bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of Running Ductile Fractures in Dense-Phase and Supercritical CO2 Pipelines Designed Per DNV-RP-F104 and ISO-27913
Authors: Ghoraishi Parnian , Zhou Wenxing , Kang Jidong
Published: December 2024

Transmission pipelines carrying dense-phase and supercritical CO2 are susceptible to running ductile fractures (RDF). This vulnerability arises from the unique thermodynamic characteristics of dense-phase and supercritical CO2 during its release from an orifice in the pipeline. Dense-phase and supercritical CO2 pipelines operate at high pressures, and depressurization resulting from a through-wall fracture can lead to a phase change in CO2. The present study investigates the differences between two well-known standards DNV-RP-F104 and ISO-27913 in terms of the minimum wall thickness and Charpy v-notch (CVN) impact energy required for the RDF control for a set of analysis cases representative of dense-phase and supercritical CO2 pipelines. The prediction of RDF is commonly carried out using the Battelle two-curve method (BTCM). Given the long plateau in the decompression wave speed curve that is typical of CO2 pipelines, a simplified BTCM is employed in this study for the RDF assessment by comparing the arrest pressure with the saturation pressure. The arrest pressure is computed using the Battelle through-wall crack model with modifications based on full-scale experimental data reported in the literature. The open-source tool RAMDECOM is used to compute the saturation pressure for a given set of initial operating pressure and temperature based on the one-dimensional isentropic decompression assumption and rigorous equation of state. It was observed that the wall thickness and CVN impact energy values determined per ISO-27913 are higher than those determined per DNV-RP-F104, suggesting a more conservative design based on ISO-27913. DNV-RP-F104 emerged as more straightforward for designing the analysis cases considered in the present study, whereas ISO-27913 necessitated adjustments in the calculated wall thickness to adhere to its maximum CVN impact energy requirement.
Stress-Strain Simulation of Viscoelastic Model of Sealing Disc Material for In-Pipe Detector
Authors: Wang Xingyu , Guo Yanbao , Zhang Zheng , Wang Deguo
Published: December 2024

In the pipeline inspection industry, polyurethane materials are chosen as the material for sealing discs in pipeline inspection detectors due to their excellent oil resistance, chemical stability, and mechanical stability. However, polyurethane materials are highly prone to generating interface frictional heat and adhesive wear during operation, presenting challenges in signal acquisition and detection. The simulation of frictional heat and adhesive wear necessitates the utilization of a viscoelastic model. Currently, the mechanical performance simulation of polyurethane materials often employs hyperelastic models, such as the Mooney-Rivlin model, which neglects the mechanical hysteresis losses induced by viscosity. This not only hampers the accurate evaluation of the sealing disc’s mechanical performance but also precludes the description of the generation of frictional heat and wear. In this study, compressive stress-strain tests and compression relaxation tests carried out on polyurethane materials. The generalized Maxwell model representing the viscoelasticity and the Mooney-Rivlin model representing the hyperelasticity were obtained. The Abaqus software’s “dynamic, explicit dynamics module” was employed to calculate the stress-strain distribution over time for the two models under different pressures. The models were constructed for polyurethane annular materials and steel annular materials using a face-to-face contact form, with a load range of 0.1 MPa to 0.5 MPa. In comparison with the hyperelastic model, differences in the stress-strain relationship over time were observed between the two models. Moreover, the material’s strain was found to be correlated with the change in stress. The viscoelastic model can provide a more accurate description of the material’s mechanical performance, with differences primarily manifested in the phase lag effect of the angle. This research opens up a new research direction for establishing a viscoelastic mechanical model for sealing discs in pipeline inspection detectors, enabling the possibility of studying the dynamic face-to-face friction model of viscoelastic materials (including frictional heat simulation and wear distribution calculations) through simulation calculations.
CO2 Dispersion Analysis Factors and Their Impacts on Pipeline Routing
Authors: Compton Nicola
Published: December 2024

Carbon capture and storage projects worldwide have grown by 48% in the last year [1]. This industry’s growth has also seen an increased need to transport carbon dioxide (CO2). The analysis performed and discussed in this paper is based on real project examples. The projects demonstrate how the application of dispersion analyses impacted significant project and pipeline routing decisions, with major potential capital and public safety implications. This is particularly relevant to our industry, which expects to increase the CO2 transport capacity significantly.

There are many hazards associated with CO2 due to the following properties: CO2 is colorless, odorless, heavier than air, is an asphyxiant and is an intoxicant. An uncontrolled release may spread undetected near the ground or in confined spaces.

With the rise in CO2 pipelines, challenges associated with pipeline routing need to be addressed. Ideally, pipelines should be routed in areas with sparse population densities due to the hazards to people associated with a CO2 release. Several factors affect how far from populated areas a pipeline should be routed. These include the most common local weather conditions (average temperature and average wind speed/direction), pipe size, the surrounding terrain, and the pipeline inventory.

This study will show the comparison of dispersion modelling results from three pipeline diameters (12″, 20″ and 36″) in a rural and an urban setting for four types of weather conditions, (stable and neutral atmospheric conditions for both summer high temperatures and winter low temperatures). The comparison of results will demonstrate the variables that must be considered at the early stages of pipeline routing.
Full-Scale Physical Modeling of Axial Soil-Pipe Interaction in Organic Soils
Authors: Jayasinghe Thushara , Wijewickreme Dharma
Published: December 2024

Organic soils (i.e., muskeg, peat deposits) cover 18% of the Canadian landscape and many energy pipelines cross these soil terrains over large distances. Thermal changes due to operational and environmental reasons pose a significant threat to the structural integrity and safety of pipeline systems in these soils. Engineering design of pipelines in muskeg terrains involves many challenges, mainly due to the lack of understanding of the mechanical behavior of organic soils. Such knowledge gaps have caused an absence of well-adapted soil-pipe interaction (SPI) assessment methodologies for pipeline design in organic soils, unlike the methods readily available for pipes buried in mineral sandy/clayey soils (e.g., PRCI guidelines [1]). In view of the above, a detailed research program is undertaken to study the soil-pipe interaction in organic soils. As a part of this program, a series of full-scale axial pipe displacement tests was conducted using a sand blasted 114 mm diameter steel pipe buried in organic soil simulating different H/D ratios, directly yielding axial p-y curves (i.e., soil springs). The “soil springs” representing muskeg are compared with those computed using equations given in PRCI guidelines [1] for pipes buried in clayey soils. Based on this, adjustments to these clay-based equations are proposed for generating axial soil springs for pipes buried in organic soils.
Performance of Terrain Mapping Estimation of Depth to Bedrock in Pipeline Construction Planning: A Case Study
Authors: Waddington Betsy , Toussaint Luc , Ghazali Rami , Baumgard Alex
Published: December 2024

Terrain mapping is the delineation of polygons with unique surficial geology, landforms and processes, and is often conducted at the start of a project to provide preliminary ground information, particularly in areas that have not been subject to significant development. Depth to bedrock, one of the attributes typically assigned to terrain mapping polygons, can be a key input in estimating rock excavation volumes through the design phase of a project. In this case study, design-level depth to bedrock estimation for three short new pipeline alignments routed through southeastern British Columbia are compared to detailed ground condition observations collected through construction. Possible causes of discrepancies are then discussed, leading to a review of the approach to conducting design-phase estimates for future projects.
Impact of Inline Isolation Tool on the Integrity of Onshore Pipelines
Authors: Debnath Suborno , Roy Kshama , Liu Tina , Yin Ole , Zhang Ken
Published: December 2024

Inline pressure isolation tools are widely used for offshore pipelines for planned maintenance and emergency repair work, e.g. valve replacement, repair, tie-ins. Design and engineering analysis of such tools for offshore application have been well developed. Although inline pressure isolation technology is widely used in offshore pipelines, its use in onshore application is limited. However, because of its capability of providing reliable in-line isolation with significantly reduced blown-down length and methane emission for integrity and capital projects that traditionally require pipeline outages, the inline pressure isolation tools are getting increased attention from the onshore pipeline operators in recent years. Consequently, there is a growing need for better understanding of applicability and limitations of using established offshore design rules for onshore applications and developing engineering assessment workflow to ensure successful execution and prevent potential irreversible damage to existing assets. One of the challenges for the application of pressure isolation tools to onshore pipelines is to better understand the pipelines stresses that are exerted by these tools during their operation. This paper investigates the impact of these tools on the integrity of onshore pipelines from stress perspective through leveraging 3-D continuum finite element (FE) analysis using Abaqus FE software, with consideration of actual loading and boundary conditions that onshore pipelines could involve. The FE model was first calibrated with a full-scale test to ensure accuracy and validity of the simulation. Subsequently, a total of 137 FE models were developed for a wide range of pipe sizes (NPS 10 to NPS 48) and wall thicknesses (4 mm to 26.4 mm). The resulting stresses were compared with the allowable stresses for the pipelines. Furthermore, a sensitivity study was performed for various pipe material properties to ensure that an adequate factor of safety is maintained throughout the analysis. Outcomes of the investigative study was fed into a streamlined assessment workflow that includes a series of simplified graphs for determining the allowable pressure for various pipe sizes for future applications. The results demonstrate advantages of using FE based streamlined approach over conservative case-by-case analytical solutions. The outcome of this study provides insights on the various stress conditions that could result from the inline isolation tool for onshore pipelines and could potentially impact pipeline integrity.
Fracture Toughness and Management of Cracking in Hydrogen Pipelines
Authors: Gallon Neil , Wynne Dominic , Baby Benjose
Published: December 2024

Due to the embrittlement effects of hydrogen on carbon steel, cracking has become a key technical focus for industry practitioners looking at the feasibility of converting existing pipelines to hydrogen operation. A prudent repurposing study should establish what crack size would be acceptable under hydrogen operation and at what rate it would grow through fatigue. This information allows for informed decision making when receiving baseline crack inspection data or considering what plausible crack-like anomalies could be present in the pipeline.

Although the potential repurposing of pipelines to hydrogen is new to the industry, the threat of cracking is not and there is extensive experience in the management of cracking. This experience includes quantifying acceptable crack sizes and the predicted remaining life of a pipeline. This quantification is based upon Engineering Critical Assessments, which rely for their inputs on knowledge of the crack dimensions and material properties (principally fracture toughness). For existing pipelines there is already a large body of work which helps define how to assess fracture toughness when different fracture toughness measurands (e.g. CTOD measurements or J-R curve data) or only Charpy V-notch tests are available. The applicability of these methods to a hydrogen pipeline is questionable.

This paper will explore what fracture toughness means in a hydrogen pipeline by comparing the different test methods and measurands, for example the threshold stress intensity factor (KIH) as defined in ASME B31.12 / ASTM E1681 as compared to fracture toughness measured under a rising load (ASTM E1820 type testing) and a potential “da/dt” threshold for crack growth under a static load. It will also illustrate some of the uncertainties around how to define fracture toughness in a rising load test, together with a discussion of the use of Charpy V-notch data in hydrogen service.

The paper will next illustrate what some of the uncertainties mean in terms of assessing cracks in hydrogen pipelines and demonstrate how the choice of test protocol and measurand can affect the critical crack size and detection capability. It will investigate the validity of the 50 ksi.in1/2 threshold stress intensity factor defined in ASME B31.12 and the implications of assuming this as a minimum fracture toughness value for a hydrogen pipeline.

In summary, the paper intends to provide an overview of quantifying the threat from cracking in H2 while showing how to establish a suitable operation window to meet remaining life expectations.
An Insight Into What it Takes to Validate Inline Inspection Tools for Reliable Hard Spot Identification and Measurement
Authors: Farnie Steven , Tindall Anthony
Published: December 2024

A hard spot is a localised area of increased hardness, defined in 49 CFR Part 192 as “an area on steel pipe material with a hardness greater than or equal to Rockwell 35 HRC (Brinell 327 HB or Vickers 345 HV10)”. Hard spots result in localised areas of increased residual magnetic field following magnetisation by an inline inspection tool run. These magnetic fields can be measured using a low or no field approach and used to detect and classify hard spots and to predict the hardness.

There are significant challenges in moving from pull test or dig data to creating a validated specification for hard spot inspection. The essential variables for hard spot inspection — sources of variation which must be controlled within defined limits for a successful result — are more numerous than for comparable inline inspection technologies. This is due to the two-step magnetization and measurement process and the range of factors related to the pipeline conditions, the hard spots themselves, and the inspection tool which could affect the magnitude of the residual field. The relative scarcity of hard spot examples and the difficulty in manufacturing hard spots to predictable tolerances means that the data required to validate across the range of all essential variables is not readily available.

This paper describes how Baker Hughes, in collaboration with industry partners, are using a multi modal approach to combine FEA, pull test and dig data to cover the essential variables required for inline inspection of hard spots and establish a validated POD, POI and POS specification.
Implementation and Optimization of a Multiphase, Transient Release Rate Model for Consequence Estimation
Authors: Middleton Steven , Svitich Aiden
Published: December 2024

The life safety consequences of CO2 pipelines and those carrying other toxic chemicals, unlike natural gas pipelines, are affected to a great extent by the outflow’s response to time and phase behaviour over a long timescale. Therefore, a critical part, of evaluating the hazard of releases is outflow modelling. To bridge this technical gap, as well as to produce a general model suitable for evaluating a range of product types, including natural gas and natural gas-hydrogen blends, a multiphase, transient release rate model is required. This paper outlines the enhancements applied to a method of characteristic-based flow solver, described by the University College of London, to facilitate its practical application to repeated simulations. These improvements include an adaptive grid and locally defined timestep; a REFPROP-derived equation-of-state property lookup table; a 1D wall heat-transfer treatment; a domain-extending boundary condition; and a numerical construct that uses a steady-state approximation of the conservation equations to extrapolate beyond the calculation domain to better approximate a semi-infinite pipeline.
The Blending of Hydrogen and Natural Gas by Direct Injection Into High-Pressure Large-Diameter Gas Transmission Pipelines
Authors: Curson Nigel
Published: December 2024

For many countries, blending hydrogen with natural gas into the existing gas transmission network is one of the critical steps towards energy transition. Blending allows relatively direct access to a market for hydrogen. It targets CO2 emissions associated with domestic and industrial consumption via existing connections. This is evidenced by the fact that in the EU 40% of households are connected to the gas network [1]. Blending has been trialled with medium-pressure, small-diameter public networks at relatively low volume flow rates for consumers, equivalent to a village. These first trials have proven hydrogen blending using a blending skid [2]; however, scaling a skid concept up from medium-pressure distribution diameters to transmission diameters and high pressures (32-inch and 85 barg, respectively) would require significant investment with sizeable equipment and a potentially disruptive intervention. Considerable economies can be obtained by injecting the hydrogen directly into the pipeline and using the pipeline itself as a mixer component. The challenges associated with this are achieving adequate mixing within a reasonable number of diameters downstream from the injection point, not exposing the inside surface of the pipeline to unacceptable percentages of hydrogen with the risk of embrittlement, and designing a nozzle or nozzles that are practical from a manufacturing perspective, allow inline inspection, don’t introduce a structural weakness, or have demanding construction or operational implications. This paper proposes various solutions with results backed by analytical modelling using Computational Fluid Dynamics (CFD).
Dent Safe Excavation Pressure and Fracture Reliability Assessment With Machine Learning
Authors: Tang Huang , Di Blasi Martin , Okoloekwe Chike , Yoosef-Ghodsi Nader
Published: December 2024

Dents can potentially cause cracking or pipeline leaks posing a threat to pipeline integrity. Engineering critical assessment of dents interacting with cracks plays an important role in the risk and integrity management of pipelines. It is not an easy task to conduct fracture assessment on a dent-crack defect due to the complexity of the stress field in the dent area. The failure assessment diagram (FAD) method has been widely used to conduct elastic-plastic fracture mechanics analysis of structural components [1, 2]. The FAD approach can be used to conduct fracture assessment for an arbitrary through-wall thickness stress distribution in a pipe with cracks. Finite element simulations are normally required to extract the stress distributions for a pipeline dent. However, the process is computationally demanding and tedious.

A machine learning-based methodology has been developed to improve the efficiency of the process of dent fracture assessment. The machine learning algorithms were trained using a dataset built from finite element simulations of dents. Through-wall thickness stress distributions at multiple critical locations with potential cracks in the dents were extracted for varied dent geometries at multiple pressure levels. The extracted stress distributions were used to calculate stress intensity factors (SIFs) for a wide range of crack dimensions based on the SIF solutions obtained from API 579 [3]. The output variable of the machine learning model was defined as the ratios of SIFs with and without dents. The inputs to the machine learning algorithms to train on include pipe and dent geometries, crack dimensions and pipe internal pressures. The model performance was evaluated through a three-way holdout method. It was shown that the trained machine learning models were able to effectively predict SIFs for dent-crack defects with varied dent geometries. The models were also shown to be robust when used to conduct Monte-Carlo simulations as part of a reliability assessment to develop a distribution of SIF accounting for uncertainties on the model input variables.

Dent fracture assessment with the trained machine learning models was employed in the determination of safe excavation pressure (SEP) based on a reliability analysis. The fracture assessment was conducted using the API 579 FAD approach. The effectiveness of the FAD method on the prediction of burst pressure limits for dent-crack defects was validated with full-scale tests. It was then shown that the machine learning model-based approach was effective in conducting reliability-based fracture assessment on dent-crack defects with the FAD method to determine SEPs corresponding to given reliability targets. The efficiency on the process of SEP determination has been significantly improved compared with the surrogate modeling approach using stress distributions extracted from the finite element simulations [4].
The Influence of Pipe Toughness in the Consequences of Third-Party Damage – A Comparison Between EPRG and Fracture Mechanics Methodologies
Authors: Anilkumar Suvarnalatha Vipin , Curson Nigel , Mcintyre Thomas , Alani Ali
Published: December 2024

Onshore and offshore pipelines provide one of the safest modes of transportation for oil and natural gas. Some offshore pipelines pass through areas where large vessels are active and risk third-party damage, particularly if the pipeline is not trenched. Most prominent ship traffic-related incidents are caused by anchoring in an emergency or indiscriminately. These incidents can cause bending, denting and gouging of the pipe wall leading to immediate rupture of the pipeline or fatigue failure over a short period if not remediated. Examples of severe pipeline damage incidents caused by anchor drop/drag damage include 2021 San Pedro Bay oil spill incident in USA [12] and the 2023 Baltic Sea gas pipeline incident in Finland [13].

In December 2022, an anchor was found to have damaged a 16-inch pipeline in the UK North Sea. The damage was not initially apparent, so the pipeline continued to operate for a few months until visual inspection revealed two severe dents. The pipeline was also displaced by 1.36m over a length of 30m. Gouges and cracking were expected but, initially, could not be confirmed. The Pipeline Defect Assessment Manual (PDAM) [6] recommends the use of European Pipeline Research Group (EPRG) methods [3,4] for assessing the tolerance and resistance of pipe to external damage by estimating the failure stress of a dent and gouge. However, the complexity of the interaction between a dent and a gouge, with the potential for cracking in the base of a gouge, limits the accuracy of this generalised method and demands a reasonable level of conservatism. An assessment of the dent using the methodology described in ASME B31.8 Appendix R revealed a high strain level (up to 12.7%) and a risk of material failure.

To establish whether a return to service is possible, an Engineering Criticality Assessment (ECA) was carried out based on the procedures given in BS 7910 [5]. The ECA results concluded that the dent is not expected to threaten the pipeline’s integrity during its service life.

This paper draws upon a case study to compare the EPRG dent/gouge model and the combination of Finite Element Analysis (FEA) and BS 7910 assessment methodology based on an arbitrary defect equal to a typical gouge and crack at the bottom of the gouge (this is an assumption specified in PDAM, based on the principle that it is hard to rule out the presence of a crack or limited dimensions).

Correlations were made between the low material test temperature and the pipeline ambient temperature to obtain a less conservative CVN value for use in the EPRG assessment. However, a more accurate and comprehensive methodology to calculate fracture toughness and assess the fracture resistance as per BS 7910 proved to be a more rational approach for assessing defects in a modern high-toughness line pipe.
Burst Pressure Prediction for Axial Cracks in Pipelines With Non-Ideal Depth Profiles
Authors: Dessein Thomas , Anderson Ted L. , Moritz Jason , Sun Xiaoyu
Published: December 2024

Crack-like anomalies in pipelines are complex features that typically have an irregular profile. However, due to modelling complexity, the common practice is to approximate such profiles with a semi-elliptical crack whose length is equal to the total flaw length and whose depth corresponds to the maximum depth of the flaw. This approach can result in significant underestimates of burst pressure.

The PRCI MAT-8 pipeline fracture model has become widely used in the industry since it was developed in a PRCI project in 2015 [2]. The original version of the MAT-8 model was derived from over 200 3D elastic-plastic finite simulations of pipe joints with axial cracks. The PRCI study considered three crack types: semi-elliptical surface cracks, constant depth (canoe-shaped) surface cracks, and through-wall cracks. In 2019, the Modified MAT-8 model was introduced to address non-ideal crack depth profiles [3]. An extensive finite element study was undertaken to model numerous non ideal longitudinal crack profiles in pipe joints. The output from these analyses led to a procedure to convert an arbitrary crack profile into an equivalent semi-elliptical crack. The depth of the equivalent crack is equal to the maximum flaw depth, but the length is typically much less than the total flaw length. Accounting for actual depth profiles, as opposed to the semi-elliptical assumption, affects computed burst pressures by as much as a factor of 2.

The procedure described in this study improves upon an earlier phase of work [3] that developed an approach which was accurate for cracks with a single isolated deeper section that dominates the fracture demand. Since then, more real-world profiles have been assessed and several cases identified for which the previous procedure underestimated the fracture demand. The new procedure resolves this while ensuring a slight conservative bias and maintaining an accuracy that is comparable to typical inline inspection tool length sizing accuracy.

The algorithm considers interactions between deeper sections of the crack profile to increase the length of the equivalent semi-elliptical crack. While the algorithm was developed and calibrated using machine learning techniques, it can be implemented without any specialized machine learning tools.

To apply the algorithm in a probabilistic framework, the in-line inspection (ILI) measurement uncertainty must be characterized at all points along the crack profile. ILI vendor specifications on measurement uncertainty however only cover the uncertainty in reported maximum depth and total length. In this study a method to automatically align over 17,500 ILI profiles collected from repeated measurements of over 8,800 crack-like features was developed so that the repeatability of the reported maximum depth and total length could be quantified and the point-to-point error along the profiles characterized.
Data Fusion of Complementary Axial and Circumferential Magnetic Flux Leakage Inline Inspections and Effects on Safe Remaining Life
Authors: Peng Xiang , Siggers Kevin , Wright Mark , Palmer Johannes
Published: December 2024

Measurements from magnetic flux leakage (MFL) in-line inspection tools include two types of uncertainty: random uncertainty arising from essential variables such as velocity and magnetization level; and systemic uncertainty from the measurement principle. The accuracy of the measurement principle is subject to the angle between its magnetic field and the metal loss anomaly. To gain a comprehensive assessment of anomalies, pipelines can be inspected with two MFL techniques with perpendicular magnetic fields, i.e., axial MFL (MFL-A) and circumferential MFL (MFL-C). Currently, the inspection data from each MFL tool is analyzed separately, and two inspection reports are generated respectively. Comparing the two inspection reports, the conflicting results due to the change in angle become obvious and expert opinion is relied upon to make the most appropriate assessment. Fusing the original complementary data sets together overcomes the subjectivity, enables one unique outcome, and greatly reduces the uncertainty. To take advantage of the complementary information of two MFL inspections, ROSEN’s novel machine learning-based data fusion model is applied to the aligned MFL data sets to generate a high-resolution 3D metal loss depth map. The validity of the proposed model is verified using the field data from six operational pipelines of varying diameters. The performance regarding depth prediction and burst pressure calculation is assessed using API STD 1163 Level 3 validation methods. The depth comparison of the derived 3D metal loss depth maps versus laser scans shows strong correlation in both morphology and depth. The safe remaining life of metal loss anomalies in the studied pipelines have been calculated to demonstrate differences due to the new levels of measurement certainty. In addition, as 3D depth maps are now generated, the results differ from traditional box profiles for burst pressure calculations such as Remaining Strength (RSTRENG) and Plausible Profiles (Psqr). The consistent performance on all six pipelines proves the generalization of the data fusion model.
Preliminary Considerations of a Risk-Informed Approach for Climate Change Resilient Pipeline Geohazards Management
Authors: Read Rodney , Rizkalla Moness , Di Blasi Martin , Kowis Jared
Published: December 2024

Risk-informed management of pipeline geohazards within the bounds of historical climatic records has been adopted widely in the pipeline industry. The emergence of extreme rainfall events, and related indicators of climate change, that fall well outside the historical data pool presents a challenge in terms of reliability of predictions of significant geohazards capable of damaging pipelines. A review is undertaken of several major precipitation events outlying from their respective recorded historical trends that have impacted pipeline assets globally. Several sites are selected to estimate magnitude and frequency of future extreme weather events characterized in the context of different extreme-value statistical distributions. A general approach is evaluated based on the back analysis characterization of this sample of events to assess if and how these events may be prudently treated as part of a risk-informed pipeline geohazard management program. Several aspects of implementing this approach are discussed including its application based on geological provinces and microclimatic zonation, and the integration of rainfall ground-movement models and the associated effect on pipeline strain accumulation. An elaboration of a fuller evaluation and implementation of this approach as part of a machine learning supported pipeline geohazard management workflow to address climate change resiliency of pipelines is discussed. The findings of this paper support focused implementation of an extension of the practice of risk-informed geohazard management accounting for events that may deviate significantly from historical records for select critical high consequence areas of interest. For the purposes of illustration, this paper focuses on landslide hazards.
Industry Material Property Databases and Their Use in Integrity Programs
Authors: Guest Stuart , Slumkoski Zoe , Dinovitzer Aaron , Al-Amin Mohammad
Published: December 2024

Integrity programs can be data hungry based on the desire to fill information gaps and increase the accuracy and refine fitness-for-service assessments. The application of risk-based programs further expands the hunger for data based on their need for significant volumes of material property data to properly capture variations unique to the materials. Databases are an attractive method to store and manipulate material data however obtaining a statistically significant volume of data for older line pipe materials can be difficult. The data holdings of individual pipeline operators may have gaps and may not have a sufficient volume of data to meet these needs. PRCI, as a pipeline industry association, has created a material property database that contains strength, toughness, and chemical composition data for line pipes ranging from 1930 and newer. The data has been obtained through material testing, either from the mill test report (MTR) or supplemental testing on removed pipe, and stored in a blinded manner (to maintain anonymity) that maintains traceability to the original data record within the database.

The goal of the database is to pool PRCI Member company data and others to support industry’s material property data demands for current operating scenarios and future product types (e.g., hydrogen). To-date, this database contains over 20,000 datapoints from over 1,000 unique materials, including popular 1950–70’s line pipe. The recent regulatory requirements of traceable, verifiable, and complete material properties will be discussed within the context of a joint industry database and how pooled databases can be used to provide alternate and substantiated material properties for unique pipe attributes such as pipe mill, manufacturing year, diameter, grade, and thickness. Several case studies and examples of the database are provided in the paper, including statistical relationships used and sample distributions of material properties that could be used to bolster integrity management and risk-based programs.
Towards Solid Ground: Integrated Components of Landslide Threat Management
Authors: Bracic Jan , Chung Man Chun , Ndubuaku Onyekachi , Ferguson James , Guthrie Richard
Published: December 2024

As conduits of energy, pipelines convey products from a point of origin to end-users. On the way, each pipeline inevitably traverses natural geographical landforms, including slopes and waterways, which can impart stresses to the pipe. Over time, weather-related and outside forces alter the landscape and pipelines may be subject to interacting effects of ground movement, in terms of imparted high axial/longitudinal stresses that may not have been accounted for in the pipeline design. Evaluation of these effects can identify when the operating safety margin of the pipe is threatened and if intervention is required to maintain structural integrity.

Different than the steady progression of time dependent corrosion and axial cracking, ground movement is episodic with a trend towards accelerating rates leading to slope failure.

Successful management of ground movement therefore requires sufficient lead time to observe early effects and plan intervention. We present herein the integration of three components that form a basis for holistic landslide threat management: a structured tool that estimates probability of failure (POF) for landslides combined with a parameterized tool that evaluates pipe resilience underground movement, and a visual analytics tool for ILI/IMU bending strains, that independently validates the findings of POF and pipe resilience.

The POF Calculator for Landslides is a structured tool to calculate probability of failure (POF) using expert judgment supported by known, instrumented or observable conditions and statistics (where available). This tool is augmented with discretized Pipe Vulnerability relative to magnitude of displacement for more accurate characterization of effects due to ground movement, thereby providing a high-level screening for strain-based design and assessment (SBDA) in advance of full evaluation using FEA. We show how analysis of measured bending strains can be used to corroborate findings from the POF Calculator for Landslides, providing assurance that the model is valid.

The integration of these components is designed to provide a reliable basis for informing decisions and establishing plans to manage the threat of landslides interacting with pipelines.
Making Progress in Implementing Pipeline Safety Management Systems by Gas Distribution Operators
Authors: Tahamtani Massoud , Hulett Michael
Published: December 2024

Pipeline Safety Management Systems (PSMS) is the formal top-down, organization-wide approach to managing risk through systemic procedures, practices, and policies. A PSMS underpinned by a strong safety culture assures the effectiveness of safety controls. This paper will present the background regarding the need for PSMS in order to reach the goal of zero incidents, the status of PSMS implementation by gas distribution operators in the U. S., the feasibility of PSMS implementation by operator size, and finally, ideas that can help promote the implementation of PSMS.
Methodology to Identify Potential Sites for Susceptibility to Low Strength Girth Weld Behaviors
Authors: Guest Stuart , Salve Clifton , Dinovitzer Aaron , Szakaly Erik , Heydarimanesh Homa , Kohandehghan Alireza
Published: December 2024

Since 2000, numerous instances of field girth weld failures have led to product releases, attributed primarily to the difference between weld metal strength and unexpectedly high base metal strength or significant softening in the heat-affected zone (HAZ). These causal factors often result in girth welds of lower strength, prone to failure at low global strains, near the actual material’s yield strength. These results indicate that external loads alone are not the primary cause of through-wall failures. The documented failures consistently reveal that the presence of low-strength girth welds substantially contributes to these failures, despite meeting welding code requirements. In response, operators started conducting engineering assessments to evaluate the risk associated with low-strength girth weldments in the existing pipelines. Performing detailed engineering assessments on every pipeline weld is not feasible. Hence, a comprehensive screening engineering assessment has been developed to evaluate the risk each girth weld poses systematically, incorporating metallurgical, girth weld, and structural considerations. Metallurgical analysis involves assessing pipe grade and manufacturing year to gauge HAZ softening and potential weld metal strength undermatching. Girth weld assessment focuses on the weld metal’s strength, influenced by heat input during welding and the use of low-strength electrodes, alongside quality assurance measures such as in-field parameter monitoring, test welds, and historical performance. Structural considerations include potential exacerbating factors like weld misalignment, thickness transitions, and external load sources. This integrated approach has proven effective in identifying vulnerabilities to failures associated with low-strength girth welds, including undermatching and HAZ softening. The paper presents a case study applying this methodology to an operational pipeline, demonstrating its utility in preemptively identifying and mitigating risks associated with girth weld failures.
Next Generation Hit Rate Fault Tree for Third-Party Activities
Authors: Fujinaga Daniel , Yue Howard , Adianto Riski , Stephens Mark
Published: December 2024

Fault tree models have been developed and used over the past two decades to estimate the frequency with which buried onshore pipelines are damaged during third-party ground disturbance activities. The estimated hit rate values can be combined with an estimated probability of failure given hit to assess the likelihood of pipeline failure due to third-party mechanical damage in a comprehensive quantitative risk assessment of a pipeline. Public domain and proprietary fault tree models that the authors are aware of have all been developed from pre-2010 research efforts, which highlights the need for an updated model that better reflects the most recent third-party damage statistics and modern damage prevention measures currently being employed or considered by pipeline operators. In response to this need, a next generation model for estimating the hit rate from third-party activities on a pipeline alignment has been developed for buried onshore pipelines as part of a joint industry project (JIP) that commenced in 2020.

The new hit rate model can be considered hierarchical, consisting of an upper aggregation subtree and lower-level fault trees. The upper-level subtree delineates external interference activities based on the types of equipment involved and the season (i.e. summer versus winter) in which they occur. While previously developed models usually only address general excavation involving excavators or backhoes as the sole interference activity type, the new model also considers vertical and horizontal drilling and agricultural tilling. The lower-level fault trees address the effectiveness of the various available damage prevention measures, with due consideration of the various equipment types and season of occurrence combinations defined in the upper-level aggregation subtree.

In developing this new hit rate model, the seasonally dependent frequency of ground disturbance activity on the pipeline alignment by equipment type and the effectiveness of candidate damage prevention measures at reducing the hit frequency were calibrated using the latest available information in the public domain and from JIP participants. In addition, the outputs obtained from the new hit rate fault tree were validated using the most recent historical hit rate data found in the public domain. To illustrate the predictive capabilities of this new third-party damage fault tree model, the relative effectiveness of selected damage prevention measures is examined through a set of comparative scenario analyses.
CFD Analysis of Gas Pipeline Internal Coating Degradation on Flow Efficiency
Authors: Leung Teresa , Botros Kamal K. , Jensen Larry
Published: December 2024

Flow efficiency coating (FEC) is a thin-film, solvent-based epoxy coating that is commonly applied to dry natural gas pipelines. There are a number of benefits in using FEC on the pipe internal surface. The primary benefit is the reduction of pressure drop in the pipeline, which enables an increase in the gas flow rate through the pipeline for a given pressure drop between compressor stations. Therefore, for a given flow capacity, the application of FEC reduces the power consumption of compression and the greenhouse gas emissions for the transportation of natural gas. Secondary benefits include corrosion mitigation, easier and faster drying after hydrostatic testing, improved mobility of ILI tools, and the inhibition of black powder formation within the gas pipeline. It has been postulated that the FEC degradation over time has contributed to the observed loss of flow efficiency. Degradation of the coating film can be in the form of patches of varying area sizes peeling off, or scattered blisters like spots forming on the coated surface. Inspecting the coating quality for operating pipelines is very challenging. The objective of this work is to simulate using computational fluid dynamics (CFD) the effects of “peeling” or “blistering” on the pressure drop along a NPS 16 pipe segment. The CFD results show that only 1% of the surface area covered by small-sized blisters (1.5mm in height) could result in a 22% increase in pressure drop per pipe length as compared to that of a perfectly coated pipe. As for the case where 10% of FEC has been peeled off, this could result in over 30% increase in pressure drop, which is comparable to that of an uncoated pipe. While these quantified losses are specific to the simulated geometries, this information can help with the operation team to decide whether such degradation mechanisms are plausible in explaining the observed flow efficiency losses in their system.
A Risk-Based Approach to Managing Exposed Pipelines
Authors: Okoloekwe Chike , Sen Millan
Published: December 2024

Transmission pipelines are typically buried to meet the regulatory-specified depth of cover requirements to minimize their impact on the environment and the public. However, due to the erosion of the cover or grandfathered design, pipeline exposures are observed. Within North America, thousands of pipeline exposures are currently present (generally focused within swampy locations) as identified through depth of cover surveys.

Exposed pipelines exhibit increased vulnerability to integrity and safety threats. For example: an exposure on a trail would be susceptible to being struck by an all-terrain vehicle. Correspondingly, a holistic approach is required to quantify the risks associated with exposed pipe sections to support site remediation decisions.

Protective measures such as managing the condition of the coating, placing armored articulated mats, or cordoning off the exposed perimeter or relocation can reduce the vulnerability of exposed pipe sections. However, the selection of an appropriate and financially viable decision should be based on a thorough risk assessment that considers safety, environmental impact and cost-effectiveness.

This paper presents an approach to assess the integrity and safety risks associated with exposed pipes. The model is based on the fundamentals of reliability engineering but also requires qualitative operator-specific inputs, which would be based on the knowledge of one’s system. The key inputs to the model include the probability of failure of integrity threats aggregated over the exposed length and the geospatial characteristics of the site. The model is then applied to a set of exposures in a case study, the exposures are risk-ranked, and the results are visually represented on a risk matrix. This type of assessment allows for a systematic approach to mitigation planning, ensuring that remediation efforts are directed toward sites with the highest risks.

Both the threats and consequences of exposed pipe sections are described herein, with the potential that this may serve as a tool (with operator-specific calibrations) for decision-makers when prioritizing risk treatments at pipeline exposures.
Enhancing 1D Liquid Pipeline Temperature Modeling With Online Learning and Optimization
Authors: Vejahati Frank , Tunvir Kazi
Published: December 2024

An innovative approach has been developed in the form of transient thermal modeling, which is finely tuned as an online learning and optimization problem. Extensive testing and validation have demonstrated the effectiveness of this approach in fine-tuning temperature profile across a wide spectrum of pipelines and operations. This method integrates Dakota software from Sandia lab with the Synergi Pipeline Simulator (SPS) from DNV to carry out a derivative-free global optimization. Real-time learning is applied to an external pipe heat source and soil conductivity, using a loss function defined as the difference between the modeled and measured temperatures. The mean loss is continuously employed to adjust the values of soil conductivity and the pipe heat source. The theoretical framework can be seamlessly implemented in other pipeline simulator packages, providing a versatile solution for the industry.