bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermo-Mechanical Analysis of Compression Sleeves
Authors: Savari Ardeshir , Prestie Zach , Khayami Farbod , Park Simon , Hugo Ronald
Published: December 2024

In recent years, metallic compression sleeves have gained prominence due to their role in enhancing the integrity of pipeline systems. These sleeves can potentially extend the operational life of pipelines by mitigating crack propagation and strengthening material properties. They offer an economically viable repair method, reducing operational disruptions and risks associated with installation, especially under challenging operating conditions. While preliminary studies have been promising, a more detailed understanding of stress dynamics during both the installation process and subsequent operation of the sleeves is needed. This research aims to conduct thermo-mechanical evaluations of Type-A compression sleeves, which are notable for their absence of end fillet welds. We utilize finite element (FE) analysis with the intention of providing insight into the reliability assessment of these systems. The current study employs a coupled field transient system, accommodating the simultaneous application of mechanical variables, such as internal pressure, and thermal factors due to sleeve preheating and welding. This approach mirrors the steps of sleeve installation, from changes in operating pressure and induction heating to welding and cooling. Moreover, the study examines the performance of compression sleeves through a sensitivity anlaysis of significant parameters including internal pressure, mechanical properties of epoxy resin, tolerance fit, and contact between pipe, epoxy resin, and compression sleeve. This study holds significant promise in guiding the compression sleeve application procedures, structural design, and material choices, culminating in enhanced structural robustness and dependability of pipe systems.
Full-Scale Testing of Circumferential Stress-Corrosion Cracking Features in Pipelines: Bridging the Gap in Integrity Management
Authors: Boyce Devin , Mokry Curtis , Jensen Kalen , Brimacombe Mark , Upadhyaya Jay , Chen Qishi
Published: December 2024

Circumferentially oriented crack-like features, particularly those associated with circumferential stress-corrosion cracking (C-SCC), have emerged as a rising integrity challenge for pipeline operators. Despite considerable advancements in testing and model validation for axially oriented features, there remains a notable gap in understanding the load-carrying capacity of pipe with circumferentially oriented crack-like features. To address this knowledge deficit and enhance integrity management understanding around circumferential cracking, a Joint Industry Project (JIP) was undertaken with 10 pipeline operators. The JIP’s second phase was recently completed, which involved comprehensive full-scale testing of pipes with both machined circumferential features and natural C-SCC features from excavated pipe sections that were donated by JIP members.

The primary aim of Phase 2 of the JIP was to contribute to the integrity management of circumferential crack-like flaws identified during in-line inspection, supporting decisions such as selecting excavation sites, planning mitigation measures, determining monitoring actions, and predicting failure loads. The JIP’s focus was on assessing the load-carrying capacity of pipe affected by C-SCC in a biaxial load-state (i.e. internal pressure and axial load) by evaluating the impact of flaw dimensions, internal pressure, and natural flaws (in comparison to machined ones). The full-scale test data was also used to evaluate existing failure prediction models (see IPC2024-133091).

Testing of various flaw depths and length-to-depth ratios showed a maximum axial load reduction of 35% compared to the predicted failure load of pristine pipe. There was a minimal reduction in failure load between hoop stresses of 30% and 50% specified minimum yield stress (SMYS), and a moderate reduction between 50% and 72% SMYS when assessing the effect of internal pressure. Pipes that had severe natural flaws (up to 94% of wall thickness) were still able to carry loads that were considerably higher than predicted. Additionally, burst testing confirmed that circumferentially oriented crack-like features still maintain considerable burst capacity.

This paper provides a comprehensive overview of the executed test program, including the outcomes and findings. The investigation scrutinizes the impact of flaw dimensions, internal pressure, and the distinction between natural and machined flaws on the load-carrying capacity of the tested pipes. As pipeline integrity remains a paramount concern, the outcomes of this study will contribute significantly to advancing the field and improving the industry’s ability to manage and mitigate the risks associated with circumferential crack-like flaws. Completion of this phase represents a significant stride in understanding the load-carrying capacity and model limitations related to C-SCC.
Validation of Dent Fatigue Life Screening and Assessment Methods in API RP 1183
Authors: Tiku Sanjay , Rana Arnav , John Binoy , Dinovitzer Aaron , Piazza Mark
Published: December 2024

Mechanical damage (MD) assessment and management tools have been developed on behalf of Pipeline Research Council International (PRCI), Interstate Natural Gas Association of America (INGAA), Canadian Energy Pipeline Association (CEPA), other research organizations and individual pipeline operators. Many of these tools are included in API Recommended Practice (RP) 1183. The current paper discusses the results of a study undertaken to validate the various dent fatigue life screening and assessment methods that were developed as part of various CEPA and PRCI projects, some of which have been incorporated into the first edition of API RP 1183.

The work presented in this paper involved performing detailed analysis of data provided by pipeline operators for digs where mechanical damage features were identified by in-line inspection (ILI) systems and subsequently excavated and inspected in the ditch using non-destructive examination (NDE) methods. In total, data for 1320 dents were provided for review by pipeline operators based on their dent integrity management programs. More than 10% of these dents were found to have cracks during the in-ditch non-destructive inspection. Detailed dent geometry data, pressure data and in-ditch inspection reports were reviewed and analyzed to perform dent severity analysis. Factors such as pipe geometry, dent shape, dent restraint condition, effect of co-incident features and operational pressure cycle severity were considered to understand the strength of the relationship between various factors and the estimated dent fatigue life. The data was used to evaluate and validate the performance of the dent fatigue life screening and assessment methods developed as part of various CEPA and PRCI projects, some of which have been incorporated into the first edition of API RP 1183.
A Stochastic Approach to Accounting for Slack Line Volume Uncertainties in RTTM Based Leak Detection
Authors: Okungbowa Norense , Nicholas Ed
Published: December 2024

In liquid pipelines with significant elevation changes, the presence of slack line flow can be a significant operational problem. Firstly, slack conditions make control downstream of the slack condition difficult. Secondly, and more importantly, when the vapor bubble from slack flow is decreasing in size, the downstream flow rate will be less than upstream flow rate, which will appear as a leak to an online model.

“A Stochastic Approach to Slack Line Flow in Online Models” (Okungbowa, Brown. PSIG 2023), presented an approach based on Monte Carlo analysis to estimate the probability of slack existing considering uncertainties in physical and modeling parameters. However, it did not attempt to quantify the associated uncertainties in the calculation of the vapor and liquid volumes in the pipeline.

From a leak detection perspective, an important factor is the uncertainty in the calculation of the rate of change of pipeline fluid volume resulting from operating near or in slack line flow. In this new paper, we evaluate applying a Monte Carlo analysis in real time to calculate the uncertainty distribution inherent in the slack volume computations and to incorporate those uncertainties into leak detection parameters.

We examine several slack and near slack events from operating pipelines. As a function of time, we calculate the following for each of these events:

• The probability of being in slack as a function of time.

• The probability distribution of the fluid volume uncertainties resulting from operating near or in slack line flow.

• We evaluate the impact of these uncertainties on leak detection reliability and sensitivity.
An Operator’s Experience of Managing the Threat of Axial SCC
Authors: Bag Debartha , Rehman Hena , Vervake Gary , Fredine Gordon
Published: December 2024

Stress Corrosion Cracking (SCC) is one of the three time-dependent integrity threats classified under ASME B31.8S for managing system integrity of Natural Gas (NG) transmission pipelines. The experience of Enbridge Inc. and its affiliates (for purposes of this paper, collectively, “Enbridge”) of managing axial SCC threat through the Electromagnetic Acoustic Transducer (EMAT) In-line Inspection (ILI) program is discussed in this paper. Enbridge has run more than 9000 miles of EMAT tool in its US and Canadian transmission pipelines, of which significant mileage is baseline runs and subsequently recent mileage for reinspection. Overall tool performance is discussed for both baseline and reruns from the perspective of initial EMAT callouts and subsequent in-the ditch validation of EMAT features. Both high pH and near neutral pH SCC, confirmed in the ditch, and subsequent metallurgical laboratory assessment, has been discussed for Enbridge’s US and Canadian assets. Tool performance has been discussed leveraging Enbridge’s vast mileage of EMAT data using API 1163 unity plot methodology comparing tool called features and in-the-ditch and laboratory validation data. Finally, Enbridge’s Bellhole inspection and repair protocol has been discussed specific to EMAT related digs for managing the Axial SCC threat.
What Are My Options? Review of Non-Destructive Mechanical Tests for Steel Linepipe Yield Strength
Authors: Switzner Nathaniel , Amend Bill , Martin Peter , Anderson Joel
Published: December 2024

Methods for non-destructive estimation of steel linepipe yield strength (YS) and ultimate tensile strength (UTS) are surveyed, recognizing that YS is important for grade estimation. Operators seek rapid, accurate, precise, reliable, and repeatable non-destructive testing methods to estimate pipe YS as part of the process to determine Maximum Allowable Operating Pressure (MAOP), burst pressure, and to perform other critical calculations. We provide a description of several methods to estimate steel linepipe YS.

First, several methods of hardness testing are discussed, with the most focus being placed on two portable hardness measurement methods that have been tested extensively: ultrasonic contact impedance (UCI) and portable Rockwell testing. These two instruments work well in the field and complement one another. For example, if operating/vibrating pipe degrades UCI accuracy, portable Rockwell hardness testing can be used instead. Several additional aspects of these and other hardness tests are discussed, such as surface preparation, wall thickness requirements, indentation size, and the necessity of orienting the hardness tester normal to the surface. Note that hardness testing is not often used to estimate YS directly, but rather to establish a lower bound estimate for YS.

Second, several commercial devices have been developed to provide a direct estimate of YS, and three of them are extensively reviewed in this work, including Instrumented Indentation Testing (IIT), Hardness, Strength, and Ductility (HSD), and Profilometry-based Indentation Plastometry (PIP). Some literature data are not comparable due to different sample groups and testing conditions. Therefore, the authors tested these three instruments on a uniform set of pipes and provide a brief “at-a-glance” comparison of IIT, HSD, and PIP. The results indicate that the root mean squared error (RMSE) for the three instruments for YS ranges from 4–5 ksi for YS and 3–6 ksi for UTS. Additionally, the mean absolute percentage error (MAPE) for the three instruments ranged from 6–7% for YS and 3–5% for UTS. IIT performed the best for YS estimation, and HSD performed the best for UTS estimation, but the differences among all three instrument results were small.

An additional approach for estimating strength based on composition and microstructure alone (PRCI’s Checkmate) is also discussed.

For each method the discussion includes the mechanism (working principle), logistics, dimensional considerations, potential pitfalls, and example models of test instruments. By offering a thorough overview, we aim to assist operators in identifying the most suitable non-destructive test for their specific requirements.
Quantitative Assessment of Incorrect Operations Threat
Authors: Tomar Pushpendra , Kaur Dawinder , Harron Lorna , Sen Millan , Fazli Samir
Published: December 2024

Incorrect operations have risen to the second highest cause of incidents based on the Canadian Energy Regulator (CER) data from 2008 to September 2023 for incidents reported under the Onshore Pipeline Regulations and the Processing Plant Regulations. Despite its considerable impact on the performance of pipeline systems, a comprehensive understanding of what constitutes incorrect operations and the development of a robust risk assessment methodology for this specific threat remains limited.

Incorrect operation is identified as a threat in the American Society of Mechanical Engineering standard, ASME B31.8S Managing System Integrity of Gas Pipelines, Appendix A-8, which defines it as a time-independent issue involving deviations from proper operating procedures or a failure to adhere to established protocols. The crux of this paper lies in the introduction of an innovative and comprehensive method tailored explicitly to evaluate the diverse failure modes associated with incorrect operations. The methodology advocates a systems-based approach by establishing correlations between failure incidents and an array of contributing factors, spanning system intricacies, job-specific attributes, and individual behavioral facets.

The Pipeline and Hazardous Materials Safety Administration (PHMSA) database was leveraged to establish baseline failure frequencies specific to this threat. Additionally, incorporating data provided by a pipeline operator, the assessment of the incorrect operations threat was modified by considering factors such as construction year, temperature, state/province, high-consequence areas (HCA), maintenance, and asset type. The paper details the methodology employed in creating the model, and a preliminary evaluation of the model results is presented. Furthermore, the paper explores opportunities for further refinement of the model, discussing the “ideal” model and the data required for the ideal model to be realized. In doing so, the research aims to enhance our comprehension of incorrect operations within the complex context of pipelines, fostering advancements in risk assessment methodologies for improved pipeline safety and reliability.
Technical Challenges and Strategies for the Repurposing of Existing Gas Distribution Pipeline Networks for Hydrogen Transport
Authors: Landschoot Derek , Gomez Johana , Burkinshaw Ollie , Baby Benjose , Shanks David
Published: December 2024

Enbridge aims to assess the transport of hydrogen blends through an existing gas distribution network.

Demonstrating suitability of existing pipelines for hydrogen repurposing is a complex task, with limited industry consensus or historic empirical data on hydrogen pipelines adding uncertainty to the process. The 2023 edition of CSA Z662 [1] has provided some clarity through the Engineering Assessment approach introduced for hydrogen repurposing; however, it leaves aspects of the assessment to be further defined. Whilst more prescriptive requirements may be referred to in other standards, such as ASME B31.12 [2], these requirements are liable to change with regular updates and industry research on hydrogen.

The subject pipeline network poses particular challenges for Engineering Assessment due to assets being unpiggable, limited availability of integrity data, and the wide range of pipe populations, with construction spanning multiple decades. In the absence of specific data, inspection and testing are essential to reduce the conservatisms and refine risk assessments. Recognizing the challenges in collecting data for an unpiggable and urban distribution system, it is critical to optimize the strategy for testing and inspection.

This paper details a project completed between Enbridge and ROSEN to explore the effects of hydrogen on the integrity of the pipeline system in the face of limited data, with an approach centred around an extensive sensitivity study assessing fracture and fatigue. The approach also used an asset ranking model drawing on the findings of the sensitivity study to support effective targeting of inspection and testing to maximize the value from gathered data. In addition to the project findings, this paper provides insights on the implications for hydrogen repurposing of distribution pipelines and systems with limited specific data to support detailed Engineering Assessments.
Is Pipeline Safety Improving?
Authors: Hereth Mark , Skow Jason , Di Blasi Martin
Published: December 2024

The analysis of historical gas transmission pipeline failure trends in North America shows an improvement over the last twenty years. Many factors are driving the improvement in pipeline safety performance; the introduction of Integrity Management in pipeline regulations, such as the US Code of Federal Regulations, has set forward minimum requirements and brought consistency across pipeline operators for the minimum level of care. This paper addresses the question, is integrity management having an impact on safety performance?

Many pipeline operators have extended the application of minimum requirements beyond high consequence areas. Operators have applied and developed advanced internal inspection technologies, threat analytics and integrity planning strategies. In addition, Operators are adopting reliability and risk management frameworks, not only to prioritized assessments in a baseline program, but to perform risk-informed integrity decision-making on an ongoing basis throughout the asset life-cycle.

This paper uses publicly available pipeline incident data sets to trend failures and incidents using technically-sound analysis techniques routinely used in high reliability industries to show evidence that pipeline safety continues to improve and that the current levels of safety and reliability are aligned with the expectations of the industry, the regulations, and the public. The paper focuses on pipelines rupture incidents classified by root cause threats, location classes, and health, safety and environmental consequences. A societal risk assessment is used to estimate pipeline residual risks and provide recommendations for integrity management frameworks to advance the standard of care through continual improvement.
Hard Spot Management Framework for Gas Transmission Pipelines Using Risk-Based Approach
Authors: Shabarchin Oleg , Janousek Austin , Bolf Brady , Moran Sean , Thompson Kelly , Malinowski Owen
Published: December 2024

The presence of hard spots can be a concern for gas transmission pipeline integrity management because these manufacturing defects might fail under normal operational stress. Considering pipeline failures associated with hard spots and increasingly stringent regulatory requirements, there is a need for pipeline operators to establish a robust and efficient hard spot integrity management program. Currently many pipeline operators use industry susceptibility studies conducted in the early 2000s as a basis for their hard spot integrity management program. These studies identified that susceptibility to the hard spot threat is mostly associated with a specific pipeline steel plate manufacturer. However, these studies were limited by incomplete failure data, and lack of length-normalization, rendering them inadequate for comprehensive reliability and risk analysis. A systematic review of existing hard spot data and recent study performed by Pipeline Research Council International (PRCI) MAT-7-2 project suggests susceptibility to hard spots across a broader range of manufacturers and operating conditions. Herein, this paper discusses operators’ experience with the hard spot threat outlining learnings, findings, and challenges. Then, this study employs PRCI MAT-7-2 susceptibility criteria, integrating them with field verified-findings and operators’ experience to guide informed decisions in the pre in-line inspection stage, with the goal of establishing future inspection plan. This is achieved using a flexible Bayesian Network approach that captures uncertainties and interdependencies offering a more comprehensive solution than relying on traditional deterministic susceptibility guidelines. Next, the study extends to a post in-line inspection review of hard spots, using a risk-based approach to mitigate potentially injurious features. To accomplish this, the study leverages a structural reliability methodology using a hard spot failure pressure model applied in a Monte Carlo simulation. Such approach helps to rigorously account for uncertainties and quantify the probability of failure, considering essential factors such as ILI measurement error, pipe material properties, hard spot dimensions and hardness, etc. An operating scenario study is included to demonstrate the practical application of the proposed framework in effectively managing the hard spot threat in gas transmission pipelines.
Bayesian Approach to Coating Life Modelling for Probabilistic Corrosion Growth Rate Analysis
Authors: Stewart Ryan , Skow Jason , Jasper Evan , Schoenroth Kent
Published: December 2024

Selecting the correct pipeline coating, ensuring its proper application, and maintaining it are essential for the long-term protection of pipelines against external corrosion. While industry guidance documents recommend quality assurance and quality control procedures for the maintenance and installation of coatings, the practical service life of pipeline coatings remains a challenge to estimate. As newer generation coating technology matures, anecdotal evidence suggests that coatings can remain reliable for decades under optimal environmental conditions.

The authors developed a model based on general industry knowledge of coatings across time and findings from integrity digs. A Bayesian model was used to provide a robust framework to integrate prior knowledge and observed data. In situations where empirical evidence is sparse or unavailable, subject matter expertise acts as an informative prior.

This paper introduces a Bayesian method that quantifies the practical service life of coatings and predicts the probability of the coating being intact for a given pipeline segment over time. The model incorporates subject matter expertise with observations from pipeline excavations that reveal the coating to be intact or not. The model is updated to account for the results from integrity digs. Using generalized industry benchmarks with specific inspection findings produces a more accurate estimation of coating integrity. The results are used to estimate the effective corrosion growth rates on a pipeline in a probabilistic pipeline assessment.
Consistently Inconsistent: Lessons From Operators Comparing Multiple IMU Data Sets
Authors: Dotson Rhett , Brown Alex , Jackson Briant
Published: December 2024

Operators and regulators have demonstrated an increased awareness of the geohazard threat over the last decade. In response to this threat, many pipeline operators have begun integrating bending strain assessments based on IMU data into their integrity management programs. Bending strain assessments, which provide a direct measure of the pipe condition, can be a valuable tool in any geohazard integrity management program. Unfortunately, many operators encounter challenges or even confusion when they receive results from a bending strain assessment. The results from a bending strain assessment can be difficult to understand and even more difficult to properly sentence, especially if the assessment identifies hundreds of features. These challenges can be compounded if the operator acquires a second IMU data set and elects to perform another bending strain assessment or a strain change assessment comparing the two data sets. In these situations, operators often observe significant variations in the number of reported bending strain features and the reported strain magnitudes associated with those features. These challenges can rarely be solved by comparing the final reports as the graphical information for the bending strain features is often rendered differently between vendors. This paper presents the results of two case studies where each case study had multiple bending strain reports based on different IMU data sets. Both case studies demonstrated common challenges experienced by operators. Each assessment had significant differences in the number of reported bending strain features and the locations of those features. In both case studies, the information supplied with the final reports was insufficient to reconcile the differences between the two assessments. After demonstrating these challenges, the paper presents the results of the strain change assessments when these assessments are performed according to the same criteria and the identified features are fully reconciled. Based on these results, the paper identifies and discusses the causes of the variation in both case studies which includes gauge length, signal noise, and analyst judgment. The paper demonstrates how those variables can impact the results of a bending strain assessment, and the lessons learned from this case study. The paper concludes by identifying the necessary reporting requirements for bending strain or strain change assessments and makes recommendations on how results from these assessments can be standardized to help operators minimize future variations.
Circumferential Stress Corrosion Cracking, Bending Strains, Slopes and Landslides: An Operator’s Experience
Authors: Dewar Doug , Brimacombe Mark , Charlesworth Coleby
Published: December 2024

Circumferential stress corrosion cracking (CSCC) requires a corrosive environment, susceptible pipeline material, and tensile stress. A Canadian operator’s data set is reviewed from a geotechnical point of view to determine the potential source(s) of axial tension required to create CSCC. The initial assessment of the dataset was presented in 2018 [1] focusing on crack characteristics, growth rates, and CSCC management programs. This paper focuses on geotechnical attributes, pipeline settings and ILI IMU data complemented by additional landslide monitoring data gathered over the past 5 years to refine initial interpretations. The hypothesis is that the primary source of axial tension creating CSCC occur from or can be contributed to by construction induced strains rather than landslides or extreme weather events.
Effective Integration of Commercial and Operational Risks
Authors: Ngo Chuong , Wright Charlene B.
Published: December 2024

This paper will focus on the process of aligning commercial performance targets with operational capability and resourcing. Though this concept is applicable to multiple sectors and businesses, this paper will focus on the midstream pipeline systems sector of the oil and gas industry.

Organizations aim to maximize performance and return on investment by setting strategic goals, objectives, and targets. Line of sight across the enterprise to corporate objectives and proper alignment to common strategic goals will enhance the likelihood of success, improve efficiency, maximize business performance and minimize risk. The process of refining goals and aligning priorities with finite resources is a complex task.

Many organizations are structured with intentional separation between commercial and operational functions. This may be due to the diversity of the skill sets required for each of the functions, or as a byproduct of accounting based decisions, but the separation introduces opportunities for misalignment of objectives. Segregation of reporting structures may create conflicting directives. Such misalignment could result in counter-productive resource drains driven by duplication of efforts, contradictory initiatives that can erode value, inability to react to market shifts, inability to capture opportunistic market demand, and potential misses in forecasted performance.

Commercial functions are market and customer-facing. They require a focus on market demand, forecasts, global and local market trends, price sensitivities, political and economic factors, and customer trends and opportunities. The main responsibility of this group is to understand which market opportunities offer maximum value. Commercial managers are incentivized through their performance structure to capture as much of the market as possible. They do not focus on engineering drawings, failure data, purchase orders, reliability graphs, work permits, sparing philosophies, and operational integrity factors that are the focus of their counterparts in Operations and Integrity. They assume that the physical asset is maintained, reliable, and available.

Alignment of commercial demand with operational capabilities is a key requirement to maximize return on investment. It provides both the revenue benefits as well as the cost to capitalize on the benefits. When goals are aligned and the “right” initiatives have been defined, the organization minimizes waste, ensures risk tolerances are aligned, and allows for resources to be efficiently optimized. With this approach, scenario planning, resource management, and business strategies can be better aligned to deliberately achieve maximum return on investment. This paper discusses considerations needed to effectively integrate commercial demand with operational readiness to reduce the possibility of an over-committed market position or an underutilized asset.
Enhancing Stress Corrosion Cracking Feature Identification Using EMAT Data and Field Learnings
Authors: Langlois-Rahme Gabriel , Shabarchin Oleg , Foster Alexander , Di Blasi Martin , Chen Xueze , Fredine Gordon
Published: December 2024

As data-driven decision making is becoming more critical in managing the integrity of natural gas transmission pipelines, this paper examines statistics on the identification of Stress Corrosion Cracking (SCC) using field excavations. The main tool used to detect SCC is the Electromagnetic Acoustic Transducer (EMAT) In-line Inspection (ILI). This tool can detect many other less injurious stable features such as lack of fusion pipe mill anomalies. This paper provides novel data driven techniques to help operators differentiate non-injurious cracks and SCC from field learnings. These techniques include a general statistical model, an SME Based Logistic Regression Model, and a Data Driven Machine Learning Logistic Regression model for pipelines susceptible to high pH intragranular SCC, and near neutral pH trangranular SCC separately. Each technique provides a probability that an EMAT call is a true SCC anomaly. An impact assessment on each of these techniques is provided around quantitative risk assessments and risk informed decision making. These insights can be used for risk-informed decision making on Stress Corrosion Cracking Direct Assessments by incorporating the requirements around soil data and minimum Charpy V-Notch Toughness from the Mega Rules RIN-2.
Interfacial Turbulent Diffusivity Between Air and Natural Gas/Hydrogen Blends During Pipeline Purging Process and Implication on the Extent of the Interfacial Mixing Zone
Authors: Botros Kamal K. , Hill Colin , Ziade Paul , Johansen Craig , Van Boven Greg
Published: December 2024

The aspiration for blending hydrogen (H2) into natural gas (NG) in gas transmission systems is high and is happening globally. However, several design and operational aspects need to be developed to ensure the safe and reliable delivery of these blends to the end users. One of these aspects is the development of an effective purging procedure of air with NG+H2 blends during the commissioning of a pipe section. An important factor in achieving effective and safe purging is to accurately determine the extent of the mixing zone between the purged air and the purging medium (NG+H2 blend in this case). Since hydrogen is recognized as having a much smaller molecular size than air and/or NG, its molecular diffusivity would be higher leading to a lower Schmidt number. The present research examines the aspects of interfacial turbulent diffusivity, which is key in determining the extent of the mixing zone between air and NG+H2 blends during purging. The investigation was carried out via large eddy simulation (LES) computational fluid dynamics (CFD) simulations at different Reynolds numbers varying from 10,000 to 400,000. The spatial and temporal average of the turbulent diffusivity for an NG+H2 blend at 30% by mole H2 was extracted from the CFD results. It was found that the normalized turbulent diffusivity for the case of the NG+H2 blend studied is at least one-half order-of-magnitude higher than that from Taylor Theory, which is typically used for un-blended natural gas. The implication of this will be elucidated by examples to show that the extent of the mixing zone is longer for NG+H2 blends than that for un-blended NG. The ultimate application of the finding is to ensure that effective purging is achieved to prevent any possibility of an explosion of unpurged air, particularly when H2 is a constituent in the hydrocarbon gas mixture.
Pull Testing and Statistical Evaluation of ILI Capabilities on SSWC and Other Anomalies
Authors: Al-Hasani Zain , Cazenave Pablo , Jimenez Katina , Milligan Ryan
Published: December 2024

TC Energy (TCE) operates and maintains natural gas, refined products, and crude oil pipelines in the USA, Canada, and Mexico. The network includes more than 93,000 kilometers (58,000 miles) of gas pipelines, transporting more than 30% of the North American natural gas demand.

As part of its Integrity Management Program, TCE identified Selective Seam Weld Corrosion (SSWC) as one of the significant threats for certain seam weld types in their pipeline system. It also identified In-Line Inspection as the preferred methodology to address it. In that regard, multiple ILI vendors have claimed capabilities in detecting, identifying, and sizing SSWC features, which require careful evaluation and assessment.

A pull-through testing exercise was designed to evaluate and validate those capabilities statistically. The evaluation aims to test multiple ILI systems from different ILI vendors for SSWC and other threats that have yet to be validated and to confirm the detection capabilities for specific pipe attributes. The final objective is to have an array of ILI vendors and technologies to address each threat cost-effectively.

The 24-inch diameter string constructed for this project included joints with synthetic and natural features, including SSWC, pits at the SW and in the pipe body, axial and circumferential slots in the pipe body, individual cracks, crack colonies, laminations, wrinkle bends, hard spots, dents with gouges and plain dents.

Five ILI systems from five ILI technology providers were tested.

The project included the pipe acquisition, the testing string design, the defect creation, the NDE and Lab evaluation of the reference data, the pull-through testing, the ILI vs Reference feature matching, and the statistical analysis of the results.

This paper presents the results of this study.
Evaluation of Stress-Relief Excavation for Pipelines Affected by Landslides: Case Studies
Authors: Ahmadipur Amir , Haferd Jeffrey , Mosaiebian Arash , Karimpour Hamid , Ebrahimi Ali
Published: December 2024

One of the mitigation methods for a pipeline affected by landslides is stress-relief excavation. In this mitigation approach, the soil above and around the pipeline in the affected area is excavated to allow the pipeline to rebound and relieve some of the accumulated elastic stresses on the pipeline. This paper presents the data collected before, during, and after stress-relief excavations at four landslide sites in the USA. These case studies include a variety of pipe strain condition, geometry, and ground conditions in which the stress-relief excavations were performed. The collected information includes pipe rebound measurements using survey laths, strain change measurements during and/or after stress-relief excavations using strain gauges when available, and pipeline rebound and strain change comparison before and after the stress-relief excavations using inertial measurement unit (IMU) measurements, when available.
Essential Elements of a Holistic Framework for the Management of Geohazards
Authors: Wang Yong-Yi , Liu Banglin , Warman David , Jia Dan
Published: December 2024

Geohazards are a major contributor to pipeline incidents. A pipeline incident occurs when the demand on a pipeline segment exceeds its capacity. The demand is the loading imposed on the pipeline segment, while the capacity is the ability of the pipeline segment to resist the demand before an undesirable event, such as a leak or rupture, occurs.

Many geohazards management programs focus on the detection, characterization, mitigation, and monitoring of geotechnical hazards, i.e., demand, with limited consideration for the capacity of the affected pipeline segments. In some cases, mitigation decisions are made largely based on the characteristics of the hazards and whether the hazards are interacting with the pipeline. This approach can lead to over- or under-reaction as the hazards alone do not fully represent the level of integrity risk due to the lack of accounting for the capacity.

Geohazards could be managed more economically with a holistic approach covering the characteristics of hazards and the pipeline’s capacity. Mitigation decisions based on quantifiable safety margins, stability of the site, risk tolerance, and operational considerations can provide the most flexibility in the timing, scope, and methods of mitigation while ensuring the safety of the pipeline. A proactive integrity-focused approach can also aid pipeline operators’ decision making and response to emergency situations.

This paper presents a holistic approach to geohazards management with an ultimate goal of maintaining pipeline integrity. Lessons are drawn from incidents and successes. A contrast is made between the industry’s approach to managing common threats, such as corrosion, mechanical damage, and cracking, and its approach to managing geohazards. Different approaches to geohazards management as implemented by pipeline operators are described. Key elements of a holistic approach to geohazard management are explained and recommendations for practical actions are provided.
Case Study: Application of Best Practices for Pipeline Construction on Steep Slopes
Authors: Deelen Arend , Van Megen Clayton , Murray Carrie , Smith Colby , Bartel Riley , Bajnok Jesse
Published: December 2024

In 2019, Coastal GasLink started the construction of the 670 km-long 48-inch gas pipeline across the province of British Columbia (BC) Canada. The project was constructed across varied terrain, including construction across two mountain ranges, the Rocky Mountains and the Coastal Mountain Range. The final 83 km of pipeline (Section 8) is characterized by an ascent through the Coastal Mountains to the highest point on the project at 1,428 m above sea level and a descent to sea level at the LNG Canada terminal in Kitimat, BC. Pipeline Section 8 contained a number of steep slopes (SS) ranging in angle from 15 degrees to 63 degrees. Many of these steep slopes had unique features, ranging from topography, geohazards, construction windows, accessibility, and weather-related factors. Each factor contributed to the selection process for the most suitable method of steep slope pipeline construction.

The steep slope pipeline construction techniques which were used consisted of:

i. Conventional open cut via trenching by blasting and mechanical excavation,

a. Open cut using winch-supported equipment,

b. Open cut with hydraulic sled using a top-down pipeline installation sequence,

ii. Raise bore of an inaccessible steep slope (SS3), and

iii. Cable cranes over a steep mountain side with slope lengths of up to 1,373 m and slopes angles up to 58 degrees.

The raise bore and the cable crane construction techniques were a first in Canada for pipeline installation, providing innovative and unique solutions to pipeline construction.

The objective of this case study is to provide an overview of the various steep slope pipeline construction techniques, provide a discussion on the challenges and successes for each technique with a summary of the lessons learned. A summary of the safety practices developed and implemented will also be presented.
Application of Gaussian Process Classification to the Integrity Management of Energy Pipelines
Authors: Sun Haotian
Published: December 2024

Leveraging algorithms that autonomously evolve with data, machine learning has become integral and been extensively applied to the pipeline integrity management practice to create accurate predictive models, whose outputs can either be numerical or categorical. The latter corresponds to the classification analysis, whose models typically yield deterministic outputs, categorizing data points as of either the positive or negative class. However, practical engineering scenarios may demand a more nuanced approach. Additionally, the conventional “black-box” nature of many machine learning models often hinders their interpretability. This study introduces Gaussian Process Classification (GPC) — a probabilistic classification algorithm that has been found to be underutilized — to the realm of pipeline integrity management, where challenges in the classification accuracy and efficiency of specific problems have become noteworthy. Unlike some classifiers, GPC provides the probability that a data point belongs to the positive class, allowing for a more flexible decision-making process. Notably, users can self-determine the threshold probability. Moreover, the predictive process of GPC is analytically transparent, enhancing the overall interpretability of the machine learning model. The algorithm is applied to three distinct binary classification problems within pipeline integrity management: separating failure modes for cracked pipelines, differentiating failure modes for corroded pipelines, and predicting ignition upon rupture of onshore natural gas transmission pipelines, while each problem involves unique input features. The machine learning models for these problems undergo thorough training via hyperparameter tuning using the maximum likelihood method. This approach improves model robustness, mitigates overfitting, and optimizes performance. The developed GPC models are benchmarked against existing mechanics-based and log-logistic models for comparative evaluation, whose results demonstrate the accuracy and superiority of GPC in these specific scenarios. The present study demonstrates the value of probabilistic machine learning for improving the pipeline integrity management practice.
Integrated Methodology for Dent Gouging Susceptibility Studies: A Comprehensive Analysis Incorporating In-Line Inspection Data and Field Validation
Authors: Holliday Chris , Curtis Chris
Published: December 2024

Failure of a pipeline due to excavation damage accounts for > 11% of reported pipeline incidents in the United States between 2004 and 2023. However, perhaps more alarming is that excavation accounts disproportionately for the majority of both human fatalities and injuries; in fact, 24% of fatalities and 23% of injuries are reported to be a result of excavation damage.

With improvements in in-line inspection (ILI) technology and data analysis processes, in addition to the trending focus of the industry on deformations, it is common for an ILI to detect and report several hundred dents in a given inspected pipe segment. How, then, does an operator accurately and pragmatically determine which of these dents are a result of excavation damage and potentially contain gouging?

This paper proposes an innovative integrated methodology for the identification of dent gouging susceptibility in pipelines, with a primary focus on identifying the likelihood of potential third-party interference (TPI). The approach aims to enhance the understanding of dent-related threats by incorporating a comprehensive signal level analysis of metal loss, cracking and deformation in-line inspection (ILI) data. The study also considers various critical parameters such as depth of cover, dent restraint condition, dent shape and size, dent orientation, interaction with metal loss, ILI sensor lift-off, and other relevant factors.

The study also introduces a benchmarking process, utilizing field-validated dents with gouges. By comparing the ILI data from these validated cases with the proposed integrated methodology, both the reliability and accuracy of the approach are substantiated. This benchmarking step not only enhances the credibility of the proposed methodology, it also provides a practical validation of its effectiveness in identifying and characterizing gouges resulting from third-party interference.

The proposed methodology represents a holistic and proactive approach to dent gouging susceptibility studies, providing pipeline operators with a comprehensive toolset for the determination of the probability of TPI. By incorporating advanced data analysis techniques and benchmarking against field-validated cases, the approach offers a framework for identifying and mitigating threats associated with third-party interference-induced dents, thereby enhancing the overall integrity management of pipelines.
Trial and Error — Applications of Machine Learning Models to Pipeline Integrity Data
Authors: Kalivoda Mia , Iyer Parth , Allanbrook Wesley , Goertzen Josh
Published: December 2024

For pipeline operators, a thorough understanding of machine learning’s strengths and limitations is key to reaping the benefits of data-informed decision-making and efficient use of resources. This paper conducts an analysis of different machine learning models and data quality assessment tools/analytical methodology, bolstered by case studies, highlighting the critical need to choose a model that best aligns with the specific characteristics of the data to fully leverage these benefits. This paper undertakes an analytical exploration of the strengths and limitations inherent to each model, complemented by various case studies as a proof of concept of leveraging machine learning in the pipeline integrity workflow.

The accuracy of Bayesian Networks (BN) and Natural Language Processing (NLP) in predicting text-based data entries from inline inspection feature comments was compared, showcasing one model’s substantial superior performance.

Another case study revealed variation in the accuracy of BN in predicting absent information, by comparing predictions derived from a dataset with missing entries, against a modified validation dataset.

A final case study highlights the ability of text string comparison using Fuzzy Matching in automated Data Quality Assessment applications, to efficiently match and categorize wall thickness and outside diameter values, portraying significant time saving advantages.