignments and a comprehensive growth model through the advances in data science and machine learning can bring efficiency improvements and an overall reduction in risk.
We analyze the relationship between these parameters, ILI measurements, repair-to-dig ratios and the impact on operational spend. We examine whether a reduction in overall inspection frequency and expenses is possible through advanced growth modeling. Ultimately this would provide a more accurate view of long-term operating costs and allow for operators to consider scenarios relating to repair and replacement of assets.
Judge Me by My Size, Do You? How Reliable Are Dent Assessments Based on ILI Data?
Authors: Dotson Rhett , Sager Ryan , Curiel Fernando , Le Roy Marcus 
Published: January 2021

Abstract
Pipeline dents have historically been regulated and assessed using dent depth as the primary metric. Many of the earliest analytical models for dent remaining life are based upon depth. Current assessment guidelines from ASME and the Code of Federal Regulations utilize depth as a primary metric. Consequently, ILI geometry tool capabilities are stated in terms of dent depth. However, the best modern dent assessments, including both strain and fatigue assessments, are based on dent shape. At a minimum, these models require both axial and circumferential dent profiles, or the models may utilize the full three-dimensional shape of the dent. The utilization of advanced dent assessments is expected to grow in the future as the methods are incorporated into API Recommended Practices and US regulations. While operators may have confidence in the ability of an ILI tool to confidently capture the dent depth, the shape of a dent is a recent consideration that is not addressed by current tool specifications. Unlike depth alone, dent shape is often a function of sensor coverage, speed, and caliper technology. Unfortunately, there is virtually no information available on the reliability of these assessment methods when they are based on ILI data. To-date, there have been no published comparisons examining the variation in strain or fatigue life in identical dents between multiple inspections. The reliability of these dent assessment methods is critical when choosing safety factors or reinspection intervals. This study presents a first look at the repeatability of strain and remaining life assessments based on two separate geometry inspection using different technologies. The study examines dent strain according to ASME B31.8 and fatigue life calculated using shape factors and finite element methods for 257 dents. The paper examines the variation in each of the methods and provides guidance on how users should understand the results when they are based on a single geometry inspection.
Dense and Sparse Stress Corrosion Crack Initiation in an X65 Pipeline Steel With Mill Scale
Authors: Wang Shidong , Lamborn Lyndon , Chevil Karina , Gamboa Erwin , Chen Weixing 
Published: January 2021

Abstract
Near-neutral pH stress corrosion cracking (SCC) is a significant threat to the operational safety and reliability of gas and oil pipelines. The SCC cracks are typically formed in colonies with different crack density populations on the external surface of the pipe. The density of SCC cracks affect how pipeline integrity and remaining lifetime are assessed. Although sparse and dense crack colonies are commonly observed on pipelines, it has not been well established how these crack colonies with different crack populations were developed in the field.
This research was made in an attempt to replicate near-neutral pH SCC cracks with different crack densities in the laboratory with realistic loading conditions commonly found during field operation. An X65 pipeline steel with different surface preparations was used. The results showed that the dense near-neutral pH SCC cracks were successfully reproduced on the primer-coated samples, whereas sparse cracks were reproduced on the mill-scaled and polished samples. The densely spaced cracks could transform into sparsely spaced cracks when most of the primer layer and mill scale had been removed during the long period of corrosion under cyclic loading and further corrosion occurred thinning the crack density. The results of crack initiation obtained from this investigation have also been found to be quite consistent with crack initiation scenarios found during field operation.
Demonstration of Limit States Design Method for Assessment of Corrosion and Crack Features
Authors: Adianto Riski , Ibrahim Mahmoud , Nessim Maher , Hassanien Sherif , Bott Steven 
Published: January 2021

Abstract
A reliability-based limit states design (LSD) method for assessment of corrosion and crack features has been developed for onshore transmission pipelines as part of a joint industry project. The rule-based LSD approach is a simplified form of the reliability-based approach that reduces the latter to a set of deterministic checks. The LSD corrosion assessment method and a comparison of its performance against one operator’s reliability approach were published in previous IPC papers [1,3]. This paper compares the LSD corrosion and crack assessment methods to another simplified reliability-based approach, namely the Pipeline Integrity Reliability Analysis (PIRA) Level I, that was published in a previous IPC paper [2]. The PIRA model is staged into three levels, where Level I analysis is a simplified form of the reliability-based approach where the probability of failures of predefined features’ sizes are precalculated using conservative assumptions for a fast turnaround screening analysis of the entire pipeline system in order to identify areas requiring more in-depth full probabilistic Level II or III analyses. This paper describes the application of both LSD and Level I methods on two low vapour pressure (LVP) liquid pipelines and provides a comparison of the results.
The comparative analysis was based on the number of features not meeting reliability targets in both methods and, thus, are eligible for repair according to each method. Out of the two pipelines considered, one has corrosion and the other has cracks as the dominant threat. The results show that there are noticeable differences between the outputs of the two methods. The root cause of these differences was investigated by conducting a sensitivity analysis on the input parameters, including: reliability target, wall thickness distribution, feature depth and length distributions, pipeline sectioning procedure and the usage of model error (which is used in the LSD method but not in the PIRA Level I method). For cracks, differences between the Modified Ln-Secant model used in the LSD method and the CorLAS model used in PIRA Level I were also considered.
It was observed that the discrepancies in the required repairs resulting from the two methods can be mostly attributed to the feature depth distribution, wall thickness distribution and the reliability target. For cracks, the burst pressure model selection also had a significant impact on the results.
Numerical Simulation of Crude Oil Spreading in a Complex River Channel
Authors: Yu Dongliang , Wang Ji , Cao Quan , Zhang Xinglong , Liu Xueguang 
Published: January 2021

Abstract
Crude oil leaking in rivers may cause serious damages, such as environmental pollution and death of river animals. The crude oil spreading in rivers could be much faster than that on lands, as the leaking crude oil may flow rapidly downstream with the flowing water. Therefore, accurately estimating the transient crude oil spreading area in rivers is a vital task for emergency response and disaster rescue. However, the estimating methods in the literature mainly refer to spreading process in underwater, ocean and soil, which commonly happened in the history. The crude oil transportation pipelines in China pass through many rivers with very complex channel geometries, introducing the necessity of estimating of leaking crude oil spreading in actual river channels. In the current study, the crude oil spreading process along an actual river channel is numerically simulated. The river channel geometry is extracted from a map database, which is further treated using image binarization and edge extraction to obtain the discrete river channel data. The river channel data is then smoothed by picking less data representing main geometric characteristics. The smoothed data is used to reconstruct the river geometry and generate calculation mesh. The mesh is a two-dimensional structured grid with several possible leaking points along the actual crude oil transportation pipeline passing through the river. A multi-fluid MIXTURE model is used to simulate the crude oil spreading process on the water surface, meaning crude oil blending in the flowing water. Cases with a leaking mass flow rate of 240 kg/s and a river flow velocity of 1.58 m/s are simulated for 10 possible leaking sources on the traversing pipeline. The effect of leaking locations and river channel bending on crude oil spreading on river surface were significant according to the simulation results. Sudden widening river channel may result in vortexes and slightly delays the crude oil spreading. The simulated data could be used to make the rescue strategy of crude oil leaking in this specific river.
Subset Simulation for Structural Reliability Analysis of Pipeline Corrosion Defects
Authors: Bandstra Daryl , Fraser Alex M. 
Published: January 2021

Abstract
One of the leading threats to the integrity of oil and gas transmission pipeline systems is metal-loss corrosion. This threat is commonly managed by evaluating measurements obtained with in-line inspection tools, which locate and size individual metal-loss defects in order to plan maintenance and repair activities. Both deterministic and probabilistic methods are used in the pipeline industry to evaluate the severity of these defects. Probabilistic evaluations typically utilize structural reliability, which is an approach to designing and assessing structures that focuses on the calculation and prediction of the probability that a structure may fail. In the structural reliability approach, the probability of failure is obtained from a multidimensional integral. The solution to this integral is typically estimated numerically using Direct Monte Carlo (DMC) simulation as DMC is relatively simple and robust. The downside is that DMC requires a significant amount of computational effort to estimate small probabilities.
The objective of this paper is to explore the use of a more efficient approach, called Subset Simulation (SS), to estimate the probability of burst failure for a pipeline metal-loss defect. We present comparisons between the probability of failure estimates generated for a sample defect by Direct Monte Carlo simulation and Subset Simulation for differing numbers of simulations. These cases illustrate the decreased computational effort required by Subset Simulation to produce stable probability of failure estimates, particularly for small probabilities. For defects with a burst probability in the range of 10−4 to 10−7, SS is shown to reduce the computational effort (time or cost) by 10 to 1,000 times. By significantly reducing the computational effort required to obtain stable estimates of small failure probabilities, this methodology reduces one of the major barriers to the use of reliability methods for system-wide pipeline reliability assessment.