bluuebunny/crossref_metadata_2025 huggingface dataset:
“Lord, Have Mercy on Me, a Sinner”: Aquinas on Grace, Impetration, and Justification
Authors: Colberg Shawn
Published: November 2018

This article explores St. Thomas Aquinas's doctrine of grace for the way in which it heals and moves the sinner towards justification. It exposits Thomas's use of the language of “impetration” to express a causal yet non-meritorious role for human action, and it applies this conception to the free will's movement in justification. It argues that Thomas understands the prayer of a sinner to illumine the way in which God's infallible and predestinating will unfolds through human actors without destroying their contingent nature. To that end, it first exposits critical points in Thomas's doctrine of grace, including the notions of habitual grace and auxilium, intact and fallen human nature, and operative and cooperative grace. It then introduces the language of impetration for the way in which it elucidates a valuable role for human action in justification. It concludes that impetration illustrates the on-going perfection of nature in such a way that God's grace draws human beings into the causal sequence of divine providence. The sinner's impetration captures the indispensable movement of the free will while recognizing that, in its appeal to divine mercy, it has already been graced by God and cannot earn the gift of justification.
Left atrial appendage electrical isolation for persistent atrial fibrillation
Authors: Madaffari Antonio , Große Anett , Conci Elisabetta , Geller J. Christoph
Published: November 2018

Left atrial appendage (LAA) may be the source for initiation and maintenance of atrial fibrillation (AF). This report shows restoration of sinus rhythm in the atria during radiofrequency wide‐area LAA electrical isolation, whereas AF persists in the LAA.
Effects of an educational program on disaster nursing competency
Authors: Huh Seong‐Soo , Kang Hee‐Young
Published: November 2018

Objective

The purpose of this study was to examine the effects of an educational program on disaster nursing competency among Korean nursing students.

Design and Sample

A quasi‐experimental design with a nonequivalent control group was used. We randomly assigned 60 junior nursing students from two nursing colleges in Korea to an experimental group (n = 30) and a control group (n = 30).

Measures

A disaster educational program for nursing students was developed based on the International Council of Nurses framework of disaster nursing competencies. The program sought to teach nursing activities by stage of disaster (i.e., prevention/mitigation, preparedness, response, and recovery/rehabilitation). Disaster nursing knowledge, disaster triage, and disaster readiness were measured as dependent variables.

Results

Compared with the control group, the experimental group showed a significant increase in disaster nursing knowledge (t = 14.37, p < 0.001), disaster triage (t = 7.90, p = 0.002), and disaster readiness (t = 10.82, p < 0.001).

Conclusion

The disaster educational program developed in this study was effective in increasing disaster nursing competency among nursing students and is therefore a useful intervention strategy for nursing students.
GPS precise point positioning for UAV photogrammetry
Authors: Grayson Ben , Penna Nigel T. , Mills Jon P. , Grant Darion S.
Published: November 2018

The use of Global Positioning System (GPS) precise point positioning (PPP) on a fixed‐wing unmanned aerial vehicle (UAV) is demonstrated for photogrammetric mapping at accuracies of centimetres in planimetry and about a decimetre in height, from flights of 25 to 30 minutes in duration. The GPS PPP estimated camera station positions are used to constrain estimates of image positions in the photogrammetric bundle block adjustment, as with relative GPS positioning. GPS PPP alleviates all spatial operating constraints associated with the installation and the use of ground control points, a local ground GPS reference station or the need to operate within the bounds of a permanent GPS reference station network. This simplifies operational logistics and enables large‐scale photogrammetric mapping from UAVs in even the most remote and challenging geographic locations.
Culture‐dependent diversity of boron‐tolerant bacteria from boron mine tailings pond and solid wastes
Authors: Nural Yaman Belma , Deniz Sonmez Gorkem , Aytar Celik Pinar , Korkmaz Ferhan , Mutlu Mehmet Burcin , Cabuk Ahmet
Published: November 2018

Boron is a vital micronutrient for the growth of plants and different organisms. However, boron may be toxic to living cells at high concentrations. Nevertheless, microorganisms can be grown in harsh conditions such as environments with higher boron concentrations. It is also known that boron‐tolerant microorganisms have significant biotechnological potentials. In this study, it is aimed to isolate microorganism from a boron containing place in Kırka, Eskişehir using culture‐dependent methods. After extracting genomic DNAs, Amplified Ribosomal DNA Restriction Analysis (ARDRA) profiles were constructed with HaeIII, MspI, HinfI‐HpaII and AluI‐CfoI. Sequence analyses were performed by chain‐terminating method. Consensus sequences were completed and similarities were determined by RDP Release 11. According to ARDRA, 10 profiles and five different species such as Pseudomonas sp., Enterecoccus sp., Acinetobacter sp., Bacillus sp. and Halomonas sp. were identified.
Cyclotomic analogues of finite multiple zeta values
Authors: Bachmann Henrik , Takeyama Yoshihiro , Tasaka Koji
Published: November 2018

We study the values of finite multiple harmonic $q$-series at a primitive root of unity and show that these specialize to the finite multiple zeta value (FMZV) and the symmetric multiple zeta value (SMZV) through an algebraic and analytic operation, respectively. Further, we prove the duality formula for these values, as an example of linear relations, which induce those among FMZVs and SMZVs simultaneously. This gives evidence towards a conjecture of Kaneko and Zagier relating FMZVs and SMZVs. Motivated by the above results, we define cyclotomic analogues of FMZVs, which conjecturally generate a vector space of the same dimension as that spanned by the finite multiple harmonic $q$-series at a primitive root of unity of sufficiently large degree.
An Investigation on Microstructural Evolution of X70 Steel Pipe During Hot Induction Bending
Authors: Meschian Moe , Duncan Andy , Yarmuch Matt , Myschuk Fred
Published: November 2018

It is generally accepted that hot induction bending (HIB) results in a decrease in strength and an increase in fracture toughness in bend area, heat affected zone (HAZ) and weld metal (WM). As the result, Post bend heat treatment (PBHT) is not considered to be a requirement and could be waived for saving money and time. This research work raises the concern that factual verification of proper microstructure and no localized brittle zone is vitally necessary prior to waving PBHT.

Evaluation of the steel microstructure and mechanical properties as the result of various pipe chemistries during pipe bending has been verified in this experimental work. It is emphasized that knowledge and control of prior steel pipe chemistry, control of temperature, cooling rate and bending speed assures the reliability and repeatability of induction bends, especially in critical environments such as low temperature application.

In the present work, qualitative and quantitative microstructural analysis, hardness and impact test performed and evaluated on samples from X70 line pipe with 3 different steel chemistries. The samples prepared from different locations on body, weld and HAZ in the as received and as bent condition. It was found that the final microstructure and mechanical properties in the as bent condition is dependent on the chemistry, steel cleanliness and microstructural uniformity. It was observed that small localized brittle zone with traces of upper Bainite and Martensite islands could be transformed in the microstructure with rich chemistry containing non-homogenous central segregation. It is concluded that factual verification of proper microstructure with no localized hard zone is required prior to waving PBHT.
Integrated Scheduling for a Multi-Product Pipeline Network With Delivery Due Dates
Authors: Xu Ning , Liao Qi , Liang Yongtu , Li Zhengbing , Zhang Haoran
Published: November 2018

Currently, pipeline is the most effective way to transport large-volume products over long distance. To effectively satisfy market demands for multiple refined products by delivery due dates, the multi-product pipeline network usually transports several refined products in sequence from refineries to certain destinations. The integrated scheduling of multi-product pipeline network, including inventory management, transport routes planning, batch sequence, batch volume, et al., is one of the most strategic problems due to its large-scale, complexity as well as economic significance. This subject has been widely studied during the last decade. However, most researches focus on large-size scheduling models whose computational efficiency greatly decreases for a complex pipeline network or a long time horizon. Aiming at this problem, the paper develops an efficient decomposition approach, which is composed of two mixed integer linear programming (MILP) models. The first model divides the entire time horizon into several intervals according to delivery due dates and optimizes the transport routes and total transport volume during each interval with considering market demand, production campaigns and inventory limits. Then the solved results are used by the second model which sets the objective function as the membership function based on fuzzy delivery due dates. Besides, a series of operational constraints are also considered in the second model to obtain the optimal batch sequence, batch volume, delivery volume and delivery time in each node. Finally, the proposed approach is applied to a Chinese real-world pipeline network that includes 5 complex multi-product pipelines associated with 6 refineries and 2 depots. The results demonstrate that the proposed approach can provide a guideline for long-term pipeline network scheduling with delivery due dates.
Assessment of the Threat From Wildfires on Above Ground Natural Gas Facilities
Authors: Robinson Clive G. , Wattis Zoë E. , Dooley Colin , Popovic Sladjana
Published: November 2018

In the light of recent experience of wildfires in Alberta and British Columbia, Alliance Pipeline has strengthened their emergency preparedness in dealing with external fire events that have the potential to affect above-ground facilities connected with their high pressure natural gas pipeline system. As part of this initiative a quantitative methodology has been developed that enables the effects of a wildfire on an above-ground pipeline facility to be assessed.

The methodology consists of three linked calculations which assess:

1. the severity of the wildfire, based on information from the Canadian Wildland Fire Information System,

2. the transmission of thermal radiation from the wildfire to the facility, and,

3. the response of equipment, structures and buildings to the incident thermal radiation.

The predictions of the methodology agree well with the actual damage observed at a lateral block valve site following a wildfire in 2016. Application to example facility types (block valve sites, meter stations and compressor stations) has demonstrated that, in general, damage is only predicted for more vulnerable items such as cables.

The sensitivity of the predictions of the methodology to the input parameters and key modelling uncertainties has been examined. This demonstrates that the results are sensitive to the distance of the facility from the tree line and the assumed vegetation type. This shows the importance of verifying the location relative to the vegetation and selecting the appropriate vegetation type from the Canadian Wildland Fire Information System for site specific assessments. The predictions of the methodology are particularly sensitive to the assumed flame temperature. However, a value has been chosen that gives good agreement with measured thermal radiation values from wildfires.

Of the mitigation options considered, the most effective and practical is to increase the distance to the tree line. This measure has the advantage of reducing radiation levels for all items on the site. Even though the work shows that failure of exposed pipework due to wildfires is unlikely, maintaining the flow within pipes is recommended as this increases the radiative flux at which failure is predicted to occur. However, as failure of cables and hence control systems would occur at a lower flux levels the fail-safe actions of such systems needs to be confirmed. Shielding of cables or items of equipment in general is likely to be impractical but could be considered for particularly vulnerable equipment or locations.
Control of %age Shear Area in DWTT at Low Temperature in Niobium Microalloyed Line Pipe Steel
Authors: Subramanian Sundaresa , Ma Xiaoping , Wang Xuelin , Shang Chengjia , Zhang Xiaobing , Miao Chengliang , Collins Laurie
Published: November 2018

Microstructural engineering to obtain 100% shear area in DWTT at low temperature requires target parameters to suppress brittle fracture. In-depth characterization of benchmarked steels has confirmed that %age shear area is decreased by high number density of ultra-fine precipitates (<10nm) that contribute to precipitation strengthening, high intensity of rotated cube texture and coarse brittle constituents like M/A or carbides. The control of these parameters by nano-scale precipitate engineering of TiN-NbC was covered in a previous presentation in IPC 2016 [1]. The present paper focuses on crystallographic variants selection that controls the density and dispersion of high angle boundaries, which arrest microcracks to suppress brittle fracture, thereby increasing %age shear area in DWTT at low temperature.

Studies on crystallographic variants selection in single undeformed austenite grain have clarified crystallographic variants configuration which gives rise to high angle boundaries is influenced by hardenability parameters, i.e., alloying, cooling rate and austenite grain size. The profound effect of carbon and solute niobium on density and dispersion of high angle boundaries in CGHAZ is demonstrated by analyzing EBSD data to reconstruct the shear transformation of undeformed austenite using K-S relationship. Moreover, pancaking of austenite influences crystallographic variants through Sv factor and dislocation density. Experimental results on nano-scale TiN-NbC composite precipitate engineered steel confirm that adequate solute niobium (>0.03wt%) is retained in the matrix, which is aided by the suppression of delayed strain induced precipitation of ultra-fine precipitates of NbC. The hardenability from solute niobium is found to be adequate to give high density of high angle boundaries to give about 95% shear area in DWTT at −40°C in 32 mm gage K-60 plate and 100% shear area in 16.3 mm X-90 strip. Both steels were processed by nano-scale precipitate engineering of TiN-NbC composite to control size and uniformity of distribution of austenite grains before pancaking.
A Strain Based Criterion to Evaluate the Tensile Capacity of Transmission Pipelines Under Large Scale Cyclic Bending
Authors: Plata Uribe Y. Andrés , Ruggieri Claudio
Published: November 2018

This study explores the capability of a computational cell methodology and a stress-modified, critical strain (SMCS) criterion for void coalescence implemented into a large scale, 3-D finite element framework to model ductile fracture behavior in tensile specimens and in damaged pipelines. In particular, the cell methodology provides a convenient approach for ductile crack extension suitable for large scale numerical analyses which includes a damage criterion and a microstructural length scale over which damage occurs. A series of tension tests conducted on notched tensile specimens with different notch radius for a carbon steel pipe provides the stress-strain response of the tested structural steel from which the cell parameters and the SMCS criterion are calibrated. To investigate ductile cracking behavior in damaged pipelines, full scale cyclic bend tests were performed on a 165 mm O.D tubular specimen with 11 mm wall thickness made of a pipeline steel with very similar mechanical characteristics to the structural steel employed in the tension tests. The tubular specimen was initially subjected to indentation by 3-point bend loading followed by a compressive axial loading to generate large localized buckling in the dented region. The axial loading was then reversed to a tension loading applied until a visible ductile crack could be observed in the pipe surface. These exploratory analyses predict the tensile failure load for the pipe specimen associated with ductile crack initiation in the highly damaged area inside the denting and buckling zone which is in good agreement with experimental measurements.
Case Studies Highlighting Rapid Repair Methods of Pressurised Pipelines Damaged by Anchors
Authors: Millward Dale
Published: November 2018

Effective pipeline design and regular maintenance can assist in prolonging the lifespan of subsea pipelines, however the presence of marine vessels can significantly increase the risk of pipeline damage from anchor hazards. As noted in the Health and Safety Executive – Guideline for Pipeline Operators on Pipeline Anchor Hazards 2009. “Anchor hazards can pose a significant threat to pipeline integrity. The consequences of damage to a pipeline could include loss of life, injury, fire, explosion, loss of buoyancy around a vessel and major pollution”.

This paper will describe state of the art pipeline isolation tooling that enables safe modification of pressurised subsea pipelines. Double Block and Bleed (DBB) isolation tools have been utilised to greatly reduce downtime, increase safety and maximise unplanned maintenance, providing cost-effective solutions to the end user. High integrity isolation methods, in compliance with international subsea system intervention and isolation guidelines (IMCA D 044 / IMCA D 006), that enable piggable and unpiggable pipeline systems to be isolated before any breaking of containment, will also be explained.

This paper will discuss subsea pipeline damage scenarios and repair options available to ensure a safe isolation of the pipeline and contents in the event of an incident DNV GL type approved isolation technology enables the installation of a fail-safe, DBB isolation in the event of a midline defect.

The paper will conclude with case studies highlighting challenging subsea pipeline repair scenarios successfully executed, without depressurising the entire pipeline system, and in some cases without shutting down or interrupting production.
Optimizing Electrical Protection for Medium Voltage Controller Lineup to Improve Liquids Pipelines Operation Reliability and Safety
Authors: Yu Ting , Chaitanya Tushar
Published: November 2018

MV (Medium Voltage) controller lineup electrical protection is crucial in protecting the equipment from large scale damage upon the occurrence of an electrical fault, reducing the time to restore power, thereby minimizing the impact to liquids pipelines operation. The paper discusses typical electrical failure modes that may occur in MV controller lineups, and demonstrates practical relaying engineering techniques that enable fast and effective fault clearing. Electrical faults in the MV controller lineup are often arcing type, commonly involve ground. Mitigating arc hazards in MV Class E2 controller lineups has traditionally been challenging without sacrificing the protection selectivity. As the paper demonstrates, a relaying scheme with the combined use of high-speed light-sensing and overcurrent detection will effectively mitigate the incident energy, while maintaining the protection selectivity for non-arcing overcurrent events.

For new MV controller lineups, in addition to the “high-speed light detection and fault interruption”, zone-selective interlocking (ZSI) can also be a practical solution in improving relay protection speed, thus reduce the chance of severe arc flash occurrences. ZSI is particularly effective for fault occurrences on the line side of the phase CTs, busways or main incoming circuits. The ZSI scheme can be implemented on both Class E2 and circuit breaker (VCB) type MV controller lineups, however, with slightly different trip logic due to the limited fault clearing capability of the contactor.

Although there are multiple contributing factors, the direct causes of electrical failures in MV controller lineup are commonly related to improper power cable installation and handling, potentially leading to premature insulation breakdown due mainly to the proximity effect and/or partial discharge. Inadequate cable separation and prolonged fault trip delay can increase the possibility of arcing fault occurrence. This can usually be mitigated through appropriate cable spacing, adequate conductor insulation, and optimized fault detection schemes. The paper provides overviews of the mechanisms of proximity effect and partial discharge propagation, and the modern relaying approaches for accurate fault type discrimination and facilitating fast fault interruption.

Two case studies are provided in the paper as an aid in understanding the electrical fault mechanism originated from cable insulation failure, demonstrating the incident energy reduction before and after the implementation of high-speed light detection and fault interruption solutions on an existing MV controller lineup.
Corrosion Growth Modeling by Learning a Dynamic Bayesian Network From Multiple In-Line Inspection Data
Authors: Xiang Wei , Zhou Wenxing
Published: November 2018

This paper establishes a dynamic Bayesian network to model the growth of corrosion defects on energy pipelines. The integrated model characterizes the growth of defect depth by a homogeneous gamma process and considers the biases and random errors associated with the in-line inspection (ILI) tools. The distributions of the mean value and coefficient of variation of the annual growth of defect depth are learned from multiple ILI data using the parameter learning technique of Bayesian networks. With the same technique, the distributions of the biases and standard deviation of random errors associated with ILI tools are learned from ILI data and their corresponding field measurements. An example with real corrosion management data is used to illustrate the process of developing the model structure, learning model parameters and predicting the corrosion growth and time-dependent failure probability. The results indicate that the model can in general predict the growth of corrosion defects with reasonable accuracy and the ILI-reported and field-measured depth can be used to update the time-dependent failure probability in a near-real-time manner. In comparison with existing growth models, the graphical feature of Bayesian networks makes it more intuitive and transparent to users. The employment of parameter learning provides a semi-automated and convenient approach to elicit the probabilistic information from ILI and field measurement data. The above advantages will facilitate the application of the model in the practice of corrosion management in pipeline industry.
Uncertainty Quantification of Nondestructive Techniques to Verify Pipeline Material Strength
Authors: Kornuta Jeffrey A. , Ames Nicoli M. , Louie Mary W. , Veloo Peter , Rovella Troy
Published: November 2018

The Pipeline and Hazardous Materials Safety Administration (PHMSA) Notice of Proposed Rulemaking (NPRM), with Docket No. PHMSA-2011-0023, substantially revises 49 CFR Part 191 and 192. Notable among these changes was the addition of §192.607, verification of pipeline material. This section calls for the verification of material properties of pipe and fittings located in either high consequence areas, class 3, or class 4 locations where traceable, verifiable, and complete records do not exist. Material properties include grade (yield strength, YS, and ultimate tensile strength, UTS) and chemical composition. The proposed regulations include an independent third-party validation for non-destructive testing (NDT) methods to determine material strength and require an accuracy of within ±10% of an actual strength value.

Among the NDT technologies currently available to pipeline operators to estimate material strength is instrumented indentation testing (IIT). IIT is based on the principal that there exists a relationship between the indentation response of a material and its stress-strain curve. The indentation response is measured during the IIT process whereby an indenter is sequentially forced into the material during testing. The link between the indentation response and the material stress-strain curve is established often through the use of iterative Finite Element Analysis (FEA). The IIT vendor’s proprietary software performs this calculation, converting force-displacement measurements into an estimate of YS and UTS.

In this study we extracted force-displacement data from IIT performed using FEA on an idealized steel. This data was then coupled with literature algorithms developed at Seoul National University (Kwon et al.). Parametric sensitivity analysis was then performed on estimated YS with respect to the algorithm parameters. Preliminary results indicate that while variations in the indenter constant, ω, used to estimate surface deformation do not significantly alter the predicted UTS or YS, the sensitivity to deviations in the empirical constant, Ψ, relating normal load to representative stress was more pronounced due to an effect on the calculated power-law constant, K.

PHMSA’s NPRM accuracy requirements for NDT to establish yield and tensile strength should be driven by a rigorous understanding of material inhomogeneities, uncertainties in actual tensile strength determination, experimental uncertainty, and modeling uncertainties. The analysis performed in this paper provides part of this rigorous framework to establish realistic accuracy requirements for NDT that must drive federal rulemaking. In addition, this research highlights the need for pipeline operators to establish controls on the algorithms adopted by commercial NDT vendors.
Is Public Safety Impacted by the Multiple Regulatory Regimes for Gas Pipelines and Networks?
Authors: Hayes Jan , Chester Lynne , King Dolruedee Kramnaimuang
Published: November 2018

Gas pipelines and networks are subject to multiple regulatory governance arrangements. One regime is economic regulation which is designed to ensure fair access to gas markets and emulate the price pressures of competition in a sector dominated by a few companies. Another regime is technical regulation which is designed to ensure pipeline system integrity is sufficient for the purposes of public safety, environmental protection and physical security of supply. As was highlighted in analysis of the San Bruno pipeline failure, these two regulatory regimes have substantially different orientations towards expenditure on things such as maintenance and inspection which ultimately impact public safety.

Drawing on more than 50 interviews, document review and case studies of specific price determinations, we have investigated the extent to which these two regulatory regimes as enacted in Australia may conflict, and particularly whether economic regulation influences long-term public safety outcomes. We also draw on a comparison with how similar regulatory requirements are enacted in the United Kingdom (UK).

Analysis shows that the overall orientation towards risk varies between the two regimes. The technical regulatory regime is a typical goal-setting style of risk governance with an overarching requirement that ‘reasonably practicable’ measures are put in place to minimize risk to the public. In contrast, the incentive-based economic regulatory regime requires that expenditure should be ‘efficient’ to warrant inclusion in the determination of acceptable charges to customers. How safety is considered within this remains an open question.

Best practice in performance-based safety regimes such as those used in the UK and Australia require that regulators adopt an attitude towards companies based on the principle of ‘trust but verify’ as, generally speaking, all parties aim for the common goal of no accidents. Equally, in jurisdictions that favor prescriptive safety requirements such as the United States (US) the common goal remains. In contrast, stakeholders in the economic regulatory regime have significantly diverse interests; companies seek to maximize their individual financial returns and regulators seek to exert downward price pressures. We argue that these differences in the two regulatory regimes are significant for the management of public safety risk and conclude that minimizing risk to the public from a major pipeline failure would be better served by the economic regulatory regime’s separate consideration of safety-related from other expenditure and informed by the technical regulator’s view of safety.
An Optimization Model for UAV Inspection Path of Oil and Gas Pipeline Network
Authors: Yan Yamin , Zhang Haoran , Zhang Wan , Wang Bohong , Liao Qi , Liang Yongtu
Published: November 2018

Currently, the oil and gas pipeline network is a key link in the coordinated development of oil and gas upstream and downstream cohesion. To ensure the reliability and safety of oil and gas pipeline network operation, it is necessary to inspect the pipeline periodically to minimize the risk of leakage, spill and theft, as well as documenting actual incidents and the effects on the environment. Traditional manpower inspection is extremely labor-intensive and inefficient. Through the use of UAV (unmanned aerial vehicle) inspection, it is possible to greatly increase efficiencies by reducing the amount of manpower and resources required by traditional inspection methods.

The integrated optimization for UAV inspection path of oil and gas pipeline networks, including physical feasibility, performance of mission, cooperation, real-time implementation, three-dimensional (3-D) space, et al, is a strategic problem due to its large-scale and complexity. Aimed at improving inspection efficiency and maximizing economic benefits, this paper proposes a novel mix-integer linear programming model which could be used for inspection path planning. Minimizing the total inspection time is the objective function of this model. The constraints of the mission scenario and the safety performance of UAV are taken into account. By using evolutionary genetic algorithm, each candidate route can be measured through the evaluation function that takes into account the cost of the route, the mission scenario as well as the cooperative and coordinative requirements among the unmanned aerial vehicles constraints.

Finally, the proposed approach is applied to a virtual oil and gas pipeline network. Compared with the traditional inspection approach, the proposed method is 66.48% less in inspection cost and 22.07% shorter in total inspection time, verifying the rationality and superiority of the model.
A Methodology to Assess the Gas Supply Capacity and Gas Supply Reliability of a Natural Gas Pipeline Network System
Authors: Yu Weichao , Wen Kai , Li Yichen , Huang Weihe , Gong Jing
Published: November 2018

Natural gas pipeline network system is a critical infrastructure connecting gas resource and market, which is composed with the transmission pipeline system, underground gas storage (UGS) and liquefied natural gas (LNG) terminal demand. A methodology to assess the gas supply capacity and gas supply reliability of a natural gas pipeline network system is developed in this paper. Due to random failure and maintenance action of the components in the pipeline network system, the system can be in a number of operating states. The methodology is able to simulate the state transition process and the duration of each operating state based on a Monte Carlo approach. After the system transits to other states, the actual flow rate will change accordingly. The hydraulic analysis, which includes thermal-hydraulic simulation and maximum flow algorithm, is applied to analyze the change law of the actual flow rate. By combining the hydraulic analysis into the simulation of the state transition process, gas supply capacity of the pipeline network system is quantified. Furthermore, considering the uncertainty of market demand, the load duration curve (LDC) method is employed to predict the amount of demand for each consumer node. The gas supply reliability is then calculated by comparing the gas supply capacity with market demand. Finally, a detailed procedure for gas supply capacity and gas supply reliability assessment of a natural gas pipeline network system is presented, and its feasibility is confirmed with a case study. In the case study, the impact of market demand uncertainty on gas supply reliability is investigated in detail.
Vibration and Fatigue Failures at Pipeline Facilities
Authors: Matta Lawrence M. , Szasz Gyorgy
Published: November 2018

Vibration related issues can be a challenging part of pipeline integrity management, because they are frequently difficult to predict, diagnose, and remediate. Often, vibrational issues are not even considered until pipe movement is observed or failures occur. A wide variety of vibration problems are associated with pumps and compressors, and piping at pumping stations are often susceptible to vibration related issues. Excessive piping vibration may result in leaks at connections and flanges, and fatigue failures can occur, leading to leaks that present safety and environmental concerns.

The energy responsible for pipeline vibration is usually provided by rotating or reciprocating pumping equipment, and is transmitted to the piping either by direct mechanical contact, pressure pulsations, or turbulence in the pumped fluid. Vibration problems usually occur when a mechanical natural frequency of the piping system, an acoustic natural frequency of the contained fluid, or both, is excited by the driving force.

In this paper, a brief overview of vibration issues that occur in pipeline facilities is presented. Next, a selection of case studies is provided to illustrate some of the types of vibration induced failures that have been observed at pipeline facilities, and how they were addressed and resolved. These examples provide some insight into how to potentially avoid such issues, or if they occur, how to identify and mitigate them.
Risk-Based Inspection Optimization for Valve Inspections
Authors: Vibien Patrick M. , Joyal David A. , Oliphant Ken E. , Luff William
Published: November 2018

Many different inspections are conducted on gas transmission and gas distribution pipelines — valve inspections, cathodic protection system inspections, in-line inspection, odorant monitoring, etc. — demanding significant resources and operational expenditures from pipeline operators. Risk-based optimization relating to these kinds of operational activities has been applied in analogous industries. The result has been measurable savings consistently ranging at a level between 20–40%. Significantly, this explicitly means that 20–40% of many operational activities have been proven not to bring a benefit. In the pipeline industry, however, there has not been a basis to determine which activities bring no value in terms of risk reduction. In this paper, a detailed example is provided for risk-based optimization of valve inspections and the savings are found to be within these expectations. These savings can be taken in either a risk reduction benefit or completely in cost savings. Through development of a valve failure risk model (which independently considers loss of function and loss of containment failures) and an inspection cost model, a set of the optimum risk-cost combinations is developed and can be presented as an optimized inspection curve. Using the curve to establish inspection frequencies is demonstrated, including the impact on operating expenditures. As demonstrated via the presented case studies, the general framework is suitable for optimization of any gas pipeline inspection or maintenance activity.
Developing a Full Risk Picture for Gas Pipeline Consequences
Authors: Oliphant Ken E. , Joyal David A. , Meidanshahi Vida
Published: November 2018

Properly characterizing the consequences of pipeline incidents is a critical component of assessing pipeline risk. Previous research has shown that these consequences follow a Pareto type distribution for gas distribution, gas transmission and hazardous liquid pipelines where low probability – high consequence (LPHC) events dominate the risk picture. This behavior is driven by a combination of deterministic (e.g. pipe diameter, pressure, location factors, etc.) and random factors (e.g. receptor density at specific time of release, variable environmental factors at time of release, etc.). This paper examines how the Pareto type behavior of the consequences of pipeline incidents arises and demonstrates how this behavior can be modeled through the use of a quantitative pipeline risk model. The result is a more complete picture of pipeline risk, including insight into LPHC events. Use of the modelling approach for integrity management is discussed.
Optimization of Hydrate Management in Deepwater Gas Well Testing Operations
Authors: Song Shangfei , Shi Bohui , Yu Weichao , Li Wang , Gong Jing
Published: November 2018

Low temperature and high pressure conditions in deep water wells and sub-sea pipelines favour the formation of gas clathrate hydrates which is very undesirable during oil and gas industries operation. The management of hydrate formation and plugging risk is essential for the flow assurance in the oil and gas production. This study aims to show how the hydrate management in the deepwater gas well testing operations in the South China Sea can be optimized. As a result of the low temperature and the high pressure in the vertical 3860 meter-tubing, hydrate would form in the tubing during well testing operations. To prevent the formation or plugging of hydrate, three hydrate management strategies are investigated including thermodynamic inhibitor injection, hydrate slurry flow technology and thermodynamic inhibitor integrated with kinetic hydrate inhibitor. The first method, injecting considerable amount of thermodynamic inhibitor (Mono Ethylene Glycol, MEG) is also the most commonly used method to prevent hydrate formation. Thermodynamic hydrate inhibitor tracking is utilized to obtain the distribution of MEG along the pipeline. Optimal dosage of MEG is calculated through further analysis. The second method, hydrate slurry flow technology is applied to the gas well. Low dosage hydrate inhibitor of antiagglomerate is added into the flow system to prevent the aggregation of hydrate particles after hydrate formation. Pressure Drop Ratio (PDR) is defined to denote the hydrate blockage risk margin. The third method is a recently proposed hydrate risk management strategy which prevents the hydrate formation by addition of Poly-N-VinylCaprolactam (PVCap) as a kinetic hydrate inhibitor (KHI). The delayed effect of PVCap on the hydrate formation induction time ensures that hydrates do not form in the pipe. This method is effective in reducing the injection amount of inhibitor. The problems of the three hydrate management strategies which should be paid attention to in industrial application are analyzed. This work promotes the understanding of hydrate management strategy and provides guidance for hydrate management optimization in oil and gas industry.
The Effect of Material Strain Hardening on the Determination of CTOD R-Curves Using SENB Specimens
Authors: Moore Philippa L. , Khor Wee Liam
Published: November 2018

In ductile materials the fracture toughness is usually characterised by a tearing resistance curve, or R-curve, plotting the fracture toughness in terms of J or CTOD against crack extension. Recent research has evaluated the methods to determine CTOD in engineering alloys with a wide range of yield to tensile (Y/T) ratios for single point CTOD. This work develops the investigation into R-curves, and reviews the assumptions about SENB specimens deforming under rigid rotation, the evaluation of CTOD from J for R-curves, and the nature of tearing initiation in low Y/T ratio stainless steel, from comparisons against a series of silicone replicas cast from the SENB specimen notch during fracture toughness tests.

For CTOD R-curves, the methods based on CTOD from J in ISO 12135 and ASTM E1820 gave lower and less accurate R-curves than the rigid rotation methods in BS 7448-4 and WES 1108. However, the accuracy of the BS 7448-4 formula varied for the different strain hardening materials, and overestimated the R-curves in the low tensile ratio stainless steel.

Investigations into the effect of the assumption about rigid rotation in different strain hardening materials led to a rotational factor function of tensile ratio, rp sh, to be developed from numerical modelling. When this function was substituted into standard equations in place of the fixed value of rp an improvement in the accuracy of BS 7448-4 R-curves compared to replica measurements was seen for the range of strain hardening investigated, but it did not significantly improve the accuracy of the WES 1108 formula, which accounts for strain hardening in other parameters.

A combination of the elastic CTOD part of the WES 1108 formula, with the plastic CTOD incorporating the modified rotational factor, was concluded to offer the optimum method to determine CTOD R-curves for a range of strain hardening materials.
Quality Assurance for Quenched and Tempered Pipeline Fittings: A Regulator’s Perspective and Plan of Action
Authors: van Schalkwyk Negar , Wang Hong , Colquhoun Iain , Paviglianiti Joe
Published: November 2018

Heat treated pipeline fittings (principally elbows, tees, and reducers) require careful process control. For example, furnace temperature, placement of the fittings in the furnace, transfer time to quenching tank, adequacy of quench or tempering time can all impact the fittings’ mechanical properties if not done properly.

In recent years, the National Energy Board (NEB) became aware of instances of quenched and tempered (Q&T) pipe and fittings having mechanical properties that did not meet Canadian Standards Association (CSA) or similar standards, being installed on pipeline systems under NEB and other regulatory bodies’ jurisdiction. In 2013, a pipeline rupture occurred on an NEB-regulated pipeline. Although failure to meet mechanical specifications was not the cause of the incident, the investigations revealed that there were fittings installed on the pipeline with yield strength of less than Specified Minimum Yield Strength (SMYS). The NEB undertook further investigations to determine if this low yield issue might indicate a systemic problem. In the cases examined, contrary to the recorded information in the Material Test Reports (MTRs), not all fittings met the specified mechanical properties requirements, and this was due to inadequate controls in the Quality Assurance Programs (QAPs) of different stakeholders. It is also important to note that MTR results based on a coupon test may not always reflect the properties of each fitting produced following that process.

The NEB has taken several actions in order to address this potential issue including:

- Issuing industry-wide Safety Advisories

- Issuing Orders to all companies under its jurisdiction

- Commissioning a third party to investigate and write a technical paper on this issue

- Hosting a technical workshop to facilitate broad dialogue between various stakeholders (using the technical paper as a seed document)

In this paper, the authors first review the manufacturing process of Q&T fittings. Then case studies are discussed involving four instances of nonconforming fittings. Lastly the authors propose solutions for different stakeholders to effect improvement in Quality Assurance (QA) of pipeline fittings. The authors also recommended enhancement of applicable clauses in related standards and initiation of several research and development (R&D) projects.
Industry Best Practices for Hot Tap Branch Connections
Authors: Bruce William A. , Etheridge Brad , Gould Melissa , Boring Matt , Fleck Patrick
Published: November 2018

When faced with an opportunity to install a branch connection using the “hot tapping” technique, pipeline operating companies have a wide variety of choices when it comes to branch connection design and installation practices (e.g., welding procedure options) depending on the application. The objective of a recently-completed joint industry project (JIP) was to develop industry best practices for hot tap branch connections, including a compendium of properly qualified procedures, guidance pertaining to specification of branch connection design for specific applications, and guidance pertaining to related areas of concern for which there was not widespread agreement.

The core group of welding procedures that was developed and qualified for branch groove welds and sleeve fillet welds all involve the use of shielded metal arc welding (SMAW) and conventional low-hydrogen electrodes. There are applications for which other welding processes and consumables have advantages, so procedures for a broader range of applications were also developed and qualified. All of the procedures were qualified in accordance with the requirements of a range of relevant industry codes, including the Twenty-first Edition of API Standard 1104.

The various options for branch connection design include integrally-reinforced fittings (e.g., Weldolets®), fabricated branch connections, and full-encirclement pressurized tees (e.g., Stopple® fittings). Some designs are better suited to some applications than to others. The guidance for specifying branch connection designs focused on geometric parameters, such as branch diameter, header diameter, and branch-to-header diameter ratio. Several antiquated branch connection designs that should no longer be used were also identified.

The related areas of concern for which guidance was developed included the need for sleeve end fillet welds, burnthrough prediction for in-service welding on thin-wall pipelines, pressure limits/pressure reduction requirements, flow rate limits, heat-affected zone (HAZ) hardness limits, welder qualification requirements, branch connection location and fit-up, pipeline support requirements, branch connection welding sequence, preheating for in-service welds, fillet weld size requirements, extent of welding required for integrally-reinforced fittings, inspection/non-destructive testing (NDT) requirements, delay time prior to inspection for hydrogen cracking, pressure testing prior to tapping, and grouting of larger diameter, larger diameter-ratio branch connections. This guidance, along with the branch connection design guidance, was used to develop a generic company specification for installing hot tap branch connections in the field. The use of this guidance and the compendium of properly qualified welding procedures that was developed during the JIP will reduce the cost of installing hot tap branch connections, increase safety during installation, and increase the reliability of completed connections.