bluuebunny/crossref_metadata_2025 huggingface dataset:
Engineering Approach for Ductile Fracture Arrest Based on CTOA
Authors: Xu Su , Bassindale C. , Wang X. , Williams B. W. , Tyson W. R. , Guan C.
Published: December 2022

Ductile fracture propagation control and arrest are important elements in fracture control of pipelines transporting natural gas and other high-vapour-pressure media (e.g., dense-phase carbon dioxide). The most familiar crack arrest methodology, the Battelle Two-Curve Method (BTCM), is based on Charpy absorbed energy, and is well known to under-predict requirements for current high-strength high-toughness steels. Adjustments have been made, either by using correction factors or using absorbed energy from the drop-weight tear test (DWTT), but these remain empirical. The crack-tip opening angle (CTOA) has been proposed for a number of years as a fundamental parameter to characterize propagation toughness in aerospace and pipeline applications. It is convenient for finite element (FE) modelling of fracture in full-scale structures such as pipe. However, early procedures to measure pipe CTOA by a “two-specimen” method have been shown to be unreliable. Moreover, previous CTOA models (PFRAC and PICPRO) produced very different results.

Recent work has addressed both shortcomings, including validation of a practical test for determining CTOA of pipe steels (ASTM E3039) and development of reliable FE models for axial crack propagation in pipes. Fracture resistance curves (crack velocity as a function of pressure at constant CTOA) including the effect of backfill have been computed over a wide range of variables. For a given design (pipe geometry, gas pressure and backfill) only tensile properties and CTOA are required to determine conditions for arrest; there are no adjustable constants in the methodology. Results to date are in good agreement with full-scale burst tests (FSBTs) by researchers at TC Energy and at the University of Tokyo, and with Maxey’s original treatment of the effect of backfill on fracture velocity at high pressures.
Learnings From Implementing an API 1173 Compliant Management System
Authors: Potter Dale , Jean Mark S.
Published: December 2022

In July of 2015, the American Petroleum Institute (API) published Recommended Practice (RP) 1173 to provide an industry framework for the development of a Pipeline Safety Management System (PSMS). Regulators and industry companies worked together to develop the RP, providing the basis for enhanced public safety and protection.

Recognizing the inherent benefits to their organization, CHS’ pipelines and terminals division began developing their API RP 1173 compliant management system in February 2016. They were early adopters of this new management system approach and have had several years to not only develop their frameworks, policies, procedures, templates, and tools, but also to implement and ingrain them within their organization. The approach taken was methodic and systematic and focussed on right-sizing their system to match their specific organizational requirements. This supported CHS’ focus on building and applying the right pieces of their system in the right order to build organizational momentum and adoption. Roles and responsibilities throughout the organization were carefully defined to support implementation, administration, and management of the system. The establishment of CHS’ management system not only supported improved safety, but it also helped support the integration and alignment of different pipeline business areas. Throughout CHS’ development and implementation of its management system, key challenges and learnings were identified.

This paper will outline the approach taken by CHS to assess and implement API RP 1173 within their pipeline and terminals division. The paper will outline the specific steps taken, the approach to building their company-specific framework and the learnings that were discovered along their journey. This paper will be of specific interest to those companies that may be in various stages of developing and implementing API RP 1173 within their respective organizations.
Pig Sweep®: Nanoparticles Transform Pipeline Cleaning & Integrity Management
Authors: Clapper Justin , Williamson George , Pearson Kyle , Allred Bud
Published: December 2022

This paper details the evolution of a new and innovative cleaning agent for heavy oil and natural gas pipelines. Information is offered regarding the reason for development and the research involved in formulation of a nanotechnology product. Application details, economic and operational benefits from case histories involved with cleaning two different pipelines, and a preview of a recently developed laboratory testing program is presented.

Oil, gas, and multi-phase pipelines can be fouled with several types of deposits or internally restrictive debris. Common types of foulants and the detrimental effects on pipeline operation are reviewed. A nanotechnology product has shown to be highly effective at removal of a wide variety of foulants. Pig Sweep® provides a nanotechnology-based mechanical cleaning mechanism as opposed to a chemical reaction. The cleaning mechanism and model that potentially protects the pipe wall surface from future deposition or debris collection is reviewed.

The case histories include on-line cleaning of two different pipelines. The first resulted in the removal of more than 41,000 pounds of solids from a 344-mile long, 36″ diameter, dry gas pipeline system. The second case study was performed on a 63-mile, 24″ diameter, dry gas pipeline which resulted in reduced pressure drop, significant operational savings from reduced compression requirements, and significant increased throughput.
Probabilistic Analysis Applied to the Risk of SCC Failure
Authors: Riccardella Scott , Malinowski Owen , Riccardella Pete , Potts Steve , Moran Sean , Thompson Kelly , Reo Ann
Published: December 2022

This paper discusses a model developed and applied to evaluate the probability of Stress Corrosion Cracking (SCC) failure in a large gas pipeline system spanning approximately 8,500 miles. A machine learning algorithm (neural network) was applied to the system, which has experienced nearly 500 prior instances of SCC. Subject matter experts were interviewed to help identify key system factors that contributed to the prevalence of SCC and these factors were incorporated in the neural network algorithm. Key factors such as coating type, vintage, operating stress as a percentage of SMYS, distance to compressor station, and seam type were evaluated in the model for correlation with SCC occurrence. A Bayesian analysis was applied to ensure the model aligned with the prevalence of SCC encountered. A Probabilistic Fracture Mechanics (PFM) model was then applied to relate the probability of SCC existing to the probability of rupture.
Advanced Reliability Analysis at Slope Crossings
Authors: Fowler Matthew , Ndubuaku Kachi , Yoosef-Ghodsi Nader
Published: December 2022

Pipelines cross diverse terrain and as a result are subjected to a variety of geotechnical hazards. Depending on the location of the pipeline relative to a geotechnical threat, it may be subjected to external forces which could lead to pipeline deformation or failure. Generally, geotechnical threats manifest as slope movement, subsidence/settlement, seismic waves, or frost heave/thaw settlement. While similar analysis techniques may have tangential applicability to all these threats, this paper focuses on the landslide/slope movement scenario. Here, the authors present an approach for evaluating pipelines in areas where slope movement is known or has the potential to occur. The methodology uses advanced finite element analysis (FEA) and statistical reliability techniques to estimate the probability of failure (PoF) of the pipeline at a given site. A case study where the method was employed is also presented. The presented process serves as an advanced analysis tool within a geohazard reliability program. This in-depth PoF analysis can be conducted after a screening level assessment has highlighted a given site.

The data required for the analysis includes, at minimum: basic pipe properties, operational information, inertial measurement unit (IMU) in line inspection (ILI) pipeline centerline data, depth of cover survey data, and some estimation of relevant soil to pipe interaction parameters. Other information that can be incorporated to enhance accuracy and reduce conservatism include geotechnical reports and instrumentation measurements (e.g. slope inclinometers or strain gauges). The uncertainties associated with the inputs are estimated based on standards or subject matter expert (SME) input. Incorporating the defined uncertainties, numerical models are created using the commercially available finite element (FE) analysis software ABAQUS, where the pipe is modeled using pipe beam elements and the soil to pipe interactions is modeled using pipe-soil interaction elements. The FE models are processed using a design of experiments (DoE) approach to define response surfaces for both compressive and tensile strain demands. Strain capacities are estimated using the Dorey (U of A) and CRES (PRCI) models for compressive and tensile strains, respectively. Using the resulting relationships for strain demands and capacities, Monte Carlo simulations are completed using the previously defined uncertainties. The simulated cases where strain demand exceeds capacity produce an estimation of probability of exceedance (PoE). Finally, the PoF is obtained by multiplying the PoE by an estimated likelihood of slope movement occurring and impacting the pipe.
Optimizing Operator Systems Through the Use of Flexible Composite Pipe
Authors: Nemeth Alex , Czapski Debra , Alexander Chris
Published: December 2022

Pipelines play a critical role in the world-wide demand for energy. Pipeline operators face ever-increasing challenges in operating high-pressure pipelines, and the need for safely and reliably transporting oil and gas products has never been more demanding in terms of our world-wide aging infrastructure. Global expectations associated with Environmental, Social, and Governance (ESG) criteria present even greater challenges for pipeline operators.

The installation of flexible composite pipe offers an alternative to current integrity management practices such as localized repair methods, as well as more invasive methods such as HDD and pipe replacements. In addition to rehabilitating aging pipelines, flexible composite pipe can be used as a means for repurposing existing infrastructure for transporting and storage of non-conventional products like hydrogen and CO2 for carbon sequestration.

With the aging pipeline infrastructures and the world-wide interest in ESG, flexible composite pipe offers an opportunity as a transformational technology to meet the current and future needs of pipeline operators. It is not uncommon for innovative technologies to experience slow adoption. This is especially true in industries that are capital intensive and regulated, such as the transmission pipeline industry.

This paper looks at the use of flexible composite pipe technology on operator systems, the selection criteria involved in determining where installation would be most advantageous to an operator, and the long-term benefits offered by the installation of flexible composite pipe during a time where the ability to navigate through the energy transition towards a carbon neutral industry is critical. Worldwide demand for energy will continue to increase with growth in population and standards of living. As pipeline operators look to the future, flexible composite pipe is sure to play a critical role in ensuring the continued safe operation of high-pressure pipelines.
A Simple Baseline of Pipeline Data Simulation Algorithm Based on DGM
Authors: Hu Xu , Wang Hengyu , Zhao Hongyang , Liu Gaoling , Wang Di
Published: December 2022

Data is the cornerstone of data science development. This implies the significance of emphasizing information protection found in oil and gas pipeline operating data generated throughout the development of digitalization in relevant companies. Despite of the abundance of sensitive information contained in real data, the availability of open public data sets for professionals in the industry is considerly scarce. This has in turn become the greatest obstacle in producing any forms of research achievements in the industry. At the same time, the sensor deviation leads to a weak reference of the simulation data obtained by the traditional physical formula. Generative deep learning networks are able to directly learn from data and generate high-fidelity as well as diversified samples, allowing them to complete data set generation and information desensitization. This paper presents the application of two deep generative model algorithms, i.e., VAE (Variational Auto-Encoder) and GAN (Generative Adversarial Networks), for pipeline operating data generation. Three main contributions have been made with this approach: (1) Research and release the pipeline operation simulation algorithm generated by the deep generation model based on the big historical data. (2) the algorithms were found to be capable of exporting operating data as a reference for the pumps according to specific pipeline parameters, e.g., pressure corresponding to a certain flow. A data set with the same probability distribution as the actual pipeline operation data could be generated; (3) data-distribution-based detection of abnormalities in pipeline operating conditions using a GAN algorithm identifier was proposed for the very first time. The experimental results presented < 1% mean square error (MSE) between the optimal model and the normalized real data — 0.4% to be more specific, verifying the algorithm’s capability of generating a desensitized data set similar to the real data. Moreover, a classifier trained with the generated data using the GAN algorithm identifier was able to detect as much as 69% abnormal operating conditions, further verifying the effectiveness of the proposed algorithm. Code are publicly available in https://github.com/ShawnHoo7256/BOGC_Project.
Quantitative Evaluation of Microstructure to Support Verification of Material Properties in Line-Pipe Steels
Authors: Martin L. P. , Switzner Nathan , Oneal Owen , Curiel Sophia , Anderson Joel , Veloo Peter
Published: December 2022

Federal rule changes governing natural gas pipelines have driven operators in the United States to establish materials verification programs (MVP) for pipelines that lack reliable records. One component of a successful MVP is the use of nondestructive testing (NDT) to assess pipe properties in situ. Pacific Gas and Electric Company (PG&E) augments traditional NDT with quantitative analysis of pipe microstructures. The microstructures are acquired non-destructively by surface replication, and are quantitatively evaluated to assess the ferrite grain size and fraction of pearlite. To support interpretation of the data, PG&E has compiled a database of steel line pipes for which microstructures from both destructive cross-sections (cutouts) and in situ surface replicas have been evaluated, and for which mechanical test data are available. The database is currently comprised of more than fifty pipe samples with manufacturing dates between 1931 and 2017, and a variety of grades and seam types.

This work presents a comparative analysis of the different methods used by PG&E to quantify pipe microstructures, and shows that microstructures from surface replicas are generally consistent with those from cutout cross-sections. In addition, semi-quantitative correlations between micro structure and mechanical properties are presented. The data suggest a correlation between grain size and the ductile-brittle Charpy V-notch (CVN) transition temperature, and an inverse correlation between fraction of pearlite and the upper-bound of the CVN upper-shelf energy. In addition, the analysis shows that grain size can provide a lower bound on the manufacturing year (vintage) due to the advent of steelmaking practices that produce refined grain structures. By themselves, the observed trends can provide semi-quantitative bounds for these properties; however, the predictive value of the microstructural assessments may be improved by the development of more sophisticated algorithms that consider additional information, such as composition and hardness.
Design and Finite Element Analysis (FEA) of Bulkheads for a Pipe-in-Pipe Flowline: Application of ASME Boiler and Pressure Vessel Code
Authors: Shekarforoush Mehdi , Hoorzad Hamid , Hothi Jaspreet , Forcinito Mario
Published: December 2022

Evaluating a pipe-in-pipe (PIP) system with bulkheads is not explicitly covered by the Canadian Standards Association (CSA) Z662 for oil & gas pipeline systems and refers to the rules in the ASME Boiler and Pressure Vessel Code (BPVC Section VIII, Division 2) as alternative reference code. However, the BPVC does not specifically address the pipeline design. Due to the nonlinear nature of the PIP and bulkhead geometry and loading condition, careful modeling and an appropriate interpretation and application of design criteria by BPVC code are required. The current paper addresses the challenges and recommendations for geometric design of the bulkheads, the appropriate modeling of the problem using FEA method, as well as analysis and accurate interpretation of the results based on the BPVC rules. The bulkhead design was checked per ASME B&PV VIII.2, design-by-analysis, and showed that the assembly has met the criteria for protection against 1) plastic collapse, 2) local failure and 3) failure from ratcheting.
A Comprehensive New Look at Type B Sleeves
Authors: Futch David B. , Denowh Chantz , Wilson Josh
Published: December 2022

Type B full encirclement steel sleeves have been used for the past fifty-plus years as a viable repair method for most, if not all, features encountered on a pipeline. A Type B sleeve includes an in-service weld at both ends of the sleeve. The science behind performing these welds in a safe manner has greatly evolved over the past 20+ years. However, many of the original concepts regarding the design and application of a steel sleeve have not been further examined since the original research on the subject.

This paper investigates a series of sleeve circumstances to better understand the long-term integrity of the common repair method. The circumstances examined within this paper include: the effect of a fabricated sleeve vs split pipe, the influence of the Bauschinger effect on fabricated sleeve properties, the effect of filler material applied within a dent, the effect of steel sleeve fit-up, and the influence of a mill groove relief for a longitudinal backing strip. All test configurations examined confirm the long-term integrity of a Type B sleeve, however, the information presented in this paper from the above tests can be used when utilizing a Type B sleeve as a permanent repair.

A combination of sub-scale and full-scale tests were performed to fully investigate the circumstances mentioned above. Sub-scale tests were performed to evaluate the Bauschinger effect, which indicated minimal effect from the fabrication processes of the sleeve. Full-scale tests were performed for the remaining circumstances. Through a series of one-for-one comparison tests, a fabricated steel sleeve performed in an equivalent manner to split pipe. The application of filler material, and the application of a suitable filler material, had a large effect on the load sharing of the repair. During this test protocol, tight fitting sleeves resulted in a life approximately 3.5 times longer than one installed in a loose manner. While a mill groove did not affect the life of the sleeve, it does result in a tighter fitting sleeve, shown to have a significant benefit if the sleeve becomes pressurized.
Pipeline Repair Planning Using a Digital Environment to Improve Integrity Tasks
Authors: Sharman William , Sander Phillip , Hall Owen , Martin Jonathan , Spurlock John
Published: December 2022

In the transition to a digital environment for pipeline integrity management, the traditional methods for assessment of in-line inspections (ILI) and subsequent repair planning, are progressing from a manual process of utilizing paper-based information sources and relatively simple spreadsheet calculations, to an all-encompassing digital process.

There have been significant improvements to the management and alignment of pipeline and related inspection / survey data. The subsequent algorithms and procedures used to determine pipeline repairs need to evolve in conjunction to benefit from the extra information readily available. As part of the development of integrity management software, we made advancements in repair planning procedures and this paper describes the challenges encountered and the subsequent solutions adopted.

The traditional approach to repair and dig site planning has been based on the ILI vendor’s dig sheet, reviewed in conjunction with the pipeline listing, allowing an integrity engineer to identify necessary repairs following an integrity assessment and repair rules adopted by the pipeline operator. It can then be determined whether multiple repair locations can be combined into a single dig site, or if a more advanced repair method is required due to the presence of other pipeline features (e.g. an existing pipeline repair). An experienced engineer, provided with sufficient information about the state of the pipeline, should be able to provide an appropriate repair solution that requires only minor adjustment once excavations begin, saving a significant amount of cost and effort for the repairs, at the expense of high efforts on the engineer’s part.
Optimizing Blended Hydrogen Uniformity Within Natural Gas Pipeline Distribution Networks
Authors: Li Guohua , Moyer Michelle , Bidmus Hamid
Published: December 2022

Blending hydrogen into existing natural gas pipeline distribution networks is becoming prominent in the alternative energy industry. Non-uniformity of the hydrogen concentration can occur in the blends delivered at the demand locations of these networks. The non-uniformity can significantly reduce the total hydrogen blending capacity of the whole network due to concentration limitations of industrial and household equipment or materials. Thus, maximizing hydrogen uniformity can become a necessity in the modeling and design of some hydrogen blended natural gas distribution networks where multiple supplies exist but hydrogen can’t be injected at each supply site.

This paper introduces a methodology to optimize blended hydrogen uniformity. The methodology is illustrated using a hypothetical natural gas distribution network. A natural gas supply tracing study is conducted to establish the order of priority of the supply sources in a demand area. A hydrogen and natural gas blending and parametric study is then carried out to determine a ranking for priority selection of the hydrogen injection sites. Subsequently, an operational optimization study is performed to minimize the number of hydrogen injection sites and maximize the volume of the hydrogen injected.

Using the hypothetical natural gas distribution network, a cost and benefit analysis is performed. The relationship between the total costs and the total hydrogen injection flow rates, as a function of the number of hydrogen injection sites, are tabled and plotted.
An Automatic Dent Assessment Tool Using Finite Element Method
Authors: Bao Ji , Zhang Shenwei , Zhang Billy , Wang Rick , Zhang Ken
Published: December 2022

Dents are permanent plastic deformations of the pipeline that occur during pipeline construction and operations. Stress and strain concentration at dents may initiate cracks, which pose a threat to the integrity of the pipeline. Since formation of dents involves plastic deformation, a traditional depth-based assessment method cannot accurately capture the strain concentration, e.g. a sharp dent. Dent assessment methods have shifted to strain-based approach in recent years.

Engineering Critical Assessment (ECA) procedures are evolving with the development of new methods to calculate the strains associated with a dent. It has been well established that three-dimensional (3D) elastic-plastic Finite Element Analysis (FEA) is the most accurate in the denting process simulation and dent strain calculation. However, FEA modelling of dents interacting with other threats can be extremely laborious and requires high level of FEA expertise. Moreover, continuum FEA is usually computationally expensive and imposes onerous demands for analysis efforts.

This paper describes the process that was used to develop an automatic dent assessment tool via FEA. The tool is capable of simulating the denting process of a plain dent and a dent interacting with other threats (e.g., metal loss or gouge). The dent geometry and curvature in FEA are shown to agree well with captured In-line Inspection (ILI) caliper data. The tool also supports batch processing of numerous dents with a highly intelligent post-processing engine that automatically calculates von Mises equivalent strain, ductile failure damage indicator (DFDI) and strain limit damage (SLD) and outputs the results with visual contour plots. The Rainflow pressure cycling counting algorithm and Miner’s rule are incorporated in the tool to predict the fatigue life of the dent utilizing historical pressure data. Case studies are provided to demonstrate the effectiveness of the tool. The development of the tool greatly facilitates the ECA of dents allowing for accurate and efficient management of dents impacting TC Energy’s pipeline system.
Using Advanced Probability of Exceedance Methods for Defining Remediation Options
Authors: Bubenik Thomas , Hanna Benjamin , Harper William , Ellinger Matt
Published: December 2022

The Probability of Exceedance (POE) methodology is used by pipeline operators to manage corrosion. It prioritizes anomalies identified by an in-line inspection (ILI) based on their likelihood of exceeding one or more failure thresholds. Two types of thresholds are commonly used: leak and rupture. The calculations represent the likelihood an anomaly will leak or rupture as a function of time. By assessing the likelihood of such a release as a function of time, an operator can design rational and statistically valid remediation programs.

In this study, the likelihood that an anomaly will cause a leak or rupture was based on the ILI dimensions, the ILI system’s accuracies, and the corrosion growth rate at the anomaly location. The ILI dimensions were adjusted by the mean error as determined using ILI-to-field comparison data. The same ILI-to-field data were used to determine the scatter (standard deviation) in reported dimensions for different categories of anomalies.

The POE (likelihood) of a leak or rupture was taken as a function of the mean and standard deviation of a corrosion growth rate at the anomaly location. Anomalies were “grown” using mean growth rates that were established by performing ILI run-to-run comparisons. By using accurate growth rates and ILI performance characteristics, realistic estimates were made of the POE of an anomaly, pipe joint, pipe segment, and the overall pipeline itself.

This paper discusses improved methods of calculating leak and rupture POEs using realistic assumptions on how anomaly growth occurs as a function of time. Case studies are used to demonstrate the effectiveness of the advanced POE method.

The introduction and select portions of this paper are based, in part, on “Advanced Probability of Exceedance Method Overcomes Previous Weaknesses,” by the authors,1Pipeline Pigging and Integrity Management Conference, February 2–4, 2022.
Chasing Ghosts: An Integrative Approach to Properly Qualify a Pipeline Threat
Authors: Turnquist Michael
Published: December 2022

The execution of in-line inspection (ILI) as the primary assessment methodology to manage a specific pipeline integrity threat has become standard practice for pipeline operators. The ability for ILI to properly size and characterize pipeline anomalies is better than ever. However, there are challenges that operators should be aware of when it comes to understanding the limitations of ILI. These challenges can differ depending on the threat being managed.

The threat of cracking in a pipeline longitudinal seam weld can be particularly challenging to manage. Recent improvements in the detection capabilities of crack-detection ILI technology present a challenge for pipeline operators. It is not uncommon for ILI to report several hundred or even several thousand seam weld anomalies on a single pipeline. Managing this large number of features can be very difficult, and the repercussions of excavating features that do not pose a true integrity threat extend well beyond the financial. The elimination of unnecessary excavations will in turn decrease risk related to safety associated with every excavation and allow the operator to focus solely on the features that pose a true integrity threat.

This paper presents a case study in which a liquid pipeline operator was dealing with these exact challenges. A recent ultrasonic crack detection (UC) ILI reported several thousand linear longitudinal seam anomalies on a post-1980 vintage pipeline containing high-frequency electric resistance welded (HF-ERW) seams. To properly qualify the integrity threat, an integrated approach was executed that combined non-destructive evaluation (NDE), destructive material property testing, full-scale burst and fatigue testing, metallurgical analysis, raw ILI data review, and engineering critical assessment.

The results of the integrated testing and analysis identified that a large number of ILI-reported features were mis-characterized due to the presence of excessive internal trim associated with many of the seam welds contained in the pipeline. The analysis provided the necessary technical justification to forego excavations associated with the features that were mis-characterized by the ILI. Integrated testing and analysis provided the operator with a superior understanding of the true nature of the seam weld integrity threat for this pipeline.
Settlement Risk Assessment and Monitoring for Direct Pipe® Construction Beneath Critical Infrastructure
Authors: Campos Urso A. , Robison Jonathan L. , Castleberry Gary W. , Azimi Amin
Published: December 2022

Direct Pipe® (DP) is an innovative trenchless construction method that combines aspects of micro-tunneling and horizontal directional drilling (HDD). In the DP method, ground excavation and pipeline installation are simultaneous. In this method, the jacking frame in micro-tunneling is replaced with a pipe thruster and coupling is eliminated. Additionally, reaming the bore hole, which is common with the HDD method, is eliminated. The DP method of construction is typically applied when subsurface conditions beneath a surficial obstacle are not conducive for the HDD method of construction due to final hole diameter, granular soils, and/or high risks of hydraulic fracture leading to inadvertent drilling fluid returns. During tunneling operations, the microtunneling boring machine (MTBM) excavates a space or tunnel that is typically a few to several centimeters larger in radius than the jacking pipe; which is thrust into place continuously behind the TBM. This overcut annular space and the potential, occasional temporary extraction of the MTBM and jacking pipe represent settlement risks during construction. For this reason, the pipeline construction team should consider assessing settlement risks associated with DP construction, and subsequently prepare and deploy a settlement monitoring plan during the pipeline construction phase, particularly where the proposed DP alignment will cross railroad, highway, and/or other sensitive features that may be adversely affected by settlement. This paper presents an adopted settlement risk assessment and monitoring plan for a recent trenchless crossing where the DP method of construction was utilized to install a pipeline section beneath two major interstates and a railroad outside of Washington D.C., United States. The paper also includes a Finite Element Analysis (FEA) using Plaxis software with the purpose of exploring the time variable in settlement analysis. Furthermore, the paper expands on the planning characteristics of settlement monitoring utilized during construction, which consisted of conventional surveying and vehicle-mounted LiDAR scanning.
TMCP Pipe for Sour Service: A New Qualification Approach
Authors: Newbury Brian , Schwinn Volker , Schroeder Jens , Alderton Graham , Prescott Andrew , Wasson Andrew
Published: December 2022

Historically, C-Mn steels have been extensively used in line pipe applications for sour service oil and gas environments, i.e. in the presence of hydrogen sulfide (H2S). In the past few decades, the emergence of the Thermo-Mechanically Control Process (TMCP) manufacturing method has further optimized the benefits of increased fabricability, weldability, and large cost benefits over alternate materials for large diameter pipe manufacturing techniques. However, implementation of C-Mn steels in sour service does require increased focus on steel cleanliness and hardness control to avoid susceptibility to hydrogen damage mechanisms such as hydrogen induced cracking (HIC) and sulfide stress cracking (SSC). These additional requirements have been addressed in industry standards such as NACE MR-0175/ISO 15156. Despite these industry practices, recent pipeline projects have experienced failures related to SSC and have found increased surface hardness due to Local Hard Zones (LHZs) in delivered and installed pipe. The LHZ phenomena appears to be a relatively new concern to the industry, and has led to concern over use of TMCP steels after the Kashagan pipeline failure in 2013. ExxonMobil has developed a qualification program based on the requirements of NACE MR-0175/ISO 15156 and new insights regarding the root cause of LHZs. This work reports details on this qualification approach implemented for X65 grade line pipe from recent qualification activities with TMCP plate and line pipe suppliers.
Advanced Non-Destructive Methods for Defect Characterization Under Coating for In-Service Storage Tanks
Authors: Sohail Touqeer , Bohaichuk Katarina , Eley Devin , Hill Mike
Published: December 2022

In recent years there has been significant development of non-destructive technologies for on-stream inspection using remotely operated tools. Many operator companies have a keen interest in adopting such technologies to fulfil the integrity, reliability, and regulatory requirements while minimizing the operational impact. There has been substantial development of in-line inspection tools for pipeline defect characterization, but there is an industry gap of such tools for in-service floor inspections of crude oil storage tanks. Further research and development are required to overcome the challenges of sludge removal, sensor data acquisition under sediments, tool navigation in a viscous product, and electrical hazards in flammable and combustible products.

To accelerate industry innovation, Enbridge has designed and constructed a test tank environment which is a small-scale version of a large-capacity crude storage tank with prefabricated floor defects for vendors to evaluate their robotic in-service inspection equipment. This paper will describe the test tank design as well as the stages of the project for evaluating tool performance in different product environments. In the first stage, the tools will be tested in water, and their performance will be compared with conventional technologies used in out-of-service inspections.
Development of CTOA Requirements for Ductile Fracture Arrest in Gas Pipelines: FE Model and Simulations
Authors: Bassindale Chris , Wang Xin , Tyson William R. , Xu Su
Published: December 2022

In this paper, an engineering analysis approach is presented to predict fracture arrest CTOA requirements for gas pipelines using finite element (FE) analysis. A model with constant CTOA as fracture criterion was developed using the commercial FE code ABAQUS 2017x-explicit. Dynamic pipe fracture simulations were performed to determine fracture resistance curves (crack velocity as a function of pressure at constant CTOA) for an American Petroleum Institute (API) X80 steel pipe of diameter 914 mm to 1422 mm and thickness 13 mm to 26 mm. The model incorporated a user subroutine and shell elements. Backfill effects were modelled using smooth particle hydrodynamics and the flap pressure profile was modelled using experimental data from previous burst tests. Fracture resistance curves were compared with the gas decompression curve to determine the minimum arrest CTOA (point of tangency) for a given pipeline design (material, geometry, and gas). Results (arrest CTOA) of the given steel grade and design parameters (thickness, diameter, and backfill) are presented and compared with two previous arrest models that use the CTOA as fracture toughness parameter.
In-Service Welding Onto Methane/Hydrogen Mixture Pipelines
Authors: Bruce William A. , Huising Otto Jan , Boring Matt , Amend Bill , Gould Melissa
Published: December 2022

The objective of the recently completed Phase 1 of a joint industry project (JIP) at DNV, the results of which are described in this paper, was to determine if welding onto an in-service pipeline that transports a mixture of methane and hydrogen results in an increased risk of hydrogen cracking and, if so, to develop guidance pertaining to measures that can be taken to mitigate the increased risk. The mechanisms and the extent to which steel line pipe can become charged with hydrogen when transporting methane/hydrogen mixtures were reviewed. An experimental program was undertaken to determine the extent to which elevated weld hydrogen levels can result during welding onto pipe pressurized with blends of hydrogen and methane (Task 2a) and from welding onto steel that has been exposed to high pressure blends for an extended period of time (Task 2b). The results of Task 2a showed various increases in weld hydrogen level, depending on the pipe wall thickness, the weld heat input, and the partial pressure of hydrogen. Reactions between the pipe contents, the line pipe steel base material, and surface oxides were also observed. Task 2b resulted in no significant increase in weld hydrogen level as the result of welding onto steel that had been exposed to a high pressure blend for an extended period of time.

Additional work is required to determine threshold conditions beyond which increased weld hydrogen levels do not occur and to quantify increases in weld hydrogen levels for a broader range of conditions, including higher and lower partial pressures of hydrogen.
Influence of Model Error as Epistemic Uncertainty in Reliability-Based Integrity Management
Authors: Koduru Smitha , Ibrahim Mahmoud , Shahzad Khurram , Hassanien Sherif
Published: December 2022

Uncertainties that influence the estimated probability of failure (PoF) are of two types: uncertainty due to inherent randomness of the physical properties and measurement error (termed ‘aleatory uncertainty’), and uncertainty due to lack of knowledge or simplification of physical processes represented in the empirical models (termed ‘epistemic uncertainty’). The objective of this study is to demonstrate the effects of epistemic uncertainty, represented as model error related to 1) reliability-based decision making for single features; 2) development basis of model error distributions; and 3) system wide reliability assessment.

In this study, the effect of model error is demonstrated with two approaches. First, the model error is estimated for various subsets of population features to demonstrate the effect of sub-populations on the model error distributions. Second, the epistemic uncertainty due to model error is separated in the estimation of failure probability. The effect of model error is represented by estimating the failure probability as an interval instead of a point estimate. The effect of using the range of failure probability, instead of a point estimate, on the reliability-based integrity management of both individual features and the system-wide decision-making is demonstrated.
Implementation and Validation of Reliability-Based Crack Assessment for Natural Gas Pipelines
Authors: Xiang Wei , Zhang Shenwei , Yan Jason , Sanjuan Riverol Elvis , Myden Kyle
Published: December 2022

Traditional in-line inspection (ILI)-based crack management programs use deterministic methods, where the calculated failure pressure ratio (FPR) and ILI-reported crack depth are compared with their respective thresholds. In recent years, TC Energy has developed a probabilistic crack assessment method, where annual probability of small leak (POSL) and probability of failure (POF, i.e., probability of burst) are evaluated. The mitigation plan is then made by comparing the annual POSL and POF with their respective thresholds. The advantage of the probabilistic method over deterministic method is that the former portrays reality better by explicitly accounting for the uncertainties associated with pipeline geometric and material properties, ILI-reported crack sizes, crack growth and burst pressure models.

This study demonstrates the safe implementation of the probabilistic assessment method for stress corrosion cracking (SCC) based on EMAT-reported ILI data and correlated dig data associated with three natural gas pipelines in Canada. Comprehensive validation was conducted by comparing the EMAT-based mitigation plan with the in-ditch assessment of a large set of dig data. Three key questions were addressed in the validation: (1) Does the probabilistic method capture all critical features identified in the field? (2) Whether the features avoided by the probabilistic method were unnecessary to excavate based on in-ditch assessment? (3) What is the benefit of the probabilistic method in comparison with the traditional deterministic method?

The examination indicates that the developed probabilistic assessment process captures all the critical SCC features identified in the field, and the digs avoided by the probabilistic method are confirmed to be unnecessary in the field. The result demonstrates that the reliability-based method can reduce a significant number of unnecessary digs without compromising safety.
The November 2021 British Columbia, Canada Storm: Observations and Lessons Learned From Assessing Pipeline Infrastructure Subject to Natural Disasters
Authors: Baumgard Alex , Thompson Matt , Van Hove Harmen , Sullivan Sean
Published: December 2022

In mid-November 2021, southwest British Columbia (BC), Canada was struck by a significant storm system dropping record rainfall over a 2-day period. This storm manifested resulted in significant impact and damage to critical infrastructure including bridges, highways, railways and pipelines, as well as leading to flooding that cut-off the most populated region of BC from the rest of Canada and an estimated rebuilding cost of $10 billion Cdn. This paper provides a background on the storm and the conditions that preceded it, remote sensing data that was gathered during and immediately following the event, mitigations that were implemented, and learnings needed to return the impacted pipelines into service.
Comprehensive Pipeline Record and Inspection Data Review and Assessment in Response to Safety Advisory on Girth Weld Strain-Induced Failures
Authors: Arbeau Craig , Clyne Alasdair , Bhatia Arti , Young Andy
Published: December 2022

Recent incidents outside Canada prompted the Canadian Energy Regulator (CER), the British Columbia Oil & Gas Commission (BCOGC) and the Alberta Energy Regulator (AER) to advise pipeline operators regarding the possibility of girth weld strain-induced failures in high strength pipe. In early 2020, the CER issued a Safety Advisory (SA) relating to the possibility of girth weld strain-induced failures in high strength (Grade X 70 or higher) steel line pipe. There was a concern that similar incidents could occur in Canada, given comparable conditions. Furthermore, the SA stated that.... “The CER expects that regulated companies can demonstrate that longitudinal strains resulting from loadings such as those described in Section 4.2.4 of CSA Z662-19 [essentially external loading over and above typical operating loads] have been accounted for in the design, construction and operation of pipelines where strain could potentially accumulate in under-matched girth welds”.

With respect to the SA, the failure causes were consistently linked to combinations of:

i) high strength pipe with a minimum tensile strength exceeding actual weld strength values,

ii) girth weld HAZ softening as a result of the welding process,

iii) loads applied to the pipeline causing additional longitudinal strain, and

iv) pipes welded with a standard bevel and alignment of approximately 45° between the heat affected zone (HAZ) and the root bead.

Emera New Brunswick (Emera) initiated an assessment of the 30 inch diameter, 145 km long, API 5L Grade X70 Brunswick Pipeline that evaluated:

i) pipeline material, welding and construction records with respect to specified requirements, and

ii) the propensity of the pipeline to external loading via the analysis of repeat inertial measurement unit (IMU) data and a geohazard review of locations exhibiting bending strain to understand the stability of the pipeline in relation to potential external loading.

This paper describes the systematic approach taken to address the potential concerns, the key results and recommendations of the study and how Emera has incorporated those findings into processes within its management system and protection programs.
Subset Simulation of Pipeline Corrosion, Crack, and Dent Defects Considering Multiple Limit States With Large-Scale Validation
Authors: Bandstra Daryl , Fraser Alex , Rojas Juan S.
Published: December 2022

Structural reliability is an engineering method that focuses on the calculation and prediction of the probability of failure for a structural system. Structural reliability is used by many pipeline operators to assess the probability of failure, and these probability of failure estimates are then used to manage safety, environmental, and operational risks for threats such as corrosion, cracking, and third-party damage. In the structural reliability approach, the probability of failure is obtained from a multi-dimensional integral, for which the solution is commonly estimated numerically using Direct Monte Carlo (DMC) simulation. DMC is straight-forward and robust but requires a significant amount of computational effort to estimate small probabilities, which are typical of threats to pipeline integrity. Subset Simulation is an approach that improves on the efficiency issues of DMC by representing the rare event probability as the product of a number of more frequent events, which are each estimated separately. Previous work published at IPC in 2020 by Bandstra and Fraser [1] showed very close agreement between DMC and Subset Simulation for a single defect reference case with a single limit state. This study extends that initial work by applying Subset Simulation to various failure models for a variety of pipeline defects. Subset Simulation is applied to the CSA corrosion model, PRCI MAT-8 crack model, and the EPRG dent failure model, and the performance is evaluated by comparing the results to DMC. For each of these comparisons, simulations are performed across a large-scale grid of validation cases that consider a range of pipeline and defect sizes. An approach that utilizes Subset Simulation to handle multiple limit states is also presented and applied for relevant failure models and the results are evaluated against DMC.