bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Risk and Reliability in Designing Facility Site Containment
Authors: Ballard Geoff , Ferdous Refaul , Payoe Anthony , Kulhawy Amanda
Published: January 2021

Enbridge is North America’s premier energy infrastructure company delivering the energy people need and want. Enbridge’s business value is asset intensive. With over 200 onshore liquids pipelines facility assets, operational safety and environmental protection are always top priorities. The embedment of risk management practices in business decisions is an effective way to appropriately optimize asset performance while avoiding catastrophic impacts to people and the environment. This includes understanding and managing these risk events and establishing barriers to prevent the impact.

Facility site containment is an independent protection layer that mitigates the consequences of a spill. The United States Environmental Protection Agency and the National Fire Code of Canada provide requirements to contain overland flow of a spill from liquids pipelines facility assets. Although there are specific volumetric requirements for spill containment for facility tanks, there are no specific volumetric requirements for spill containment for pipeline facility assets such as pumps, valves, etc. Industry typically employs an index-based approach to determine the specific design volumes using catastrophic rupture volumes and facility location. This approach has several shortcomings, including design inadequacy, inconsistency, and challenges with scalability.

A risk-based approach is appropriate in determining the required site containment volume based on oil spill history, facility assets, and environmental sensitivities. A probabilistic model can be created using historical facility oil spill data based on the Pipeline and Hazardous Materials Safety Administration’s (PHMSA’s) facility incident database to estimate the likelihood of a given size of release occurring. If available, company oil spill history can also be used or integrated with the PHMSA dataset. Combining the likelihood of the size of release occurring with the estimated consequence (by accounting for the volume of a release and the environmental sensitivity at the release location), it is possible to evaluate the risk of a release. This estimation of risk can then be leveraged to support facility site containment design to manage the risk to an acceptable level.

By informing facility site containment with volumetric requirements using reliability and consequence models and risk management principles, an organization can prudently balance pipeline safety and capital constraints to comply with federal regulations. This paper demonstrates this approach and describes:

• The value of available data and model development

• Reliability modeling and consequence assessment

• Risk-informed decision-making

• Future model enhancements
A Bayesian Approach for Effective Use of Multiple Measurements of Crack Depths
Authors: Koduru Smitha D. , Nessim Maher , Bott Steven , Al-Amin Mohammad
Published: January 2021

A Bayesian methodology was applied to use data from multiple inline inspection (ILI) runs and field measurements with non-destructive examination (NDE) tools to increase confidence in crack size estimates. Multiple crack depth measurements were used in two different ways — namely, to improve the characterization of ILI sizing error bias and to update the maximum depth distribution of individual crack features. This methodology was applied to selected datasets from an industrywide database for crack ILI data collected over a series of Pipeline Research Council International (PRCI) projects. The results of the approach are presented for two datasets, showing reduced variance in sizing error bias and improved confidence in crack depth estimates. In addition to the PRCI datasets, an additional dataset was collected and used to investigate the effect of multiple ILI runs on estimates of rate of detection and depth distribution of undetected features. The results of this analysis are also summarized.
Effects of Profile Data Grid on Deformation Capacity of Line Pipes
Authors: Asano Kanako , Watanabe Hidetaka , Mori Takeshi , Suzuki Nobuhisa , Arakawa Takekazu
Published: January 2021

The effects of the profile data grid on the compression or bending capacity of line pipes are discussed in this paper. An X65 600 mm line pipe and an X80 1200 mm line pipe are used in the sensitivity study. The initial profiles of the 600 mm line pipe are used for finite element analyses with different data grid sizes from 600 mm to 25 mm squares. Those of the 1200 mm line pipe are considered by varying the data grid from 1200 mm to 50 mm squares. With decreasing grid size, the compression or bending capacity tends to decrease and become stable when the data grid becomes 1/3 of the pipe diameter. The compression capacity is as small as 90% of that without profile data. The bending capacity of the 600 mm pipe pressurized to 60% SMYS decreases to 35%, while bending capacity of the 1200 mm pipe is 46% of that without profile data at the same pressure.
An Improved Methodology for Prioritizing Pipelines With Respect to Fatigue Cracking of Seam Weld Flaws
Authors: Turnquist Michael , Al-Otaibi Nader A. , Teshin Nauman , Al-Rabeeah Mohammed A.
Published: January 2021

The threat of pressure cycle induced fatigue cracking of flaws associated with the longitudinal seam weld continues to be a primary concern for pipeline operators. Cyclic pressure loading can cause initial manufacturing flaws in a seam weld to sharpen and grow over time. While this behavior is most prevalent in pre-1979 electric resistance welds (ERW) and electric flash welds (EFW), historical data also shows that submerged arc welds (SAW) have been observed to develop cracks at the toe of the weld, and those cracks have exhibited fatigue growth from transit fatigue, operating pressure cycles, or both.

When managing a large pipeline network, it is important to understand which pipelines exhibit higher priority with respect to seam weld fatigue cracking. While there are industry-accepted methodologies used to prioritize pipelines with respect to seam weld integrity (TTO-5 [1] and API RP 1176 [2] being the most well-known), these methodologies can be improved upon when specifically considering fatigue.

Saudi Aramco and Quest Integrity developed a detailed methodology to determine a prioritization for a group of pipelines specifically with respect to seam weld fatigue cracking. This improved methodology was specially tailored to consider additional data available in Saudi Aramco’s records to rank the likelihood for a fatigue failure to occur. This initial prioritization will be used to implement a more rigorous program to manage their assets. Additional data gathered in subsequent assessments can be included to refine the prioritization.

The primary metrics used to determine the prioritization are pressure cycle aggressiveness, predicted remaining life with respect to recent hydrostatic testing, and the API 1176 Annex B prioritization classification.
Life Expectancy of Decommissioned Pipelines Under External Corrosion: Probabilistic Modeling
Authors: Wong Chee , Dann Markus R. , Wong Ron
Published: January 2021

The typical service lives of operational energy pipelines are up to 50–70 years. The existing lines would subsequently be decommissioned and replaced with new lines. As one approach to dealing with a decommissioned line is by leaving the line untouched in the ground, there exists uncertainty in the structural integrity of decommissioned lines under external corrosion over time. This paper introduces reliability-based integrity assessment of decommissioned pipelines that remain in the ground. Two limit state functions are developed to quantify (i) formation of perforations under pitting corrosion, and (ii) thinning of pipe wall thickness under uniform corrosion and initiation of pipe yielding under soil and traffic loading. Corrosion occurrence and growth are modeled as stochastic processes to account for its spatio-temporal uncertainty. The reliability and safe remaining lifetime of an entire pipeline sections are determined using enhanced Monto-Carlo simulations. A sensitivity analysis is performed to identify the governing factors of the life expectancy. The proposed integrity assessment is illustrated on an example.
The Coarse Particle Influence on the Strength of Wax Deposition
Authors: Zhang Xun , Huang Qiyu , Zhang Yu , Li Yaping , Liu Xin
Published: January 2021

Wax deposition has always been an essential issue for flow assurance, especially in subsea pipelines. The coarse particles, which are usually measured in millimeters, will be carried out by oil flow during the deep-water oil fields production. However, due to insufficient understanding of the structure of wax deposits and the complexity of sandy crude oil deposition, the interaction between coarse particles and wax deposits in the pipeline have rarely been investigated.

In this paper, the effect of coarse particles on the yield stress of wax deposits has been studied. The sample was mixed at reversible structure temperature so that the impact of shear history could be eliminated, and the rapid particle settlement at high temperature could be avoided. Experimental results have found that there is a critical fraction in coarse particle influences, below which a small number of coarse particles added will lead to a slight increase in bulk yield stress. On the contrary, a dramatic decrease in yield stress when exceeding the critical mass fraction and increasingly marked enhancement of yield stress as the fraction increases.

This phenomenon has been explicated microscopically by the structural interaction between coarse particles and wax deposits. The interlock between wax crystals is the major contribution of the structure as the less particle fraction contains. Even though the silica sand is a typical non-colloidal particle, the asphaltene and resin could be absorbed on the surface of particles and forming a cluster of colloidal particles. As the fraction of particles slightly increased, the slip between colloidal particles and wax crystal interlock accelerates structural failure. Nevertheless, more particles involved the overall yield stress may depend on the friction and the adhesive force between solid particles. The subtle changes induced by coarse particles would have a harder deposit, which can hinder pig passing and affect pipeline pigging operations.
Crack Initiation and Propagation in Static Loaded Fracture Mechanics Tests in Steels Containing Atomic Hydrogen
Authors: Moore Philippa L. , Hoekstra Menno , Pargeter Alex
Published: January 2021

Hydrogen is well known to have a detrimental influence on the ductility of low alloy steels, reducing the fracture toughness. Standard test methods to characterize fracture toughness of steels in terms of ductile tearing resistance curves have not been developed to account for any hydrogen-driven contribution to the crack extension, Δa. Simply plotting J or CTOD against Δa is not necessarily appropriate for defining the initiation fracture toughness for tests performed in a hydrogen-charging environment. This paper explores a method to further analyse experimental data collected during fracture toughness tests, which allows the contribution of plasticity (i.e. when blunting precedes ductile tearing) to be considered separately from the initiation of crack extension (which could be by stable tearing and/or by hydrogen-driven crack extension). The principle is based on the assumption that a crack growing by a hydrogen-driven mechanism in a quasi-static fracture mechanics test performed in environment may not be associated with significant ductility in the plastic zone (which would accompany crack growth by stable tearing). The analytical method presented in this paper compares the different points of deviation from linear behavior of the components of J, to isolate the effects of ductility within the plastic zone from pure crack extension. In this way, the point of crack initiation can be defined in order to determine the relevant initiation fracture toughness; whether by blunting and stable tearing, or by hydrogen-driven crack growth. This approach offers a screening method which is illustrated using examples of fracture mechanics specimens tested in environments of varying severity (air, seawater with cathodic protection, and sour service). This method can be used to identify the relevant definition of initiation fracture toughness while allowing for a combination of ductile tearing, hydrogen-driven crack extension, or both, to be present during the test.
How Do I Ensure “Staff Competency” in My Pipeline Safety Management System?
Authors: Collins Karen , Unger Michelle , Dainis Amanda
Published: January 2021

Standards and regulations are clear: all staff who work on pipelines need to be both “competent” and “qualified.” Standards such as API 1173 are clear about competence within a safety management system: “The pipeline operator shall ensure that personnel whose responsibilities fall within the scope of the PSMS [Pipeline Safety Management System] have an appropriate level of competence in terms of education, training, knowledge, and experience.” The burden of defining and specifying competence falls on pipeline operators, but they have little guidance regarding the required skills, knowledge and levels of competency. Additionally, we are all biased — different operators will have different ideas and emphases on competencies, which will affect their decision-making. The only way to avoid these cognitive biases is to use consensus standards supported by rigorous surveys that capture the required competencies.

This paper explores some of the more common biases that can affect decisions and presents the results of a controlled, independent, survey aimed at both specifying and quantifying the necessary competencies needed by a specific engineer working within a PSMS: a pipeline integrity engineer. The paper identifies and ranks these necessary competences.

The survey was completed by 100 pipeline integrity engineers from 25 different countries. Its specific objective was to investigate the key skills and knowledge requirements needed in a junior engineering position (i.e., a pipeline engineer with less than three years of relevant experience) working under supervision to be ‘competent’. It listed eight core competencies (identified by subject matter experts) considered essential for a pipeline integrity engineer. Each of these core competencies contained a set of skills. Respondents were first asked to rank the eight core competences, and then rank the skills within the competency.

An analysis of the data provides insights into how 100 pipeline integrity engineers view the key skills required to be “competent.”

The results of the survey can assist pipeline companies in setting objective competency requirements for their engineering personnel, developing learning programs to address any gaps, and improve the overall safety of their pipeline system.
Manufactured Cracks in Pipe Used to Evaluate ILI Measurement Performance
Authors: Skow Jason , Krynicki Joseph W. , Peng Lujian
Published: January 2021

Recently, transmission pipeline operators have started designing pipe spools with manufactured cracks of very precise size and orientation for the purpose of qualifying measurement technologies. The manufactured cracks are very similar to naturally occurring cracks and can be made to have varied profiles and off-planar shapes (like hook cracks). The manufactured spools are installed on a transmission pipeline at either the pipe launcher, the receiver or in-line such that an in-line inpsection (ILI) tool passes through it during a transmission pipeline ILI field run. This produces highly valuable data to evaluate measurement performance because the crack sizes are precisely known, crack morphologies are similar to realistic cracks and the ILI tool is tested in field conditions. This paper describes the effect on the estimated ILI tool measurement performance for various combinations of manufactured cracks in a pipe spool. The cases described vary the number of manufactured cracks in the spool to estimate the value of each additional crack and vary the distribution of cracks sizes to compare the value of large versus small cracks.
Cross-Sectional Grain Size Homogeneity Effect on Structural Steel Fatigue Performance in Air and Hydrogen Environments
Authors: Stalheim Douglas , Slifka Andrew , Uranga Pello , Kang Dong-Hoon , Lucon Enrico
Published: January 2021

Structural steel mechanical properties of strength and ductility for a given microstructure are predominately driven by the average ferrite grain/packet size and by the through-thickness homogeneity of the ferrite grain/packet size in the final product. Fatigue performance, a ductility property, in air for applications of wind towers, bridges or high-rise buildings along within environments of high-pressure gaseous hydrogen for various pipeline systems is critical to the end-use design. Fracture and fatigue testing of a commercially produced low carbon 20 mm thick API X60 Sour Service steel had been completed which showed good and stable performance when compared to other commercially produced pipeline and structural steel microstructures. This commercially produced API steel was reported as “Alloy D” in prior published work. The microstructure was predominately polygonal ferrite with industrial quality of steel cleanliness, minimum of microstructural banding and a small but relatively homogenous through-thickness grain size required for a successful API X60 Sour Service specification/application. Based on the initial fatigue performance reported for the “Alloy D” through-thickness microstructure a more comprehensive study on the effect of the through-thickness grain size/homogeneity on fatigue was initiated. To isolate and study this effect of the, laboratory developed samples of a low carbon API X60 Sour Service steel with the same alloy design as “Alloy D”, which is characterized by a predominately single-phase polygonal ferrite microstructure with excellent cleanliness and no microstructural banding. Two sets of steels were made with the only difference being variations in average through-thickness and homogeneity of the final ferrite grain size.
Pipeline Geohazards Screening: Using Results of Flood Scour Assessments to Provide a Simple Screening Tool for Pipeline Watercourse Crossings for Western Canada
Authors: Ryherd Julia , Small Colleen , Guthrie Richard , Ling Song , Beaugrand Hawley
Published: January 2021

Pipeline watercourse crossing assessments typically require field investigations, river surveys, and detailed scour analyses to predict whether or not a pipeline may be subject to flood scour deeper than their depth of cover (DOC). Flood scour algorithms rely on discharge, median grain size, and some measure of channel cross-sectional area to determine the tractive force of water on the stream bed. These algorithms are applied to non-cohesive sediments typical of fluvial systems. To better define pipeline threats at a screening level, reducing unnecessary field and analytical expenses, and focusing effort on credible hazards, we developed a flood scour screening tool that uses return period discharge (Q) as the only input requirement. In order to develop the tool, we plotted the results of over 400 detailed scour assessments for several grain sizes (1100 data points) completed in Alberta and British Columbia, in 2017, 2018 and 2019. The results clearly show the importance of channel variability and grain size, but also show definable discharge related trends. We compared the results of the National Engineering Handbook (NEH) and the United States Bureau of Reclamation (USBR) methods, both of which use industry accepted algorithms. We developed, and provided herein, relationships that can be used to screen out scour assessments at watercourse crossings where DOC is already known, or to support and expedite field programs where DOC is being obtained. If only Q is known, then a single graph, or single equation is used for a given region using fine sand as the assumed median grain size. If both Q and median grain size are known, then the user can determine a slightly less conservative result from a series of complementary equations. In all cases, we propose using the mean result of the USBR method, originally intended for design, to fully capture the potential variability in the calculated NEH flood scour. While conservative, the tool is easy to use, and we expect it will substantially reduce the assessment effort on smaller, or less erosive streams.
Pipe Knocked From Supports by Hydraulic Transient Event
Authors: Matta Lawrence M. , Manuel Jacob , Ramamoorthy Sathish
Published: January 2021

Following what was considered a routine realignment of liquid product lines and tankage at a storage and transfer facility, an incident occurred that resulted in significant movement of a 20-inch pipeline, causing a large section of it to fall from its supports. The event also resulted in the failure of a gasket at a valve flange and loss of containment.

The alignment activities and pump startup were investigated for the potential to generate a hydraulic transient capable of generating sufficient force to cause the movement. A transient hydraulic model of the fluid in the piping as it was aligned at the time of the event was generated to assist in determining the cause and to help prevent a similar occurrence in the future. Several scenarios were modeled and are discussed in this paper: 1) pump shutdown from steady flow, 2) pump start up with the discharge valve open, 3) pump startup with the discharge valve closed, and 4) pump start up with a vapor cavity present near a closed valve at the high point in the line.

Pipe stress and finite element analysis were used to assess the displaced pipe and to determine if it could be placed back into service. The piping stress analysis indicated that the highest stress in the piping was below the yield stress of the material. Results from a detailed finite element analysis with material nonlinearity confirmed that there was no global plastic strain in the piping due to the event. This left a potential for local plastic strain due to the impact of the pipe against any hard surfaces, and this was addressed with visual examination. In the end, the pipe was lifted back onto the supports, lateral restraints were added at pipe support locations, and procedural changes were implemented to reduce the likelihood of future events.
Puddling Puddle Welds
Authors: Burden Dane , Roniger Nic , Romney Matt
Published: January 2021

Unique characteristics of individual pipelines come from over a century of evolving design, construction, maintenance, regulation and operation. These characteristics are especially true for legacy, pre-regulated pipelines. Due to the unique nature of the threats present on these assets, there is a need for unique inspection technologies and techniques that can increase pipeline integrity. Reconditioned and repaired pipe utilizing puddle weld repairs is one such threat.

An advanced analysis was completed on a 10-inch, 68-mile light products pipeline. The pipeline was constructed with reconditioned pipe that was estimated to contain tens of thousands of puddle welds. Historical in-line inspection (ILI) data generally underperformed in classifying and discriminating puddle welds versus metal loss features.

The primary objective of this project was to assess the probability of identification (POI) of a multiple dataset ILI tool utilizing multiple magnetic flux leakage (MFL) magnetization directions and residual (RES) magnetization measurements. A secondary objective was to scrutinize data for signs of coincident features. Hydrostatic testing failures showed that puddle welds with porosity and cracking were susceptible to failure and that the identification of these features would be beneficial.

Analysis of historical puddle weld investigations and newly completed multiple dataset ILI data revealed strong identification capabilities in the RES dataset. The high-field magnetizations offered secondary confirmation but often saturated out thermal effects or material differences. The final report included over 40,000 identified puddle welds and five classifications for further investigation. Field investigations for 212 features were completed and the results compared to the ILI data to assess performance. A confusion matrix was created for true positive (TP), true negative (TN), false positive (FP) and false negative (FN) conditions. The smallest TP puddle weld dimension was 0.7″ × 0.7″, and the population had a statistical sensitivity value of 98% (132 TP and 3 FP).

Three additional anomalies denoted as atypical were also investigated. The ILI signatures at these locations were consistent with previous repairs in which puddle welds with cracking were found and repaired. Two of the three features investigated were found to have cracking. Crack propagation was found to be both axial and non-axial in orientation. The results show that puddle welds can be detected and identified with extremely high accuracy. In addition, the preliminary classification results for atypical puddle welds show a high potential for identifying secondary coincident features. This paper details the stages, deliverables and results from an ILI advanced analysis focused on puddle welds.
A Novel Approach to Risk Management of Belowground Natural Gas Migration From Leaks on Low-Pressure Pipelines
Authors: Maddin Kim , Lu Dongliang , Tomic Aleksandar
Published: January 2021

Small-diameter, low-pressure pipelines (operated at pressures below 40 percent of specified minimum yield strength [SMYS]) are unlikely to experience a rupture but may be vulnerable to leaks. In general, gas leaks result in less significant consequences to public safety than ruptures; however, under certain circumstances leaks may represent a significant threat. In particular, leaks resulting in belowground gas migration from low-pressure pipelines to a nearby confined space (e.g. the basement of a nearby structure to which the pipeline is not physically connected) may result in significant consequences as accumulation of gas to flammable or explosive levels may be possible. This paper explores the methods by which an Operator may address the threat of gas migration from leaks on low pressure pipelines in its risk assessment and leak management programs.

Research was conducted into the specific conditions that contribute to belowground gas migration and included: a literature review of studies into gas migration phenomena, and a review of historical incidents within the United States on similar pipeline systems which resulted in significant property damage, injuries, or fatalities. The research included consideration of the effect of pipeline operating conditions, pipeline attributes (including diameter and depth of cover), leak duration, proximity of nearby structures, attributes of nearby structures (including presence of basements, slabs, and openings in the foundations), leak severity (e.g. pinhole, full separation), ground conditions (including soil permeability and presence of belowground features), and gas odorization. Key conditions impacting the potential for belowground gas migration are identified, and risk assessment methods and leak management practices are recommended based on the likelihood of migration.

Based on the research conducted and the environmental conditions identified, a quantitative risk assessment approach, taking into account the likelihood of a leak on a low-pressure pipeline, the likelihood of belowground gas migration, and the potential consequences to public safety, is proposed.
Overcoming Challenges of EMAT Inline Inspection Validation for SCC Management in Natural Gas Pipelines: A Practical Approach
Authors: Phlipot Jake , Rapp Stephen , Whaley Daniel , Spencer Kevin , Williams Dan
Published: January 2021

Pipeline operators rely on a variety of tools and technologies to manage threats to their pipeline assets. For natural gas pipelines, the management of Stress Corrosion Cracking (SCC) has benefited from the introduction and evolution of in-line inspection (ILI) technologies, specifically Electro-Magnetic Acoustic Transducer (EMAT) technology, that can reliably detect, identify and size cracking anomalies.

Since its introduction in the early 2000’s, the performance of EMAT technology has been evaluated and documented through many industry research projects and published articles that describe operational experiences. This paper builds upon that body of shared knowledge to provide an update of observed EMAT performance on a gas transmission system that has undergone extensive EMAT ILI assessments, on a large number of pipeline segments, with a specific focus on the practical strategies employed to overcome the challenges unique to EMAT ILI validation. Practical insights into effectively using EMAT ILI validated data as a key input to the SCC management plan are thereby provided.
In-Service Cracking/Leak at Bottom-Side Repaired Dent
Authors: Quickel Gregory T. , Bratton Joseph , Bruce William A.
Published: January 2021

Pipeline operators are often faced with excavating deformations caused by bottom-side indenters (e.g., rock dents). These dents are typically constrained by the rock, but during excavation, after the rock is removed, the dent is no longer constrained. Many operators have felt that it is prudent to perform in-the-ditch (ITD) non-destructive examination (NDE) techniques, such as liquid penetrant testing (LPT) and magnetic particle inspection (MPI), to determine if external cracking is present so that an appropriate repair method can be selected. Unfortunately, these external surface NDE methods do not identify the presence of internal cracking. Recent research [1], along with metallurgical analyses of cracks at bottom-side dents, demonstrates that the fatigue behavior of constrained dents is different than that of unconstrained dents, and that identifying the correct crack mechanism can be difficult.

The paper discusses cracking mechanisms (e.g., stress corrosion cracking, fatigue, etc.) at bottom-side dents, ITD crack identification methods, differences between constrained and non-constrained dents, repair methods for dents, and presents a case study that uses NDE (MPI, unconventional LPT, and laser scanning) and destructive techniques (metallography, fractography, and hardness testing) to determine the metallurgical cause of a failure. The case study involves a pre-formed composite sleeve system that was used to repair dents in which correct installation procedures were followed but ultimately resulted in a delayed in-service failure.

In hindsight, if ITD NDE methods were chosen based on our current knowledge of recent research, the operator may have been aware of the presence of cracking and selected a different repair method, and therefore would have likely prevented an in-service failure. This paper provides a case study to help increase awareness regarding how to properly evaluate cracking in dents. Operators should ensure that their excavation and repair procedures are updated to reflect the most current industry knowledge to help prevent a similar failure.
Integrity Management of Flange Connections Using Reliability Model
Authors: Haider Syed , Sen Millan , Lawrence Doug , Rodayan Angela
Published: January 2021

There is demonstrated potential for failures to occur on station piping assets in facilities, therefore it is critical to take measures to manage preventable releases. In 2018, Enbridge developed a reliability model that uses available asset information to quantify the likelihood of failure of station piping assets. Enbridge based this model on the CFER PIRIMID software, with some modifications to minimize the use of default values and to meet the company’s integrity management program requirements. With successful implementation of station piping model, Enbridge realized opportunity to develop a much-needed flange model leveraging the station piping model.

Historical leak data indicates that flanged connections often experience a higher leak frequency than other assets in a facility. While there are industry guidelines that provide guidance for the assembly of process flange connections in a facility, there are few that discuss integrity management of flange connections once they are operational. Most published condition assessment flange models require inputs which are not readily available, e.g. condition of flange faces and gaskets. These inputs often require the flange to be disassembled just to obtain the data. For pipeline operators, data gathering is even more challenging as there are stations (with numerous flanges) that are spread out along the entire pipeline.

Given the high number of flange connections and their wide variation in parameters within transmission pipeline facilities, there is benefit in developing a reliability-based model to guide the integrity management of flange connections. A reliability model that works in two stages was developed for this purpose. The pre-inspection assessment stage was designed to utilize available inputs to prioritize groups of flanges for inspection, and the post-inspection assessment (second) stage is then applied to select the specific flanges that require maintenance action.

Enbridge utilized industry guidelines, relevant standards, historical failure data, and subject matter experts’ inputs to develop the station piping and flange models. This paper will discuss the design concepts, model architectures, the contributing factors, and their sensitivities to the likelihood of failure results. These concepts may be utilized by any operator managing such assets, and the model designs may be tailored to suit a wide range of facility environments.
The North Saskatchewan River Valley Landslide: Slope and Pipeline Condition Monitoring
Authors: Holliday Chris , Young Andy , Funk Terri , Murray Carrie
Published: January 2021

Following a loss of containment incident in July 2016 on a 16-inch diameter pipeline on the south slope of the North Saskatchewan River located in Saskatchewan, Canada, Husky completed extensive studies to understand and learn from the failure.

The cause of the incident was ground movement resulting from a landslide complex on the slope involving two deep-seated compound basal shear slides as well as a near surface translational slide in heavily over consolidated marine clays of the Upper Cretaceous Lea Park Formation. One aspect of the studies has been to undertake structural analysis of the pipeline response to the loading imposed from the ground movement to minimize the potential for a similar occurrence from happening in the future and determine the integrity of the pipeline at the time of the assessment.

Given the scale and complexity of the landslide, slope stabilization measures were not practical to implement, so repeat ILI using caliper and inertial measurement technology (IMU), in addition to a robust monitoring program was implemented. Realtime monitoring of ground movements, pipe strain and precipitation levels provided a monitoring and early-warning system combined with documented risk thresholds that identified when to proactively shut-in the pipeline.

The methodology and findings of the slope monitoring and structural analysis that was undertaken to examine the robustness of the pipeline to withstand future landslide movement are presented herein. The work involved modelling of the pipeline history on the slope including loads that had accumulated in the original pipeline sections based on historical ILI results and slope monitoring. The pipeline orientation was parallel with the ground movement in the landslide complex, so the development of axial strain in the pipeline was the dominant load component, which are particularly damaging in the compression zone. The work provided recommendations and technical basis to continue safe operation of the pipeline with consideration of continuing ground movement and assisted the operator with decisions over the long-term strategy for the pipeline.
A Method of Leakage Parameters Estimation for Liquid Pipelines Based on Conditional Generative Adversarial Network
Authors: Zheng Jianqin
Published: January 2021

At present, pipeline transportation is a very common mode in the long-distance transportation of liquid materials such as oil. Compared with other transportation ways, pipeline transportation is not only high-throughput and continuous, but it is also reliable and of low energy consumption. Although the probability of pipeline leakage is low, the result of leakage is catastrophic, including economic losses, personal safety, and environmental pollution. Once the liquid pipeline leakage occurs, risk assessment and emergency repair measures are urgent. The key to these is to determine the leakage parameters of the pipeline. However, many current leakage detection methods are based on physical mechanism and hydraulic calculations with assumptions, resulting in poor accuracy and a high false alarm rate. Therefore, from the perspective of data-driven, the relationship between leakage parameters and the operational flow rate and pressure is mined in this paper. First, due to the limited leakage accidents for one pipeline, a large amount of leakage data is generated through experimental simulation. For every second, the pressure and flow rate in upstream as well as downstream should be recorded, making it hard for common deep learning algorithms to cope with such a high-dimensional complex dataset. To overcome the dimensionality problem, a conditional generative adversarial network is then introduced to treat the dimensional data as labels when the leakage parameters model is trained. After training the leakage data, the leakage parameters can be estimated based on the detected data, when the leakage occurs. Finally, four examples of pipeline leakage are tested to demonstrate our superiority over two traditional algorithms, i.e. artificial neural network and support vector machine. Thus, this method has a potential prospect in the estimation of leakage parameters, and can effectively guide site management when the leakage occurs.
Research on Virtual Metering System of Offshore Oilfield Based on Multi-Level Electrical Submersible Pump
Authors: Bai Zonghan , Kang Qi , Wu Haihao , Gong Jing , Yao Haiyuan
Published: January 2021

In the production management of offshore oil field, the production of single well is very important for reservoir understanding and production allocation. Because of the high cost and short life of the conventional underwater flowmeter, the virtual metering technology has gradually become a trend. ESP (electric submersible pump) is a kind of mechanical equipment commonly used in artificial lift oil recovery method, and used in offshore oil field development and production. Based on the characteristics of ESP and real-time production data, this paper establishes the oil well flow inversion model and proposes a fast calculation method to meet the application requirements, which provides a new method for the acquisition of production information of offshore oil fields.
Communication and Mitigation Strategies Related to the Leading Indicator of Pressure Cycle Fatigue
Authors: Le Phat , Olson Scott , Shie Taylor
Published: January 2021

Pressure cycle fatigue has been shown in industry to be a contributing factor to pipeline failure. There are methods for pressure cycle fatigue monitoring that can be used as a leading indicator for the risk of the pipeline to fatigue related failure. Once lines with high cycling are identified, the risk of the cycling to the asset and the mitigation strategies for the cycling can be discussed within the organization. By mitigating the driving force of crack initiation and grow to failure in-service, the pipeline community is safer.

Shell Pipeline Company, LP. (SPLC) experienced two in-service failures on the same pipeline in under a year where fatigue was a common root cause. Following the investigation of these failures, management requested communication of the risk of pressure cycle fatigue throughout the organization with the intent to mitigate the levels of pressure cycling across the system. All pipelines were put on a monthly dashboard of pressure cycling and sent to all staff for awareness and action.

The company measures pressure cycling on all pipelines by normalizing the number of cycles to 25% of the specified minimum yield strength (SMYS). From January 2016 to December 2019, the number of monthly cycles on the top ten highest cycled segments were reduced from 45,000 cycles per month, to 18,970 cycles. This is a reduction of 58%. The number of Very Aggressively cycled pipelines was reduced from 2 to 0. The number of Aggressively cycled pipelines were reduced from 13 to as low as 3. This paper will share the strategies and methodologies used to achieve these results.

The paper will share how the list of highly cycled pipelines and the monthly status reports were developed. The paper will also share how pressure cycling mitigation strategies for pipeline systems were developed in collaboration with facility engineering, business unit leads, controllers, schedulers, and integrity staff. The effectiveness of mitigation methods such as pressure reduction, installation of back-pressure control valves, changing of valve timing on startup and shutdown, changes to the scheduling on the pipeline, utilization of flying switch between tankage, etc. will be discussed.

By reducing pressure cycling, the risk of fatigue related failures can be reduced. This program is continuously being improved because there is both management commitment and ownership of the issue throughout the organization.
Study on the Distribution of Submarine Pipeline Corrosion Defects Based on Internal Inspection Data and Data Mining Method
Authors: He Guoxi , Chen Sijia , Liao Kexi , Zhao Shuai
Published: January 2021

Submarine pipelines in the sea are applied for oil, gas, water and mixed transportation. Among them, 91% of the pipes contain CO2. Here, based on the existing pipeline internal inspection data of submarine pipeline, the APRIORI algorithm and least-square-support-vector-machine (LSSVM) are applied to analyze the distribution rules and defect characteristics of internal defects along the pipeline. The corrosion defects are divided into 7 types and the pipeline section is divided into 12 intervals. Also, the pipe segment has been defined as J (general pipe), W (weld) and C (close to weld). The contents include the analysis of the characteristics and types of defects, the distribution of defects along the pipe, the severity of the corrosion defects, the size characteristics of defects, and the comparison of the data detected in multiple rounds. The defect depth of four kinds of pipelines is mostly 10%–20% of the wall thickness, hereby the severity of defects is studied via the percentage distribution of corrosion depth. The data of multi-round inspection shows that the corrosions in the mixed pipeline are active and the defects are increasing. The methods and results in this paper can be employed to predict the most likely defect type, mileage location, clock orientation, and shape size of submarine pipeline corrosion. This is helpful for the integrity management of submarine pipelines.
Large Standoff Magnetometry As a Practical Screening and Monitoring Tool for Pipelines Subjected to Geohazards
Authors: Xu Tianzong (David)
Published: January 2021

Large standoff magnetometry (LSM) as a non-intrusive NDE technology has been used many years in commercial trials for above-ground detection of underground pipeline anomalies associated with stress concentration zones (SCZs). As a passive geo-magnetization flux leakage measurement method, it has been mainly targeting common anomalies such as corrosion, gouges/dents and cracks that are often very localized in small scale. Insufficient consistency and reliability are still the major concern due to technical challenges in getting high resolutions and signal strength at large standoff distance. In comparison, geohazard related external forces induce much large-scale elevated stresses/strains with stronger stress-magnetization signals. Lack of economically viable solutions for pipeline screening and monitoring under geohazard conditions provides a good opportunity to establish LSM’s market position.

This work is part of Pacific Gas and Electric Company’s effort in better fundamental understanding of the state-of-the-art LSM technology and its potential to enhance the current industrial practices of pipeline assessment under geohazard conditions. Specifically, 3D mapping of pipelines including depth of cover (DOC) measurement, locating girth welds and peak stresses/strains with risk rating, verification of strain relief operation and continuous monitoring afterwards. Inline inspection (ILI) and geotechnical analysis data together with field excavation and strain-gauge data are utilized as references to cross-check the LSM results. The outcomes indicate geohazard application is very likely a viable application for LSM technology in near future.
A Coupled Thermo-Hydro-Mechanical Model for Capturing Frost Heave Under Chilled Gas Pipelines
Authors: Na SeonHong , Malekzade Kebria Mahyar , Roy Kshama
Published: January 2021

This paper presents a thermo-hydro-mechanics theory and corresponding computational framework to capture the freezethaw action of frozen porous media and associated frost action under chilled gas pipelines. Based on the mixture theory, frost-susceptible soils are formulated to capture the Darcy flux and thermal actions below the pipelines. Constitutive models that combine the cryo-suction are presented to reproduce the changes in volume, strength, and thermal characteristics of solid grain, pore water, and ice crystal. A generalized hardening rule is adopted to replicate the elasto-plastic responses which strengthens the frozen porous media due to ice crystallization. Changes in permeability and thermal diffusivity are also incorporated by considering the phase transitions of pore water and ice crystal. Numerical examples for pipeline applications are designed to analyze the influence of the freezing and melting process around the pipelines.
Vehicle Load Distribution Under Timber Mats and Flexible Slab
Authors: Zand Benjamin B.
Published: January 2021

Pipeline operators commonly use means of temporary crossing such as timber-mat, airbridge, and slab to reduce surface loading induced stresses in a buried pipeline at locations where a heavy vehicle crosses the buried pipeline. When a temporary crossing has a continuous contact with soil, (e.g. timber mat, flexible slab) load distribution over the ground surface is not immediately known. Load distribution under a timber-mat or flexible slab is a function of the slab to soil stiffness ratio. The load distribution tends to become more uniform with increasing timber-mat or slab stiffness. In this work an analytical model using beam-on-elastic-foundation has been developed and Laplace transform has been utilized to find the solution and apply free-end boundary conditions. The analytical solution can be used for any arbitrary load distribution over a beam-on-elastic foundation. In this work the solution for a point load and a partially distributed uniform load were employed as these scenarios can accurately represent conventional vehicle foot-prints, while being computationally efficient. The analytical solutions are compared to finite element analysis to validate the model. This model can be used in conjunction with the Canadian Energy Pipeline Association (CEPA) surface loading calculator (or similar tools) to analyze pipeline encroachment problems when means of temporary crossing is installed. This model can help the operators determine dimensions and bending stiffness of timber-mat or flexible slab to assure a desirable load distribution will be achieved. The model can also be used for structural analysis of a timber-mat or flexible slab under vehicular load.