bluuebunny/crossref_metadata_2025 huggingface dataset:
Pipeline Circumferential Cracking in Near-Neutral pH Environment Under the Influence of Residual Stress
Authors: Shirazi Hamed , Chen Weixing , Eadie Reg
Published: December 2024

Despite the implementation of protective coatings and cathodic protection in buried pipeline steels, the occurrence of Near-Neutral pH Corrosion Fatigue (NNpH-CF) remains a critical pipeline integrity management challenge. (Note that this mechanism has previously been termed near-neutral pH stress corrosion cracking.) This form of corrosion fatigue can only occur when the pipeline’s protective coating is damaged, exposing the pipe to corrosion conditions. Circumferential near-neutral pH corrosion fatigue (C-NNpH-CF), where residual and axial stresses play a pivotal role in service failures, is less understood than the more common axial form.

C-NNpH-CF failure involves several stages, including crack initiation and early growth (Stage I), sustainable crack growth (Stage II), and rapid crack propagation leading to failure (Stage III). Using the digital image correlation (DIC) method, this research examined the effects of bending residual stress (as a source of axial stress) and cyclic loading (simulating pipeline pressure fluctuations) on these stages. The evaluation included crack re-initiation from simulated dormant cracks, stage II crack growth, and failure mechanisms, considering various parameters such as applied loading, initial notch depth/position, and bending angle/direction.

The study determined the threshold conditions for crack reinitiation, highlighting the intricate factors influencing this phase. Additionally, crack growth rates during Stage II were compared with those from earlier works on longitudinally oriented NNpH-CF, providing a comprehensive understanding of the circumferential near-neutral pH corrosion fatigue process. Under the influence of maximum bending angle and axial cyclic loading, the highest crack growth rate was obtained at the bent centerline in the inward direction, where maximum tensile stress is concentrated on the external surface. Stage III was primarily governed by a high stress intensity factor, contrasting with Stage II, which was influenced by a medium stress intensity factor and hydrogen-enhanced fatigue. The stress gradient in the depth direction of a bent pipeline emerged as a significant factor affecting crack growth rates at different stages. This research has enhanced circumferential cracking modelling accuracy, aiding operators in mitigating risks, reducing costs, and minimizing environmental consequences associated with these failures.
Development of the Dynamic Model of Mass Movements Threat for the Corridor of the Central Oil Pipeline S.A., “OCENSA” in the Framework of the Management of the Climate and External Forces Threat
Authors: Correa-Calle Oscar , Botía-Díaz Manuel , García-Orozco Francisco , Quintero-Londoño Joan
Published: December 2024

A landslide threat analysis model is presented for the Central Oil Pipeline of Colombia, operated by OCENSA. It is part of an early warning system under development for making timely decisions to guarantee the integrity and operability of the infrastructure. The model combines susceptibility and accumulated rainfall thresholds triggering landslides with a probabilistic approach. The susceptibility analysis was performed using the weights of evidence method, considering geological, morphological, morphometric, and anthropic variables. It uses 1104 terrain instability events in a corridor of 836 × 50 kilometers. The input and output variables have a resolution of 30 × 30 meters. The validation of the model was done using the area under the receiver operating characteristic curve ROC, reaching a performance of 87.9%. The thresholds for accumulated rainfall triggering landslides are obtained using probabilistic models. Satellite monitoring of daily rainfall is conducted at 41 virtual stations using data from NASA’s Global Precipitation Measurement (GPM) mission. The stations are spaced every twenty kilometers along the pipeline axis in a 50-kilometer-wide corridor. The daily rainfall reports in the virtual stations are accumulated for different previous periods. Comparison of accumulated rainfall with thresholds allows calculating the temporal probability of landslides for different accumulation periods. The maximum temporal probabilities of instability in each sector are selected. By combining the susceptibility or spatial probability and the maximum temporal probability, the sectorized daily threat is obtained. The daily threat or space-time probability of landslides is analyzed for about 42.9 million pixels. This is represented on base cartography in five levels included in a probability range between 70% and 99.995%. The threat level at each pixel about the location of the pipeline enables prevention, preparedness, surveillance, and emergency decisions to be made to ensure the integrity and operational continuity of the system.
Fracture Toughness Evaluation of JCOE Pipe Under High Pressure H2 Gaseous
Authors: Nakashima Kota , Ishikawa Nobuyuki , Imayama Hikaru
Published: December 2024

Hydrogen embrittlement is one of the major phenomena that deteriorates fracture toughness of pipeline steels. The stress intensity factor which is used for expressing resistance to fracture was investigated under high pressure hydrogen gaseous 21MPa according to ASTM 1820-21, using longitudinal submerged arc welded JCOE pipe of X65 grade with outer diameter (OD) 24″ and wall thickness (WT) 23.8mm rolled from a TMCP plate with Nb micro-alloying, which can create fine microstructure of base metal and HAZ. X65 UOE pipe with fine microstructure by using Nb microalloyed-TMCP plate but coarser grain size than the JCOE pipe was also tested for comparison. In this test, the loading rate was set low enough to represent high effectiveness in hydrogen embrittlement. The elastic-plastic fracture toughness JQ was derived from J-Δa curve. The stress intensity factor values converted from JQ for base metal, weld metal and HAZ of X65 JCOE pipe were all greater than 100 (MPa·√m), which met the criteria of ASME B31.12. The fracture initiation toughness of the X65 JCOE base metal in hydrogen was higher than that of the UOE pipe with coarser grain size. Weld metal of the JCOE pipe exhibited very fine acicular ferrite microstructure and showed highest toughness. While the limited experimental data was presented in this paper and further investigation should be necessary, it can be stated that finer microstructure consisting of acicular ferrite and polygonal ferrite exhibits higher fracture initiation toughness in high pressure hydrogen gaseous.
New Aspects on Modeling Ductile Fracture Arrest Performance of Large-Diameter Pipes in Dense-Phase Carbon Dioxide
Authors: Mondry Andreas , Bosch Christoph
Published: December 2024

When designing pipelines for the transport of compressible media, the required minimum toughness is usually determined by using the Battelle Two-Curve model and expressed as Charpy V-notch (CVN) impact energy. For modern, high-toughness line pipe steels, in particular in the context of carbon dioxide (CO2) as liquid or dense phase, this concept becomes questionable since the CVN impact test loses significance for high-strength steels exhibiting high CVN toughness levels. However, due to the small number of full-scale test results in CO2 available to date that additionally encompass only a narrow envelope of geometries and material properties, it is difficult to derive both validated toughness concept improvements as well as requirements for pipeline design.

This paper examines a numerical modeling approach to ascertain the fracture arrest behavior of pipe transporting dense-phase CO2. The model was tuned to published data on full-scale CO2 burst tests. Multiple pipe diameters and wall thickness/diameter ratios were evaluated. The new model was developed with the intent of better characterizing modern line pipe steels as well as the unique operating aspects of dense-phase CO2.

The results follow the predictions of a DNV RP F104 assessment and show the expected conservatism of the given recommendations.
Pragmatic Study of Dent Restraint Conditions for ILI-Reported Dents Based on API RP 1183
Authors: Wang Rick , Hu Tao , Zhang Shenwei
Published: December 2024

The restraint condition of a dent significantly influences the fatigue life of pipelines subjected to mechanical damage. Two primary methods are commonly used to determine this condition: the clock position-based method based on dent orientation and the restraint parameter-based (RP-based) method using the restraint parameter (RP) developed by PRCI MD4-9 project. In the clock-based method, a dent is classified as restrained if it lies between 4 o’clock and 8 o’clock, and as unrestrained otherwise. The RP-based method calculates RP from the dent shape obtained via in-line inspection (ILI) caliper tools. Specifically, a dent is considered restrained if RP > 20, and unrestrained otherwise. Both methods are included in API RP 1183-2020.

To evaluate effectiveness of the RP-based method, we established a comprehensive database of over 9000 dents. Each dent has a three-dimensional (3D) profile obtained from a caliper tool. These dents were collected from 20 pipelines with outer diameters ranging from NPS 6 to NPS 48, involving four ILI vendors. About 60 dents were excavated, and their actual restraint conditions analyzed and compared to RP-based method calculated from dent shape using caliper ILI.
Different Vintage Pipeline Coating Failure Mechanisms and External Corrosion Conditions Between Liquids and Gas Transmission Pipelines
Authors: Kazmi Hermain , Liang Jiajun (Jeff) , Bai Amanda , Rehman Hena , Tsaprailis Haralampos (Harry)
Published: December 2024

Within North America, vintage pipeline coatings, such as Polyethylene (PE) tape and Coal Tar Enamel (CTE) were widely used in transmission pipelines that transported both liquid and gas commodities during the 1950s–1980s. At the time, these coatings were believed to be the most reliable method of preventing damage to a pipeline from external corrosion. After more than half a century of operations, it is observed that some of these pipeline coatings have more failures and defects than others, which leads to more severe corrosion conditions. This paper outlines the vintage pipeline coating failure mechanism (i.e., PE tape, CTE) and root causes of variable corrosion conditions, on liquids and gas transmission pipelines of similar age. These potential root causes include operation temperatures, pressure cycling, and pipe diameter size. A detailed analysis of corrosion feature population and density from In-line Inspections (ILI) is conducted to provide evidence of potential root causes. The review of field verification reports was also completed to confirm the coating failure mechanism. The data is gathered from the operator’s active liquids and gas transmission pipelines with similar conditions so that the coating correlation can be understood. Any data skew will also be highlighted to prevent biases in this assessment. The corrosion growth rates (CGR) shall also be considered to compare the effect of coating and justify the increase in the frequency of inspection on certain vintage assets. The outcome of this study is to recommend the “best operating practices” to prevent or reduce failures of vintage coating systems. The suggestions of recoat types on different pipeline systems will also be discussed based on pipe size, original coating types, and products being transported.
Approach to Assess the Effectiveness of Isolation Valves as Part of Pipeline Risk Assessment
Authors: Fontenault Jeremy , Franey Tara , Khushoo Nitish , Borjas Leal Armando
Published: December 2024

Valves are installed on pipelines to help reduce the amount of product that can be released in the event of a pipeline loss of containment. Valves can be closed both up- and downstream of the release location to limit the amount of product that can drain out of the pipeline under gravity. Often operators perform assessments to understand the optimal locations to place valves or to assess the optimal valve type to use. This is done for pipelines currently operating and new pipelines being planned. This paper discusses an approach using similar tools, which have been adapted to assess the effectiveness of existing valves. It includes details on how this information can be analyzed and applied to improve pipeline risk assessments and integrity management programs. This approach was recently applied to a large North American pipeline, which has been used as case study for this paper.

The pipeline covers over 1,000 kilometers and has over 100 valves across several distinct pump sections. The valves are a mixture of manually operated, remotely operated, and check valves. The effectiveness of each valve at reducing potential release volumes was assessed by excluding each valve individually and comparing release volumes with and without that valve. Release volumes were modeled as hypothetical full-bore rupture releases at a maximum of 30-meter intervals along the full length of the pipeline segment. This paper covers the details of this approach as well as provides a summary of some of the key findings.

This analysis results in a large amount of data that can be difficult to assimilate into the decision-making process. An interactive data insights dashboard can be a useful tool to quickly filter, summarize, and analyze each valve. This tool can be used to filter by pump section or individual valve, see how the release volumes change along that pipeline segment based on each valve, and see summary statistics for each scenario. Lastly, this tool can be useful to understand what portion of the pipeline segment is affected by each valve.

Lastly, this paper will review how these data insights can be used to improve pipeline risk assessments and pipeline integrity management. The result of this analysis specifically feeds into the optimization of an equipment failure risk model which helps to reduce risk by focusing on valves with higher probabilities of failure or those with significant consequences in case of failure. Valve effectiveness analysis for each pipeline pump section also enables the operator to develop effective emergency response plans and mitigation strategies.
Defining an Environment Where Internal SCC Occurs
Authors: Futch David , Tanner Brandon
Published: December 2024

This paper discusses and defines an environment where internal stress corrosion cracking (SCC) can form. Over the past few years, ADV performed several forensic analyses where internal SCC on gathering pipelines was identified. The identification of broad colonies of longitudinal cracks along the internal pipe surface, a quasi-cleavage fracture surface examined using a scanning electron microscope, and branched tight transgranular cracking were identified supporting the assertion of internal SCC.

All SCC requires three conditions to be simultaneously present: stress, material, and environment. The stress to generate longitudinal cracking is largely a result of the operating pressure generating hoop stress. Carbon steel utilized during the pipeline construction is susceptible to SCC in specific environments. The environment to form internal SCC is dependent on the product/fluid within the pipe, which is drastically different than traditional external SCC. All incidents contained the same general product and added chemicals (inhibitor and biocide). Therefore, characterizing and mitigating the subject environment is critical to managing the internal SCC threat.

In order to characterize susceptible conditions, a series of slow strain rate tests (SSRTs) utilizing varying environments, varying materials, and varying test durations were conducted to gain a better understanding of the internal SCC mechanism present. Based on these tests, the following was concluded: The SSRT cracking produced within a mixture of the chemicals resulted in the same mechanism identified within the forensic analyses. The individual fluids did not result in cracks. Therefore, the mixture of the inhibitor and biocide results in an environment that produces cracks; this crack producing environment appears to be exacerbated by the presence of 3% brine solution. Comparison of the results to a filmed SSRT indicated these cracks form in a submerged environment, such as that encountered in a low spot, rather than one where the chemicals are filmed on the steel surface. Tests performed on three materials and vintages indicated that all low carbon line pipe steels are susceptible to the cracking mechanism discussed in this paper.
Evaluating the Effects of Emergency Depressurization on a High-Pressure High-Temperature (HPHT) Gas Injection Onshore Pipeline
Authors: Lakshmipathy Jagan , Herrera Sierralta Carlos , Jain Arun , Fallatah Mohammed , Jurca Thomas
Published: December 2024

An operating strategy is proposed for the emergency depressurization of a NPS30 gas-gathering manifold (GGM) and its associated NPS24 trunk line transporting high-pressure, high-temperature (HPHT) gas to a storage reservoir subject to various system constraints.

Abrupt pipeline depressurization containing lean gas causes cooling downstream of the blowdown valve (BDV) and at locations within the pipeline due to Joule-Thompson (J-T) expansion. A safe operating envelope for the injection system was developed through rigorous flow assurance, materials and buckling analysis.

Pipeline fracture tests indicated the GGM material transition temperature (MTT) is approximately 20°C (35°C with margin) and recommended to maintain GGM above this temperature. Pressure corresponding to a metal temperature of 35°C during depressurization was calculated as an increase in the inlet gas temperature to mitigate low temperature during depressurization. This was used as an input for stress calculations to determine the propensity of fracture propagation. An increase the inlet gas temperature will mitigate low temperatures during depressurization.

The risk of pipeline failure due to upheaval buckling at elevated pipeline temperatures and pressures was also considered. Upheaval buckling of pipelines can occur when axial force reaches a critical limit. This force is accentuated during episodes of large temperature differences and high internal pressures. An operating strategy presented here incorporates the impact of these limits on upheaval buckling.
Prioritizing the Correct Crack-Like Feature for Remediation Requires Burst and Fatigue Calculations
Authors: Polasik Steven J. , Hanna Ben , Booth Zach , Bubenik Tom
Published: December 2024

Prioritization of crack-like features for remediation requires a burst pressure assessment as well as a fatigue life assessment to ensure all features are managed accurately. As the ability of in-line inspection technologies to provide complex feature profiles becomes more commonplace, a process for estimating the criticality of crack-like features with these profiles becomes more imperative. One approach is to apply an effective area method (e.g., similar to RSTRENG) to estimate criticality. This method evaluates all contiguous combinations of feature dimensions that can be defined via the detailed profile. The effective areas from these combinations are converted into semi-ellipses, or other idealized shapes, which can then be analyzed using fracture mechanics models. The lowest predicted burst pressure of these combinations is considered the burst pressure of the feature. As an extension, the fatigue life of each combination can also be estimated such that the effective dimensions resulting in the shortest predicted life define the overall fatigue life of the feature. While the effective area approach is mostly applicable to metal loss rather than crack-like features, this approach has been used in the past and its application can yield illustrative results.

For some profiles, the effective dimensions corresponding to the lowest burst pressure are not the same as those corresponding to the shortest fatigue life. This points to a larger implication that can be applied to any set of features, whether they have simple or complex profiles. Specifically, the most critical feature based on burst pressure may be different from the feature with the shortest fatigue life. Different features could be prioritized for remediation differently depending on the failure condition being evaluated. A full understanding of which features to prioritize for remediation efforts therefore requires both a burst pressure assessment and a fatigue life assessment. This paper seeks to explore this implication in more detail by examining the ranges of assumptions and feature parameters under which this phenomenon occurs as well as the extent of its influence when using the MAT-8, Raju-Newman, and CorLAS™ fracture mechanics models.
Development of Pipeline Standards for the Delivery of Hydrogen and Hydrogen Blends
Authors: Blackwell Chris , Wallace Howard , Khan Mervah , Weinkauf Brett
Published: December 2024

This paper will discuss the near-, mid-, and long-term development of requirements for the design, material selection, construction, testing and operation of pipeline delivery systems intended for use with hydrogen gas and hydrogen gas blends. CSA Z662, Oil and gas pipeline systems, establishes oil and gas pipeline delivery system requirements in Canada, with natural gas (methane) being the dominant gaseous focus.

To provide a mechanism for immediate reduction in greenhouse gas emissions, a significant demand for hydrogen and natural gas blended with hydrogen has emerged. These fuels must be delivered in a safe and effective manner. Addressing hydrogen in standards is currently a focus area around the world with support from many international research organizations, industry, and levels of governments.

As the applications of hydrogen blending in existing natural gas pipelines begins to increase and expand, so must the standards that have traditionally been applied for those projects. Recognizing the speed with which the demand for hydrogen is increasing, the CSA Z662 Technical Committee formed a hydrogen task force to focus on 3 deliverables:

• A primary framework, covering design, construction and operation requirements for existing and new hydrogen and hydrogen blend systems, suitable for publication in the 2023 edition of CSA Z662;

• A detailed set of objective provisions suitable for publication as early as 2027; and

• A mechanism for integration of standard maintenance and updating for hydrogen requirements in future editions.

In June 2023, CSA Group published the new edition of CSA Z662, which includes a new clause to address provisions for hydrogen and hydrogen blended systems and simultaneously establishes a home for future provisions.

The paper will conclude with a summary of the approach and key topics of focus for the next edition of CSA Z662.
Fels Glacier Valley Slope Deformation Analysis and Geohazard Assessment for the Trans Alaska Pipeline System (TAPS)
Authors: Read Rodney , Reger Richard , Preston Geoffrey , Wuttig Frank
Published: December 2024

Alyeska Pipeline Service Company (Alyeska) conducts ongoing pipeline integrity monitoring of the Trans Alaska Pipeline System (TAPS), including sites prone to slope instability and potential future landslides. Fels Glacier valley, an eastern tributary of the upper Delta River valley in the glaciated, rugged east-central Alaska Range, is a site of active slope movement on the valley’s south-facing slope. Located about three miles east of the Richardson Highway and the TAPS pipeline, Fels Glacier valley is drained by Lower Miller Creek, which is crossed by the TAPS pipeline. Several university researchers have postulated that a long-runout rock avalanche or a sequence of events involving catastrophic failure of the deforming slope, damming of the drainage from Fels Glacier, and subsequent outburst flooding, could severely impact the TAPS oil pipeline. However, this conclusion was reached without a structured geohazard assessment to estimate the probability of occurrence of these scenarios and vulnerability of the TAPS pipeline to their occurrence.

In 2016, Alyeska initiated a geohazard assessment of Fels Glacier valley to assess the potential risk exposure of TAPS. In addition to several field reconnaissance surveys and review of satellite and ground-based radar monitoring conducted by others, desktop analysis of LiDAR data using a novel image analysis technique to estimate 3D displacement vectors was conducted to establish the pattern of ground displacement and develop a geologic model. This paper provides an overview of the geohazard assessment and details of the LiDAR image analysis. The findings illustrate the utility of comparative image analysis using repeat LiDAR surveys and orthophotos to estimate a true 3D displacement field as part of quantitative geohazard assessment of pipelines.
An Overview of the 2021 Edition of the PRCI Pipeline Repair Manual
Authors: Gould Melissa , Bruce William A. , Noecker Fredrick F.
Published: December 2024

The 2021 edition of the Pipeline Research Council International (PRCI) Pipeline Repair Manual contains added and updated information on repair technologies gleaned from the literature, vendor publications, and industry experience. The most recent update focused on repair methods and practices that are commonplace or have emerged and have become commonplace since the 2006 version of the manual.

Additionally, the updated manual provides guidance to pipeline operators for choosing an appropriate repair method for a specific type of defect or combination of defects in an operating pipeline, developing or improving their pipeline repair procedures and manuals, and training or qualifying engineering and maintenance personnel. It also contains two (2) new appendices. Appendix B includes additional information related to composite repairs, including a summary of completed industry-wide research and the application status of composite repairs for various types of defects. Appendix D is a training slide deck covering the changes in this edition compared to the previous Pipeline Repair Manual.

One example of a major change in this edition is the decision to limit references to “permanent” and “temporary” repairs, as the anticipated life of a repair depends on many circumstances and could include consideration of risk. Therefore, the determination of “permanent” and “temporary” is left to the user. Furthermore, the tabular summary of repair options for various types of defects was significantly updated to align with current industry best practices.

To help disseminate information in the 2021 Edition of the PRCI Pipeline Repair Manual, PRCI is developing an online and in-person training course. The purpose of this paper, and the associated training course, is to increase understanding of the major changes in the 2021 Edition of the PRCI Pipeline Repair Manual, and current industry best practices for pipeline repair methods.
A Review of a Satellite-Based Solution for Pipeline Right-of-Way Monitoring
Authors: Chayangkul Na Aduthaya Tanat , Chonjaroen Thidarat , Sanlung Sasiphan , Wongpanich Amnuay , Van Den Berg Arnaud
Published: December 2024

PTT Public Company Limited (PTT) is a leading entity in Thailand’s energy sector, managing both onshore and offshore gas transmission systems with a total length of over 5,800 kilometers. To ensure safety and integrity, PTT utilizes various patrolling methods, including vehicle surveillance and unmanned aerial vehicle (UAV) inspection. However, with these methods, challenges emerge in onshore areas due to restrictions or inaccessibility. Therefore, PTT initiated a pilot project in 2022, leveraging satellite technology to overcome these challenges.

Within this pilot, PTT evaluated Orbital Eye’s satellite-based monitoring solution, leveraging Synthetic Aperture Radar (SAR)-, Multispectral-, and High-Resolution optical satellite data to detect activities within the pipeline right-of-way (ROW).

Within a year, more than 3,000 unique activities were detected through the analysis of satellite data, with an accuracy rate exceeding 90%. The activities were all verified by PTT’s GIS staff and operational field crews, either through the analysis of optical data or through traditional on-site patrolling. Classifications of detected activities showed that almost 50% of the activities were related to construction or ground works. The results of satellite-based monitoring were also compared with results of vehicle- and UAV-based monitoring, which showed that there was a commendable 53% match.

Integrating this advanced technology into pipeline monitoring enhances efficiency and increases the information level of PTT about activities going on in its pipeline corridor, especially in remote, and hard-to-access areas. The pilot also showed many opportunities to improve. This paper presents the results achieved during a year of satellite-based monitoring, along with the lessons learned and the operational impact of adding this advanced technology to PTT’s monitoring methods.
Vibroacoustic Technology for Pig Tracking: Case Studies and Operational Insights for Permanent or Temporary Installations
Authors: Gomes Ana Paula , Marino Marco , Chiappa Fabio , Rota Matteo
Published: December 2024

The aim of this paper is to present case studies of pig tracking using Vibroacoustic Technology (VT), encompassing both temporary and permanent deployment on a pipeline. This system offers real-time tracking, even if installed mid-operation, providing accurate location information. Additionally, VT, already extensively deployed worldwide in Oil & Gas pipelines, yields valuable data that can be retrieved using this method.

Originally developed for detecting and localizing leaks and third-party interference in pipelines, VT has demonstrated its capability to reliably identify the location of pigs as they traverse the pipeline and pinpoint the position of a stuck tool. Its movement inside the pipeline generates vibroacoustic waves that propagate for tens of kilometers at the speed of sound.

It is possible to determine the source of the vibroacoustic waves, i.e., the pig, employing the time difference of arrival method. Sensor blocks can be installed at any hydraulic derivations along the pipeline or even in parallel with other instruments. These sensor blocks are equipped with batteries allowing for several days of autonomous operation and SIM cards for data transmission during temporary installations. In this work we show data from tracking campaigns in different pipelines.

The first case study involves a 160 km offshore gas pipeline. Sensor blocks at the ends monitored the pig’s passage. Despite the distance, it was feasible to discern the precise moment welded joints were encountered. If it traverses a slightly deformed pipeline section, its location could be accurately determined.

In the second case study, an onshore pipeline for refined products, though under VT surveillance for leaks, at the beginning of the inspection, the pig was not being monitored. When the control room detected the tool was stuck at an unknown location, VT specialists promptly analyzed available data, pinpointing its location within minutes.

The last case study demonstrates VT’s effectiveness in monitoring two pigs within the pipeline. Introducing the second tool aimed to dislodge the first, highlighting the technology’s adaptability and valuable role in managing operational challenges within pipelines.

Accurate pig tracking enables the pipeline operator to promptly address and effectively manage any challenges that might arise during the inspection. The versatility of VT as a pig tracking technology is showcased through cases involving both temporary and permanent installations. This includes instances where tracking was provided from the beginning of the operation and also situations where the stuck tool location was accurately determined after the operation had started.
Metallurgical Analyses of 26 EMAT Anomalies on a 1949 Vintage Electric Flash Welded Pipeline
Authors: Buckingham Katherine M. , Quickel Gregory T. , Wang Jing
Published: December 2024

There are more than 2.6 million miles of oil and gas pipelines in the United States, all of which can be characterized as either seamless or longitudinally seamed. The majority of longitudinally seamed pipelines constructed between 1940 and 1970 involved submerged arc welded (SAW) or either electric resistance welded (ERW) or electric flash welded (EFW) seams. While SAW line pipe is formed with filler metal, ERW and EFW line pipe are autogenous and require no filler. Both ERW and EFW pipes are formed with pressure and electrical current and are both prone to similar manufacturing flaws including hook cracks and lack-of-fusion (LOF) flaws. Hook cracks and LOF flaws can grow pre-service or in-service but are less likely to fail at pressures below the mill and commissioning hydrostatic burst testing (hydrotest). Thus, these flaws are typically considered stable in gas transmission pipelines. This paper summarizes the findings of metallurgical and hydrotesting performed on multiple manufacturing seam weld flaws from an EFW natural gas pipeline.
Evaluation of the Use of 6Al-4V ELI TSJ (Grade F23) in Gas Export Risers in the SEAP Field
Authors: Magalhães Ferreira Fábio , Gomes de Carvalho Kleberson
Published: December 2024

The Sergipe Águas Profundas (SEAP) field, stands out as one of the newest production frontiers in deep waters in Brazil. Located in the Sergipe-Alagoas Basin, 100 km from the coast and at depths reaching 3000 m, it poses several technological challenges for the development of the field. Divided into two modules, the field is planned to have several Steel Lazy Wave Risers (SLWR), including two for Gas Export associated with a trunk line linking two FPSO to shore. Due to the low level of contaminants present in the transported gas, and the possibility of wet park these risers empty in an ultra-deep-water depth, which may be challenging for Flexible Joints, a comprehensive study for the use of TSJ in-stead, as top termination of these Gas Export SLWRs, was carried out.

Although the use of Titanium Stress Joint is widespread throughout the world, especially in the Gulf of Mexico, the application in spread mooring FPSO (as SEAP) is still limited, and costly. On the other hand, the Stress Joint option can be a more reliable alternative than the Flexible Joints, due to the properties of titanium and the absence of structural elastomeric supports, making it resistant to prolonged operation at high temperature and pressure and less susceptible to pressure cycles during their service life.

Several numerical simulations (global analyzes) are performed to verify the technical viability of the Titanium Stress Joint and the riser configuration for the intended use, and the opportunity to use the Ti-6Al-4V ELI alloy (grade F23), which has lower cost and greater availability on the market, is investigated.

Advantages of the Stress Joints over the Flexible Joints in the specific scenario of pre-lay of the Gas Export risers for a long period without the need of special tools, and the possibility of reducing diving inspections for integrity management of the riser’s top termination throughout the operational life are also discussed in this article.
Flow-Induced Vibration Assessment and Mitigation for Compressor Station Expansion
Authors: Harper Chris , Bibby Chris , Hartford Nathan , Harris Chase , Popa Cristian
Published: December 2024

Compressor station expansion projects present a risk of fatigue failure due to flow-induced vibration. Flow-induced vibration mechanisms relevant to compressor stations include flow-induced turbulence, vortex-induced vibration on barred tees and thermowells, and flow-induced pulsations within deadlegs and strainers. Risk and severity of these vibration mechanisms increase with flow rate. Methodologies for assessing each are presented.

The flow-induced turbulence mechanism is excitation due to turbulent kinetic energy in the flow. Screening assessment approach provided by the Energy Institute demonstrates that gas pipelines typically have low turbulent excitation provided the pipework is well supported.

Barred (also called pigging or scraper) tees are commonly found in gas pipeline stations adjacent to pig barrels. They can be a vibration and failure risk due to flow-induced vibrations. Flow through the bars can create vortex shedding, similar to other bluff bodies in fluid flow, and excitation forces at the wake frequency. These forces can then excite the lateral modes of the bars. Common bar designs have several different bar lengths, each with their own natural frequency of vibration. This range of vibration frequencies increases the chance of resonance where a vortex shedding frequency coincides with a natural frequency of a bar. Other complicating factors are the non-uniform flow profile as the flow goes from the main header into the branch and the non-symmetrical shape of the bars that have a radius on the header side.

Flow-induced pulsations from deadlegs occur when the vortex shedding frequency across a branch opening coincides with an acoustical natural frequency of the deadleg. These pulsations create shaking forces which can lead to high vibration and risk of fatigue failure. Vibration is amplified if the pulsation frequency coincides with a mechanical natural frequency of the pipework. A methodology is presented for identifying deadleg pulsation and assessing the resulting vibratory stress in the piping system.

Inline cone strainers can generate very high-amplitude high-frequency vibration and noise local to the tee. Fatigue failure can occur. Strainer noise and vibration is known to occur when vortices are shed through the strainer holes at a frequency that coincides with acoustical cross modes in the pipe. This is further amplified if the acoustic mode coincides with a mechanical shell mode in the pipe wall.

Both vibration and noise field data will be presented for the above mechanisms with techniques for identifying and evaluating risk during operation. Simple solutions will be given for reducing the risk of fatigue failure.
Impact of High Speed Hydrogen Flow on System Integrity and Noise
Authors: González Díez Néstor , Belfroid Stefan , van Lier Leonard , Meijer Irma
Published: December 2024

Existing infrastructure used for transporting natural gas could be used in the future to transport hydrogen. The HyDelta program aims at resolving open questions connected to the transport of hydrogen in The Netherlands. Infrastructure is developed and operated safety by abiding by proven standards and norms for pipeline integrity. An open question is whether the integrity of the transport system is affected when repurposing for hydrogen, provided that the same amount of energy is as it currently is with natural gas.

To ensure the same transport capacity, higher hydrogen flow velocities are necessary, in comparison to natural gas. This in turn results in potentially larger pressure drop, and with it a larger potential for erosion, vibrations and radiated noise. Transport capacity, operating pressures and temperatures, sizing of the hardware and optimized economic return determine what the optimal design flow speed in the system shall be. However, the flow speed is also limited by integrity risks. For natural gas, this limit is commonly placed at 20 m/s (∼60 ft/s). Applying the same limit to hydrogen may represent an overly conservative constraint and bottleneck the capacity of new and re-purposed gas transport systems.

In this paper, a review of integrity risks related to high gas flow velocities in the system is offered: flow-induced risk mechanisms for intrusive equipment, flow-induced turbulence, flow-induced pulsations, acoustics-induced vibration, flow-induced noise and erosion. The method is based on benchmarking hydrogen against (Dutch) natural gas, at equal energy rates. This means that hydrogen should flow about 3 times faster than natural gas. The objective is to assess whether any of the integrity risks analyzed present a barrier to allowing the flow velocity for hydrogen to be larger than that used for natural gas.
Optimal Balancing of ILI Excavations and Integrity Confidence Through Engineering Assessment Methods
Authors: Biagiotti Stephen F. , Bruce Daniel , Neogi Bhaskar , Nidd Phillip G. , Prescott Jonathan
Published: December 2024

This paper demonstrates the utilization of an engineering assessment method to effectively balance the reduction of costly inline inspection (ILI) excavations while maintaining high pipeline integrity confidence levels. Faced with the challenge of frequent and expensive ILI excavations that disrupt operations and inflate maintenance costs, the pipeline industry seeks more efficient and targeted strategies. This study addresses this need by integrating and applying advanced engineering assessment techniques in the context of pipeline maintenance.

The process starts with a critical analysis of the current state of pipeline integrity management, identifying the primary issues related to reliability-based timeliness of ILI-driven excavations in achieving fitness for service. We then delve into a comprehensive review of various engineering assessment methods, including statistical analysis, predictive modeling, and risk-based assessment, highlighting their potential in enhancing decision-making in pipeline maintenance.

The paper uses a case study where various methodologies have been applied, providing empirical evidence of their effectiveness in reducing unnecessary excavations while preserving or enhancing pipeline integrity confidence levels. This case study demonstrates cost savings and operational efficiencies, underscoring the practicality and benefits of these methods.

A notable aspect of these efforts is the examination of the role engineering evaluation plays in processing and interpreting ILI data. These techniques, with their advanced predictive capabilities, offer nuanced insights that support more accurate and sophisticated engineering assessments and long-range planning.
Collapse Testing and Analysis of High Frequency Welded (HFW) Steel Pipes
Authors: Gavriilidis Ilias , Stamou Aris G. , Palagas Christos , Dourdounis Efthimios , Voudouris Nikos , Tazedakis Athanasios , Karamanos Spyros A.
Published: December 2024

Among many factors affecting the collapse limit of pipelines, the line pipe fabrication process has the strongest impact. The present study examines the collapse resistance of pipes fabricated by the High Frequency Welding (HFW) method and focuses on quantifying the effects of heat treatment with respect to the collapse limit of this class of cold formed pipes. The research is carried out for the case of two HFW line pipe specimens with 16 inch outer diameter (Do), 19.1 mm wall thickness (WT) and length equal to 17 times the outer pipe diameter (17Do). One of the HFW pipes has been coated prior to testing (“heat treated” pipe), while the other pipe remained bare (“as fabricated” pipe). Both pipe specimens were subjected to full-scale collapse in a large external pressure testing chamber to determine the collapse pressure and the propagation pressure of both pipes. The full-scale tests are simulated using advanced finite element (FE) tools, considering the actual material properties/geometry of each pipe before full-scale tests. The numerical predictions of the collapse pressure and propagation pressure are in a very good agreement with the experimental ones, while the FE models are also capable to predict the enhanced collapse pressure after coating.
Exploring the Role of Residual Stress in Correlating Yield Strength From Indentation-Based Nondestructive Measurements and Destructive Tensile Testing
Authors: Martin Peter , Brady Emily , Kornuta Jeffrey , Thorsson Solver , Nasouri Reza , Gibbs Jonathan , Veloo Peter
Published: December 2024

Nondestructive determination of the yield strength (YS) for in-ditch materials verification of line pipe is routinely accomplished using indentation methods such as the instrumented indentation test (IIT). While the IIT-predicted YS (YS(IIT)) is generally within ±10 % of the tensile test value (YS(TT)), it occasionally differs by as much as 25 %. This work explores the possible contribution of residual hoop stresses introduced during forming to this aspect of the IIT performance. While in-ditch inspections are rarely informed by prior knowledge of residual stress levels, a better understanding of the potential contribution from manufacturing-induced residual stresses may improve the ability to forecast when measured YS(IIT) values are most likely to accurately reflect benchmark YS(TT) values.

The current work compares results of IIT performed on 20 line pipes and on smaller coupons extracted from those same pipes. The results are interpreted based on the assumption that residual hoop stresses introduced during pipe forming are relieved in the coupons when they are extracted from the larger pipe sections. FEA simulations were performed for two of the pipes to explore the potential effect of residual stress and to guide analysis of the experimental data. The analysis revealed probable contributions from residual tensile hoop stresses in half of the pipes. Additional analyses identified limitations in using the Hollomon power law to model the plastic deformation and predict the yield strength from the indentation process. The results indicate that the Hollomon power law tends to underpredict yield strength in materials where the strain hardening exponent is below approximately 0.130 and overpredict it when it is above approximately 0.180.
Detailed Elastic-Plastic Finite Element Analysis Study to Determine an Optimal Process for Type-B Repair Sleeve Welding
Authors: Holloman Ryan L. , Baxter Samuel J. , Gowardhan Chinmay , Thorwald Greg , Turnquist Michael
Published: December 2024

A typical type-B sleeve consists of two half cylinders fillet-welded to the carrier pipe and joined together with butt welds. The butt welds will not impact the carrier pipe, but the residual stress produced from the fillet weld installation will impact the stability of any existing crack-like flaws in or near the new weld. The orientation and severity of the residual stresses can be reduced depending on the installation method. For instance, the residual stresses may differ if the upstream and downstream fillet welds are installed simultaneously versus sequentially, as simultaneous welding can restrict thermal contraction as the welds cool.

The sequence in which the fillet welds are installed can also impact the orientation and severity of residual stresses. Prior studies have demonstrated that sequential welding and more stopping points can decrease residual stresses. However, it is not clear whether this benefit will effectively offset the increased time needed to execute these procedures. Excess time required in the ditch presents commercial concerns and, more importantly, increased risk to safety and quality. It is increasingly difficult to maintain proper quality control requirements as more time is spent in the ditch. This, in turn, elevates the risk associated with environmental threats such as the formation of hydrogen cracking in the welds due to poor moisture control.

Quest Integrity and Colonial Pipeline executed a study utilizing detailed elastic-plastic finite element analysis to demonstrate if sequentially welding type-B repair sleeve fillet welds is beneficial compared to a simultaneous welding approach. Sleeve lengths of 0.5, 1.0, 2.0, and 4.0 ft were modeled for both sequential and simultaneous approaches. The initial results from this study identified that for longer sleeve lengths, the post-welding residual stresses were nearly identical between the two welding techniques. However, for shorter sleeve lengths, a sequential welding sequence generated lower residual stresses than the simultaneous process.

Additional analysis is in progress to further identify an optimal process for type-B sleeve repair welding to minimize residual stresses while also limiting the amount of time required in the ditch to execute the welding process. This additional work includes quantifying the impact of these welding procedures on the stability of potential crack-like flaws located in the repair welds, as well as the probability of failure associated with these potential flaws.