bluuebunny/crossref_metadata_2025 huggingface dataset:
The Thermal-Hydraulic Analysis and Optimization of Annular Fuel for Lead-Cooled Fast Reactor
Authors: Kefan Zhang , Chong Qin , Wenmeng Dong , Rui Pan , Wenshun Duan , Hongli Chen
Published: December 2022

The annular fuel element is a safe and efficient new fuel element type. According to previous studies on PWRs, it can bear higher core power density while maintaining or even improving reactor safety when compared to traditional rod lattice fuel rods. In this paper, the application of annular fuel element in lead-cooled fast reactor is studied. Firstly, the flow and heat transfer characteristics of lead-bismuth in annular channel are analyzed by using the computational fluid dynamic method. On this basis, a thermal hydraulic calculation code suitable for annular fuel in lead cooled fast reactor has been developed, which is verified by comparing with CFD results. The application and design optimization of annular fuel in the lead-cooled fast reactor core are carried out using the developed annular fuel single channel code. The effects of different annular fuel parameters on the results are studied, and the core design with rod lattice and annular fuel element is compared and analyzed. The calculation results show that with the same fuel volume and coolant mass flow rate, the maximum core temperature of the annular fuel element is about 600K less than that of the rod bundle fuel element, which shows that the annular fuel element has significant safety superiority.
Machine Learning Modelling of Decay Heat Removal in High Temperature Gas-Cooled Reactor
Authors: Wu Hao , Yu Liangzhi , Niu Fenglei , Tu Jiyuan , Jiang Shengyao
Published: December 2022

In decay heat removal processes of the pebble-bed high temperature gas-cooled reactors, particle-scale radiative heat transfer between spheres is complicated for modeling and numerical simulations with traditional approaches. Artificial intelligence (AI) provides a new aspect to solve the dense granular dynamics. A machine learning model was developed for predicting the obstructed view factor between all possible pebble pairs in the large-scale nuclear pebble bed. The view factor dataset is obtained by random generation for sphere positions and thermal ray tracing method by CUDA paralleling for the view factor. The regression models are trained by gradient boosting decision tree (GBDT) method of XGBoost software for 2 ∼ 10 spheres cases. It is shown that the model performance will be greatly improved without overfitting by adding more trees rather than going deeper for every tree to reach R2 scores greater than 0.999. For engineering application, the trained XGboost models are applied to predict view factors in large-scale nuclear pebble bed during decay heat removal processes. From the transient numerical results, it takes about 10 h to get its maximum 1520°C only with thermal radiation and it is still less than the design upper limit.
Numerical Analysis of Shell-Side Flow Field Characteristics of Condenser in Nuclear Power Plant
Authors: Dai Shoubao , Xu Huiqiang , Zhan Tengteng , Zhang Dongyang
Published: December 2022

Integrated and modular design is an inevitable requirement for marine nuclear power plant to realize high power under the condition of limited cabin capacity. Heat exchange equipment is an important part of marine power system, occupying a large amount of space weight. The extensive development and application of multi-medium casing integrated condenser has a decisive influence on the improvement of comprehensive performance of marine such as high power and flexibility.

In this paper, according to the compact structure and operation characteristics of the condenser of nuclear power plant, the finite volume method is used to calculate the air, steam flow and condensation process. The model adopts continuous porous media to simplify the tube bundle structure, flow and heat transfer process. The influence of tube bundle and corresponding solid structure on steam flow and heat transfer process is characterized by defining the resistance coefficient of porous medium and heat transfer term.

The model developed in this paper is used to simulate the flow field on the shell side of a condenser sample, and the calculation results are compared with the experiment results, which verify the accuracy of the model. This model is used to simulate and analyze the characteristics of multi-media flow field on the shell side of the casing integrated condenser, which provides an effective means for the structural optimization design and operation of the integrated condenser.
Experimental Study of Droplets Collision and Bag Breaking in Rotating Gas Flow Field
Authors: Ouyang Shuo , Xiong Zhenqin , Zhao Jiyun , Kang Ruiqi , Li Zhen
Published: December 2022

In swirl-vane separators, the liquid phase is separated from the rotating gas flow under the action of centrifugal force. The droplets are carried by the rotating gas flow to the wall of the separator. In this paper, the phenomenon of a single droplet hitting on a stationary droplet on the wall in the rotating flow field is recorded by using a high-speed camera. Different types of droplet collisions appear as the inlet airflow velocity increases from 4 m/s to 4.8 m/s. Results show that the binary droplet impacts in the rotating flow field occur in asymmetric outcomes such as coalescence, finger spreading, finger breaking and splashing with the increase of the Weber number. The spiral characteristic of the rotating flow field leads to the asymmetry of the droplet collision. The bag breaking occurs in the rotating flow field. The number of droplets of bag breaking and breaking time are increased with Weber number increasing. This study provides basic characteristics for the impact of binary droplets in the rotating flow field and bag breaking, as well as improves the understanding of the separation efficiency mechanism of the gas-liquid separator.
Numerical Analysis on Heat Transfer Characteristics and Buoyancy Effects of Supercritical Pressure Water in Vertical Tube
Authors: Lou Yining , Zhang Zhen
Published: December 2022

Water is widely used in various nuclear power plants as coolant and moderator due to its good thermal conductivity and stability. However, when the pressure and temperature exceed its critical points, the physical properties of water change drastically, especially the specific heat capacity, which makes the heat transfer phenomenon near the critical point more complicated, even deteriorating. On the other hand, the curved geometry of the spiral pipe leads to a special secondary flow phenomenon in the fluid, which will intensify the heat and mass transfer and improve the heat transfer efficiency. At the same time, the flow will be more complicated in the joint influence of gravity, centrifugal force and Coriolis force. This paper studied the heat transfer characteristics of supercritical water in heated vertical tube by numerical simulation and found that changes of physical properties are the main reason for changes of heat transfer characteristics of supercritical water. And as the heat flux in the tube wall increases, heat transfer deterioration is more prone to occur around the pseudo-critical point. Then it verified the relationship between the criterion of buoyancy and heat transfer deterioration. Last, it explained the mechanism of heat transfer deterioration caused by buoyancy effect by calculating shear stress. In the future, works on the relationship between Bo* and shear stress are expected to carried out.
Effects of Power Oscillations on Natural Circulation Flow Instability With a Neutronic-Thermo-Hydraulic Loop
Authors: Chen Xianbing , Long Chengyi , Zhu Dongbao , Gao Puzhen , Kong Xiaming , Yao Lu
Published: December 2022

Nuclear power in a water-cooled reactor changes with reactivity under the influence of temperature and void fraction. Effects of power oscillations on natural circulation are experimentally investigated with a neutronic-thermo-hydraulic loop to better understand neutronic-thermo-hydraulic effects. Heating power can be precisely controlled by a DC power supply. Both stable natural circulation flow and flow instability experiments are conducted. Amplitude of flow oscillations increases with the increase of amplitude of power oscillations for the stable natural circulation flow. Period and amplitude of power oscillations are compared with those of flow oscillations. Period of flow oscillations corresponds with the period of power oscillations due to the relative balance between driving force and resistance. Amplitude and period of power oscillations are changed to obtain stability boundary by keeping other parameters constant. Experimental results indicated that small amplitude and short period power oscillations has little influence of the stability boundary. However, power oscillations cause the premature of flow instability when period and amplitude of power oscillations are further increased. The destabilizing effects of power oscillations on natural circulation flow depend on the period and amplitude. The stability region reduces with the increase of amplitude and period of power oscillation in this experimental loop.
Multiscale Thermal-Hydraulic Analysis of the ATHENA Core Simulator
Authors: Cioli Puviani Pietro , Di Piazza Ivan , Marinari Ranieri , Zanino Roberto , Tarantino Mariano
Published: December 2022

The Advanced Thermal Hydraulic Experiment for Nuclear Application (ATHENA) will play a fundamental role in the design, safety assessment and thermal-hydraulic (TH) characterization of the ALFRED reactor components. In ATHENA, full-scale systems and their mutual interactions will be tested in steady state and relevant transient conditions. The Core Simulator is the electrical heating system and aims to be representative of an ALFRED average fuel assembly (FA). CFD codes are gaining attention for the analysis of complex systems in pool-type reactors, since they are able to reproduce with high accuracy 3D TH phenomena. In this paper a multiscale approach based on porous media (PM) is proposed to reduce the computational cost of the Core Simulator CFD model. Firstly, the PM hydraulic behavior is characterized by means of CFD simulations on the infinite lattice domain. Then PM are applied in the system model in place of fuel assemblies (FAs). Three different approaches are investigated: (1) adopting a single porous domain for the entire FA ; (2) representing the FA with two porous domains; (3) adopting the so-called hybrid medium model. The results obtained with the PM models are validated against a detailed CFD simulation of the Core Simulator to evaluate the performance of the three approaches. Then, the best solution is applied on a model of the entire ATHENA Core Simulator integrated with the feeding region. The model is tested in simple transient conditions. The numerical experiment demonstrates the effectiveness of the multiscale approach in reducing the computational cost while maintaining high accuracy in representing the quantities of interest.
Effect of Crack Orientation on Toughness of Contemporary EW Pipe Seam Welds
Authors: Xu S. , Yang L. , Xue J. , Liang J. , Tyson W. R.
Published: December 2022

Toughness values of pipe steel and welds are key mechanical properties for material specification and integrity assurance. Toughness is influenced by crack size (deep vs. shallow), loading mode (bending vs. tension), crack orientation and sampled microstructure (notch location in weldments). To the best of the authors’ knowledge, no data exist in the open literature for crack orientation effects on Electric Welded (EW) welds. Charpy notch toughness and single-edge-notched bend (SE(B)) fracture toughness tests using surface-notched specimens of three modern (EW) pipe seam welds were performed at −20°C and −45°C, and the results are compared to those for through-thickness-notched (TTN) specimens.

Charpy results indicated that the tests were in lower-transition or lower-shelf regions. Charpy impact V-notch absorbed energies (CVNs) of EW welds displayed large scatter; the effect of crack orientation was small. The initiation J-integral values of SE(B) surface-notched specimens were higher than those of TTN specimens, although when brittle fracture initiation occurred the effect of orientation on toughness was negligible. Note that the specimen geometry likely affects the results; surfaced-notched specimens were B×B and through-thickness-notched specimens were B×2B, although they are all standard SE(B) specimens in ASTM E1820. A limited study of geometry effects on crack-tip stress was done in the present work by Finite Element Analysis (FEA). It was found that these geometries all have similar maximum crack-tip opening stresses at the same J value although the stress gradient through the ligament and hence the constraint parameter Q (measured at a distance 2J/σy from the crack tip) and the J-Q curves differ. Thus, differences in fracture toughness values for brittle fracture would be expected to be small because cleavage is stress controlled, although ductile fracture toughness may reflect the differences in J-Q curves. There was considerable scatter in both notch toughness and fracture toughness, and much of this may be attributed to slight variations in notch or crack location with respect to the weld bond line because the toughness can vary markedly across an EW weld. The variation in location is superimposed on the variation in toughness inherent in each weld microstructure.

The present data shows that the conventional use of TTN specimens is appropriate for EW weld toughness specification because toughness in this orientation is either equivalent to or lower than the toughness of surface-notched specimens (i.e. it is conservative).
Performance of Twelve Different Equations of State for Natural Gas and Hydrogen Blends
Authors: Botros Kamal K. , Jensen Larry
Published: December 2022

The aspiration for blending hydrogen (H2) into natural gas (NG) in gas transmission systems is high and is happening globally. However, the principal properties of the blended mixtures and their thermodynamic derivatives can significantly vary depending on the Equation of State (EOS) employed. There is a need to arrive at the best performing EOS for the prediction of the blended mixtures from low to high concentration of H2 in the blend with NG. Twelve different EOS were evaluated against measured data found in the open literature of pure H2, binary mixtures with alkanes and mixtures with NG. Three measured properties were found, namely density, speed of sound and isobaric heat capacity (Cp) in the range of pressures up to 50 MPa and temperatures in the range of −20°C to +80°C and H2 concentration up to 88%(mole). The total number of measured data points are 629 for pure H2 and 1788 for Binaries and NG mixtures with H2.

Performance of each EOS is based on the average of the absolute error (deviation%) between predicted vs. measured parameters. These were: density, which represents the principal performance of the EOS with respect the basic formulation of P, ρ and T, the speed of sound, which represents a thermodynamic derivative with respect to entropy, and isobaric heat capacity which represents a thermodynamic derivative with respect to enthalpy. All other thermodynamic derivatives can be related to these three parameters (e.g., J.T coefficient, isochoric heat capacity, enthalpy, internal energy,, compressibility factor and Helmholtz and Gibbs free energies, etc.). Transport properties predictions are based on other empirical and semi-empirical correlations that are independent of the EOS and hence were not considered. It was found that, for the most part and for pure H2, GERG2008 EOS performed best in predicting the above three principal parameters followed by AGA8. For Binary and NG mixtures with H2, again GERG2008 was found to be the best performing EOS for all ranges of P and T, while the second-best performer is BWRS in the range of 0.1–3 MPa and AGA8 in the range of 3–25 MPa, respectively.
Factors Affecting SMAW Pipeline Girth Weld Strength and Strain Concentration Under Tensile Loading
Authors: Willett Eric , Lehnhoff Greg
Published: December 2022

This paper presents the findings of a study to investigate the phenomena of girth weld strength undermatching and strain concentration in SMAW girth welds of API 5L X70 pipe, and to identify the significance of some key factors that may affect these phenomena including filler metal strength, heat input, and carbon equivalency of pipe base material. Test welds were subjected to a novel small-scale instrumented cross-weld tensile testing (ICWT) method employing multiple extensometers in different regions of the gage section. Hardness mapping of each weld cross-section was also performed.

This study highlights the importance of considering filler metal strength relative to base material strength when designing welded joints, as well as the importance of controlling welding heat input. It also points out potential issues with relying on failure location as an acceptance criterion in cross-weld tensile testing (CWTT) samples. The observations from this study may be useful in the development of strategies and practices for mitigating the risk of excessive weld strain concentration and premature girth weld failure under moderate tensile or bending loads typical of stress-based pipeline designs.
A New GIS-Based Method to Estimate Annual Probability of Pipeline Failure Resulting From Landslides Based on Actual Failure Locations
Authors: Varela Patricia , Cheng Sam , Sancio Rodolfo , Cook Doug , McKenzie-Johnson Alex , Koduru Smitha
Published: December 2022

Risk assessment and reliability models try to predict the probability of landslide-induced pipeline failures based on detailed, site-specific studies. Because these models are mainly designed to be used on a site-by-site basis, applying them over long pipelines is a challenge due to the challenges of collecting vast amounts of data for those long distances.

A new GIS-based method has been developed to produce an order of magnitude approach to estimating the annual probability of landslide-caused failures (POFs) of pipelines over entire transmission systems using historical data that can range from loss of containment, loss of serviceability, and significant deformations caused by landslides.

This new method uses high-resolution light detection and ranging (LiDAR) mapping to detect and delineate terrain anomalies interpreted to be the geomorphic response to ground deformations caused by landslides. The possible landslides are inventoried to record their activity, relative relationship with the pipeline, proximity to the centerline, length of intersection with a pipeline, and the angle of incidence between the perceived direction of movement of the potential landslide and the pipeline. This method also integrates regional landslide susceptibility maps depicting the relative likelihood of soil units to landslide occurrence along the pipeline corridor and its surrounding areas.

In the presented study case, the developed method is applied to an approximately 19,312-kilometer (12,000-mile) pipeline system located in the United States and Canada. The application of the model yielded results that significantly help the operator to prioritize and optimize the allocation of resources for landslide management. The model can be replicated over multiple pipeline systems and customized to the particular needs of the end-users.
Literature Review of Repair Technologies for Wrinkled Pipelines
Authors: Johnson Tyler , Mokry Curtis , Apps Chris , Parsibenehkohal Nima , Henderson Matthew
Published: December 2022

Wrinkles on a pipeline, whether produced intentionally by construction methods of vintage pipelines or unintentionally by bending loads from subsurface geotechnical movements, introduce significant stress concentration factors. However, common options for pipeline repair usually cannot be used given the protruding wrinkle geometry (e.g. steel sleeves), or are costly and can introduce additional safety concerns (e.g. pipe replacement). Numerous composite repair technologies have been developed that take the form of the underlying structure and, thus, may provide an alternative for this application. However, composite repairs have focused on restoring axial defects in pipelines (i.e. hoop reinforcement), while restoring the bending capacity of wrinkled pipe is less common. Therefore, this literature review consolidates the current state of knowledge regarding the effects of composite repairs on the bending load capacity of pipes.

The reviewed literature identified 14 studies (using finite element analysis, full-scale testing, or a combination of both) that investigated composite repairs on wrinkled pipe or under bending loads. Typically, for pipe with non-sharp flaws (e.g. corrosion or wrinkles), the bending capacity of the pipe with a sufficient repair is increased near or beyond that of pristine pipe. The latter case usually results in a new wrinkle forming outside of the repaired pipe section. Most repairs have also been shown to prevent significant plastic deformation of the base pipe beneath the repair. However, knowledge gaps are also identified by this review and present opportunities for future studies to further improve the performance of composite repairs for this application.
CSA EXP16: Human and Organizational Factors for Optimal Pipeline Performance
Authors: Bradley Claudine , Capper Sue
Published: December 2022

Human and Organizational Factors (HOF) as a discipline applies tools, theory, principles, data and methods to optimize human, organizational, and overall system performance. To date, there has been relatively little guidance available to pipeline operating companies regarding the integration of HOF within and across organizational management systems, pipeline protection programs, and operational activities. CSA Group Express Document EXP16 (EXP16) entitled Human and organizational factors for optimal pipeline performance is intended to address this deficiency. It builds upon a previously published express document, which was more limited in scope: CSA EXP248 Pipeline Human Factors.

EXP16 is intended to offer practical guidance regarding the management of Performance Influencing Factors (PIFs) and provide greater content dedicated to organizational factors such as leadership, governance, management system effectiveness, and safety culture.

EXP16 has been prepared and reviewed by the CSA Group’s Development Committee on Human and Organizational Factors for Optimal Pipeline Performance. The committee was comprised of representatives from pipeline companies, consulting firms, regulatory agencies, investigative bodies, and HOF subject matter experts from various technical fields (e.g., nuclear). The goal of the document was to marry the introduction of key concepts with practical guidance and best practices that a pipeline company may apply to support enhanced performance, including the prevention of harm to people, property, and the environment caused by a major hazard accident (e.g., unintended product release, spill, explosion, fire).

This paper will review the content and application of EXP16. It will discuss seven key HOF principles and introduce several relevant PIFs associated with People, Organization, and Task, Technology, and Workplace. The impact and management of PIFs throughout the pipeline life cycle will be explored.

This paper will also present the key concept of “the learning organization” and how this outcome may be facilitated through both the proactive and reactive application of HOFs.
A Quantitative Risk Assessment Framework for Natural Gas Storage Wells
Authors: Dessein Thomas , Ayton Brent , Fraser Alex , Smith Shawn , Shironishi Mari , Sera Travis
Published: December 2022

A quantitative framework for risk assessment of natural gas storage wells, including the wellhead and connected piping, has been developed to assess SoCalGas’s underground gas storage sites in California. The approach has been developed to meet and exceed the risk assessment requirements of API RP 1171 (incorporated by reference in U.S. regulation 49 CFR 192.12) and the recent changes to the California Code of Regulations. Further, several of the recommendations made in the recent PHMSA study, “Risk Assessment and Treatment of Wells” (2021), have been addressed and incorporated.

The framework uses a dynamic fault tree to aggregate the barrier failure rates from over 80 potential failure mechanisms to quantify the combined probability of an accidental release to the atmosphere and the resulting hazards. The modular architecture allows operators to use threat-specific models with differing levels of sophistication. Additionally, the framework accounts for the interplay between barriers to failure in a well, the benefits of continuous monitoring, and the effect that wellhead spacing, cement quality, and well-inflow performance have on the expected consequences.

Priority to develop quantitative models is given to the threats that potentially have high probability or high consequences and to threats with effective mitigation options, such as corrosion and external interference threats. For threats with very low consequences or likelihood of occurrence, simple models with conservative assumptions are typically sufficient because the contribution to overall risk is low. This process minimizes the overall analysis complexity and allows mitigations to be tailored to the higher-risk threats.

This paper describes example assessments to illustrate how the framework can quantify the benefits of integrity management activities, such as an erosion monitoring program, continuous pressure monitoring of the annuli, and adding protections to minimize risk from vehicle collisions.
Safety Considerations for the Transport of Hydrogen Gas in Line Pipes and Induction Bent Pipes
Authors: Genchev Georgi , Mentz Juliane , Brauer Holger , Kalwa Christoph , Muthmann Elke , Ratke Daniel
Published: December 2022

With increasing impact of hydrogen-based economy it is necessary to consider relevant hydrogen embrittlement effects and risks resulting from it. As higher gas pressures are in discussion, the use of higher steel strength levels as compared to existing pipelines appears reasonable. Clarifying the product requirements is necessary for safe operation. Lately, the interaction of pressurized hydrogen gas with steel has been studied more detailed. This allows more precise safety considerations for the transport of hydrogen gas. The results of laboratory trials of different semi-finished products (medium and large diameter line pipes, induction bent pipes) exposed to hydrogen gas will be used to clarify this point. Several laboratory test methods were selected, allowing to focus on local effects of hydrogen enrichment in conjunction with mechanical loads. Challenges when testing in high pressure hydrogen environment result mainly from the safety aspects to be respected, but also from precautions required to achieve reproducible test conditions and to avoid unwanted system contaminations.

Substantiated test results indicate excellent behavior of the materials tested in terms of ductility and fracture toughness in high pressure hydrogen applications; all relevant ASME criteria for material selection are fully met.

To support the ongoing discussion regarding hydrogen testing protocols and relevant material properties (toughness parameters) in both, qualification of components and design of pipelines, Salzgitter and its Steel Processing business units are planning further extended R&D studies.
An Improved Axial Surface Crack Model to Predict Crack Growth and Burst Pressures Based on FE Analyses For Jplastic And J-R Curve Methodology
Authors: Wilkowski Gery , Hong Jeong K. , Brust Frederick W. , Hioe Yunior
Published: December 2022

During an in-depth review of the MAT-8 method, it was noted that there were assumptions for determining the FAD-curve shape by matching three points along FAD curves from FE analyses to get the plastic contribution of the crack-driving force (Jpl). Because the FAD-curve shapes from the FE analyses for different flaw sizes (depths and lengths) of interest for liquid line operation were quite different from both the MAT-8 assumed FAD-curve shapes and the FAD-curve fitting function for the FE-based FAD curves, an alternative procedure was pursued. For the cases of deeper and longer flaws, FAD-curve shapes cannot be found easily due to the highly nonlinear plastic behavior. To develop a new FE-based crack-driving force equation, a modification of the GE/EPRI basic formulation with contributions for elastic and plastic crack-driving force relationships was implemented. Several hundred FE analyses for axial surface cracks in pipes were performed. The new procedure was developed first by separating the elastic contribution from the total Japplied, then using the plastic part of Japplied versus pressure (Jpl-P) curve to establish an analytical solution. A nonlinear-regression analysis of the FE results from the entire Jpl-P curve was used, not just a few selected points. The new Jpl-P analytical solution showed good agreement with the carefully conducted FE-based solution from short, shallow flaws to deep, long flaws. The MAT-8 based solutions were good for short flaws, but deviated from the FE-based solution with both larger flaw depths and lengths. In addition to the new procedure, we included the use of the J-R curve for surface cracks which has been found to be a function of the surface crack a/t in pipe and SEN(T) tests, i.e., toughness is not a constant for all surface crack geometries which is discussed in other papers. Predicted burst pressures from the various methods including the new procedure were compared to pipe tests are presented.
Assured Utilization of Vintage Pipelines Through Effective Pressure Fluctuation Management
Authors: Al-Otaibi Senhat , Al-Muslim Husain
Published: December 2022

New policies driven by climate change concerns have made the construction of new pipelines more difficult with uncertain prospects in the years ahead. With expected increasing demand in hydrocarbon transportation, pipelines operators have no alternative but to plan for further use of existing vintage pipelines. These pipelines have inborn flaws such as longitudinal seam weld defects or environmentally assisted defects such as stress corrosion cracking (SCC). Therefore, the need to proactively maintain pipeline integrity and mitigate failure probability has become essential to meeting customers’ demands and protecting the public. This paper discusses Saudi Aramco’s experience in monitoring pressure fluctuation for vintage pipelines that are susceptible to SCC.

Pressure fluctuation contributes to an increase in crack-like longitudinal defects that are common in vintage pipelines. Therefore, a pipeline integrity management program should consider pressure fluctuation-induced fatigue damage. In addition, a crack growth prediction model can help determine an appropriate re-inspection interval. This paper discusses an innovative approach to evaluating, categorizing, real time monitoring, and reducing pressure cycle aggressiveness by reviewing the pressure cycle history in a complex pipeline network and analyzing several factors contributing to pressure fluctuation.

There are several pipeline operation modes; the transmission pipeline pressure cycling index is mostly critical at the pump or compressor stations and is dependent mainly on the equipment operations. As upstream gathering pipeline systems most often have multiple tie-ins at several wellheads, each wellhead becomes a source of pressure in the pipeline network. Moreover, pressure fluctuation is a result of different operation activities; for instance, pigging operations contribute in some cases to up to 20% pressure fluctuation during each pigging activity.

In this paper, an innovative real-time monitoring method is utilized to proactively determine which pipelines are subjected to pressure fluctuation. Meanwhile, cyclic index monitoring was conducted with a digital tool to facilitate large data processing utilizing introduced methodologies that are dependent on fatigue damage rate instead of material strength. More than half a million data points were processed to identify the cyclic index for each pipeline segment for one year. A cyclic index categorization was introduced; therefore, when the pressure cycling index is moderate or higher, pipeline operators should investigate the operational factors to reduce the fluctuation effects. In addition, a fatigue assessment with the recently developed PRCI MAT-8 fracture mechanics model was conducted to predict remaining lifetime and determine appropriate inspection intervals. The technique for assuming the initial flaw size was based on API 1176, which is critical for pipelines with no hydrotesting history.
Use of Inertial Measurement Unit In-Line Inspection Data to Support Code Stress Compliance and Integrity Evaluations
Authors: Prescott Jonathan , Patterson Curtis , Najeeb Arfeen
Published: December 2022

Pipelines are an essential segment of infrastructure required to transport a variety of products to markets in our economies. The integrity and safe operation of those pipeline necessitates that pipeline operators have a thorough understanding of their pipeline systems, their configuration, and the changing operating condition within their pipeline networks. Inertial measurement unit (IMU), a technology that can measure the angular rate and acceleration and when combined with global positioning and navigation equipment such as pipeline above ground markers, can calculate position and orientation with 6 degrees of freedom: x, y, z, and pitch, roll, and yaw. IMU launched within the pipeline via in-line inspection tool trains, can be used to develop accurate three-dimensional geometry of the pipelines they inspect. This information can be used to confirm the geometry of the pipeline (i.e. degree of roping, bend angle, bend radius, and other abnormalities observed within the generated centerline from the inspection based on conventional construction practices). Therefore, the application of IMU technology within pipeline design and integrity work can be a useful tool in providing the necessary input information which can support ongoing studies such as verification of maximum operating thermal differentials which can be imposed on a pipeline to remain compliant with governing pipeline codes, and/or the information can be used to perform gap analysis studies with other integrity records (alignment sheets, as-built pipe tallies), or to support other pipeline integrity evaluations. When IMU data is processed with mathematical techniques essential information from IMU data can be obtained such as bend angle, bend radius, and degree of installed curvature. A case study showing the results of the application of processed IMU data for as-built evaluation is presented and its use to help support a variety of decision making is discussed. The IMU data is a key data input when constructing detailed finite element models for on-going stress analysis studies.
Probabilistic Flaw Growth Rate Estimates Using Multiple Inline Inspection Tool Run Data Analyses
Authors: Scott Colin , Philpott Kregg
Published: December 2022

Many pipeline operators perform run comparisons (or “run-corns”) during assessment of their inline inspection data. Analysts match corrosion pit depths reported in back-to-back tool runs and estimate corrosion growth rates, remaining lives, and appropriate reinspection intervals. This approach is generally deemed more accurate than using an assumed constant growth rate for all reported features. However, the accuracy of each estimate is subject to the depth sizing error inherent in the measurements. The larger a dataset, the higher the likelihood of many calculated corrosion growth rates being misleading. This is due to there being a higher likelihood of extreme depth sizing errors. A first run undercall followed by a second run overcall compounds the depth sizing error and may result in an overly conservative decision. A first run overcall followed by a second run undercall and may result in a missed defect. Both scenarios can lead to a misuse of resources.

This work is a statistical analysis of flaw growth that considers and accommodates for depth sizing errors. The result is that the growth rate for each ILI reported flaw is considered probabilistically. Advanced data ingestion algorithms allow analysts to align multiple ILI tool run data sets quickly and conveniently, opening the door to advanced data analytics, including work with non-linear flaw growth rates. This work looks at corrosion and SCC growth rates (approximated as linear) and fatigue crack growth rates that follow established Paris Law behavior (non-linear).
Squeeze the Crack Out of It - With Type A Compression Sleeves
Authors: Futch David B. , Ganpatye Atul , Wilson Josh
Published: December 2022

Type A Compression Sleeves have been a technically viable repair method for corrosion, lamination-like features, and longitudinal crack-like features for the past 20+ years. A Type A Compression Sleeve relies on thermal expansion/contraction of the steel sleeve, which once the sleeve long seam welds are made, results in a compressive hoop stress in the carrier pipe at levels equal to or greater than generated at max operating pressure. This repair technology has been mostly marketed in Canada, and therefore, CSA Z662 includes the Type A Compression Sleeve in their list of approved permanent repair technologies. Over the past five years, there’s been an increased awareness in the United States as the technology has become referenced in industry documents such as the PRCI Pipeline Repair Manual and API 1176.

This paper provides an overview of a Type A Compression Sleeve, including the basis of how the repair system functions and how the sleeve is installed. Finally, this paper presents a series of full-scale tests and numerical modeling validating this innovative repair system. The use of induction heat, rather than open flame, provides a more consistent and traceable heat signature, allowing for confidence in the installed repair. Tests include synthetic cracks generated by precracking an EDM notch to generate a sharp-tipped crack, then heat tinted to provide a distinguishable boundary. The EDM notches, installed at a maximum of 50% of the wall thickness within the ERW seam, were subsequently repaired via the induction heating sleeve technology with and without flowing water in the carrier pipe. Test samples were cycled to 100,000 cycles, burst, and metallurgically examined. Post-test examination of the fracture surfaces revealed no discernable growth, therefore, indicating the technical viability of the repair technology as a permanent repair of crack-like features and provides an Operator another option when making repair decisions.
Stress-Relief Excavation for Pipeline Geohazard Mitigation
Authors: Ahmadipur Amir , Ebrahimi Ali , Mosaiebian Arash , Cook Doug
Published: December 2022

Pipelines are linear structures that cross various slope geometries and geologies and are susceptible to various ground movement geohazards, including landslides and subsidence. The ground movements from the geohazards can potentially induce axial, bending, and torsional stresses in pipelines.

The objective of this paper is to summarize the strain relief process, demonstrate that strains can be estimated without IMU using the shape of the pipe measured in the field, and describe the pipeline performance before, during and after stress-relief excavation.

This paper will also present planning considerations prior to conducting a stress-relief excavation, including design considerations, geotechnical stability, and considerations related to conditions of the pipe. This paper will present an approach to approximate pipe shape and estimate bending strains in the pipe and includes a discussion on results of three case-studies of stress-relief excavations. These case studies include landslide movements of various directions with respect to a pipeline. A summary of pipeline out-of-straightness, inertial measurement unit bending strain, rebound measurement during the stress-relief excavation, and strain measurement using strain gauges are included.
A Risk-Based Safety Class System for Onshore Pipelines
Authors: Nessim Maher , Stephens Mark , Yue Howard
Published: December 2022

A consequence-based safety class system was developed as an alternative to the class location system currently used as the basis for defining the maximum allowable hoop stress in Canadian Standard Association’s Standard Z662. The system accounts for the key pipeline, service fluid, and right-of-way parameters affecting the safety and environmental impact of releases from pipelines transporting natural gas, low- and high-vapour-pressure liquid hydrocarbons, sour gas, carbon dioxide, multiphase, and oilfield water pipelines. This paper describes the safety class system and the simplified release consequence modelling approach developed to support its implementation.

Companion papers provide more detail on the release hazard analyses used as a basis for consequence modelling, and the application of the safety class system as a basis for defining pressure design hoop stress factors that achieve acceptable and consistent public safety and environmental protection levels for all pipelines considered.
Predicting the Future by Mapping the Past: Revolutionary Innovations in Lidar Change Detection Analysis are Enabling Regional Scale Mapping and Identification of Threats From Geohazards
Authors: Lato Matthew , van Veen Megan , Ferrier Alex , Weidner Luke , Graham Alex
Published: December 2022

Managing pipeline integrity with respect to natural threats requires geoprofessionals to consider how the earth may behave into the future. Predicting morphological change involves a deep understanding of geology, geological processes, climate change, and knowledge of physical changes that have happened in the past or may occur in the future. One of the most capable techniques for mapping changing terrain through time across spatially extensive regions is lidar change detection (LCD) with airborne lidar scanning (ALS) data.

LCD has typically been performed on a site-specific basis at known geohazard locations. However, with recent developments in data acquisition and processing, LCD is now a cost-effective tool that can be used on a systemwide scale to aid in the identification of potential geologic hazards and monitor known geohazard sites for active ground displacements that may be impactful to pipeline infrastructure. It enables monitoring of hazards directly impacting the right of way, as well as peripheral hazards that could encroach on the right of way. This proactive method of identifying and monitoring geohazards significantly enhances the ability of pipeline operators to make informed decisions and design resilient infrastructure. The work presented demonstrates how over 40,000 linear kilometers of LCD analysis was executed and integrated with a geohazard management program to support proactive decision-making across the eastern US.
Post-Heating as an Alternative to Delayed Nondestructive Examination (NDE)
Authors: Gould Melissa , Bruce William A. , Scoles Russell
Published: December 2022

The current preference of regulators in the United States and Canada is to require a delay time prior to nondestructive examination (NDE) of welds for cracking; for both welds made manually during construction of new pipelines and during maintenance activities for existing pipelines. A better approach than imposing a delay time is to prevent cracking, by lowering the bulk hydrogen below a threshold value necessary for cracking to occur. The proactive approach of using post-heating immediately after welding to prevent the weld from cracking in lieu of an inspection delay was explored.

An experimental program was carried out to determine the hydrogen diffusion rate in pipe materials, as well as the typical weld hydrogen levels in both a baseline (room temperature) and time and temperature conditions. Experiments were also conducted to measure hydrogen levels in simulated welds in the as-welded condition, after 24 hours at ambient temperature, and after post-heating. The experimental program showed that post-heating newly constructed girth welds made using cellulosic-coated electrodes for approximately 20 minutes at 200 °C (400 °F) and in-service welds made using low-hydrogen electrodes for approximately 20 minutes at 120 °C (250 °F) may be used to mitigate the risk of hydrogen-assisted cold cracking (HACC), thereby justifying immediate inspection.

Various heating methods were evaluated to determine how effectively the post-heating time and temperature targets could be achieved for new construction welds and for in-service welds.

To aid in the successful implementation of post-heating, guidance material suitable for use by field personnel in the application of post-heating, as well as recommendations for industry standards improvement were developed.
Diagnosis and Recognition of Pipeline Damage Defects Based on Neural Network Algorithm
Authors: Zhang Min , Guo Yanbao , Wang Deguo , Du Qiang
Published: December 2022

Oil and gas are the main sources of energy for national economic development. Pipelines are the main means of transportation for oil / gas. It is an important national energy infrastructure, which is known as a “lifeline project”. As the mileage of pipelines increases, defects such as cracks, dents, corrosion as well as mechanical defects caused by changes in external forces occur frequently. Defects can result in pipeline ruptures, fires, property damage, and casualties. According to professor Giovanni’s assessment of pipeline accidents, pipeline defects are mainly caused by third party activities, corrosion and mechanical failure, accounting for 78.1% of all pipeline defects. Therefore, it is particularly important to conduct safety checks on pipelines. There are many pipeline defect detection techniques. One of these is the widely used pipeline magnetic flux leakage detection technique, having the advantage of being fast and efficient, which is suitable for detecting defects in pipeline ferromagnetic metallic materials. Most pipelines are located in harsh outdoor environments with various corrosion and mechanical damage defects. There are axial damage and circumferential damage to the pipeline, resulting in a wide variation in the leakage field. Coupled with this, there is a variety of interference in the signal, so the current pipeline defect identification diagnosis and prediction accuracy are low, with the identification accuracy maintained at around 90%. Therefore, to improve the recognition accuracy, a neural network algorithm was designed to identify and analyze the detection signals. By using a multilayer neural network for training and learning, the recognition accuracy and reliability of pipeline defects are improved. Further, a safety detection basis is provided for the development of the pipeline business. The main contributions are as follows: First, a pipeline defect magnetic flux leakage detection simulation platform is described. Then, pipeline defect detection as good as signal collection are completed. Second, the data is fused and processed, togethering with setting to produce a neural network dataset. Third, a neural network structure is produced to analyze and study the collected pipeline signals. This paper completes the identification of magnetic flux leakage information of pipeline defects, and lays a foundation for future pipeline safety assessment to establish a safe pipeline operation system.