bluuebunny/crossref_metadata_2025 huggingface dataset:
The Forest and the Trees: Investigating Groups and Individuals in Longitudinal Second Language English Speaking Development
Authors: De Wilde Vanessa , Lowie Wander
Published: December 2024

Studies looking into second language development have shown that findings about a group of learners cannot be transferred to individual learners. In this study, we explored ways to meaningfully group individuals starting from the data and investigated whether this grouping can give extra information about learning trajectories that goes beyond the individual learner. We followed 61 learners for 10 months, collected information about various individual difference variables at the start of the study, and investigated speaking development by collecting data on a weekly basis. We investigated whether it was possible to discern learner types through cluster analysis starting from five individual difference variables. This resulted in three learner types that differ from each other in their speaking development. Within each learner type, there are differences but also clear similarities across learners. The study shows that adopting a person‐centered approach to grouping learners can contribute to uncovering patterns in learners’ development.
Genetic algorithm optimized frequency‐domain convolutional blind source separation for multiple leakage locations in water supply pipeline
Authors: Liu Hongjin , Fang Hongyuan , Yu Xiang , Xia Yangyang
Published: December 2024

In the realm of using acoustic methods for locating leakages in water supply pipelines, existing research predominantly focuses on single leak localization, with limited exploration into the challenges posed by multiple leak scenarios. To address this gap, a genetic algorithm‐optimized frequency‐domain convolutional blind source separation algorithm is proposed for the precise localization of multiple leaks. This algorithm effectively separates mixed leak sources and accurately estimates the delays of source propagation. Signal simulations confirm the algorithm's effectiveness, revealing that the distribution of leak positions, signal‐to‐noise ratio, and frequency characteristics of the leakage source all influence the algorithm's performance. Comparative analysis demonstrates the algorithm's capability to eliminate signal interactions, facilitating the localization of multiple leaks. The algorithm's efficacy is further validated through extensive full‐scale experiments, underscoring its potential as a novel and practical solution to the complex challenge of multiple leakage localization in water supply pipelines.
Effect of Tinted Lenses on Migraine Patients as Assessed by Pupil Response and Heart Rate Variability Analysis
Authors: Kamata Yasuaki , Hara Naoto , Nozaki Takahiro , Niida Takahiro
Published: December 2024

Background

Patients with migraines cite light as a trigger for headaches, highlighting the need for preventive measures like visual environment improvements. Tinted lenses are optical aids that suppress visible light transmission. Since their selection relies on subjective evaluation, objective assessment is necessary to confirm their effectiveness.

Aim

To investigate the effects of tinted lenses on the autonomic nervous system of patients with migraines by analyzing pupil response and heart rate variability.

Methods

Ten patients with migraine and 16 controls were included. The participants performed the experiment in a completely dark room in a supine position. A display projecting a white background was fixed 30 cm in front of the eyes as a light stimulus. Changes in pupil size and heart rate were measured before and after light stimulus. The experiment was performed under three conditions: no lenses, blue‐tinted lenses, and green‐tinted lenses. In addition, a visual analog scale was used to measure photophobia.

Results

When green‐tinted lenses were used, a decrease in the pupil constriction rate was observed. In the heart rate variability analysis, the sympathetic nerve index was significantly higher in patients with migraine than in the control group with no lens and blue‐tinted lenses, but there was no difference in the green‐tinted lens group. Photophobia was significantly higher in the migraine group than in the control group under all conditions.

Conclusion

Wearing tinted lenses that suppress short‐wavelength transmission in patients with migraine has been suggested to decrease the pupil constriction rate and suppress sympathetic nervous system indices.
Cognition, Depression, Pain, and Exercise Motives as Predictors of Longitudinal Profiles of Physical Activity During a Seven‐Year Follow‐Up Among Older Adults
Authors: Kyrönlahti Saila , Lehtisalo Jenni , Ngandu Tiia , Kivipelto Miia , Strandberg Timo , Antikainen Riitta , Laatikainen Tiina , Soininen Hilkka , Tuomilehto Jaakko , Havulinna Satu , Kulmala Jenni
Published: December 2024

This study investigated longitudinal physical activity (PA) profiles over 7 years in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER). Cognition, depression, pain, and PA motives were included as determinants of the PA profiles. The 1259 participants, aged 60–77 years at baseline, were randomized into either a control group receiving general health advice, or an intervention group offered a comprehensive 2‐year multidomain intervention including physical exercise, diet advice, cognitive training, and vascular risk factor management. The participants reported weekly moderate‐intensity PA at baseline and 1, 2, 5, and 7 years after the baseline. Those providing PA data at two or more time points were included (n = 1188). Longitudinal PA profiles were determined using latent class growth analysis, and their associations with baseline determinants via multinomial logistic regression analysis. Interaction terms were added to investigate whether the intervention modified these associations. Six PA profiles were identified: Very high–stable (6%), High–stable (22%), Moderate–declining (47%), Moderate–steeply declining (5%), Low–increasing (9%), and Constantly low (12%). Participants in the intervention group and those motivated by distal and proximal benefits of exercise were likelier to maintain high PA level. Conversely, depressive symptoms and pain were predictors of Constantly low profile. Results show that high baseline PA was generally maintained, while greater variability in PA changes was observed among initially less active participants.
Investigation of Fracture Prediction Capability of XFEM and Finite Element Method Using SENT Specimens
Authors: Kheirkhah Gilde Mohammad , Najari Enayat , Imanpour Ali , Yoosef-Ghodsi Nader , Adeeb Samer
Published: December 2024

This study investigates the fracture behavior of single-edge notched tension (SENT) specimens made from API X52 vintage pipeline steel by comparing the extended finite element method (XFEM) and the traditional finite element method (FEM). Both methods are implemented in abaqus finite element software to simulate specimens with varying notch length-to-specimen-width ratios, whose fracture properties have been experimentally determined. The analysis focuses on plotting force versus global displacement, crack tip opening displacement (CTOD), and crack mouth opening displacement (CMOD) for each method. These simulation results are then compared with experimental data. A mean absolute percentage error (MAPE) calculation quantifies the level of agreement between the model and test results. The findings demonstrate that both methods can replicate the experimental force–crack opening displacement (COD) and force–displacement curves. However, XFEM offers distinct advantages, including the elimination of the need for mesh refinement, easier numerical convergence, and accurate visualization of the crack propagation path.
Data Center Waste Heat Reuse: An Investment Analysis
Authors: Khalid Rehan , Wemhoff Aaron P. , Khuc Mai , Nayar Ajay J. , Schon Steven
Published: December 2024

A thermo-economic analysis (TEA) of a novel cooling and enhanced heat recovery (CEHR) system for data centers (DCs) is presented. Three financial metrics (net present value—NPV, return on investment—ROI, and payback period—PP) are calculated for hot and chilled water generation. Hot water generation uses vapor recompression to produce water at approximately 75 °C. Chilled water generation builds upon the hot water generation scenario by feeding the hot water stream into an absorption chiller. Without considering the additional costs for connecting the infrastructure with the customer, a payback period shorter than 2 years is found for a hot water generation system for a base case assuming a 10-MW data center (DC) in Philadelphia, PA, when carbon (reduction) credits are included. Chilled water generation is found to be economically unfavorable in this location. Sensitivities of economics to data center power, hot water versus chilled water generation, geographic region, and carbon credits are evaluated for five additional global locations in Europe and Asia. The economies of scale enable favorable payback periods for integrating hot water generation for facilities beyond 7 MW. Hot water generation is especially favorable in Singapore when replacing natural gas-based heating or hot water heat pumps.
Effect of Orientation on CVN and K-CVN Toughness Correlation of SAW Pipe Seam Welds
Authors: Xu Su , Liang Jie , Qian Cheng , Tyson William R.
Published: December 2024

Charpy absorbed energy (CVN), and fracture toughness (stress intensity factor K) using single-edge notched bend (SE(B)) specimens, were measured for submerged-arc welded (SAW) pipe seam welds using two typical two-pass seam welds. Because the intent is to derive K values for engineering critical assessment (ECA) of surface flaws, a correlation between K and CVN was assessed. A crack depth of a = 2 mm was used (i.e. the normal notch depth for CVN specimens, and similar target depth for SE(B) specimens representative of real-world weld flaws). The effect of orientation on CVN values was studied because a through-thickness notch (TTN) is specified in standards but a surface notch (SN) is more relevant for real-world flaws. The results indicate that there is little effect of orientation on CVN of TTN and SN specimens for these X70 and X100 SAW seam welds, implying that TTN specimens can be used to infer SN specimen values.

To be relevant to Charpy tests in lower-transition or lower-shelf regions, fracture toughness tests were performed at the corresponding temperatures. Most SE(B) specimens showed some ductile tearing before instability except for the specimens of X100 weld at −45°C that displayed full ductile tearing. Ductile fracture initiation toughness values (J0.2) were stable over the temperature range studied. Fracture toughness (Ju) corresponding to instability (cleavage fracture) increased with temperature along with CVN values that ranged from 24 J to 69 J for X70 and 45 J to 95 J for X100. Based on results of these two SAW welds, the BS 7910 K-CVN correlation was found to yield highly conservative estimates of K for a shallow-notched external surface flaw from CVN.
Crack Arrestors: Closing the Design Basis Gaps
Authors: Laughlin Shawn , Leewis Keith
Published: December 2024

The demand for pipelines to transport increased volumes of hydrogen and CO2 in the future is widely anticipated. The specific potential sources and nature of the fluids that are anticipated have led to concerns regarding potential gaps related to fracture control plans and operational integrity efforts. One of the specific gaps that has been identified is that of the design basis for the external devices (non-integral) which we generally refer to as “crack arrestors”. Specific concerns focus on anthropogenic CO2 with a more challenging decompression and hydrogen blends which could affect the pipe steel ductility. Crack arrestor devices are generally intended to arrest running ductile fractures or propagating shear. This paper reviews the technical history of this topic. Technical paper publications and intellectual property sources are reviewed. It will document the 1970’s understanding that the deformation in front of the fracture was considerable with specific characteristics. A review of effective and ineffective efforts over a 5-decade period is reviewed, as well as the design basis for these efforts. A review of the commonality of characteristics of effective and non-effective efforts is reviewed with a focus on identifying design basis flaws and the reasons for success. This paper will suggest that the mechanism of the phenomena of propagating shear is a plastic collapse of the pipe structure, with the propagating fracture an artifact. The means to stop the running ductile fracture is to add capacity to the structure or Resistivity to plastic collapse. In this context, the BTCM (or alternatives) with a focus on the speed of the gas decompression and the speed of the crack, are not necessarily the precise or sole path for a complete understanding of how to stop or arrest the event. A change in perspective is suggested from a focus on the speed of the propagation to adding capacity to the pipe structure. This paper will provide the basic details of an updated design basis for these crack arrestors devices.
Finite Element Analyses of Burst Capacities of Pipelines Containing Pinhole-in-Corrosion Defects
Authors: Shen Yufei , Zhou Wenxing
Published: December 2024

This study investigates the burst capacity of pipelines containing pinhole-in-corrosion (PIC) defects through elastoplastic three-dimensional finite element analyses (FEA) and quantify the extent to which the burst capacity of the PIC defect is affected by sizes of the corresponding pinhole and general corrosion anomaly and the relative position of the pinhole within the corrosion anomaly. The PIC defect in this study is idealized as a cylindrical-shaped pinhole located within a cuboidal-shaped general corrosion anomaly. Results of extensive parametric FEA reveal that, in general, the burst capacity decreases as the pinhole depth increases; however, the bust capacity is insensitive to the diameter the pinhole. The location of the pinhole is found to be a significant factor, with pinholes closer to the edge of the general corrosion having a smaller impact on the burst capacity, while a pinhole at the center of the general corrosion can greatly impact the burst capacity. The pinhole location effect is explained by considering the impact of the bulging effect on the burst capacity of PIC. The outcomes of the study provide the basis for developing an accurate, practical burst capacity model for pipelines containing PIC defects.
Impact of Operating Temperature Increase on Liquid Pipeline Corrosion Management
Authors: Yu Mengshan , Gibeault James , Li Yanping , Place Trevor
Published: December 2024

Some liquid pipeline operators are experiencing an upward trend in operating temperatures. This trend is influenced by increasing flowrate through fixed pipeline inventory (viscous heating), hotter product entering some pipelines, and environmental warming (less heat loss to soil and atmosphere).

While increasing temperature is known to increase the degradation rate of some coatings and the often-mentioned Arrhenius Equation suggests chemical reaction rate could double with every 10°C temperature increase, the true effect on pipeline corrosion is not fully understood. The real-world impact of temperature changes is a complex interaction of physical and chemical processes. To find the impact of temperature increase on pipeline external corrosion growth rate (CGR), results from laboratory studies and field case studies will be presented.

Long term corrosion testing was performed under a simulated coating disbondment condition at various fixed and modulated temperatures (to simulate seasonal variation). Corrosion rates were measured gravimetrically and by measured pit depth. It was demonstrated that Arrhenius level CGR-temperature correlations could be emulated under artificially severe conditions, but more realistic conditions produced a far lower CGR.

Long term case histories were conducted on liquid pipelines by investigating their temperature profiles, CGR (derived from consecutive in-line-inspections) and repair frequency before and after temperature increase. For a portion of one pipeline, an increase in maximum and average operating temperature of up to 10°C was observed starting in 2014. This line is 1960s vintage with polyethylene (PE) tape coating. After several years of operation at the increased temperature, no clear correlation was observed between operating temperature increase and corrosion degradation or repair frequency. This same trend is observed on another PE coated line. These observations align with the above laboratory testing.

However, in another unique case study, a 1950s vintage coal tar coated pipeline experienced very rapid external corrosion within a cased crossing shortly after the pipeline operating temperature was increased, suggesting that operating temperature increases may still require change management consideration.

Recommendations on liquid pipeline corrosion management with increased operating temperature will be presented.
A Pipeline Is a Pipeline Is a Pipeline, or Is It? Product Type, Project Differentiation, and Risk Today
Authors: Gillespie Jason , Schmidt Jon , Raun Jeff
Published: December 2024

In the past ten years, many pipeline and other linear energy projects have been cancelled in North America for economic, regulatory, or social license reasons. This trend is continuing today for energy transition-related pipelines and other linear projects. While the reasons for project cancellation are complex, key themes have been identified including a changing regulatory environment; political influence; increased opposition from affected and unaffected stakeholders; and market forces. Numerous project examples exist to support the analysis of oil and gas pipeline project execution risk. The paper explores how these examples illustrate future projects integral to enabling the transportation of carbon dioxide, hydrogen, biofuels, power or other products relevant to energy transition in Canada and the US. Traditional pipeline projects are compared to energy transition-related projects, testing the question of whether project differentiation and product type matter. Finally, the analysis identifies opportunities for reducing risk in pipeline project execution during the planning and regulatory phases. Energy transition faces significant new challenges requiring projects to manage an evolving regulatory, stakeholder and political landscape. Understanding these challenges helps proponents better position their projects with stakeholders who are similarly learning how modern technologies and products will be planned within existing pipeline development frameworks.
Benchmarking of Three Girth Weld Flaw Assessment Models: A Validation Methodology
Authors: Munoz Eduardo , Fateminia Seyed Hamed , Chirinos Saul
Published: December 2024

The application of quantitative risk assessment involves the utilization of pre-existing fitness for service calculators. This departure from the original intent of these calculators necessitates a comprehensive evaluation of their efficacy within an extended domain. This article elucidates the methodology employed to gauge the performance of three girth weld flaw assessment models: namely, the Kastner model, API 1104 Appendix A Option 2, and API 579.

The proposed framework delineates a comprehensive analysis, originally devised for financial models, surpassing the conventional validation process, which typically entails a comparison of predicted values against selectively chosen experimental data, commonly referred to as the “least square error Olympics”. A sensitivity analysis of the models was employed to evaluate the impact of data sparseness and ascertain the optimal data collection strategy. Furthermore, we advocate for the measurement of the decrease in entropy as a more effective means of demonstrating the predictive information encapsulated within distinct models.

The benchmarking exercise revealed that the venerable Kastner model exhibits a confined range of applicability but maintains a high level of accuracy. Additionally, it was observed that there are instances where a synergistic combination of models can be employed to enhance predictive capabilities.
Pipeline Operators Forum (POF) White Paper on In-Line Inspection Tool Readiness for Hydrogen Pipelines
Authors: van de Camp Peter , Fernandez Charles , Koops Sieger , Klein Stefan , Roovers Paul , Lewis Chris , Santamaria Wilson
Published: December 2024

The Pipeline Operators Forum (POF) is a non-profit organization enabling pipeline integrity engineers to share and establish industry best practices to improve the quality of pipeline integrity management at every level. POF set up a working group (WG) on hydrogen pipelines to investigate ILI tool readiness for hydrogen pipeline inspection. This paper summarizes the current perspective of the WG on the state-of-the-art ILI tool readiness level including providing a gap analysis based on joint discussion and feedback of various ILI companies.

The WG will rely on the previously published POF standards (for example POF 100 Specifications and requirements for in-line inspection of pipelines) and recommended practices such as for example POF 300 Achieving successful in-line inspection, POF 310 Field verification procedures for ILI, and POF 320 In-line inspection contractor compliance check but recognizing if hydrogen is a new threat.

This paper outlines key elements recognized today to be considered for inspection of hydrogen pipelines and possible technology options to address possible issues in terms of threat categories (internal and/or external corrosion, hydrogen embrittlement fatigue, geohazard, third party damage, material properties) and morphology/appearance. In the introduction an overview of ILI technologies and anomaly types considered is given. A proposition for mapping state-of-the-art ILI technologies (axial magnetic flux leakage [MFL], circumferential MFL, ultrasound [UT], resonance UT, liquid coupled UT, electromagnetic acoustic transducer [EMAT], gas coupled Lamb wave, Eddy current, inertial measurement unit [IMU], axis stress measurement, low field MFL) versus pipeline integrity threats is provided by examples. The ILI tool readiness is defined and discussed in detail in terms of key ILI tool component material compatibility. Beside operational safety considerations, options to achieve acceptable inspection data quality are analyzed and elaborated on. The paper concludes by providing a technology gap analysis summarizing required technology development for ILI of hydrogen pipelines. Detailed guidance on how gaps can or should be closed is out of the scope of the paper.
Innovations in Long Gas Pipeline Loading Procedures: Staged Pressure Method From High-Pressure Rich Natural Gas
Authors: Botros Kamal K. , Strandlund Dale , Caruth Douglas , Yin Ole
Published: December 2024

Current trends in long gas transmission systems are to operate at high pressures in the dense phase region. When the gas is rich in composition, i.e. containing appreciable amounts of C2+, as well as relatively higher water, problems arise during loading newly constructed large diameter and long pipelines, e.g. 600+ km. In such a case, condensate dropping out and hydrates formation can occur downstream of the throttling loading valves due to Joule-Thomson (T-J) effects causing potential flooding of Hydrocarbon (HC) condensation and plugging due to hydrates formation in the pipeline near the loading location. In order to circumvent this, an innovative procedure was ideated and implemented on a newly constructed NPS 48, 640 km long gas pipeline in a cold environment where hydrocarbon condensation and hydrates formation are imminent as the supply pressure is in the dense phase and the temperature is relatively low. The new procedure is based on loading every sub-section to an intermediate pressure first, e.g. 50% of the supply pressure upstream, then the next sub-section will be loaded from the upstream sub-section now maintained at the intermediate pressure. In this case, the isenthalpic expansion of the gas from the intermediate pressure will be clear of intersecting the hydrate equilibrium line corresponding to the water content in the supply gas, and only a small amount of HC condensate could drop out. The loading process starts with partially filling of the very first upstream from the high pressure to an optimally determined intermedium pressure. Once this step is completed, the rest of the pipeline sections between Main Line Block Valves (MLBVs) can be loaded, from the now, intermediate pressure in the section upstream, and sequentially to the following section(s) between consecutive MLBVs. The third step is then to load the upstream sections (again in sequential manner) to the full supply pressure. Hence, the new concept is called “staged-pressure loading”. The paper describes the new procedure along with an example of specific loading conditions which was implemented successfully on an NPS 48, 640 km long transmission line. No appreciable hydrates or HC condensate were observed during loading based on the new procedure.
Refinement of Reliability-Based Safety Factors for Corrosion Assessment
Authors: Adianto Riski , Nessim Maher , Lu Dongliang
Published: December 2024

Reliability-based safety factors for corrosion assessment have been developed for onshore natural gas and low vapor pressure (LVP) pipelines and published in 2018. These safety factors were developed using the limit states design (LSD) approach and are designed to achieve consistent safety levels for a broad range of pipeline designs and corrosion conditions. The factors were calibrated for two corrosion limit state categories: ultimate limit state, representing large leaks and ruptures; and leakage limit state, representing small leaks. They can be applied with a deterministic limit state equation (such as the corrosion burst pressure model) and a set of calibrated characteristic values of key input parameters for the equation (such as wall thickness and feature depth) to assess the acceptability of a corrosion feature. With this set of reliability-based safety factors, a corrosion feature assessment can be carried out deterministically while still achieving a consistent risk level. For the ultimate limit state, the safety factors were calibrated for a safety class system that is aligned with the six safety classes described in the Annex C of the 2023 edition of CSA Z662.

Refinement of the previous formulation of the safety factors includes: 1) addition of more pipeline cases in the calibration to expand the applicability of the safety factors; 2) addition of the pipeline material strength in the safety factor calculation equations; and 3) further calibration of the safety factors to cover both the Annex O and Effective Area corrosion burst pressure models. These refinements were developed for natural gas pipelines, and LVP liquid pipelines are not considered in this paper.

To ensure that these safety factors lead to practical solutions for real cases, the performance of the reliability-based safety factors was compared to that of the CSA Z662 Clause 10.10.2.5.1 and the full probabilistic approach of TC Energy (“TCE”). The comparison was based on the number of corrosion repairs required by each method and was conducted using a comprehensive set of TCE pipeline cases that covered a wide range of pipeline diameters (NPS 6 to 42), hoop stress factors (0.23 to 0.80), and corrosion severity (feature density from < 1 to > 5000 per km).
Analysis of a Third-Party Action Incident in a Gas Pipeline: A Case Study of the Cuiabá Lateral Pipeline in Brazil
Authors: Silva Bruno , Morais Filho Pedro
Published: December 2024

The impact of third-party actions remains a primary cause of induced failures in transportation systems. In response, the operational safety management system needs continual revision and robust implementation to mitigate such risks effectively. This study goes through the analysis of an incident involving the rupture of a gas pipeline, specifically examining the event that happened in January 2021 along the Cuiabá Lateral Pipeline in Mato Grosso, Brazil. A comprehensive comparative evaluation is undertaken, contrasting the investigation taken by the pipeline operator, and the analysis conducted by the regulatory body. Within the Brazilian context, operators are mandated to adhere to the Technical Regulation of Onshore Oil and Gas Pipelines (RTDT), a regulatory framework grounded in process safety, encompassing requirements for inspection, community engagement, and incident investigations. The regulator assumes an important role in evaluating the investigations carried out by operators. This research sheds light on the divergent perspectives surrounding the management system, depending on whether it is viewed from the operator’s lens or the regulator’s standpoint. Operators tend to emphasize community actions, whereas regulators focus on the efficacy of preventive measures against third-party actions, underscoring the significance of inspection frequency.
Advanced Assessment of Pipeline Stress-Relief
Authors: Fathi Ali , Ndubuaku Onyekachi , Fowler Matthew , Yoosef-Ghodsi Nader
Published: December 2024

Pipelines traversing landslides can be subjected to forces due to ground displacement. Stress-relief projects are usually planned before strain in the pipe, or a girth weld reaches one of the strain capacities associated with a limit state event using a certain safety margin. Accurate estimation of the pipe strain growth due to the slide movement is a key input for planning stress-relief projects. Through presenting a case study, this paper introduces the concept of an advanced stress-relief assessment approach. This method uses finite element simulation of pipe-soil interaction, to estimate the evolution of strain before stress-relief, pipe rebound as a result of stress-relief, and extension of the asset life after the backfill is completed. Using this modeling, the effects of additional improvements that can be added to a stress-relief project can also be estimated properly. These measures can enhance the performance of the pipe by increasing its strain capacity or reducing the impact of the slide movement.

The primary benefit of completing such assessment is to be able to optimize the timing of stress-relief projects. Given that the strain growth rate usually accelerates as more strain accumulates in the pipe, timely stress-relief can prevent excessive plastic deformations and consequently increase the benefit of stress-relief projects. This is especially important for lines, for which pipe replacement is much more expensive than a simple stress-relief (without cutouts).

The next step in this assessment is to use the output of this model for different scenarios of stress-relief in a risk assessment. This risk assessment provided an opportunity to compare the stress-relief option with horizontal directional drilling with a completely different cost/performance combination. The result of this assessment showed that if planned and executed as recommended, the stress-relief option can result in risk reduction below the risk target with significantly lower cost and complexity.
Optimization of Emergency Gas Supply Schemes in Natural Gas Pipeline Networks Under Extreme Conditions Considering Customer Characteristics
Authors: Zhao Sirui , Zuo Lili , Liu Dingzhi , Hou Haoyuan , Wu Changchun
Published: December 2024

During peak periods of natural gas consumption, extreme conditions can lead to a shortage in gas supply, reducing operator profits and customer satisfaction. This study proposes evaluation indexes for emergency supply schemes from the perspectives of profit and customer satisfaction. The study analyzes the characteristics of different customers and introduces reduction coefficients to constraint demand. Considering the hydraulic operation constraints of each pipeline, equipment, and nodes in the pipeline network, as well as the tiered pricing constraints of each customer, a multi-objective emergency supply scheme optimization model under extreme conditions is established. The spatial branch and bound algorithm in the Gurobi solver is employed to solve the established Mixed Integer Quadratic Programming (MIQP) model. The min-max method makes a trade-off among the Pareto solution sets to obtain the optimal supply scheme. Taking a large-scale loop-topology pipeline network in a province of China as a case study, the conflicting relationship between profits and customer satisfaction is analyzed under extreme conditions of source supply shortage and customer demand surge. The results indicate that the proposed method can effectively balance profits and customer satisfaction. The solution time under different conditions does not exceed 1 second. Compared with the SPS simulation software, the relative error of the node pressure does not exceed 3%, demonstrating high solution efficiency and feasibility. The method developed in this study can provide decision support for network operators to formulate gas supply schemes reasonably under extreme conditions, offering strong guiding significance.
Decompression Behaviour of Natural Gas-Hydrogen Mixtures: Shock Tube Test and Numerical Prediction
Authors: Michal Guillaume , Liu Xiong , Lu Cheng , Botros Kamal K.
Published: December 2024

Blending hydrogen into existing natural gas pipelines is a transition option to progressively increase the energy share of hydrogen. As part of the fracture control plan, pipelines must be capable of controlling a running ductile fracture for all blend ratios used in operations. It is important to understand the decompression characteristics of Natural Gas-Hydrogen (NGH2) mixtures at those ratios.

Under the aegis of the Future Fuels Cooperative Research Centre (FFCRC), a project was initiated to investigate the implication of the use of NGH2 blends on the Australian network, under the assumption that pipe properties are not affected by hydrogen during ductile fracture propagation.

In this work, a desktop study is carried out to evaluate the impact of hydrogen on the toughness requirements. The potential increase in toughness requirement with a rich gas mixture within a given range of hydrogen fraction is revealed. This provides a basis for the design of shock tube tests.

Eleven shock tube tests of NGH2 mixtures were carried out at TC Energy’s Gas Dynamic Test Facility in Didsbury, Canada. The mixtures targeted concentrations of 0%, 9%, 30% and 100% hydrogen.

The outcomes of the shock tube tests are reported. 1D isentropic numerical decompression wave speed predictions using the GERG-2008 equation of state are compared with experimental data.
Hot Tap Coupon Drop and Drag Test
Authors: Huang Hannah , SanJuan Riverol Elvis , Saunders Joseph , Zhang Shenwei
Published: December 2024

This paper presents an experimental study to investigate the potential damage to the pipeline from large-diameter hot tap coupon drop during hot tap activities. To this end, a hot tap coupon drop and drag test is designed to simulate the hot tap coupon drop and travelling process, and is conducted in a shop with two NPS 36 pipe joints to examine the extent of damage from the hot tap coupon contacting with the internal pipe surface and travelling along the pipeline. After the drop test was completed, Magnetic Flux Leakage (MFL) tool pull test on one joint and Non-Destructive Examination (NDE) measurement test for both joints were performed. The experimental results substantiated safe operation of the carrier pipeline subsequent to hot tap coupon drop event and affirmed adequacy of using MFL in-line inspection (ILI) technology to monitor the carrier pipeline.
Applying Advanced Machine Learning to Enhance Indication Discrimination and Data Analysis Results in Ultrasound Crack Diagnosis Surveys
Authors: Träumner Katja , Ferrer Victor , Mas Ricard , Notheisen Achim
Published: December 2024

In-line inspection (ILI) ultrasound for crack detection is a well-established inspection method providing pipeline vendors with a high probability of detection, identification, and sizing, and a low rate for unnecessary digs. In recent years, manual data analysis work by human analysts has been increasingly supported by algorithms, especially in terms of anomaly detection and classification. More recently, conventional rule-based algorithms are being replaced by algorithms based on machine learning, which can deliver deeper logical connections from the data itself and provide higher efficiency.

However, the industry is still cautious about adding extensive automation to the processes. Although, the advantages for pipeline vendors of a higher degree of automation are clear: results are more robust and consistent, the human impact is reduced and the achievable times for priority notifications and final reports can be reduced. Discriminating non-relevant anomalies allows highly skilled human analysts to focus on complex situations, which leads to more reliable results in complex defect and pipeline geometries.

In this paper, we will present a successfully applied anomaly discriminator based on machine learning (ML) to reduce the initial false positive rate from a previous automatic detection algorithm in ultrasonic crack technology. The goal of this paper is to achieve a deeper understanding of new algorithmic possibilities and how they are integrated into ILI analysis processes to successively build up trust and reveal their high potential to accomplish better and faster outcomes.
Evaluation of Composite Crack Arrestor Design for Running Ductile Fractures on High Pressure Pipelines
Authors: Rebrov Kirill , Wilson Josh , Baraniecki Kurt
Published: December 2024

The topic of running ductile fracture arrest has seen renewed emphasis in the transmission pipeline industry as high-pressure pipelines transporting natural gas or CO2, operating under a variety of conditions, can potentially be susceptible to running ductile fracture. This is less of a concern for pipelines transporting liquids (such as oil), where the content’s rapid decompression behavior does not leave much energy for driving a running ductile fracture. Pipelines repurposed for transportation of dense phase CO2 are particularly susceptible to the threat of running ductile fracture due to the specific properties of CO2 and the existing transmission lines. Further, high-pressure natural gas transmission lines, the focus of this effort, can also be vulnerable to running ductile fracture. A number of methodologies have historically been deployed to combat this threat, including the use of pipe material with sufficient toughness to arrest a running fracture or the installation of pipe joints with greater wall thicknesses at designated intervals along the pipeline. Another methodology involves the installation of externally applied crack arrestors. Using non-metallic composite materials for these externally applied arrestors has the potential to provide substantial cost advantages over other methods and has led to significant interest in employing this advancing technology. Despite the growing interest, the pipeline industry has not achieved consensus on the most appropriate design methodology for composite crack arrestors.

This paper presents the results and findings of a study that reviewed several design approaches for composite crack arrestors. The primary goal was to achieve an optimized design that minimizes the material requirements of a composite crack arrestor, while still achieving fracture arrest. A large diameter gas transmission pipeline operating at an elevated MAOP was used as the operating asset. Two different methods were evaluated in the study. The first approach targeted a “soft” arrest that would slow the progression of the fracture and limit the potential for pipe “ring-off”. A second approach was examined that did not consider the mode of arrest. The Battelle Two-Curve Method (BTCM) was used to assess the likelihood of running ductile fracture for the subject pipeline.

A parametric study was performed to assess the influence of various operating conditions on the decompression curve for the projected gas composition. Additionally, a literature review was conducted to compare existing arrestor designs, validation efforts, and appropriate BTCM modifiers. This research shows the feasibility of implementing composite crack arrestors to achieve either “soft” or “hard” arrest of a running ductile fracture in high-pressure pipelines. Both design methods considered possess notable advantages over traditional methods.
Use of Communication Cable for Geohazard Monitoring and Event Early Detection: The Transportadora Del Perú Case Study
Authors: Ravet Fabien , Mas Fillol Ricard , Melo Alberto , Oliveros Francisco , Grecco Cristian , Rochat Etienne
Published: December 2024

Optical fiber cables (OFC) are well known for their long distance and high-speed transmission capabilities. OFC are often the communication backbone of hydrocarbon transportation systems that carries the operating companies Information Technologies and SCADA services. In some cases, part of the fibers is also used to bring internet services to isolated communities. As an example, the Transportadora de Gas del Perú (TGP) system has about 790 km of cables laid in its Right of Way (ROW) that have been in use since the beginning of its operation in 2004. More recently, OFCs have started to be used as sensors. In these applications, an Optical Fiber Communication Cable (OFCC) can be applied as a continuous temperature sensor to detect intrusion, leak and erosion. A dedicated Strain Measuring Cable (SMC) can also be spliced to the OFCC for monitoring landslides and subsidence in areas of special interest. In case of large ground displacements, it is common to observe induced deformation on the OFCC. Integrated to a pipeline integrity monitoring system, the OFC solution improves the early detection of potential risks and allows the implementation of protection or mitigation measures.

The current work describes the retrofitting of 256km of the TGP backbone which included a pilot project over 18 km of ROW section composed of a mix of OFCC and SMC. In addition, a detailed and experimental study of the sensitivity of OFCC to environmental stresses was conducted to validate the approach. The full-scale installation of the system along the 256km stretch comprising the geographical area of the Amazon rainforest and part of the Andes Mountain range was completed at the end of 2022. The installation of this technique was timely to increase monitoring and surveillance during the 2022–2023 and 2023–2024 rainy seasons, which is the most complicated season for infrastructures crossing the Andes. Several events have been detected early enough to allow the implementation of preventive measures. The system demonstrated its effectiveness in operability, complementarity with other geotechnical monitoring systems and follow-up of the stability condition of the ROW in the instrumented section.
Rupture Proof CO2 Pipelines by Design – Not by Chance
Authors: Wilkowski Gery , Twombly Elizabeth , Hioe Yunior
Published: December 2024

CO2 pipelines are being proposed for CCS of anthropogenic CO2. CO2 can be transported by pipelines in gaseous or liquid (dense-phase) states. In the dense-phase state, the traditional fracture control design procedure frequently requires such a high toughness for axial ductile fracture arrest in the pipe body that crack arrestors are needed. Even if material could be procured to meet the regulatory arrest criterion, such design conditions might result in an undesirable double-ended full-bore for hazard analysis. The full-bore opening from a pipe rupture can involve significant safety risk to the population along the right-of-way, as was experienced in the Denbury CO2 pipeline failure.

An alternative design of a dense-phase CO2 pipeline that can prevent large openings/ruptures from happening was explored in this paper. With this design criterion, a new CO2 pipeline can become “Rupture-Proof”, and evaluations to date have shown that the hazard zone could be reduced by a factor of ∼100.

The “Rupture-Proof” design for a CO2 line involves two modifications to the traditional pipeline design. The first design modification is to ensure that there is a “Quick Crack Arrest” of any potential axial flaw. With the appropriate thickness and material toughness specification, the crack would only propagate a few inches, ergo the “Quick Crack Arrest.” The material aspects for the quick axial crack arrest require understanding of the material developments over the decades, and as shown there are four different types of line pipe behavior when conducting ductile fracture control analyses. An assessment of more recent CO2 full-scale burst tests in the UK is presented to show a more precise way of determining the arrest toughness for axial ductile fracture control. Using the best of the current material types, the methodology for a “quick crack arrest design” procedure was found viable with sample calculations.

The second modification is to eliminate the circumferential pipe break at a girth weld, like what occurred at Denbury. From work done in the nuclear piping industry for repair of circumferential flaws in girth welds, a modest change to the weld cross-sectional geometry can make it so that even with large unintentional girth weld defects or undermatched weld metal, the girth weld would not fracture, and the rest of the pipe body could take the longitudinal strain.
Dynamics of Purging, Loading and Venting of Compressor Casing and Piping Between Unit Isolation Valves in Natural Gas Compressor Stations
Authors: Hartloper Colin , Botros Kamal K. , Leung Teresa , Lu Jason , Szuch Greg
Published: December 2024

Purging, loading and venting are unsteady processes required prior to the start-up (in the case of purging and loading) or shut-down (in the case of venting) of compressor units on gas transmission systems. Compressor stations have valves on the suction and discharge of the unit for isolation purposes and incorporate small diameter lines (a bypass line on the unit suction isolation valve and a blowdown line upstream of the unit discharge isolation valve) to facilitate the purging, loading and venting of the total volume between the valves, including the compressor casing. Flow rates through these small diameter lines are typically limited by a control valve and/or a restricting orifice on the line. Correctly designing for such flow rates is necessary to achieve design objectives such as purging efficiently, effectively and safely or venting at the maximum permissible depressurization rate established by compressor original equipment manufacturers (OEMs). This paper describes a dynamic model used to calculate the purging, loading and venting of compressor units. The model accounts for the dynamics and thermodynamics in two parts: one for the total volume (defined as the volume between the unit’s suction and discharge valve, including the compressor casing), and one for the purge, load and vent lines. The total volume model balances the mass and energy flow into and out of the total volume to calculate the instantaneous gas pressure in the compressor casing. The purge, load and vent line model identifies the choke location along each line and calculates the instantaneous mass flow rate, taking into account each line’s control-valve open position. The paper compares the model results to plant data from compressor stations and offers insights into the relationship between parameters such as purge time, purge pressure, load time and depressurization rate.