bluuebunny/crossref_metadata_2025 huggingface dataset:
Adapting Existing Quantitative Risk Assessment Tools for the Energy Transition
Authors: Horn Matthew , Franey Tara , Fontenault Jeremy
Published: December 2022

The energy transition from fossil fuels to renewable or cleaner energy sources is upon us. There is also a global focus on reducing atmospheric carbon dioxide emissions. Several major companies are placing an emphasis on solutions such as hydrogen and carbon capture and sequestration or reuse. While this will provide new business opportunities for the pipeline industry, there are inherent risks, especially as they are scaled up to meet societal demand. Therefore, there is a need to assess the potential for harm to people and the environment.

Hydrogen is a flammable gas with the potential for both fire and explosion. Carbon dioxide is an asphyxiant at high concentrations and can dissolve in water, having unintended environmental effects. Traditional oil dispersion models have been used by the oil and gas sector and pipeline industry for decades to investigate overland, downstream, and in water movement, behavior, and potential effects of hypothetical and real-world releases. Atmospheric dispersion models have been used to assess vapor transport, resulting potential impacts (e.g., asphyxiation and or toxic effects) to humans and the environment, and risk of fire and explosion.

Based upon our experience with the current regulatory environment, the scrutiny placed upon operators by regulators and intervenors (especially with other products such as oil), and the large amount of time required to plan, permit, construct, and operate pipelines, we believe these comprehensive and quantitative assessments will be at the forefront of decision making. The use and potential adaptation of these existing modeling tools will be crucial in assessing risk from transport, storage, and use to ensure safety of each project through all phases of its life cycle (e.g., prior to permitting, construction, operation, and decommissioning) during this energy transition.
Improvements to Strain Hardening Exponent and the Implications to Failure Pressure Predictions
Authors: Brady Emily , Kornuta Jeffrey , Anderson Joel , Steiner Adam , Veloo Peter
Published: December 2022

Federal rule changes governing natural gas pipeline operation and safety have driven operators in the United States to establish materials verification programs (MVP) for pipelines that lack reliable records. The ongoing MVP at the Pacific Gas and Electric Company (PG&E) developed an extensive database of laboratory (destructive) tensile testing on over 144 coupons from pipe samples to quantify, in addition to yield strength and ultimate tensile strength, strain hardening exponent (n). A material’s strain hardening exponent quantifies the stress-strain behavior in work hardening and is also used in fracture mechanics-based tools, such as CorLAS™, for assessing flaws in cylindrical bodies, such as pipelines.

There is limited strain hardening data for pipeline steels in available literature. This led to the development of a correlation utilizing the ratio of yield stress to ultimate tensile strength (R-ratio) as part of NG-18 research in the 1970s. The original publication for the CorLAS™ model, by Jaske and Beavers in 2002, used this correlation to propose a quadratic relationship between n and R-ratio; however, this relationship was based on a total of four data points each from a different grade of line pipe. As a result, the uncertainty of this empirical relationship is large.

A more robust relationship that would be applicable across multiple grades and vintages was sought. Using the PG&E’s materials verification database, this paper presents an improved relationship for strain hardening exponent based on 58 pipe features ranging from the 1930’s to the 2010’s and grades ranging from Grade A to X70. Several case studies highlighting the impact of this change on downstream failure pressure evaluations using CorLAS™ are provided. In some instances, the authors have found that using this new model for the strain hardening exponent in conjunction with CorLAS™ can result in differences of approximately 10% in the calculated failure pressure.
Assessing Soil Corrosivity for Buried Structural Steel: Field Study
Authors: Beauregard Yannick , Lehew Julie , Mah Andrea , Hansen Lexya , Neuner Matthew
Published: December 2022

The corrosion of steel structures in soils has been a topic of industrial research for many decades. Research has shown that the corrosivity of a soil is highly variable and a function of numerous interconnected parameters including soil resistivity, moisture content and pH. Despite the complexity of the soil environment, methods have been developed to evaluate soil corrosivity and guidelines for corrosion control during the design phase and lifetime of a steel structure. An opportunity exists to apply this understanding to optimize the corrosion protection and capital expenses for new projects. For example, the identification of regions of low corrosivity where coatings are not required could lead to cost savings without compromising the long-term integrity of the structure.

This paper presents work conducted to assess the applicability of three soil-corrosivity standards, AASHTO R27-01 [1], DIN 50929-3:2018 [2], ANSI/AWWA C105/A21.5 [3] for this purpose. A field study was conducted which involved collecting buried structural steel samples and soil samples from eight pipeline meter stations and one light industrial facility located across Alberta. The corrosion damage of the buried structural steel samples was assessed through visual examination and pit depth measurements. The soil corrosivity was determined with the three soil-corrosivity standards using soil properties (e.g., pH, resistivity, sulphide and chloride concentration) collected in the field and measured in the laboratory. The corrosion damage was compared to the soil corrosivity predictions to evaluate the standards.

The results demonstrate that these standards provide a conservative assessment of soil corrosivity, with a tendency to overpredict corrosivity at the locations studied. Practical and economic considerations for the application of these standards to decisions on the need to coat buried structures are discussed.
Experimental Investigation Into Bulk Performance of Three Different Style Inline Separators on Natural Gas at High Pressure, Different Liquid Loadings and Gas Flows
Authors: Botros Kamal K. , Chan Nic , Geerligs John , Leong Keith , Hickey Brendan , Gong Ivan
Published: December 2022

Inline vertical separators are commonly employed on natural gas transmission facilities (e.g., receipt stations) to primarily filter out liquid contaminants such as compressor oil, glycol, free water, etc. However, these contaminants have been found invariably in the piping system downstream of these separators, indicating the separators are not performing as required. The potential consequences of not removing such contaminants includes lower gas quality, impaired gas metering accuracy, corrosion and damage to equipment/instrumentation and adverse impact on industrial or residential end users. Historically, separators’ performance claims and guarantees in terms of efficiency of liquid removal are often of the order 98–99% of liquid droplet sizes ≥ 8μm. However, there is a lack of ability to verify these claims due to difficulties in quantifying liquid injection rates and droplet characteristics vs. liquid collected while in operation. Extensive testing was undertaken at TC Energy’s Gas Dynamic Test Facility in Didsbury, Canada on three different separators from different manufacturers, two are mesh vane type (MV-1 and MV-2), and the third is dual cyclonic type (DC). The tests were conducted in the range of 4–5 MPa and flow velocity in the range of 1.3–13 m/s in the DN150 inlet nozzle to the separator, i.e., at 10:1 turn down ratio. The injected liquid was industrial compressor oil, typically used in the gas transmission industry, and was injected at a loading in the range of 0. 06–1.8%. Four different spray nozzles were used to atomize the injected oil to a range of particle size distributions (PSD), characterized by median diameter size, D50, in the range of 50–90 μm. Test results revealed that the performance of these separators varied between 90–99.8% independent of liquid loading. The effective Souders-Brown K factor also varied between 0.15–0.27 m/s. Tests were also conducted following a batch of solid injection to determine the effects on liquid separation efficiency on MV-2 separator. It was found that the separation efficiency decreased by approximately 9% following a 7.075 kg batch of solid injection, likely due to the accumulation of solids in the vane-pack.
Case Study of Progressive Cleaning for Challenging Pipeline With High Debris and Low Flow Rate
Authors: Al-Muslim Husain , Al-Otaibi Senhat , Aldosary Ibrahim , Alqahtani Abdulrahman , Aljundi Taher , AlNasser Mohsen
Published: December 2022

A critical step in ensuring that a pipeline is fit and healthy for operations is continuous scraping “cleaning” and frequent scraping inspection. If scraping activities are not properly performed, pipeline integrity can be at risk. Running effective cleaning scrapers through pipelines will remove accumulated solid debris and leftover liquids as well as smoothen the pipe wall. This will reduce pipeline pressure, increase product flow as well as maintaining product specs. Moreover, it is a pre-requisite step before conducting in-line inspection as the different technologies either magnetic flux or ultrasonic have minimum cleanliness specifications for the sensors to perform properly and achieve a successful inspection. In typical cases, few cleaning runs with proper design. In typical cases, one or two cleaning runs are sufficient before the In-Line Inspection (ILI) to meet the requirements. However, in other cases, the cleaning may become more challenging and require careful designing and planning of “progressive cleaning”. In this paper, a specific case study will be discussed where the pipeline has not been cleaned since construction due to its low velocity, which has been improved recently to meet the minimum operating parameters requirements for cleaning and ILI scraping activities, associated with a long distance of over 200 km. This led to the expected accumulation of debris left over from construction phase as well as the potential for additional debris from operations. At the beginning, operating parameters simulation was performed to ensure that the required parameters for the scraping activities was achieved. Consequently, the progressive cleaning starts with evaluation foam tool followed by non-aggressive cleaning (without brushes and magnets) then gradually to more aggressive with brushes and magnets. A gate-stage criteria was developed to move between the phases that included review of the scraper data during the run, condition of the received tool, amount of debris received and encountered operational challenges. The scraper tool design was selected based on rigorous review between the operator and the vendor to account for the expected challenged. For example, the tool was equipped with brush discs and high-resistance guide discs to compensate for the expected wear and use of a unidirectional design after confirming the safe passage of the entire pipelines by a Bi-Di cleaning scraper. Moreover, the tool was equipped with a tracking mechanism with enough signal strength considering the amount of debris, and maximum possible battery life considering run duration and anticipated challenges. The overall progressive cleaning plan, the different tool designs, and the results of each cleaning phase will be described in the paper.
Preparation and Performance Evaluation of Erosion Resistant Lining of Bimetallic Composite Pipe
Authors: Dong Jianwei , Wang Deguo , Guo Yanbao
Published: December 2022

Erosion widely exists in oil and gas production and transmission pipelines, which seriously affects the service life of pipelines. Ordinary carbon steel pipe can meet the strength and pressure of oil and gas transportation, but it has the disadvantages of poor erosion resistance, short service life and frequent replacement. The cost of using erosion resistant metal pipe is high, which is not suitable for comprehensive popularization and application. Bimetallic composite pipe includes outer layer and inner layer. It is formed by two different metals through a variety of processing technologies, which has the advantage that a single material does not have. It not only has the strength and toughness of the outer pipe, but also has the erosion resistance of the inner pipe. The service life of bimetallic composite pipeline can be 4–6 times longer than that of traditional carbon steel pipeline, and the manufacturing cost is relatively low, the service time is long, and it has good economy. Therefore, it is more and more widely used in oil and gas production and transportation. However, the common problem of bimetallic composite pipe is that the bonding interface between outer pipe and inner layer is not fully bonded and there has gaps. Or the interface binding force is not enough. When the composite pipe is eroded by the fluid in the pipe, the stress concentration at the interface will lead to the separation of the inner layer and the outer pipe, leading to the reduction of the service life of the pipe. Therefore, how to prepare the bimetallic composite pipe with good quality and strong erosion resistance has become an urgent problem to be solved. In this paper, carbon steel cemented carbide bimetallic composite pipe was prepared by electromagnetic heating through the application of centrifugal force and molten metal fluidity. The joint surface of the prepared bimetallic composite pipe was observed and analyzed, and the erosion test of the inner layer was carried out. The micro morphology of the erosion sample was observed and analyzed by shape analysis laser microscope. The erosion rate was accurately calculated according to the mass loss of the sample before and after erosion. The results show that the bimetallic composite pipe prepared by the above method has good interface bonding quality and no obvious defects. In the same erosion environment, the bimetallic composite pipe has stronger erosion resistance, lower erosion rate and higher service life than carbon steel pipe. Therefore, through the exploration of the preparation method of bimetallic composite pipe, this paper improves the preparation process of bimetallic composite pipe, improves the comprehensive mechanical properties and erosion resistance of bimetallic composite pipe, and promotes the application of bimetallic composite pipe in industrial production.
Progress of Assessment Model Development for Determining Remaining Strength of Corroded Pipelines
Authors: Zhu Xian-Kui , Wiersma Bruce
Published: December 2022

A technical review is presented of corrosion assessment models for determining the remaining strength of pipelines containing metal loss or corrosion defects. Initially, burst pressure prediction models for defect-free pipes, including strength and flow theory determined burst solutions and their experimental validations were considered. Next more accurate burst pressure predictions that cover a wide range of pipeline grades were discussed by comparing thick wall burst solutions and machine learning models with full-scale burst data that cover a wide range of pipeline grades up to X120.

Corrosion assessment models were categorized into three generations with respect to the reference stress. The 1st, 2nd, and 3rd generation models correspond to the flow stress, UTS, and both UTS and strain hardening rate. Seventeen corrosion models were evaluated and compared with full-scale burst data for a wide range of pipeline steels from low to high grades. The focus was on validating two recently developed 3rd-generation models that can determine more accurate burst strength for corroded thin-wall pipes. As the 4th-generation models, three typical thick-wall corrosion assessment models and machine learning models were introduced to predict more accurate results for corroded thick-wall pipes.

After that, advances in corrosion model development were discussed, including constraint effect, bulging factor and defect width effect. Finally, major technical challenges in development of corrosion assessment models were discussed with regard to full-scale experimental tests, numerical simulations, material failure criteria and real corrosion defect assessment.
Into the Void: Understanding the Impact of Hydrotests on Flaws in ERW Welds
Authors: Futch David B. , Dotson Rhett , Holland Mark
Published: December 2022

Manufacturing flaws are common on low frequency electric resistance welded pipe (LF-ERW), such as hook cracks and lack of fusion. One less commonly identified flaw is a lamination that terminates at the ERW weld. This interaction results in a unique flaw geometry, occurring mostly at the pipe’s mid-wall thickness but can vary in severity along the length of the affected pipe joint. This paper discusses the significance of this flaw geometry, the method of formation, and the impact of typical operations (fatigue cycling and hydrostatic testing) on the strains along the indication. First, a comprehensive set of metallurgical examinations were performed, including metallography along the flaw. Examination included light microscopy, scanning electron microscopy, electron dispersive x-ray spectroscopy, and sub-load hardness testing (HV0.5) along the flaw. This set of examinations helped identify the flaw and how it formed.

Second, several tensile straps were prepared across the indication to better understand how the feature behaves during the operation of the pipeline. Each tensile specimen was monitored using a digital image correlation (DIC) system with a focus on the ERW seam weld. Tensile straps were prepared and tested to understand the influence of a hydrotest on normal operations by completing the following three phases of simulated operations: (1) normal operations with fatigue cycling at stress ranges equivalent to operating pressures between 6% SMYS and 56% SMYS (MOP), (2) a spike hydrostatic test at stresses equivalent to an operating pressure of 80% SMYS, and (3) normal operations with fatigue cycling at stress ranges equivalent to operating pressures between 6% SMYS and 56% SMYS (MOP). This sequence of testing permitted comparison of the strains at the flaw before and after the simulated hydrotest conditions. The comparison between the strains recorded via the DIC system showed an increase in strain of approximately 40% across the feature in the sample subjected to the spike test, which included an irrecoverable strain of approximately 0.06%. The evaluation process described in this paper provided a valuable understanding of the impacts of a hydrostatic test on manufacturing flaws. This type of evaluation can be used to better understand the effect of spike hydrostatic testing on other common planar flaws including ERW hook cracks, ERW lack of fusions, and stress corrosion cracking.
Estimating Measurement Performance With Truncated Data Sets
Authors: Skow Jason , Krynicki Joseph W. , Fraser Alex , Gonzalez Gustavo
Published: December 2022

In September 2021, the API released the third edition of the 1163 Standard “In-line Inspection Systems Qualification”. This edition brought many improvements over previous versions, including more detail in Section 8 “System Results Validation”, which defines the methodologies used to validate ILI run tolerances. The standard describes three levels of validation, with ‘Level 3’ requiring the operator calculate ILI tool measurement performance with real-world data measured in validation spools and excavation sites. Real-world, inspection data sets have some characteristics that make them difficult to use to accurately estimate measurement performance, one of which is ‘truncation’, that is data with a lower- or upper-bound threshold above which no data is reported. For example, most UTCD ILI tools have a lower truncation level, such as 1 mm for crack height, which represents a signal threshold below which measurements are either not reliable, or not reported. Although small features below the reporting threshold exist on the pipeline, they are not normally reported by the ILI tool.

This paper describes a model to estimate ILI tool performance using API 1163 Level 3 methods when the data set has a lower-truncation threshold. The model is tested with simulation data to show how it responds over a wide range of feature population characteristics, and then applied to two real field data sets. Comparisons are made between the truncation algorithm and the standard non-truncated version of the algorithm, to show where the new algorithm performs best and is most useful to implement pipeline integrity mitigations. The model used in this study is consistent with the example documented in API 1163 - Appendix C, the Bayesian inference method. The results of the model produce measurement performance specifications that can be used as inputs in a pipeline risk or reliability analysis. The influence of truncated data sets is common in the field of inspection and NDE (including thickness measurements), as it reflects the reality that there are features below reporting threshold. The steps required to format the results for use, and achieve more accurate measurement performance results (e.g., unity charts), are described in this paper.
Distribution Pipeline Risk Framework
Authors: Skow Jason , Stewart Ryan , McPherson Rob , Schoenroth Kent
Published: December 2022

By nature, gas distribution is a network system; it does not fit well with traditional pipeline risk models that assume a linear geometry. Distribution system growth is multigenerational and often leads to mixed assets in the same area where transmission pipeline segments are often constructed within shorter time frames and more uniform materials. Slow, sporadic growth leads to varied record availability and quality that might not readily support commercially available risk models. The project described in this paper was initiated to develop predictive methods to prioritize mitigation and replacement activities for distribution networks. Priority is assigned to areas by risk, equipment characteristics and environmental attributes.

In a previous IPC paper, the authors developed a histori-calbased predictive model but applied it to a single city area. This work has been extended to cover the entire province of Saskatchewan. The model relies on logistic regression and a machine learning algorithm to associate the historical failure rate with the asset type, age, pipe material, diameter, pressure, and an array of geographical-dependent attributes such as soil properties and climate events. The output of the model allows integrity engineers to consider predicted failure rates to complement the lagging performance indicators used to develop integrity program planning. This model demonstrates the advantage of using available distribution system records to develop a custom historicalbased predictive model.

Consequence estimates for distribution networks are also described. Distribution leaks are often classified into hazard levels that differentiate operational response. These are assigned based on incident data records and SME input to develop an event tree for the consequence of a distribution leak. This paper summarizes the work performed during the project to calculate distribution asset probability of failure and consequences.
Implementation of Ductility and Microstructural Attributes for Evaluation of Fracture and Fatigue Performance of API X Grades in High Pressure Gaseous Hydrogen Transmission Pipeline Environments
Authors: Stalheim Douglas , Slifka Andrew , Connolly Matthew , Lucon Enrico , Litschewski Aaron , Uranga Pello
Published: December 2022

There is a strong interest in hydrogen as an energy source to contribute to combatting climate change. Hydrogen diffusion into the steel with assistance through various mechanisms of corrosion and pressure will degrade the mechanical properties, primarily critical ductility properties of fracture toughness and fatigue, through embrittlement or hydrogen induced cracking. Fracture toughness as a measure of crack arrest performance through required Charpy (TCVN) performance represents a principal mechanical property requirement of the pipeline. Ductility performance, regardless of the environment, which consists of % RA, fracture toughness, fatigue, etc. is driven primarily by metallurgical components of the through-thickness microstructure such as average high angle grain boundary (HAGB) size and homogeneity of the HAGB’s . A relationship can perhaps be developed of ductility attributes such as TCVN performance in air vs. fracture toughness ductility performance in hydrogen. This relationship of TCVN ductility performance in conjunction with through-thickness microstructural components with fracture toughness performance in hydrogen will be used to propose an additional “Option C” qualification to the ASME B31.12 Code for Hydrogen Piping and Pipelines. This paper will present the background analysis, evaluation, development of the logic, proposed B31.12 code language and how to implement the logic.
Modification of Existing Pipeline Corrosion Assessment Methods for Combined Internal Pressure and Compressive Loading - An Update
Authors: Owens Christopher , Patterson Angus , Arias Arlene , Brett Alex , Russell Andy
Published: December 2022

Corrosion anomalies in pipelines are typically assessed using methods such as ASME B31G. These methods were developed to consider the axial extent and depth of the anomaly in relation to internal pressure loading only. For the majority of pipelines internal pressure will be the primary loading; however, pipelines can also be subject to additional axial compressive stresses (e.g. thermal stresses). When these additional axial compressive stresses become significant, they can interact with the applied internal pressure to lower the failure pressure of the anomaly. ASME B31G, which now incorporates Modified B31G and Detailed RStreng, acknowledges the need to account for significant axial compressive stresses but it does not include a codified procedure to account for combined loading.

This paper considers an approach to modify these widely used existing assessment methods in order to account for the potential effects of combined loading. The approach used to modify the methods was based on the global collapse method developed for DNVGL-RP-F101, which uses the Tresca yield criterion. To validate that the modified assessment methods would provide safe failure pressure predictions, the results were compared against existing full-scale test data. This was further supported by carrying out finite element analysis (FEA) simulations to estimate plastic collapse and local failure pressures, in order to consider the impact of different corrosion profiles on predictions using effective area calculations.

This work follows on from a previous paper and includes additional FEA simulations to consider the influence of the loading order on the failure pressure. In addition, a case study is presented showing the potential benefit of using an effective area method when compressive loading is significant.
Key Considerations for Elastic Finite-Element Modeling of Pipeline Dents for Fatigue Assessments
Authors: Sager Ryan , Curiel Fernando , Holliday Chris
Published: December 2022

The assessment of the remaining life of dents in pipelines generally relies on characterizing the structural response to pressure loading and combining a known pressure history with S-N curves to determine a fatigue life. A robust method for determining the structural response of a dent to pressure loading is through the determination of a Stress-Concentration Factor (SCF) derived from the modelling of the dent using Finite-Element Analysis (FEA). For simplicity, most SCF assessments rely on the use of unrestrained models derived directly from deflection data recorded by ILI or laser scan; however, this application can lead to overly high predictions of SCF values when evaluating restrained dents. Explicit modelling of restraint using bespoke indenter profiles and elastic-plastic material models can be used to derive more appropriate SCF values for restrained dents; however, this requires significantly more analytical effort and can sacrifice the fidelity of the shape for complex geometry. An approach that utilizes the efficient modeling and high fidelity of unrestrained elastic models would provide the industry with a reliable and repeatable process for evaluating the fatigue response of restrained dents. The methodology presented within this paper will seek to validate reasonable bounds for unrestrained elastic models that can be applied to cases where restrained dents are indicated. This paper will investigate the feasibility of a plasticity-restraint correction factor that could be applied to elastic SCFs and discuss the implications for dent fatigue assessments. The response of restrained elastic-plastic models will be compared to the response to elastic models for a range of indenter shapes to show the feasibility of this correction factor.
Relative Risk of Alternating Current Power Line Faults Affecting Nearby Pipelines
Authors: Stewart Ryan , Bear Devin , Skow Jason
Published: December 2022

The co-location of pipelines and alternating current (AC) transmission lines can lead to electrical hazards on a pipeline. One example is a transient voltage that electrifies a nearby pipeline during a power line to ground fault. A power line fault, typically caused by a lightning strike, cut power line, or windstorm, results in electrical potential being transferred to ground. A buried pipeline near a fault acts as a grounding conductor, carrying energy to an area of lower potential than the incident location. Current carried through a pipe is a hazard to people and equipment. A current travelling to an above ground structure could lead to an individual becoming part of an electrical circuit if they touch the structure and the possibility of a high electrical current flowing through an individual’s entire body.

While current literature describes how to mitigate the effects of power line faults, there are limited sources that describe a process to quantify the probability of power line faults affecting pipelines.

In this paper, a method to assess the frequency of AC powerline faults and their potential impact to pipeline infrastructure is described. The model incorporates spatial and historical factors to evaluate the exposure of individual assets to AC power line faults. It estimates the powerline fault frequency and the area of ground potential rise that could lead to safety consequences for workers or members of the public. The collection of fault frequency data, the calculation of fault current from transient voltage hazards, and the estimated area of potential harm from transient voltage hazards are discussed.

The model was developed to rank the risk of power line fault incidents across a company’s pipeline system. The results of the assessment help prioritize locations to perform more detailed site-specific analysis for the design and installation of mitigation systems.
A Transparent ASME B31.8-Based Strain Assessment Method Using 3D Measurement of Dent Morphology
Authors: Zhang Shenwei , Zhang Billy , Wang Rick
Published: December 2022

This paper presents a comprehensive methodology to evaluate the geometric strain of pipeline in a dented area caused by mechanical damage. This methodology was formulated based on the approach recommended by ASME B31.8 and built the transparency of the entire process of dent strain assessment using three-dimensional (3D) measurement of dent morphology reported by the Caliper tools from in-line inspection (i.e., Caliper data). The 2D Fourier Transform in conjunction with band rejection filtering method was used to filter the signal noise and smooth the 3D morphology of dent. The cubic spline was utilized to characterize the discrete 2D longitudinal and circumferential profiles for curvature and arch length calculations, which were used to evaluate the bending strain and membrane strain, respectively. The effective strain was then calculated using the method recommended by ASME B31.8. To demonstrate the application of the methodology, a tool with user-friendly interface and powerful visualization and reporting functions was developed using the methodologies reported in this paper. The reported methodology enables development of dent strain assessment tool and benefit pipeline operators to facilitate dent integrity management program.
Effects of Hydrogen Embrittlement on the Fracture Toughness of High-Strength Steel Structures
Authors: Agbo Sylvester , Davaripour Farhad , Roy Kshama
Published: December 2022

Blending hydrogen into existing natural gas pipelines is being pursued as a means of delivering hydrogen to markets. However, as stated in ASME B31.12, high-strength steel pipelines under stress can be susceptible to hydrogen embrittlement, which is a phenomenon that could induce brittle fracture in steel. This study proposes a numerical framework using phase-field fracture modelling techniques to model the hydrogen embrittlement phenomenon in high-strength steels. The proposed numerical framework is validated against a Compact Tension experimental test specimen, which is deemed suitable to capture the crack-tip constraint observed in high strength steel. The finite element results show a good agreement with experimental results, which demonstrate the capability of the phase-field fracture model in reasonably predicting hydrogen embrittlement in high-strength steel. As such, the proposed numerical modelling framework could also be applicable to typical high strength steel pipelines.
Reliability-Based Self-Imposed Pressure Restriction / Derate Pressure Estimation for Corrosion and Crack
Authors: Yan Jason , Zhang Shenwei , Saunders Joe , Blackwell Chris
Published: December 2022

Corrosion and crack anomalies are the major threats to the safety and structural integrity of oil and gas transmission pipelines. Pipeline operators commonly manage the corrosion and crack threats by regular in-line inspection.

After inspection, operators need to identify critical anomalies and plan mitigation works. Traditionally, a deterministic approach is used to assess anomalies using characteristic values of pipe properties, anomaly size, growth rate, and considering a minimum required safety factor (e.g., 1.25). TC Energy has used a full reliability-based method to determine the mitigation plan for corrosion and stress corrosion cracking (SCC) anomalies considering all the uncertainties associated with pipe geometry, material properties, anomaly size, growth rate and assessment model error explicitly. This method enables TC Energy to maintain the annual probability of failure of all known anomalies with the same location class not exceeding a consistent threshold (e.g., 1E−3 per anomaly per year).

Anomalies that do not meet the minimum safety margin (e.g., deterministic safety factor or reliability-based threshold) and cannot be mitigated timely, are usually managed by applying short-term self-imposed pressure restriction (derate). Derate pressure is typically calculated deterministically with conservative anomaly size, growth rate and a global safety factor. To account for potential parameter variation, conservative inputs often lead to conservative derate pressure. There is inconsistency between a full reliability-based mitigation plan and a deterministic short-term derate plan.

This study introduces a new efficient reliability-based approach using a Monte Carlo simulation technique to determine the derate schedule (e.g., the minimum required derate pressure for each month) to maintain the system to a consistent safety level. Two case studies, one MFL and one EMAT inspection with reported critical corrosion and crack anomalies, are conducted to demonstrate the advantage of fully reliability-based derate approach. The optimized derate plan minimizes the economical business impact to operators. The proposed framework in this study can be widely used to improve derate programs.
Comparison of Machine Learning Models for Quantitative Risk Modelling of Pipeline Systems
Authors: Bandstra Daryl , Rojas Juan S. , Fraser Alex , Shironishi Mari
Published: December 2022

Over the past decade, machine learning models have enabled significant technical achievements in a variety of fields, however the application of these models is an area of active research and development in conventional and regulated industries, which are often more cautious to adopt new technologies. In this paper, a case study is presented where various statistical and machine learning models, including logistic regression, random forest, gradient-boosted decision trees, and artificial neural networks are trained and validated using a historical incident record dataset to quantify the probability of pipe failure on a distribution pipeline system. The relative performance of each model type is compared against a held-out test dataset using an evaluation framework that utilizes lift charts to quantify each model’s performance. Observed strengths and limitations of the different model types are discussed with respect to performance, interpretability, and ease of incorporating additional data, along with key considerations for fitting and evaluating models. Additional case studies are also presented to illustrate how model performance depends on the quantity of training data and predictor features. These additional cases illustrate the benefit of continually collecting and leveraging asset data, as well as the benefit of augmenting existing asset data with external datasets, such as those obtained from public geospatial datasets. The results of this study will provide operators with additional insights and guidance in developing and evaluating machine learning models for pipeline risk assessment and integrity management.
A More Efficient Effective Area Method Algorithm for Corrosion Assessment (Faster RSTRENG)
Authors: Yan Jason , Lu Dongliang , Khou Ian , Zhang Shenwei
Published: December 2022

Corrosion is one of the major threats to the safety and structural integrity of oil and gas transmission pipelines. The corrosion threat is usually managed by regular in-line inspection (ILI).

The effective area method (RSTRENG) is the most popular corrosion assessment model to convert the measured corrosion size to predicted burst pressure. Given a detailed corrosion measurement profile, the effective area method involves an iterative process to find the minimum burst pressure. As stated in ASME B31G, “for a corroded profile defined by n measurements of depth of corrosion including the end points at nominally full wall thickness, n!/2(n − 2)! iterations are required to examine all possible combinations of local metal loss with respect to surrounding remaining material”, the widely used effective area algorithm has at least an order of n-square time complexity (O(n2)). As n increases, the computation time increases nonlinearly.

This paper reviewed the traditional RSTRENG algorithm first, and demonstrated that it is not necessary to always loop through all the combinations and check the corresponding burst pressure one by one. Because some combinations with shallower and shorter corrosion size are certainly not the final critical combination corresponding to the minimum burst pressure. A more efficient algorithm (Faster RSTRENG) is proposed and presented in this paper, which can reduce the algorithm computation time significantly.

While the impact of efficiency of the algorithm on the integrity assessment process is insignificant if solely conducting burst pressure calculation in a deterministic way, a highly efficient algorithm is desired when assessing a large volume of corrosion anomalies by the reliability-based (probabilistic) assessment method using Monte Carlo simulation technique where millions of simulations are required.

In addition, TC Energy has developed a more accurate and precise corrosion assessment model, i.e., plausible profiles (Psqr) model, published in IPC 2018 and 2020, and reviewed by industry experts through PRCI. The use of Psqr model needs to generate hundreds of profiles for one corrosion anomaly and repeatedly uses the effective area algorithm. This needs extensive computing efforts. When Psqr model was built into the probabilistic assessment framework, the computing efforts were dramatically increased. Therefore, it is of great importance to have a more efficient effective area algorithm to facilitate the probabilistic assessment using Psqr model.

A case study was used to demonstrate the efficacy of the developed algorithm by comparing the computation time using different effective area algorithms. Engineers who are already familiar with RSTRENG model, might jump to the Faster RSTRENG section and Annex A directly.
Systematic Assessment of Risk Control Effectiveness
Authors: Grant Eric , Ambasta Shreya , Jean Mark
Published: December 2022

The inherent risks associated with pipeline operations are significant. Companies dedicate countless resources to identifying, assessing, and controlling risks across their operations. Risk management activities are completed by personnel at all levels, from field staff to senior management. This ensures that risks are identified and managed at all levels within the company to align with company risk tolerance. Where risks are identified that are higher than company tolerance levels, additional controls are typically developed. For most risks, a series of controls is developed to protect in different ways or in different scenarios. In many cases, a control may protect against multiple different risks.

When risk assessments are completed, there is the possibility that the effectiveness of controls that have been developed to manage the risk are incorrectly considered [1]. Individuals or teams completing the review of controls are assessing their effectiveness higher or lower than they actually are [2]. This is typically the result of a controls assessment that does not fully consider the functionality, availability, and reliability of the control. The result is the potential for a risk being accepted that may be beyond company risk tolerance or the allocation of additional resources on risks that are already well controlled. To account for a control’s partial effectiveness, they are often layered, with multiple controls working together to mitigate a risk [3]. In these instances, if one control is unable to manage the risk, another would be available to provide additional mitigation to reduce the possibility or consequence of a major risk event.

With the combination of thousands of hazards that can lead to different major risk events with hundreds of unique controls, it can be difficult to quantify the degree of risk to which a company is exposed. This paper explores the approach to systematically assessing risk controls, enabling improved understanding and ability to communicate the overall organizational risk and prioritization of improvements for the most critical controls.
Pipeline Defect Detection and Fine-Scale Reconstruction From 3-D MFL Signal Analysis Using Object Detection and Physics-Constrained Machine Learning
Authors: Rosenthal W. Steven , Westwood Stephen , Denslow Kayte
Published: December 2022

Sustainable operation of pipeline networks for oil and gas transportation requires diagnostics capable of both detection and characterization of pipeline defects in particular corrosion defects. Current defect analysis techniques can identify and characterize the geometric features of metal loss defects or defect clusters such as peak depth, length, and width with limited accuracy. Probabilistic data driven models have also shown an ability to predict error bounds for individual defect characteristics as opposed to overall defect tolerance. The prediction accuracy of the health of a pipeline with metal loss defects such as corrosion can be improved with additional detail in the corrosion surface profile as this affects the burst pressure. This will enable operators to apply more accurate corrosion growth models and simulations that can forecast the reduction in pipeline capacity and facilitate more targeted diagnostic and mitigation plans. To this end, a data-driven workflow is proposed to automate the detection, classification, and surface prediction of external corrosion defects. This combines experimental MFL data and validated MFL simulations and leverages both image-based and physics-informed machine learning methodologies.
Implementation of API 1183 Recommended Practice for Reliability-Based Assessment of Dents in Liquid Pipelines
Authors: Kainat Muntaseer , Virk Amandeep , Yoosef-Ghodsi Nader , Bott Steven
Published: December 2022

Prior to the publication of API 1183 (Recommended Practice for Assessment and Management of Pipeline Dents) in 2020, there was no industry consensus on one method to evaluate the Fitness for Purpose for dents to be implemented in integrity management programs. Regulations in Canada and the United States regarding the repair of dents are primarily based on depth and interaction with stress risers. API 1183 has put forth specific methodologies for screening and detailed assessment of dents which consider both strain-based and fatigue-based failure mechanisms.

Enbridge Liquid Pipelines had previously presented a framework to support systemwide dent assessment with an efficient reliability-based approach. Following the publication of API 1183, this approach has been further modified to comply with the API recommendations for dent assessment. Both the screening and detailed analyses within this framework account for the properties of the pipe, dent, and interacting features, the operating condition and history of the line, restraint condition, and associated uncertainties. These analysis techniques combine inline inspection results and engineering analysis with their uncertainties, providing a means for quantitative assessment of dents. This paper demonstrates the alignment of Enbridge’s dent management framework with API 1183 recommendations, and discusses the modifications made for probabilistic assessment of dents. In the absence of specific guidelines for probabilistic assessment in API 1183, Enbridge relied on relevant publications and industry best practices for considering uncertainties within the probabilistic assessment. This framework has been implemented for systemwide analysis with over 5,000 geometric anomalies assessed to date. From this implementation experience, the challenges with probabilistic analysis and potential areas of further improvement have been identified and discussed in detail in this paper. In particular, the recommendations in API 1183 regarding dent fatigue assessment, and the fatigue life reduction factor due to weld interaction are observed to be overly conservative. Overall, the reliability-based dent management framework following API 1183 recommendations have proven to be effective, but inefficient due to being overly conservative. Efforts have been made to validate, and where possible, to calibrate the techniques through comparison to experimental results, field findings, and historical failures. These efforts have enabled Enbridge to tackle the over-conservatism of the models for certain combinations and ranges of operating parameters through novel techniques, which are described in this paper.