bluuebunny/crossref_metadata_2025_split huggingface dataset:
Getting to Know Your Bends to Support SCC Management
Authors: Wood Chris , Merotto Fernando , Kerrigan Brian , Loback Ramon , Gea Pedro 
Published: January 2021

Abstract
Nova Transportadora do Sudeste (NTS) own and operate a gas transmission system in Brazil constructed in 1996. One of the confirmed primary integrity threats to this system is axial stress corrosion cracking. The pipelines vary in diameter, weld type, manufacturer and age. One of the pipelines failed in 2015 due to an axial stress corrosion crack. Since the failure, NTS have executed an intense inspection campaign to detect and size axial cracking within their network.
The 2015 failure occurred on a field bend. The inspection campaign and following dig campaign has confirmed that cracking (both axial and circumferential) within field bends is the primary integrity threat. Brazil has a challenging terrain and approximately 40% of joints within the network were subject to cold field bending. The influences of the pipeline geometry within these areas have resulted in localised elevated stresses where the axial stress corrosion cracking colonies are initiating and growing. To date, no cracking (axial or circumferential) has been verified within their straight pipe joints.
NTS initially took a conservative baseline assessment approach using API 579 Part 9, due to the limited information regarding the pipe material and complex stress state. In addition to the hoop stress from internal pressure, the baseline assessment also considered weld residual stress and bending stress due to ovalization to determine immediate and future integrity.
An intensive dig campaign is underway following a crack detection in-line inspection campaign using electromagnetic acoustic transducer technology. A large number of deep cracks were reported by the in-line inspection system, these were verified to be deep and repaired with a type B sleeve. However, at one site an entire joint was removed for further analysis, to investigate the crack morphology, confirm material properties and refine the predictive failure pressure modelling.
This paper outlines how NTS have combined a burst test, mechanical testing, FEA modelling, fractography and metallographic examination to further understand the feature morphology and stresses within these areas and how they have been able to reduce conservatism from their baseline assessment with confidence and adopt a plastic collapse approach to accurately predict failure.
The Application of Numerical Simulation to Liquid Pipeline Leakage at LNG Terminal in China
Authors: Guo Zhichao , Li Zhaoci 
Published: January 2021

Abstract
In 2018, China’s natural gas import reached 90.39 million tons, and the liquefied natural gas (LNG) import was 53.78 million tons, accounting for 59.5% of total natural gas imports. With the construction of LNG terminals, more studies on the leakage of LNG storage and transportation facilities have emerged to prevent catastrophic consequences such as explosions and frostbite. However, most of previous researches focused on gas pipeline leakage after LNG gasification, and few of those have been done on LNG liquid pipeline leakage. In this paper, Fluent software is used to numerically simulate the process of LNG liquid pipeline leakage. After the occurrence of LNG leakage, it will suffer the process of endothermic, evaporation, and diffusion, which is considered as a two-phase diffusion process. The Euler-Lagrangian method is introduced to simulate the diffusion process of gas phase and liquid phase separately. In the simulation, the liquid phase is regarded as discrete droplets for discrete processing. The movement trajectory, heat transfer process and evaporation process of each droplet are tracked respectively. Different from the liquid phase, the gas phase is regarded as a continuous phase and the Navier-Stokes equations are adopted for calculation. Thereafter, coupling calculations of two phase are performed to determine the concentration field and temperature field of the LNG liquid pipeline leakage. As a supplement to this research, the influence of wind speed on LNG leakage and diffusion process is analysed in detail. Finally, the numerical simulation method is applied to a coastal LNG terminal in northern China to determine the distribution of natural gas concentration and temperature, as well as delimit the combustion range. The results can provide scientific reference for the delimitation of risky zones and the formulation of emergency response strategy.
Pipeline Plain Dent Fatigue Assessment: Shedding Light on the API 579 Level 2 Fatigue Assessment Methodology
Authors: Shirband Zeynab , Gosselin Adrian , Guest Stuart , Falcon Lee 
Published: January 2021

Abstract
For continued safe operation of pipelines, thousands of integrity digs are conducted every year to repair ILI detected defects. Integrity-driven pipeline excavations can be quite costly, present significant scheduling challenges with landowner consultation and seasonal access limitations, and an unmitigated defect may have required a pressure reduction or service outage, resulting in a loss of revenue from the asset. Dents are known to be one of the drivers for many integrity excavations, especially for liquid pipelines. A pipeline with a minimal mechanical deformation is not expected to fail immediately, however, severe pressure cycles combined with the geometric distortion can cause fatigue crack initiation and growth that can lead to failure. To account for the possibility of fatigue failure, recent changes to pipeline codes, such as CSA Z662, are requiring pipeline operators to repair any dent susceptible to fatigue failure unless an engineering assessment proves it is fit for service.
A commonly used dent fatigue assessment methodology is outlined in API RP 579, also known as the EPRG-2000 model. The assessment methodology uses an S-N curve from DIN 2413 part 1 with a safety factor of 10, which has been derived from undamaged pressurized pipe sections experiencing pressure cycles with stress ratios of zero, and separate stress enhancement factors for dents and gouges which take into account the shape of dents and gouges. To account for the effect of mean stress, Gerber mean stress correction, which has been developed for pressure cycles with stress ratios of −1 (i.e., for fatigue bar specimens), is also applied on pressure cycles. According to the literature, API 579 Level 2 fatigue assessment methodology results in very conservative estimates of fatigue lives compared to experimental data. This paper will discuss the potential factors resulting in conservative assessments and propose refinements in the methodology. This will include the safety factor used for pipes with known operating pressure fluctuations and the mean stress correction model suitable for a pipeline with pressure cycles that have R ratios greater than zero. The acceptable number of cycles obtained using the proposed refinements were compared to experimental data and EPRG-1995 model’s predictions — the comparison revealed that the proposed methodology results in a more realistic safety margin for dented pipelines. The proposed methodology can be used as a part of engineering assessments in mechanical damage integrity management programs to improve the pipeline operator’s understanding of a dent’s remaining life and enable a more appropriate repair timeline.
Preserving Critical Stormwater Storage Assets at Pipeline Terminal
Authors: Huang Vincent , Walter David J. , Treen Curtis R. , Richmond John A. 
Published: January 2021

Abstract
A slope failure compromised the integrity of a critical stormwater storage facility at a petroleum storage terminal within northern Alberta. Through periodic ground inspections and a review of LiDAR and aerial imagery, significant lateral deformation of a lined stormwater pond was identified. The potential for pond overflow and uncontrolled stormwater release into the natural environment due to compromised discharge outlets and liner integrity posed an operational and environmental risk. A fast-tracked review and assessment of both the historical and as-built construction details, a good understanding of the regional geology, and geotechnical investigation and instrumentation were required to identify remedial measures that could be implemented to restore the pond prior to the onset of major storm events.
Geotechnical investigation and assessment showed weak zones in the bedrock at shallower depths than were historically encountered at the site. Spatial constraints, uncontrolled fill placement in close proximity to the pond, expansion of the pond following original construction, and compromised subsurface drainage were identified as factors that may have contributed to the failure. Assessment of remedial options considered impacts relative to both local and global factors of safety. The selected remedial option was a combination of slope unloading, shear key construction, and improved drainage with the design and construction occurring within a timeframe of 3 months to minimize the time that the pond was out of service.
The paper highlights the challenges associated with the slope unloading and shear key construction that were required to control the ground movements. An approach involving sequential excavation and replacement was adopted to manage the risks associated with shear key construction. In addition, directional drill methods were incorporated to install some of the drainage measures due to the risk associated with an open cut approach. The project was fast-tracked to minimize exposure to high precipitation and limited stormwater storage capacity.
Dent Screening Criteria Based on Dent Restraint, Pipe Geometry and Operating Pressure
Authors: Tiku Sanjay , Rana Arnav , John Binoy , Dinovitzer Aaron 
Published: January 2021

Abstract
A safety advisory (2010-01), issued by the National Energy Board (NEB) in June 2010, referenced two incidents which were a result of a fatigue crack failure that occurred within shallow dents [1]. The dents in both instances were less than 6% (of the OD). Currently, there is no consensus on how shallow dents or shallow dents with stress concentrators, as called by the ILI tool, are assessed and acted upon.
BMT Canada Ltd. (BMT) was contracted by the Canadian Energy Pipeline Association (CEPA) to develop a definition for shallow dents, and two levels of screening method for the integrity assessment of shallow restrained dents and unrestrained dents. These two levels are known as CEPA Level 0 and CEPA Level 0.5 dent integrity assessment techniques that may be applied without finite element modelling or detailed calculations. The BMT dent assessment finite element (FE) modeling method was used to develop an extensive database of dents for different pipe geometries (OD/t), indenter shapes, pipe grades, and indentation depths. The results of the FE modelling were used to develop trends for the stress magnification factors (KM) across the range of pipes and dents modelled. These trends are used as the basis for the Level 0 and Level 0.5 dent screening and assessment approaches that can be used for both unrestrained dents and shallow restrained dents. The results show that for low OD/t pipe geometry and/or low spectrum severity indicator (SSI) [2] dent fatigue life may not pose an integrity threat.
These dent screening approached have been adopted in the API Recommended Practice 1183 Dent Assessment and Management, that is currently under development.
Full-Scale Fatigue Testing of Crack-in-Dent and Framework Development for Life Prediction
Authors: Arumugam Udayasankar , Gao Ming , Krishnamurthy Ravi , Zarea Mures 
Published: January 2021

Abstract
Dents containing crack fields (colonies) were often observed in liquid pipelines. A recent PRCI research “Study of the Mechanism for Cracking in Dents in a Crude Oil Pipeline” showed evidence of corrosion fatigue cracking mechanism in dents and estimated the crack growth rate as a function of stress intensity factor using the measured spacings of fatigue striations from fracture surfaces based on the assumption that the formation of fatigue striations on a cycle-by-cycle basis. However, due to the lack of full-scale fatigue crack growth data, the success was limited in this study. This gap prompted PRCI to launch a full-scale experimental investigation of cracks-indents under cyclic pressure load in the simulated groundwater (NS4 solution) environment. The objective of the study is to determine the crack growth rate in dent as a function of stress intensity factor, the number of cycles to failure, and the failure modes of crack-in-dent. The investigation is aimed at establishing a framework for the remaining fatigue life prediction of cracks-in-dents in liquid pipelines. This framework would benefit liquid pipeline operators to manage the integrity of dents associated with corrosion fatigue cracking exposed to groundwater in a timely manner.
A total of six pipe samples containing cracks in shallow dents excavated from a 24-inch diameter liquid transmission pipeline were selected for full-scale fatigue tests. The test system developed under the project consisted of (1) a computer-controlled hydraulic pressure cycling system, (2) an environment chamber containing NS4 solution mounted on the dent region to provide a simulated field environment condition, (3) real-time crack growth monitoring systems including direct current potential drop (DCPD) system, Clip gage, and Strain gage, and (4) a data acquisition system. The cyclic pressure range used in the fatigue test was between 78 psig (7.2%SMYS, minimum) and 780 psig (72%SMYS, maximum) with R = 0.1, which was based on historical operational pressure fluctuation data. A constant frequency of 0.0526 Hz was selected for the testing to ensure the frequency requirement for corrosion fatigue was met.
In this paper, the objective, along with the background of this research, is discussed first. Then, the pipe sample preparation, experimental setup, and test results are presented. The fatigue crack growth rate as a function of the stress intensity factor is then discussed. Following this, the fatigue crack growth coefficients were estimated using the full-scale test data and FEA. Finally, the fatigue test results are summarized and presented the framework for the life prediction of corrosion fatigue cracks in shallow dents.
Repair of Leaks in Thin Wall High Pressure Pipelines Using Composite Reinforcing Technologies
Authors: Alexander Chris , Talbi Salem , Kania Richard , Rickert Jon 
Published: January 2021

Abstract
A study was conducted to evaluate two composite repair technologies used to reinforce severe corrosion and thru-wall leaking defects in thin-walled pipe materials; conditions where the welding of conventional Type B steel sleeves cannot be conducted. This program involved the reinforcement of simulated 85% corrosion defects in 6.625-inch × 0.157-inch, Grade X52 pipe materials subjected to cyclic pressure and burst testing. The test matrix also included repaired pipe samples with thru-wall defects that were pressurized using nitrogen gas and buried for 90 days. The program was comprehensive in that it evaluated the following elements involving a total of 81 reinforced corrosion defects.
• Corrosion features with a depth of 85% of the pipe’s nominal wall thickness in thin-walled pipe material (i.e., 0.157 inches, or 4 mm).
• Thru-wall defects having a diameter of 0.125 inches (3 mm).
• Repairs made with leaking defects having 100 psig (690 kPa) internal pressure.
• Strain gage measurement made in non-leaking 85% corrosion defects; it should be noted that the remaining “15%” ligament was 0.024 inches (0.6 mm); to the author’s knowledge, no high-pressure testing has ever been conducted on such a thin remaining wall.
• Long-term 90-day test that included pressurization with nitrogen gas, followed by relatively aggressive pressure cycling up to 80% SMYS followed by burst testing.
This is the first comprehensive study conducted by a major transmission pipeline operator evaluating the performance of competing composite technologies used to reinforce severe corrosion features with thru-wall defects. The reinforcement of leaks has not been accepted by regulatory bodies such as the Canadian Energy Regulator (CER), or the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA). A goal of the current study is to validate composite repair technologies as a precursor to regulatory approval.
The results of this study indicate that viable composite repair technologies exist with capabilities to reinforce leaks in pipelines that experience operating conditions typical for gas transmission systems (i.e., minimal pressure cycling).
Developing a Representative Soil Response Model
Authors: Phillips Ryan , Martens Michael 
Published: January 2021

Abstract
A testing procedure and methodology has been developed to provide more realistic pipe-soil response curves which account for differing soil types, pipe and trench geometries and backfill conditions. Such curves increase the reliability of the pipe-soil interaction analyses, and help to reduce overall conservatism in definition of springs for pipe-soil interaction.
Pipe-soil spring response is now generally determined by geotechnical engineering estimation of the soil properties which are used as inputs to simple pipe-soil interaction guidelines. A new dual axis field test procedure, including equipment and interpretative methodology has been developed to directly measure soil response curves for bearing and shear interactions. A numerical modelling protocol interprets these measurements to directly assess pipe-soil spring responses, rather than relying on simplified guidelines.
This paper includes the field and laboratory testing and associated numerical modelling used in the development of the pipe-soil spring response process, as well as the initial results of trials with the new dual axis testing system. The next step for this initiative will be the development of a database of field test data, from which significant advancements can be made to further improve pipe spring recommendations.
Calibration and Compensation of Rotary Axis Angular Positioning Deviations on a SCARA-Type Industrial Robot Using a Laser Tracker
Authors: Zhao Nan , Ibaraki Soichi 
Published: January 2021

Abstract
In general, the “absolute” positioning accuracy of industrial robots is significantly lower than its repeatability. In the past research, in order to improve a robot’s positioning accuracy over the entire workspace, the compensation for the link length errors and the rotation axis angle offsets are often employed. However, the positioning error of the compensated industrial robot is still much higher than that of a typical machine tool. The purpose of this study is to propose a new kinematic model and its calibration scheme to further improve the absolute positional accuracy of an industrial robot over the entire workspace. In order to simplify the problem, this study only targets the 2D positioning accuracy of a SCARA-type robot. The proposed model includes not only link length errors and rotary axis angular offsets but also the “error map” of the angular positioning deviation of each rotary axis. The angular error deviation of each rotary axis is identified by measuring the robot’s end-effector position by a laser tracker at many positions. To verify the validity of the identified model, the effectiveness of the compensation based on it is also investigated.
Graph-Based Feature Recognition and Combination Method for Automatic Process Planning System
Authors: Xie Da , Zhu Jiang , Tanaka Tomohisa 
Published: January 2021

Abstract
Generating the Numerical Control (NC) tool path for machining a complex shaped component is highly dependent on the proficiency of a Computer-Aided Manufacturing (CAM) programmer in manufacturing field, although the CAM systems now are highly integrated. A Computer-Aided Process Planning (CAPP) system, which can automatically extract the manufacturing features from the Computer-Aided Design (CAD) model and generate the machining process planning, has been expected for a long time. In this research, a graph-based CAPP system was proposed. It mainly includes four modules, data conversion module, feature classification module, feature combination module and process planning module. The first two modules claim a graph-based feature recognition method, output the recognized manufacturing features which are classified into four classes and defined as specific types. The feature combination module generates different paths to combine manufacturing features from a goal model into raw material shape by four kinds of combination methods corresponding to the four classes. Finally, the process planning module will give a cost estimation of all those paths with the consideration of manufacturing resources and time cost. A relatively optimized machining method and machining sequence will be generated as the output of this proposed system.
Tribological Properties Between a-C:H Coatings and SiO2 at High Temperature
Authors: Umehara Noritsugu , Konishi Kota , Murashima Motoyuki , Tokoroyama Takayuki 
Published: January 2021

Abstract
Tribological properties of a-C:H coatings has been investigated in various friction conditions. It is clear that temperature and mating materials give effects on tribological properties. In this study, we especially focus on the effect of mating material on its tribological properties of a-C:H coatings. Ball-on-disk friction test is conducted between a-C:H coating and 5 kinds of mating material, which is SiC, SiC(O)_800 (SiC oxidized at 800°C), SiC(O)_1050°C, SiC(O)_1300°C, and Quartz glass. It is found that a-C:H coatings shows low friction coefficient and low specific wear rate when O/Si ratio of the element content of mating material is 2, in other words, mating material is SiO2. In the wear scar of a-C:H coating after friction test with SiC, severe damage was confirmed. It is considered that a-C:H coating and SiO2 show low adhesion even at high temperature, which leads low friction and wear. Compared SiC(O) with Quartz, the friction coefficients with a-C:H coatings are respectively 0.013 and 0.038. Even though SiC(O) and Quartz are both SiO2, the tribological properties are different. On the wear track of SiC(O), transferred things from a-C:H coating are confirmed.
Proposal of a Tool Path Generation Method to Ensure Workpiece Stiffness for Efficient Rough Machining
Authors: Kumanotani Maho , Kusino Hitoshi , Nakamoto Keiichi 
Published: January 2021

Abstract
Recently, the demand of complex shape parts has increased in the aircraft and medical industries. In these parts machining, the displacement and vibration of workpiece that strongly affect the machining efficiency are induced due to the heavy change of the unmachined workpiece shape and stiffness during rough machining. However, it is difficult to automatically determine machining parameters of operation planning by using a commercial CAM software because there is a large number of combinations. Therefore, in order to improve the efficiency of complex parts machining, the authors proposed a determination method of workpiece shapes during rough machining based on topology optimization relevant to maximizing static stiffness. On the other hand, tool paths that directly affect the workpiece stiffness are not generated automatically to create the calculated workpiece shapes in the previous study. From these reasons, this study proposes a generation method of tool paths by using design variables obtained through the calculation of topology optimization. The tool paths are simply generated based on design variables and enables to ensure the workpiece stiffness during rough machining because design variables are strongly related to the objective function. By conducting a machining experiment assuming complex parts machining, it is confirmed that the proposed method has a potential to realize efficient rough machining.