bluuebunny/crossref_metadata_2025 huggingface dataset:
An Improved Analytical Strain Analysis Method for Buried Steel Pipelines Subjected to Abrupt Permanent Ground Displacement
Authors: Liu Xiaoben , Zhang Hong , Xia Mengying , Liu Jianping , Zheng Qian
Published: January 2021

Abrupt permanent ground displacement is a typical loading condition for pipelines crossing geotechnical hazard areas. An improved analytical method for calculating longitudinal strain of buried pipeline under tension combined with bending load induced by permanent ground displacement (PGD) was proposed, in which, the pipe steel was considered as a bilinear material and the soil constraint on pipe was considered as a series of elastic-plastic nonlinear soil springs. Effects of elastic deformation of axial soil springs on pipe strain was derived accurately. Effects of axial force in pipe on pipe’s bending deformation was considered directly in the governing equation of pipe. Equilibrium between the section stresses in the large deformed pipe sections near fault trace and the section force and moment at the same position derived by the beam theory was used to obtain the nonlinear stress distributions in the pipe section and furtherly to obtain the equivalent modulus describing the locally decreased pipe stiffness. This method makes it possible to accurately derive the pipe longitudinal strain considering the effects of pipe material nonlinearity induced locally decreased pipe stiffness in large bending deformed pipe segments. A three dimensional nonlinear finite element model was also established by general software package ABAQUS to serve as a benchmark to validate the accuracy of proposed analytical method. Shell and pipe elements were employed to simulate pipes in large deformation and small deformation regions respectively. Distributed nonlinear soil spring elements were employed to simulate nonlinear soil constraints on pipe. Various loading conditions were performed to compare the efficiency and accuracy of the proposed analytical method comparing with the FE method. Results show the proposed analytical method can predict accurate longitudinal strain results even large plastic deformation appears in pipe. And comparing with FE method, analytical method has advantages in calculating efficiency, which is more suitable for application in engineering practice.
Distribution Reliability Using Machine Learning
Authors: Skow Jason , McPherson Rob , Shoenroth Kent
Published: January 2021

This paper describes the reliability assessment of a distribution pipeline network in the city of Regina, Saskatchewan. The results of the assessment help prioritize integrity program activities by complementing existing programs based on leak surveys, ground movement events, and excavation damage.
Assessing Potential Impacts to Waterways From Small Volume Releases Originating From Facilities or Equipment
Authors: Fontenault Jeremy , Franey Tara , Horn Matt
Published: January 2021

The pipeline industry strives for continuous improvement and reaching zero incidents. The risks associated with below grade pipelines are typically assessed in detail as part of operators’ pipeline integrity management program. However, the level of risk associated with above grade facilities and equipment is often not investigated to the same level. As part of an effort, with an anonymous pipeline operator, to refine the calculated risks associated with these facilities and valve sites, a focus was made on enhancing the consequence calculations with more accurate site-specific information. An approach was developed to assess whether smaller volume releases from these locations may impact nearby waterways following a release.

The operator identified 150 sites throughout North America where releases had the potential to contaminate a waterbody. In order to confirm/disprove this potential impact to water, hypothetical releases of multiple hydrocarbon products were simulated using oil spill modeling tools to assess the potential overland and downstream transport and fates of the released products. Hypothetical release scenarios were simulated until all of the modeled oil had been released and had either adhered to the land surface, filled a depression in the land surface, and/or evaporated to the atmosphere; or when oil was predicted to enter a perennial waterbody (stream or lake). The goal was to assess the potential for each release to reach a waterbody. A single release was simulated for each site based on a historical maximum volume for a release associated with the specific equipment type (e.g. valves) that could be released over a 24-hour period. Releases were simulated using conditions selected to produce reasonable, conservative results to maximize the potential for the largest volume of oil to enter a waterbody. These conditions were based on the spring season, where rivers and streams would be under some of the highest flow conditions, intermittent streams and waterbodies would contain water feeding larger water bodies, cool air temperatures would reduce evaporative losses, and no snow cover maximize overland transport.

This screening level analysis allowed for identification of each location’s potential to reach a nearby waterbody under the conservative set of conditions and assumptions. By eliminating sites where oil would not reach a waterbody, the operator was able to focus efforts on the highest consequence areas in order to complete more detailed field-level analysis. In regard to spill modeling, more detailed analyses could be conducted in the future to predict the range of possible outcomes from other types of releases and using more site-specific and season-specific data. As an example, slower releases/leak rates, enhanced evaporative losses, a range of environmental conditions, and/or losses to infiltration could be assessed to bound the range of potential impacts.
Design and Construction Challenges of a Roped Insulated Pipeline
Authors: Prasad Neetu , King Graeme , Najeeb Arfeen
Published: January 2021

Thermally insulated hot buried pipelines pose a unique set of challenges. This paper discusses those challenges and how they were met during design and construction of the 150 km long Husky LLB Direct Pipeline, the longest thermally insulated oil pipeline in Canada.

Thermal insulation materials are soft and can be easily damaged during construction and backfilling, and by large restraining forces at bends when the pipeline is operating at high temperatures. The large temperature difference between pipeline installation temperature and maximum operating temperature leads to large axial compressive forces that can cause movement at bends, crush insulation, increase temperatures at ground surface, cause loss of restraint, and in the worst case, lead to upheaval buckling and loss of containment. Special design and construction features to deal with these challenges, including insulation specifications, insulation of pipe bends, pipeline pre-straining, long radius bends, deeper burial, and pipeline roping, were therefore necessary.

After pipe has been insulated with polyurethane foam it cannot be bent in standard field bending machines used for uninsulated pipes because the foam is too soft. The induction bends and cold bends that are shop insulated after bending are expensive. The Project minimized the number of these expensive insulated bends by using an engineered ditch bottom profile. This meant that shop bends were only needed to reduce excavation depth at sharp changes in ground surface elevation where the roped profile required excessive grading.

Care was therefore necessary in the selection and development of specifications for the insulation system and shop fabricated bends, and to design and construct a ditch profile to minimize forces on the insulation and control upheaval buckling. Close co-ordination with vendors and the construction contractor was crucial for a successful and timely completion.
Comparison Between Yield Strength Results Obtained From Methods Using Both Flattened and Non-Flattened Specimens
Authors: Nayyar Pratham , Dimopoulos Dimitris , Walsh William
Published: January 2021

Tensile properties of API 5L large diameter pipes are typically determined with the use of full thickness flattened strap samples extracted in the transverse direction with respect to the longitudinal pipe axis (TPA) [1, 2, 3, 4]. It has been well established that the process of sample flattening has a significant influence on determination of the yield strength of the pipe [5, 6]. The flattening process is sensitive to a number of variables such as method of flattening, equipment used, number/sequence of strokes, and operators conducting the flattening. As a result, issues with repeatability are frequently encountered and despite several efforts, the industry lacks any type of official standard for universal use.

Historically, the industry has been focused on ensuring that the actual strength of pipes was safely higher than the specified minimum. Recently, there has been interest to also establish an upper limit on pipe strength particularly in the longitudinal direction with respect to the pipe axis (LPA) in order to avoid under matching between pipe and girth weld properties. These new requirements create the need for enhanced process control to minimize the variation due to flattening.

Samples obtained from longitudinally welded (SAWL) and helically welded (SAWH) seam Grade X70M line pipe of various nominal wall thickness to diameter (t/D) ratios were flattened using different procedures, measured for curvature, and tensile tested, all in controlled laboratory environments with minimized repeatability variation. Special attention was given to the definition and measurement of different types of curvatures observed through the range of different t/D ratios and effort was made to assess criteria for curvature measurement prior to testing. Additionally, non-flattened specimens were tensile tested using round bar and full ring expansion test methods, and a comparison between the results obtained from both flattened and non-flattened specimen methods was made.

The sample transverse yield strength results confirmed the expected variation between samples flattened by different methods. In addition, a much greater variation was observed when comparing the yield strength results between flattened and non-flattened samples. Considerations of extending the use of non-flattened specimens as a production test and benefits or limitations associated with such practice are discussed.
A Hybrid Method Based on SVM Integrated Improved PSO Algorithm for Electrical Energy Consumption Forecasting of Crude Oil Pipeline
Authors: Xu Lei , Hou Lei , Zhu Zhenyu , Li Yu , Lei Ting
Published: January 2021

Electrical energy consumption forecasting of crude oil pipelines plays a critical role in energy consumption target setting, batch scheduling, and unit commitment. For actual crude oil pipelines, because of its uncertainty, nonlinearity, intermittency, fluctuations and complexity, it is challenging to establish the electrical energy consumption forecasting model. And it is difficult to describe the non-linear characteristics of electrical energy consumption forecasting by traditional methods. Therefore, a novel hybrid electrical energy consumption forecasting system based on the combination of support vector machine (SVM) and improved particle swarm optimization (IPSO) is proposed, which includes four parts: data pre-processing part, optimization part, forecasting part, and evaluation part. In the pre-processing stage, in order to avoid large deviation caused by sampling stochasticity of small samples, the training set and the test set are divided by stratified sampling method. During the modeling process, the non-linear relationship in electrical energy consumption forecasting is efficiently represented by support vector machine, and the parameters of support vector machine regression are optimized by the improved particle swarm optimization algorithm. According to the established IPSO-SVM model, evaluation part is conducted to make a comprehensive evaluation for this framework. By comparing the evaluation indicators of IPSO-SVM with that of eight state-of-the-art forecasting methods, the effectiveness of IPSO-SVM method is evaluated. Based on the operation data of four crude oil pipelines in China, the results show that the proposed IPSO-SVM hybrid model has the best forecasting performance than other benchmark models, and its forecasting results are the closest to the actual data. It is concluded that the proposed approach can be an efficient technique for electrical energy consumption forecasting of crude oil pipelines.
Pipe Sleeve Repair Analysis of Axial Surface Cracks to Improve Remaining Life
Authors: Thorwald Greg , Kolovich Carolyn
Published: January 2021

The industry widely uses steel repair sleeves to repair defects in pipelines. This paper focuses on the types of repairs used for crack-like defects where there may be concerns of crack propagation in service from operating pressure cycles. The length of the repair sleeve, the pressure at the time of the repair, and the fillet welds of a Type B sleeve can all effect the future integrity of the repair.

Type B sleeves (fillet weld connecting the sleeve to the pipe) are widely used in the pipeline industry to repair crack-like flaws. Current standards require a minimum of two inches of sleeve material past the edge of a defect. A case study is presented to show if this length is adequate under various operating conditions to ensure the defect does not propagate in service to extend beyond the fillet welds. A pipe with a surface crack and the sleeve repair are modeled using finite element analysis to compute the crack front stress intensity. Contact interaction between the pipe’s outside surface and the sleeve’s inside surface provides the load path from the pipe to the sleeve. The contact interaction is varied from frictionless to fully bonded to vary the amount of crack opening permitted by the sleeve. The stress intensity is compared for each case to quantify the effect of the sleeve repair on reducing the hoop stress and reducing the crack’s stress intensity.

Operators often take a pressure reduction during an in-service repair both for safety reasons and to assist with obtaining a tight fit-up between the carrier pipe and the steel sleeve. An additional benefit of a pressure reduction can be gained in relation to in-service crack growth. A case study is presented that shows how a pressure reduction can extend the fatigue life of a resident defect. Comparing the crack front stress intensity shows the effect on the crack of the pressure reduction when the sleeve is applied. Fatigue crack propagation analysis of several cases shows how the pressure reduction effects the crack growth rates. The analysis method can be used to examine trade-offs between the amount of pressure reduction on fatigue life versus operational requirements.
On-Water Liquid Leak Detection Technology Evaluation
Authors: Apps Chris , Derakhshesh Marzie , Salmatanis Nikolaos , Greaney Carrie
Published: January 2021

The pipeline industry is directing their efforts toward reducing the environmental impact of their operations, improving pipeline performance, preventing and minimizing releases, and addressing evolving regulatory requirements. One key type of technology that helps with these efforts is related to detecting the presence of liquid hydrocarbons on the surface of water, either inside facilities or when crossing waterbodies. C-FER Technologies (1999) Inc. (“C-FER”), under contract to Pipeline Research Council International (PRCI) and in partnership with various pipeline operators, has completed a comprehensive research project to help operators assess the performance of various external leak detection technologies when identifying the presence of liquid hydrocarbon products on the surface of water in a controlled lab environment. Some of these results are presented in this paper.
Improved Semi-Quantitative Reliability-Based Method for Assessment of Pipeline Dents With Stress Risers
Authors: Virk Amandeep Singh , Langer Doug , Woo Janine , Yoosef-Ghodsi Nader , Kainat Muntaseer
Published: January 2021

Dents, especially those interacting with stress risers, can pose integrity threats to pipeline systems. Regulations in Canada and the United States mandate the repair of dents based on depth and interaction with stress risers, however, there have been cases in the past where dents that have passed these criteria have ended up in loss of containment. Recent industry’s recommendations regarding dent integrity analysis are predominantly based on strain, and the dent-fatigue models have been proven to be limited in their application. Additionally, these models or methodologies are generally deterministic which may not fully account for uncertainties associated with pipe properties and in-line inspection (ILI) tool measurement.

Enbridge Liquid Pipelines Inc. had previously presented a framework to support system wide dent assessment with an efficient probabilistic-based calibrated semi-quantitative analysis method for dents (SQuAD), which elicits potentially injurious features from thousands of features within a system in a reasonable analysis timeframe. This paper expands on the authors’ previous work and presents several improvements that have since been made to the SQuAD model to address the limitations in the initial version of the model.

The previous version of SQuAD was strain-based and did not explicitly account for pressure-cycling induced, fatigue-based failure quantitatively. An approximate circle fitting method was adopted for estimating the dent’s radii of curvature in order to calculate strains. In the improved model, filtering techniques have been employed to reduce the noise in the ILI-reported data while preserving the dent shape. Furthermore, a simplified FEA process has been developed to calculate the stresses within a dent due to pressure cycles, thus the fatigue-based Probability of Failure (PoF) of a dent can now be estimated using S-N approach. The filtered data allows for better accuracy in quantifying the radius of curvature of dents as reported by ILI tools, which are used for calculating dent strain as recommended in the updated version of ASME B31.8, Appendix R. Finally, the feasibility of applying this improved SQuAD model is discussed from an operator’s perspective.

The improvements allow the enhanced SQuAD model to be used as an effective screening tool on a system-wide basis as part of a comprehensive, reliability-based dent assessment framework.
High-Pressure Natural Gas Pipeline in Geohazard Region of Papua New Guinea Sustains Mw7.5 Earthquake: Key Factors of Successful Outcome
Authors: Albrecht Robert , Calame John , Cook Mike , Falcon Ignacio , Lee Patrick
Published: January 2021

ExxonMobil PNG Limited (EMPNG) operates the Papua New Guinea Liquefied Natural Gas Project (PNG LNG), an integrated LNG project comprising wellpads, gathering lines, gas conditioning plant, onshore and offshore export pipelines, liquefaction plant and marine terminal in Papua New Guinea (PNG). The PNG LNG project is a joint venture with participation by ExxonMobil, Oil Search Limited (OSL), Kumul Petroleum, Santos, JX Nippon Oil and Gas Exploration and Mineral Resources Development Company, and began production in 2014. The highlands of PNG presents a challenging physical environment, with high rainfall, steep terrain, active tectonics and seismicity, and ongoing landsliding and erosion. The PNG LNG onshore gas and condensate pipelines confront these physical challenges by having to traverse approximately 150 km of steep volcanic, mudstone and Karstic highlands along the Papuan Fold and Thrust Belt, the modern leading edge of active mountain-building, plus an additional 150 km in Karstic lowlands. During design, construction and operations of the pipelines, ExxonMobil has addressed these challenges in partnership with the engineering, construction and specialist consulting communities.

On February 25th, 2018 (UTC) a Magnitude 7.5 earthquake struck the PNG highlands. The event, along with its approximately 300 aftershocks, caused widespread community impact, landsliding and damage to over 1000s of km2, and was centered directly under the highlands portion of the PNG LNG pipelines. The pipelines however, did not lose containment or pressure, and, following inspections and repairs to the PNG LNG gas conditioning plant, PNG LNG production was restored within seven weeks of the main shock.

This technical paper and companion oral presentation discuss the key factors of this successful outcome, in particular the sustained condition of the gas and condensate pipelines. Contributing factors to the pipeline’s success include route selection, pipe material specification, early commitment to field studies, careful assessment of geohazards, high awareness of off-ROW community impacts, micro-routing during construction, and active geohazard management during startup and operations. The paper demonstrates that, with respect for the host community, thoughtful engineering, careful construction and ongoing surveillance, pipelines can be safely and successfully designed, constructed and operated in remote and extreme geohazardous environments.
Electromagnetic Induction Post Heating to Reduce NDE Delay Times of Welding In-Service Repairs
Authors: Hagel Liam , Prescott Jonathan , Kohandehghan Alireza , Guest Stuart , Lepine Sean
Published: January 2021

When a pipeline requires a repair, a pressure-containing steel sleeve or an emergency repair fitting is often fillet welded to the in-service pipe to return the pipeline to normal service conditions. During welding, the flowing product rapidly quenches the fillet weld, promoting the formation of high hardness and low ductility microstructures in the heat-affected zone. The rapid cooling rates also limit the mobility of diffusible hydrogen introduced from the welding electrodes. The hydrogen can be trapped in the weld metal and heat-affected zone and concentrated in specific locations throughout the weld based on the welding deposition sequence. Fillet welds also contain inherent locations of geometric stress concentration at the weld toes and root locations. The elevated hydrogen concentration in the in-service weld, combined with the geometrical stress concentrations at the location of crack-susceptible microstructures, can increase the likelihood of forming a hydrogen-induced crack. Delayed non-destructive examination (NDE) is often employed to wait a sufficient time for any cracks to form so they can be detected.

To reduce hydrogen concentration at the locations of stress concentration and NDE delay times, post-heating can be applied to the in-service weld. Elevating the temperature within the weld can enable hydrogen diffusion and reducing the cracking propensity. The rapid heat removal due to flowing product requires post-heating techniques with high energy outputs that will not overheat the steel surfaces. Electromagnetic induced current (induction heating) methods can produce sufficient thermal energy in the electrically conductive steel pipe and sleeve. Coupled numerical finite element analysis (FEA) models were utilized to simulate various induction cable arrangements and thermal convection coefficients, representative of various pipeline products. The analysis of the induction heating arrangements for the studied thermal convection coefficient was conducted to achieve a minimum temperature of 120 °C in the fillet weld root and toes to enable sufficient thermal driving force for hydrogen diffusion while ensuring the pipe and sleeve surface temperature does not exceed 200 °C. An optimal induction heating procedure was found to which could achieve the target temperatures within a reasonable heating time such that NDE delay times of in-service welds can be reduced by 5–6 times.
Stress Corrosion Cracking “Like-in-Kind” Reliability Approach for Pipelines Without Crack Tool In-Line Inspection
Authors: Elsisi Amal , Lee Winston Y. W. , Tomar Pushpendra , Williams Dan
Published: January 2021

Gas transmission pipeline operators increasingly rely on Electro-Magnetic Acoustic Transducer (EMAT) technology to reliably detect, identify and size stress corrosion cracking (SCC) anomalies in their pipeline system. However, scheduling EMAT in-line inspection (ILI) on every pipeline in the system is not always practicable or achievable in an expeditious manner. A means of conducting a preliminary assessment of the SCC threat on pipelines without EMAT ILI data in an objective and quantifiable manner is useful for understanding the threat level and for prioritizing or deciding on outstanding EMAT inspections. A wealth of system-specific SCC field data from historical integrity excavations across the pipeline system typically exists in a pipeline operator’s dataset and can be readily leveraged for quantitatively estimating the SCC threat reliability in other, similar (“like-in-kind”) parts of the pipeline system. This system-specific data, based on actual SCC findings from integrity excavations, is an improved and more granular alternative to applying industry-wide SCC statistics to estimates of SCC reliability levels on pipelines without EMAT ILI data.

This paper presents a robust and direct limit state approach for estimating the SCC reliability level in pipelines that have not yet had an EMAT ILI completed by leveraging system-wide SCC field findings from historical integrity excavations.
Separation Characteristics of an X65 Linepipe Steel From Laboratory-Scale to Full-Scale Fracture Tests
Authors: Davis Bradley J. , Michal Guillaume , Lu Cheng , Linton Valerie
Published: January 2021

Separations are small fissures that form along the rolling-plane of some steels when sufficient stresses are created to open planes of weakness in the material. In the pipeline industry, separations have been observed on the fracture surfaces of tensile, Charpy, and drop-weight tear tests — the key tests for determining the fracture arrest capabilities of line pipe steels. When compared, the separation appearance between lab-scale tests and full-scale fracture test are noticeably dissimilar. Therefore, the influence separations have on the fracture behaviour may not clearly scale between lab-scale and full-scale tests.

In this study, the separation severity of Charpy, DWTT, and full-fracture propagation test fracture surfaces was measured and compared. Two full-scale burst tests were carried out with pipes containing a CO2/N2 mixture. Fracture surfaces were observed along the length of the pipe and captured when the separation appearance changed. For each pipe section, the corresponding lab-scale test surfaces were compared.

With the separations measured across all fracture faces, the separation appearance of the full-scale test surfaces did not provide the same values as the lab-scale tests. However, the lab-scale tests did capture the trend in separation severity for each pipe section. Only the lab-scale test surfaces showed a correlation in separation severity.
Stress Analysis of Buried Pipelines Under Thaw Settlement of Permafrost Zone Based on Moisture-Heat-Stress Coupled Analysis
Authors: Jiang Jinxu , Zhang Hong , Liu Jianping , Chen Pengchao , Liu Xiaoben
Published: January 2021

Permafrost thawing caused by the hot crude pipeline is a major threat to the safe operation of buried pipelines in permafrost zone. In this paper, the process of thawing and consolidation of frozen soil is considered, and a three-dimensional (3D) finite element model of buried pipelines in permafrost zone is established using ABAQUS. The calculation of thaw settlement displacement of frozen soil based on moisture-heat-stress coupled was carried out, and the deformation and stress of buried pipelines were analyzed. The effects of ground temperature, oil temperature, thermal conductivity of insulation material and soil distribution along the pipeline on the vertical displacement and longitudinal stress of buried pipelines in frozen soil were studied. Research results show that in thaw-unstable soil, the vertical displacement and stress of the pipeline increase significantly with the increase of the average ground temperature, and change on ground temperature amplitude has a little effect on the vertical displacement and longitudinal stress of the pipeline in thaw settlement zone. It is 1/3 of the vertical displacement of the pipeline without a heat insulating layer. When the thermal conductivity of the insulation material is less than 0.4 W/m °C, the vertical displacement of the pipeline in the thawing zone can be further reduced by reducing the thermal conductivity of the insulation material. When clay and sand appear alternately along the pipeline, the vertical displacement and longitudinal stress of the pipeline can be reduced by reducing the length of clay section. This study has certain reference value for optimizing the design parameters of buried pipelines in permafrost zone and reducing the impact of differential thaw settlement of frozen soils on the safe operation of pipelines.
Integration of Multiple ILI Technologies for Robust Understanding of Unique Anomalies on a Pipeline
Authors: Shie Taylor , Lutz Andrew , Taverna Paul
Published: January 2021

Pipeline operators have many choices when selecting inline inspection (ILI) vendors and technologies. No single technology has a one hundred percent probability of detection, identification, and sizing for all anomaly types. Operators must match the threats on their system to the existing capabilities of the ILI technologies to achieve the goals defined by the company’s integrity management program. It is sometimes necessary to run multiple technologies to effectively assess all threats in a pipeline. Multiple technologies may be run during the same timeframe or they may be run at different times during the life of the pipeline to meet program goals.

Shell Pipeline Company, LP (SPLC) has a pipeline that is comprised of low frequency electric resistance welded (LFERW) pipe from Youngstown Sheet and Tube, seamless pipe from National Tube, double submerged arc welded (DSAW) pipe from Kaiser, and high frequency electric resistance welded (HF-ERW) pipe. The LF-ERW pipe was installed in 1948 while the HF-ERW was installed during relatively recent replacement projects. The DSAW pipe was installed in 1952 with the seamless pipe being installed in both 1948 and 1952.

From 2015 through 2018, SPLC executed an extensive integrity management program. This included: an axial magnetic flux leakage (AMFL) inspection, two circumferential magnetic flux leakage (CMFL) inspections, two deformation inspections, an electro-magnetic acoustic transducer (EMAT) inspection, an ultrasonic crack detection (UTCD) inspection, an ultrasonic wall measurement (UTWM) inspection, and a hydrotest. A dig campaign of nearly 100 excavations was completed as a result of these surveys. One of the focuses of the paper will be the comparison of EMAT to UTCD for Likely Cracks, Possible Cracks and Unlikely Cracks that have been field verified.

This paper also shares some of the unique anomalies found through the dig campaign identifying the effectiveness of each technology and their combination for integrity purposes. The paper shows the benefits of combining ILI technologies to properly characterize, assess and mitigate reported anomalies and ensure there are no blind spots in the integrity management program. Case studies including dent with gouge (e.g. AMFL + Deformation), manufacturing, and cracking anomalies as well as the analytics of ILI versus field findings are presented and discussed in the paper. The paper concludes with the knowledge creation resulting from multiple ILI technology integration assisted with subject matter expert experience and analytics to provide a robust understanding of unique anomalies in pipelines.
Study on Intelligent Controller Design of Flow Metrological Calibration System
Authors: Yin Xiong , Wen Kai , Wu Yan , Zhou Lei , Gong Jing
Published: January 2021

In recent years, China ramped up imports of natural gas to satisfy the growing demand, which has increased the number of trade meters. Natural gas flowmeters need to be calibrated regularly at calibration stations to ensure their accuracy. Nowadays, the flow metrological calibration process is done by the operator manually in China, which is easy to be affected by personnel experience and proficiency. China is vigorously developing industry 4.0 and AI(artificial intelligence) technologies. In order to improve the calibration efficiency, a design scheme of intelligent controller for flow metrological calibration system is first proposed in this paper.

The intelligent controller can replace the operator for process switching and flow adjustment. First, the controller selects the standard flowmeter according to the type of the calibrated flowmeter, and switches the calibration process. To accurately control the calibration flow for 180 seconds, the controller continuously adjusts the regulating valve with a sequence of commands to the actuator. These commands are generated by intelligent algorithm which is predefined in the controller. Process switching is operated automatically according to flowmeter calibration specifications. In order to reach the required flow point quickly, the flow adjustment is divided into two steps: preliminary adjustment and precise adjustment. For preliminary adjustment, a BP neural network will be built first using the field historical data and simulation results. This neural network describes the relationship between the valve-opening scheme and the calibration flow. Therefore, it could give a calibration flow as close as possible to the expected value during calibration. For precise adjustment, an adaptive PID controller is used. It could adjust the valve opening degree automatically to make sure the flow deviation meet the calibration requirements. Since the PID controller is a self-adaptive PID controller, the process of adjustment is very quick, which can reduce the calibration time largely. After each calibration, both the original neural network and the adaptive function of the controller will be updated to achieve the self-growth.

With the information of the calibrated flowmeter, the entire calibration system can run automatically. The experiment in a calibration station shows that the intelligent controller can control the deviation of the flow value within 5% during 4∼5 minutes.
Kalman Filter and Model-Free Adaptive Control Theory Applied to the Unsteady Flow State Estimation of Product Pipelines
Authors: He Lei , Wen Kai , Gong Jing
Published: January 2021

The accurate online estimation of unsteady flow state provides important operation information for product pipelines real-time scheduling. In practice, affected by the parameter drift and observation noises, traditional estimation methods based on the first principle can hardly provide accurate results within acceptable time. The nonlinear and fast transient characteristics of pipeline flow make it difficult to realize on-line adaptive modification of model parameters. In order to meet the requirements of computational efficiency and accuracy simultaneously, this paper proposes a methodology with two-level adaptive adjustment to realize the digital twin of pipeline nonlinear transient flow process by using simplified linear flow model. In terms of improving computing efficiency, the linear flow model based on frequency response and difference transforming is established to process the on-line state estimation of transient flow. To reduce the deviation between the actual observed value and the linear model estimation, we first introduce mode-free adaptive control method as linear compensation of the reduced order unsteady flow model. The compact form dynamic linearization method has been adopted to design the virtual input of the linear flow model. To further improve the adaptability of the linear model, the model parameters are online adjusted by using the recursive least squares with forgetting factor method. The uncertainty of the model and the interference of observation noise is eliminated by adopting Kalman filter to the state space model based on modified linear model. The effectiveness of the proposed methodology is evaluated by applying to the digital twin process of a product pipeline transient pressure in a multistation pipeline. The results show that the proposed method can make transient pressure estimation of second-order linear model agree well with the value of nonlinear flow model even under unforeseen conditions and noise interference. The performance of the proposed method is better than model-based linear method, data-driven linear method and nonlinear method.
Investigation and Adoption of APGA’s Pipeline Engineer Competency System: The Canadian Experience
Authors: Hill Darren , Ireland Yvanna , Yaremko Jim , Harvey Chris , Sahney Reena
Published: January 2021

With the recognition of demographic change and impacts on the workforce, there is an increased focus on competency management within the pipeline industry. The Canadian Energy Pipeline Association (CEPA) is a voluntary, non-profit industry association representing major Canadian transmission pipeline companies that has been particularly active in this area. With recent publication of CEPA’s guidance document on competency management, CEPA member companies identified a need for a companion set of competency standards for technical staff. As such, the Pipeline Integrity Community of Practice (CoP) within CEPA formed a task group to identify and better understand potential solutions to address this need.

The challenge in maturing competency management within the Canadian pipeline industry, as identified by the task group, is two fold:

1. First, the competency system needs to be flexible to address a broad range of topics, operation types as well as a progression of proficiencies (e.g., engineers in training through to senior level subject matter experts).

2. Second, there is a need for a system that is practical and can be developed / adopted in a relatively short time frame.

In undertaking an assessment of the options available in industry, the adoption of the system that has been developed by the Australian Pipeline and Gas Association (APGA) was selected as the optimal path forward.

The APGA Pipeline Engineer Competency System (APGA PECS) provides a mechanism for understanding competency as well as a means of assessing and documenting competency for pipeline engineers. Specifically, industry expert panels were used to develop the competency standards which were then published for broad consultation prior to finalizing. Within Australia, the system is now the responsibility of the APGA’s Pipeline Engineering Competency System (PECS) Committee for ongoing development, review and maintenance to ensure the system remains current and fit for purpose. One of the key characteristics of the APGA competency standards is the consistency of elements and a standard format for requirements in every stream of pipeline engineering. Further, the APGA System has been demonstrated to be practical and sustainable through use within Australia.

The APGA System is now being customized for use in the Canadian Pipeline industry under an agreement announced in October 2019. This paper will provide insights into key aspects of competency system, the approach taken to assess viable options as well as the experience of customizing the APGA system for Canadian use. The system is anticipated to be available for Canadian companies in 2020 and provides a pathway to meeting the two main challenges identified for managing competency in the Canadian industry.
Continuing Development of Metal-Loss Severity Criteria, Including Width Effects
Authors: Leis Brian N.
Published: January 2021

The emergence in the early 1970s of what about a decade later became the first release of ASME B31G began the development and evolution of criteria to assess the severity of metal-loss defects. Motivated by the desire to reduce the conservatism embedded in B31G, the late 1980s saw the release of Modified B31G, with that same report also introducing RSTRENG, which quantified “riverbottom” effects. The desire to avoid excessive conservatism in their application to higher-strength Grades gave rise to alternative criteria for such applications. PCORRC appeared in 1997, with early versions of DNV RP-F101 and British Gas’ LPC-1 criteria following shortly thereafter. It has since become evident for isolated smooth-bottomed features that in addition to feature length and depth, its width can be a factor, as can its planar shape, and through-thickness profile.

This paper builds on insight gained from the prior work, presenting and validating a Level 1 failure criteria for isolated metal-loss features. The defect-free term for this Level 1 criterion relies on the Zhu-Leis criterion for defect-free pipe failure. That criterion is coupled to a recalibrated defect term analogous to PCORRC, whose extension to include the effects of width is considered. The resulting Level 1 criterion is validated in reference to full-scale tests of pipe with metal-loss, which include a mix of real corrosion and flat-bottomed machined features. These tests consider Grades from Gr B to X100, a wide range of diameters and thicknesses, and in many cases the effect of width. Finite element results are used to illustrate the role of width. Benchmarked against almost 80 full-scale tests it is shown that this new approach affects a reduction in conservatism. At the same time, it provides clear benefits in regard to reduced predictive scatter, as well as a reduction in required maintenance, and the scope of features that must be considered in field-digs.
Pull Test Study of the MFL-A Performance Within Casings to Improve ILI-Based Corrosion Management of Cased Pipes
Authors: Lu Dongliang , Klementis Jennifer , Kariyawasam Shahani , Huang Terry , Sager Ryan
Published: January 2021

High resolution magnetic flux leakage (MFL) in-line inspection (ILI) technology has proven to be one of the most effective approaches to manage corrosion anomalies within the pipeline industry. However, due to the presence of extra metal, pipeline casings are suspected of impacting the detection and sizing accuracy of MFL systems for metal loss features when they are located under casings.

A research project was carried out by TC Energy (TCE) with ROSEN to better understand the effect of pipeline casings on the performance of axially-aligned MFL ILI (MFL-A) technology. The study involved full-scale pull through testing to investigate the effects of various casing conditions and the presence of different types of casing spacers on the inspection system’s sizing and detection performance for corrosion anomalies, including the casing eccentricity, the presence of metallic and electrolytic shorting, and the presence of different types of casing spacers. The testing for various eccentricity and shorting scenarios were compared to an uncased baseline scenario.

An important lesson learned by the project team through this research is the importance of identifying key factors that influence the system performance when analyzing the testing results. Failure in doing so can lead to less meaningful results: in this case, an overly conservative estimate of the sizing performance that does not discriminate appropriately where the system performed well and where the system performed worse than expected. The impact of such a broad-brushing and overly conservative estimate in the MFL system performance to pipeline integrity decisions is very significant and can result in a large number of unnecessary repairs in practice.

With comprehensive data analytics, it was identified that the key factors affecting the tool performance for cased pipes are the small annulus gaps between the casing and the carrier pipe at the feature location, and the presence of certain types of spacers. For the vast majority of cases, the ILI performance under casings is comparable to the performance for uncased pipes. The results from this research suggests that with appropriate consideration of the system performance, TCE’s probabilistic ILI based corrosion management program can effectively manage corrosion anomalies within cased pipes using ILI. Additional research and testing are underway to further support this conclusion.
A Novel Approach for Two-Stage UAV Path Planning in Pipeline Network Inspection
Authors: Qiu Rui , Liang Yongtu
Published: January 2021

Currently, unmanned aerial vehicle (UAV) provides the possibility of comprehensive coverage and multi-dimensional visualization of pipeline monitoring. Encouraged by industry policy, research on UAV path planning in pipeline network inspection has emerged. The difficulties of this issue lie in strict operational requirements, variable flight missions, as well as unified optimization for UAV deployment and real-time path planning. Meanwhile, the intricate structure and large scale of the pipeline network further complicate this issue. At present, there is still room to improve the practicality and applicability of the mathematical model and solution strategy. Aiming at this problem, this paper proposes a novel two-stage optimization approach for UAV path planning in pipeline network inspection. The first stage is conventional pre-flight planning, where the requirement for optimality is higher than calculation time. Therefore, a mixed integer linear programming (MILP) model is established and solved by the commercial solver to obtain the optimal UAV number, take-off location and detailed flight path. The second stage is re-planning during the flight, taking into account frequent pipeline accidents (e.g. leaks and cracks). In this stage, the flight path must be timely rescheduled to identify specific hazardous locations. Thus, the requirement for calculation time is higher than optimality and the genetic algorithm is used for solution to satisfy the timeliness of decision-making. Finally, the proposed method is applied to the UAV inspection of a branched oil and gas transmission pipeline network with 36 nodes and the results are analyzed in detail in terms of computational performance. In the first stage, compared to manpower inspection, the total cost and time of UAV inspection is decreased by 54% and 56% respectively. In the second stage, it takes less than 1 minute to obtain a suboptimal solution, verifying the applicability and superiority of the method.