bluuebunny/crossref_metadata_2025 huggingface dataset:
Gaps in the Current Strain-Based Dent Assessment
Authors: Wang Rick , Zhang Ken
Published: December 2022

Dents in pipelines, especially when associated with crack formation, pose a significant pipeline integrity threat. With crack formation during the initial indentation process, the fatigue life and failure pressure can dramatically reduce compared with crack-free dents. Over the past decade, cracks associated with the dent-formation process were typically assessed using strain-based engineering critical assessment (ECA), which compares the dent strain and curvature measured by in-line inspection (ILI) geometry tool, with industry-established damage criteria.

However, in recent dent management practice, TC Energy has observed cracks in several shallow dents with strain levels much lower than any established fracture criteria. Cracks were found at some dents with measured depth at only 1.3% outer diameter (OD), and the calculated strain with ASME B31.8 nonmandatory method was ∼4% [6]. It is believed that the strain-based assessment solely based on post-formation shape measured by ILI geometry tool likely requires improvement to capture additional aspects that might contribute to formation of dent-cracks.

Various dent formation processes were reviewed, and the multiple potential contributing factors are discussed in this paper, including loading rate sensitivity, temperature effect, stress triaxiality and geometrical influence. The effects of these factors on material responses, dent-crack formation and fracture damage are outlined. Observed gaps in the current strain-based dent assessment process are also outlined, and a multi-element approach to assess dents and identify dent-induced cracks is proposed, which includes evaluation of combined Caliper, magnetic flux leakage (MFL), electromagnetic acoustic transducer (EMAT) and axial flaw detector (AFD) data, enhanced dynamic testing and ductile failure damage indicator (DFDI) determination, materials modeling and finite element analysis (FEA) techniques. Results of two case studies using multiple real-life dent features are described to illustrate effectiveness of the proposed approach.
Comparison of Pressure Decay Models for Liquid Pipelines
Authors: Zhang Shenwei , Huang Terry , Dooley Colin , Lai Roger , Conrad Brett
Published: December 2022

This paper presents a comparative study of various models in characterizing the reduction of pressure severity along the length of a given liquid pipeline section. Four models were considered in this study, namely the API RP1176 model, CEPA model, SSI Linear Interpolation model and Pressure Range Linear interpolation model. A total of 132 sets of pressure spectra from TC Energy’s liquid pipelines were collected. Each set includes three pressure spectra, namely one pressure spectrum from a given intermediate valve station and other two pressure spectra from the discharge end of its immediate upstream pump station and the suction end of its immediate downstream pump station. The SSI is used to characterize the severity of a given pressure spectrum. To quantify the uncertainties of the model error associated with the four pressure decay models, the calculated SSI based on the spectrum from the intermediate valve station is compared with the model-predicted SSI at the location of the intermediate valve station based on the SSIs of the upstream discharge and downstream suction pressure spectra. The comparative analyses indicate that the CEPA model is the most accurate and precise model in evaluating the pressure decay along the length of a given pipeline section, and in a descending order followed by Pressure Range Linear Interpolation model, API RP1176 model, and SSI Linear Interpolation model. A fitness-for-service assessment program for liquid pipeline can incorporate the probabilistic characteristics of the model error associated with each of the four models derived based on the 132 sets of pressure data.
Machine Learning Tools to Predict the Burst Capacity of Pipelines Containing Dent-Gouges
Authors: He Ziming , Zhou Wenxing
Published: December 2022

Dent-gouges as a result of the mechanical damage have serious implications for the burst capacity of oil and gas pipelines. The burst capacity of pipelines containing dent-gouges is lower than that of the same plain dented pipelines without gouges and that of the same gouged pipelines without dents. The well-known burst capacity prediction model adopted by the European Pipeline Research Group, i.e. the EPRG model, results in predictions of the burst capacity with high variability. In this study, a machine learning tool is employed to improve the predictive accuracy of the EPRG model for pipelines containing dent-gouges. To this end, a relatively large number of full-scale burst tests of pipe specimens containing dent-gouges are collected from the literature. The Gaussian process regression (GPR) technique, which is a class of non-parametric Bayesian model widely used in the machine learning, is employed to improve the EPRG model based on the collected full-scale burst test data. The full-scale burst tests are used to evaluate the hyper-parameters involved in the GPR analysis and validate the predictive accuracy of the improved EPRG model after the application of GPR. To facilitate the practical application of the improved EPRG model, a computer program with a graphic user interface (GUI) is further developed to compute the burst capacity of pipelines containing dent-gouges by inputting key parameters such as the pipe geometry and material properties as well as sizes of the dent and gouge through a GUI. This research will improve the fitness-for-service assessment of pipelines containing dent-gouges.
Hard Stamp, Paint, or Chemical DNA, How to Link the Steel Product to the Material Test Report
Authors: Krom Alfons , Huising Otto Jan
Published: December 2022

The material test report (MTR) provides proof of the mechanical properties of a steel product and confirms that the tests required have been performed and are satisfactory. For this purpose, test pieces that are representative of the steel product are destructively tested and the results are given on the MTR. The MTR is essential as one cannot determine the mechanical properties non-destructively. The standard way of linking the MTR and the product is done by a specific mark on the product, usually the batch/heat number which is given in the MTR. But what if there is no confidence the MTR relates to the steel product? The steel product will then have limited value because there is no proof of compliance with the requirements.

A chemical composition is usually mentioned on the MTR. This is the chemical composition of the ladle, also called the heat analysis. The chemical composition does not change during the process of manufacturing a steel product. Therefore it can be considered as the “DNA” of the steel.

This paper will explain the use of mobile optical emission spectrometry (OES) as a reliable method for measuring the chemical composition of a steel product. The measured chemical composition, the DNA of the steel, is compared with the heat analysis. If the material test report relates to the steel product, the differences between the two chemical compositions will be very small. If differences in the composition are large we can see that the MTR and steel product do not relate to each other. This does not mean that the steel product does not meet the specified mechanical properties. Only the relationship with the associated MTR is no longer there and thus proof that the steel product complies with requirements.
Investigation of Cost-Effective Braided and Wound Composite Pipelines for Hydrogen Applications
Authors: Grigat Niels , Mölling Tim , Torres Crooks Suyin Jireh , Vollbrecht Ben , Sackmann Johannes , Gries Thomas
Published: December 2022

In order to enable an emission-free society by 2050, the distribution of green hydrogen is a key element for a successful transformation of the energy supply. This paper presents the design and manufacturing of composite pipelines made of fiber-reinforced plastic (FRP) and its potential for the transport of high-pressurized gases such as hydrogen. Furthermore, the extent to which FRP-pipelines can be a potential complement to existing steel pipelines is being discussed.

The wet winding process is an established manufacturing process for FRP-pipes which, however, provide only a fraction of all necessary requirements. Oftentimes, a trade between the different factors cost, weight, performance and feasibility is made. By means of benchmarking the alternative manufacturing approaches such as multi-supply filament winding (MFW) and radial braiding, the potential for cost-effective high-pressure composite pipelines are investigated within this paper. For the aspired operational pressure of 350 bars, suitable lay-ups are derived and validated via simulation according to ISO 14692. As pre-impregnated fibers, so-called towpregs, enable elevated winding speeds and reduced resin content variance, the study focusses on this material. Additionally, MFW allows the processing of up to 48 towpregs simultaneously and therefore, increased productivity compared to single-filament winding. Using the generated data and based on the material combinations investigated, the productivity of the MFW process is examined. The most promising design is selected for the manufacturing of a demonstrator via MFW. Finally, recommendations for the industrial upscale of composite pipeline manufacturing are presented and the manufacturing approach via radial braiding as an alternative is discussed.
Machine Learning-Based Severity Assessment of Pipeline Dents
Authors: Tang Huang , Sun Jialin , Di Blasi Martin
Published: December 2022

One challenge to pipeline operators is to identify potentially injurious dents among thousands of reported deformation features using limited information (e.g., reported dent’s length, width, and depth) and to prioritize the efforts and allocate the resources to obtain additional more detailed information (e.g., dent profiles) for those potentially severe dents. An innovative approach based on machine learning predictions stemming from a representative dictionary of finite element analysis (FEA) generated prototypes was developed. The proposed approach predicts multiple severity-based indicators for each dent, then combines them in an overall severity score, which finally is used to prioritize the acquisition of dent profiles. Once the dent profiles are available, detailed level 3 FEA quantitative reliability analyses, following previously developed and published methodology (QuAD) [1], is performed allowing pipeline operators to confirm dent’s severity more accurately and perform an integrity risk informed decision (IRIDM) leading to a safer and more efficient integrity management.

Three severity indicators were considered herein and intended to address both formation-induced and service-induced failure mechanisms. The maximum dent formation plastic strain and accumulated ductile failure damage were used for evaluating the likelihood of forming a crack during indentation. The third indicator was the stress concentration factors (SCFs) to assess the potential of service-induced failure due to fatigue.

A machine learning model, as an emulator, trained and tested using ∼4000 FEA-based dent prototypes was shown to be able to effectively predict dent severity indicators previously referred to. These predicted dent severity indicators are combined to produce an overall severity score, which was finally used to prioritize the acquisition of the detailed dent profiles. Once profiles are obtained, detailed FEA quantitative reliability assessments will ultimately confirm the severity and hence drive repair/no repair decisions, enabling in this way an efficient and effective allocation of resources.
Onshore Pipeline Safety Consequence Modelling in Support of the Development of a Risk-Based Safety Class System
Authors: Stephens Mark , Yue Howard , Halford Ann , Foster Niall
Published: December 2022

A consequence-based safety class system was developed as an alternative to the class location system currently used as the basis for defining the maximum allowable hoop stress in Canadian Standard Association’s Standard Z662. Development of the safety class system required models to quantify the safety-related consequences of pipeline releases expressed as simple analytical functions of a limited number of parameters that are typically known at the pipeline design stage. These simple analytical formulas were developed using an empirical approach, in which validated numerical models were first used to estimate the hazard zone sizes for a matrix of cases representing the feasible input parameter ranges for pipelines associated with each service fluid. Subsequent work, described in a companion paper, employed regression analysis of the parametric analysis results to develop the required simplified analytical formulas.

This paper describes the safety hazards posed by releases of the various service fluids; the numerical models employed in the parametric analysis to determine the associated hazard areas as a function of key pipeline, service fluid, terrain, and weather-related parameters; and the hazard intensities adopted to delineate the size and extent of the hazard areas bound by both the 1% and 99% lethality contours. It also discusses the sensitivity analysis undertaken to establish the minimum set of pipeline and service fluid parameters that could be used to credibly estimate the size and extent of the applicable lethality zones. It concludes with a set of examples that illustrates the relative size and extent of the model-predicted lethality zones associated with the various hazards that could develop for each service fluid in a representative set of pipelines.
Characterization of Through-Wall Cracks and Resulting Leakage Rates in Pipelines
Authors: Ebrahimnia Elaheh , Prasad Shawn , Virk Amandeep , Shahzad Khurram , Kainat Muntaseer , Akonko Saheed
Published: December 2022

Major challenges are foreseen in quantitative risk assessment of ILI detected crack-related features for thin-wall pipelines due to disproportionate ILI sizing uncertainties relative to pipe wall thickness. Therefore, the likelihood of defects growing into through-wall cracks, leading to product leakage, even at relatively low operating pressures needs to be considered in thin-wall pipelines. To support quantifying the risk associated with operating such pipelines, leak rate simulations were conducted to help with the release consequence assessment and risk ranking of ILI reported crack features to design an appropriate mitigation plan.

Finite element analysis (FEA) and computational fluid dynamics (CFD) methods were used to determine the physical characteristics of through-wall cracks and the resulting leakage rates. The study highlights that, for a given fluid, the threshold for leak occurrence and the leakage rate depend primarily on the crack geometry and the operational pressure. CFD simulation results for the sensitivity cases modelled in this study showed that the leak rate can become very significant as the crack opening and internal pressure increase. These CFD results were then compared with the results obtained from a closed-form analytical model. It was determined that the analytical model started to deviate from the CFD results as the internal pressure increased and the crack opening became larger. This was explained by the fact that the analytical model was intended to be used for single-phase flow under laminar, isothermal conditions. Since its applicability to the turbulent flow regime has not been established, the deviation between the CFD results and the analytical results suggests that the use of the analytical model in the turbulent flow regime could greatly underestimate the leak rate. In addition, the importance of the design of experiment, and proper modeling of turbulence and crack surface roughness in the leakage rate estimation was demonstrated.
Evaluation of Higher Strength E8010 Pipe Root Pass Welding
Authors: Lee Kenneth , Bruce Bill , Gould Melissa
Published: December 2022

Recent girth weld failures in newly constructed pipelines in North America have highlighted the issue of the weld strength undermatching the actual pipe strength. The lowest strength region of a manual girth weld is usually the root pass. This project evaluated using higher strength E8010 shielded metal arc welding (SMAW) electrodes for root pass welding on modern API 5L Grade X70 (L485) line pipe, as part of a solution to increase overall weld strength.

The operability, weldability, and productivity of E8010 root pass welding were evaluated by welder operability trials, weldability testing, and welding procedure qualification testing and reviews.

Feedback from North American pipeline welders support that E8010 electrodes have satisfactory operability for pipeline open root pass welding. Welding Institute of Canada (WIC) weldability test results support that an E8010 root pass does not significantly increase weld cracking susceptibility when properly used. Furthermore, welding qualification tests and production welding procedures using E8010 electrodes for all weld passes were reviewed and found that productivity is similar to current industry practices using E6010 electrodes for root pass welding. Guidance with recommendations and precautions for using an E8010 root pass was developed. In summary, a higher strength E8010 root pass can be part of an effective solution to address pipeline girth weld strength undermatching.
Advanced Assessment of Pipeline River Crossings
Authors: Pathak Saurav , Dinovitzer Aaron , Fredj Abdelfettah , Song Peter , Fathi Ali , Tetteh-Wayoe Debra
Published: December 2022

This paper presents an overview of an advanced VIV assessment process and illustrates its ability to consider a range of river crossing scenarios not readily addressed by traditional analysis approaches such as river crossing with river weights and provides better pipeline response predictions for VIV to support integrity assessment. Additional details on the advanced river crossing assessment approach are also presented to show enhancement with respect to existing CFD analysis and empirical equations. FSI sample application case studies are used to demonstrate how the technique captures coupled changes in fluid dynamics and structural response simultaneously so that both stable and unstable vibration conditions are considered. These results are used to demonstrate how the advanced river flow induced vibration assessment can contribute to pipeline integrity water crossing management.
Optimizing the Prioritization of First-Time ILIs Using Quantitative Risk and Machine Learning
Authors: Snider Brenn , Xiang Wei , Zhang Billy , Lecut Sergiu
Published: December 2022

Inline inspections (ILIs) are one of the most effective methods for managing the integrity of pipelines. However, many older pipelines were not designed to accommodate ILI tools. Pipeline operators often prioritize which pipelines to make inspectable on a risk-basis. While this risk-based approach has many merits, it does not necessarily result in the maximum risk reduction for a given budget as the risk-reduction from completing the inspection is not considered. An optimized prioritization strategy should consider both the uninspected risk and amount of risk reduction.

Since post-ILI risk are calculated based on the detected imperfections, it is not possible to directly calculate the risk-reduction from performing a first-time ILI. To overcome this, TC Energy (TCE) completed an exploratory analysis of numerous first-time ILI results to identify key parameters and built machine learning models which predicts the risk impact of performing first-time ILIs.

Several machine learning algorithms (neural network, decision tree, etc.) were trained on data from pre and post-ILI risk results from TCE’s quantitative risk assessment. The models were trained at a dynamic segment level and aggregated to an ILI assessment path evaluation. The best-performing machine learning model was selected that accurately predicts the risk reduction achieved from a first-time ILI.

These results demonstrate the risk-reduction of a first-time ILI can be accurately predicted before the inspection is performed. Combining the traditional risk-based prioritization approach with the predictive abilities to estimate risk-reduction will allow TCE to optimize the selection of first-time inspections by maximizing the amount of risk reduction.
Optimization of Through Thickness Microstructural Grain Size, Homogeneity and Niobium Metallurgy Performance for Cost Effective Improved API X80 Heavy Gauge Large Diameter Pipe Body and Weld Mechanical Property Stability
Authors: Stalheim Douglas , Jinxing Jiang , Chunyong Huo , Yongqing Zhang , Bacalhau Jose , Han David
Published: December 2022

Today’s market for API pipeline steels requires higher strength and fracture toughness performance in heavier gauges and larger pipe diameters. Meeting basic average mechanical properties of strength, TCVN and DWTT performance has been achieved by many with newer powerful plate mills and cooling systems. However, stability/standard deviations of plate/pipe strength and toughness along with pipe seam/girth weld toughness continues to be challenging for many. Current focus has been on pipe seam and girth weld HAZ toughness stability which has proven to be difficult to achieve. Optimization of the alloy and processing design are critical components of creating the desired final through thickness microstructure, grain size/homogeneity and a volume fraction of proper size Nb precipitates in the hot rolled condition and corresponding final base and weld metal ductility properties. Optimized processing of two Nb levels, 0.055% and 0.075%, Nanjing Iron and Steel Company successfully improved base metal plate strength and toughness stability that translated into improved pipe strength and toughness stability including pipe seam/girth welds HAZ toughness. The optimized 0.075% Nb girth weld HAZ fusion line average was 339 J @ −80 °C with a 9.3 J standard deviation while the optimized 0.055% Nb girth weld HAZ fusion line was 307 J @ −80 °C with a 55.2 J standard deviation.
Incorporating Measurement Uncertainty Into Machine Learning-Based Grade Predictions
Authors: Anderson Joel , Switzner Nathan , Kornuta Jeffrey , Veloo Peter
Published: December 2022

As part of the regulations published in October of 2019, PHMSA requires operators that do not have reliable records to conduct material verification in accordance with §192.607. As part of the material verification process, §192.607(d)(2) compels the operator to “[c]onservatively account for measurement inaccuracy and uncertainty using reliable engineering tests and analyses” when utilizing nondestructive examination (NDE) methods. The Pacific Gas and Electric Company (PG&E) has completed extensive testing to develop approaches that utilize nondestructive measurements to estimate grade. As part of this work, a supervised classification machine learning (ML) model was developed to predict pipe grade using NDE chemical composition measurements as inputs. While using the ML-based model provides substantial improvement over yield strength (YS) in predicting pipe grade, measurement uncertainty from NDE tools must be considered per §192.607(d)(2). Moreover, some amount of uncertainty is present in any measurement regardless of precision, and this measurement uncertainty may ultimately affect the ML model’s pipe grade classification.

This paper presents a methodology for incorporating this variability into the authors’ ML classification model using a Monte Carlo-based simulation approach. In addition, this study will discuss the various metrics that were developed for interpreting the most probable pipe grade from the large number of simulation results, including the average probability, range of probability, and the number of simulations where each grade was identified as having the highest probability. Since any ML model can misclassify a sample and there are such slight differences between adjacent grades, it is necessary to have a method of systematically validating the results based on prior knowledge. Several case studies using field data will be presented to illustrate this approach, including validation cases where the pipe grade is known.
Initial Experimental and Analytical Efforts to Predict Sustained Load Crack Growth During a Hydrotest and Subsequent Fatigue Crack Growth During Pressure Cycling
Authors: Hioe Yunior , Orth Fabian , Wilkowski Gery , Brust Frederick , Bagnoli Ken
Published: December 2022

Significant efforts were undertaken to develop experimental data to assess the effect of sustained load crack growth during a simulated hydrotest and the effect on fatigue crack growth during subsequent pressure cycling service operation. The pipe used was a 1960ERW 16-inch diameter by 0.250-inch thick X46 pipe. There were a variety of laboratory specimen tests including: standard and isochronous tensile tests at various rates, Charpy transition curves, C(T) J-R curve tests, and SENT J-R curve tests. There were axially surface-cracked pipe tests with monotonically increasing pressure to failure, as well as step-hold pressure tests. Cracks were put in the base metal as well as the ERW seam weld. Some key results to be shown are:

1. The fracture toughness of the base metal and ERW HAZ varies with a/t of the flaw in the SENT testing. Larger a/t specimens have lower toughness. It is believed that this behavior is a key aspect in leak-before-break behavior under pressure loading.

2. Slow strain rate tensile test showed that the yield point decreases with slower loading rates, but the strain-hardening exponent remained relatively constant. The drop in the stress-strain curve causes an increase in the crack-driving force, which is why crack growth can occur with sustained loading.

3. Step-hold pressurized pipe tests with axial surface cracks were conducted with a great amount of data and refined crack growth measurements. In one pipe test, there were four identical flaws. One flaw failed by leakage during a long hold-time. It could be patched, and the other three “identical” flaws all had some small (but different) amounts of ductile tearing. On subsequent pressure cycling, the crack growth rate was incredibly lower than standard fatigue crack growth rates. This was due to the crack retardation effect from the small ductile tear and crack-tip plasticity, with the reverse crack-tip compressive plasticity from unloading after the simulated hydrotest.

The fatigue crack growth rates were about 2 to 3 orders of magnitude slower. The crack retardation benefit easily overcame the small loss in the ligament from ductile tearing. Instead of failure being about 11,300 cycles it took 267,400 cycles. This is a huge benefit for liquid lines. A subsequent follow-on program to this is being undertaken by DOT/PHMSA to better characterize the crack retardation effect and also develop a methodology to predict the “Rupture Free Operational Time” after hydrotest.
Develop Standard Testing Approach for Evaluation of Materials Compatibility in Hydrogen Service
Authors: Chandra Ashwini , Prewitt TJ , Finneran Shane
Published: December 2022

Transformation and decarbonization of existing energy systems are a key part of global energy transition efforts to meet targets set in the COP21 Paris Agreement. In effort to reduce greenhouse gas emissions and decarbonize the existing energy systems, hydrogen has emerged as an attractive fuel option for energy storage and transportation. One key aspect considered is the potential for blending and transporting hydrogen in existing natural gas pipelines. It is recognized that the introduction of hydrogen in existing carbon steel pipelines may present a myriad of effects including hydrogen embrittlement, increases to fatigue crack growth rate, and reductions in ductility and yield strength when exposed to susceptible steels under stress. These potential effects may vary based on the vintage, strength of steel, weld type, and other specific pipeline characteristics, therefore the specific threats and severity of each should be evaluated for numerous pipeline configurations.

Establishing a standard and consistent approach for evaluation compatibility of pipeline materials with hydrogen service would be beneficial to the industry. The existing practice of assessing defects in hydrogen service is based on guidance from ASME B31.12. However, the guidance provided in ASME B31.12 is based on the response of hydrogen at higher concentrations and pressures than will be expected in typical transmission or distribution pipeline systems.

This paper provides a recommended approach to performing testing and analysis for existing and new pipe steels under various hydrogen blends. This would provide a framework across the industry for which a consistent approach for assessing compatibility could be assessed, and allow for improved alignment and compilation of material test data to establish a broader understanding of material compatibility.
Fitness for Service Engineering Assessment of Exposed Pipeline Sections
Authors: Kohandehghan Alireza , Debnath Suborno , Roy Kshama , Wickie Robert
Published: December 2022

Onshore pipelines are usually designed and constructed for burial conditions. However, pipeline exposures can develop from environmental and geohazard conditions such as creek crossing, soil washout due to significant rainfall events, short-term flooding, etc. Engineering assessment of the exposed pipeline sections is a vital consideration to assess the fitness of the exposed pipeline sections for continued service. A fitness for service engineering assessment methodology that was successfully used for the assessment of an NPS 10 onshore natural gas pipeline exposure is presented herein. The assessment is based on finite element analysis to evaluate several damage mechanisms, e.g., lateral and vertical longitudinal bending stresses and strains, buoyancy, hydrodynamic forces, vortex-induced vibration, mechanical damages due to foreign objects impact, and brittle fracture assessment as per failure assessment diagram approach. The proposed framework for the fitness for service engineering assessment of exposed pipe sections presented in this study helps identify potential integrity concerns and prioritize required corrective actions. The proposed methodology offers a robust framework that can significantly improve the operation and maintenance of the existing buried pipelines.
Framework for Pipeline Stress Corrosion Cracking Susceptibility Using Inspection & Mitigation Results: A Bayesian Approach
Authors: Shabarchin Oleg , Koduru Smitha , Hassanien Sherif
Published: December 2022

Stress Corrosion Cracking (SCC) is a form of cracking caused by interaction of a susceptible material, tensile stress, and a suitable environment. Considering recent SCC failures in pipelines coupled with increasingly stringent regulatory requirements, it is imperative for an operator to have an effective SCC integrity management program. To accomplish this, it is essential for the program to not only integrate multiple interacting factors that influence SCC, but also incorporate evidence from program mitigation actions. This paper presents a framework based on Bayesian approach to incorporate multiple lines of evidence while transparently treating associated uncertainty to estimate a more representative SCC occurrence and corresponding SCC failure rate. Knowledge gathered from industry SCC management best practices and SCC susceptibility models are used in conjunction with expert knowledge and ILI findings to develop the proposed framework. The framework consists of two components; first, SCC susceptibility is established to quantify the SCC occurrence rate on a pipeline. Second, field evidence is incorporated into the framework using Bayesian updating to refine the initial estimates of segment specific SCC occurrence and failure rate. The approach provides a significant flexibility to update the proposed model at any maturity level of the program as additional data becomes available.
Different Ways to Reduce Greenhouse Gas Emission in Pipelines
Authors: Zhang Jun , Anderton John , Kane Adrian
Published: December 2022

Pipelines are essential for keeping the lights on, homes warm, plants running, planes flying and water flowing. They also provide one of the safest means of transport. By taking some effective actions, they can contribute to the reduction of greenhouse gas emission significantly.

This paper explores a few ways for pipeline companies to help combat climate change.

There are of course hardware solutions, carbon capture at station equipment such as compressors or heat exchangers. Although undoubtably these solutions work, they are slow and expensive to implement. What we are going to look at are solutions that can be implemented by using existing software tools, or making a relatively small investment in a new software.

The first and most obvious way is the implementation of an effective leak detection program as defined in API 1175. The second way to reduce emission is through the optimization of fuel gas consumption by compressors. The third way is through the improvement of network operations.

With the move to hydrogen and renewable natural gas, pipeline simulation software can also help the pipeline industry to transit to greener energy, thus less emission.
New Findings in Leak Detection on Multi-Phase Pipelines
Authors: Hoffman Andrew , Zhang Jun , Wilkie Jason
Published: December 2022

With the increasing pressure to reduce greenhouse gas emission and protect the environment, effective leak detection in all pipelines has become more critical in recent years. This applies to multi-phase pipelines too. Little progress has been made in multi-phase pipeline leak detection in the last decades. Some of the main challenges in detecting leaks in multi-phase pipelines include:

• Complex and variable hydraulic conditions with flow regime changes when the fluid composition and flow-rate vary in a pipeline

• High cost and poor performance of flow meter instrumentation

• Feasibility of retrofitting leak detection hardware or equipment on operational pipelines.

Over the past few years significant research and field tests have been carried out to develop possible solutions to address the above challenges.

This paper describes some of the technologies tested on a few multi-phase pipelines. It addresses both the hardware and software used to detect leaks, the fluid withdrawal tests carried out and performance achieved. Potential applications and further development are outlined at the end.
New Approaches in Utilizing Eddy Current Testing to Address Pipeline Inline Inspection Requirement
Authors: Cornu Sylvain , Karé Raymond , Sweedy Ahmed , Sirois Michael
Published: December 2022

Eddy current testing is one of the most widely used NDT inspection techniques for both ferrous and non-ferrous materials. This may explain why it was one of the very early techniques implemented on an inline inspection tool (ILI) back in the 1970s, following the first implementation of Magnetic Flux Leakage (MFL) tools. Eddy current testing is primarily developed to accurately detect and size surface breaking defects. The technology is now mature and has been deployed in various applications, most notably for pipeline in-ditch inspection. As of today, the technology as a crack detection technique is not deployed commercially on ILI tools as it can only detect cracks on the inner pipe wall.

The most common use of the eddy current technology in ILI tools is the simple configuration for lift-off measurement. This offers a way to discriminate between internal and external corrosion on a volumetric tool (MFL) or enhance caliper-based geometry measurements. The most advanced applications of eddy current testing are targeting measurement of electromagnetic properties of the pipe wall to either measure material properties (pipe grade) or pipe stress due to external loading. Both pipe grade or pipe stress eddy current technologies can only operate successfully in combination with a magnetically saturated pipe wall, either prior to or during the measurement. The first objective of this development is to remove the requirement for magnetic saturation, thus removing the need for MFL magnets or large electromagnets.

The second objective is to progress the established Eddy current development to allow for the measurement of an additional parameter. Current commercial stress measurement method is uniaxial and aligned in the axial/longitudinal direction with limited coverage around the pipe circumference. The new development will make measurements in 2-D, longitudinal and hoop directions, and will include a full array of sensors to provide a full coverage 2-D stress map of the pipe wall.

The latest development will address accurate detection and sizing of defects on the internal wall of the pipeline. Most crack detection tools are focused on the outer wall, e.g. Stress Corrosion Cracking. However, the growing interest in hydrogen transportation and the potential for Hydrogen Induced Cracking (HIC) on the internal surface of pipelines, has focused the industry on developing tools for internal crack detection. Detection and sizing of surface breaking defects are at the core of eddy current technologies.
Guidelines to Develop Fitness-for-Service Assessment of Exposed Pipeline Due to Flood Events: Investigation, Assessment and Mitigation
Authors: Liu Kaiwen , Beltran Alejandro , Gao Serene , Greig Andrew
Published: December 2022

Over the course of the British Columbia (BC)/ Washington State (WA) flood event, the pipeline restart preparation required a significant, sustained effort to complete a detailed assessment of the pipe’s integrity. Trans Mountain Corporation was able to develop a detailed Fitness-For-Service (FFS) assessment for the exposed pipe segments due to the flood and gain approval from the CER (Canada Energy Regulator) for a successful pipeline restart.

On the evening of November 14, 2021, the Trans Mountain Pipeline LP (Trans Mountain) pipeline was shut down as a precautionary measure in response to an ongoing extreme rainfall event. There were multiple sites identified as critical pipe exposures where the pipeline was exposed and unsupported, or experienced mechanical damage, due to soil wash out. All confirmed exposure sites were reported to the CER and Trans Mountain responded in-field to support and protect the pipeline from flowing water, complete pipe inspections, determine the pipe’s FFS, and complete the required repairs before pipeline restart.

This paper provides a summary of the FFS assessment that Trans Mountain completed to ensure the integrity of its oil pipeline system after the significant geotechnical event, and the process followed to develop the long-term integrity plans.
Pipeline Crossing Significant Elevation Difference Terrain Design
Authors: Ma Te , Wu Tiantian , Qiao Sean , Harper Taylor
Published: December 2022

Liquid transmission pipeline systems passing through geological areas with significant elevation changes along their route may possibly run at “slack flow” conditions if improperly designed. Slack flow is a phenomenon in which a pipeline transporting a liquid product develops vapor bubbles at points where the pipeline pressure falls below the vapor pressure of that liquid. Slack flow operating conditions will cause the occurrence of fluid column separation (a portion of the liquid is vaporized), which can result in leak detection system inaccuracy, pipeline vibration (when bubbles collapse) and excessive PIG speed, which makes the pipe difficult to inspect with intelligent PIGs.

To eliminate the occurrence of slack flow as well as to reduce project costs, optimization methods could be used, including smaller diameter pipe, thicker walled (and/or higher-grade) pipe, and the use of a pressure control station (PCS).

The subject pipeline is a proposed liquid transmission pipeline with nominal diameters of 762 mm/914 mm/1067 mm and a length of approximately 1200 km. The pipeline passes through a significant elevation change (1326 m elevation change within 50 km, between mountain top and river valley bottom) where the static pressure can reach as high as 12,200 kPa (at a crude density of 938 kg/m3). Slack flow or overpressure may occur due to this situation if the system is not designed properly.

This paper showcases the pipeline design considerations and methodologies used to solve the slack flow operation condition while avoiding all possible overpressure threats. The considerations include maximum and minimum operating conditions for flow rates and pressures. The system optimization methods include optimizing the installation length of thicker wall pipe (higher design pressure) in combination with designing a pressure control station (PCS). Furthermore, future expansion of the pipeline system was included into design consideration.

With the optimized design, slack flow conditions can be avoided, and the pipeline will be operated in a safe, leak detectable, inspectable (intelligent pigging) and cost-effective manner.
Managing the Threat of Corrosion on the Long Seam
Authors: Davies Christopher , Nasreddine Ranine , Slater Simon
Published: December 2022

The industry has become increasingly aware of the threat posed by selective seam weld corrosion (SSWC). This has been driven by changes made to gas transmission regulation in 2020 and an increased focus on SSWC as a significant threat in both gas and liquid pipelines. A number of historical publications exist, which provide guidance on how corrosion interacting with the long seam can be addressed. However, there has been very little presented in recent years to encompass current understanding of how corrosion on the long seam, and specifically SSWC, can be managed amid present regulation requirements. Operators have recent experience that can be used to develop an optimized approach that includes technology improvements and a much more informed knowledge of how SSWC differs from coincident corrosion.

The aim of this paper is to build on existing guidance and present an optimized approach for managing corrosion interacting with the long seam, with particular attention on differentiating SSWC from coincident corrosion crossing the long seam and defining how both can be assessed to create effective remediation plans. The flow chart considers both types of corrosion and leans on existing guidance and models that can be used to assess anomalies. A key part of the process is to consider susceptibility, material properties and appropriate in-line inspection (ILI) assessments in order to define the most suitable approach based on data and a thorough understanding of the individual pipeline system. Examples will be used to illustrate how the approach can be implemented and on what basis decisions can be made to move through to an optimized remediation plan.
Stress Analysis of ASME Section X Flanges Using Classical Lamination Theory
Authors: Bouzid Sofiane , Bouzid Abdel-Hakim , Ngô Anh Dung
Published: December 2022

Fiber Reinforced Plastic composite flanges are extensively used in pressure vessels and pipping systems working under harsh and corrosive environment. ASME section X gives the design procedure to follow to verify the mechanical integrity and leak tightness of these flanges. Unfortunately, this method treats FRP bolted flange joints using the same analytical approach as that of ASME section VIII div. 1 which is derived for metallic flanges. The approach was developed in the late 30’s for flanges having isotropic material properties while the flexibility of the flange different elements and their elastic interaction is ignored. In the absence of a suitable approach such as one based on classical laminate theory, the structural integrity of FRP bolted flange joints remains an issue and some flange classes and sizes will suffer structural failure.

It is proposed to study ASME section X flanges using a recently developed model based on the classical laminate theory and the flexibility of the different elements to identify those critical ones that needs particular attention with regards to composite material selection and bolting and pressure limits. Parameters such as flange ring rotation and stresses in the bolts, flange and gaskets will be investigated. The study on the strength of FRP flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. The critical stresses and their locations on the flange will be given for each flange. The study will be conducted on flanges of NPS 1 to 48 and classes from 25 to 150. The analysis will be conducted on flanges fabricated out of Fiberglass Reinforced Plastic (FRP) laminates, manufactured with vinyl ester resins and various types of fibrous glass reinforcing. The study shows that FRP flanges of class 25 and 50 are most vulnerable and should be less loaded.
Managing Rooftopping: An In-Line Inspection Based Approach
Authors: Conrad Brett , Kopp Gerhard , Adamson Ross , Mikalson Tommy , Lai Roger
Published: December 2022

Variation in longitudinal seam weld geometries can pose a challenge for liquid operator’s crack management programs. Both, radial misalignment and angular misalignment (also known as “peaking” or “rooftopping”) contribute to what is termed an “anomalous” seam weld geometry. These anomalous geometries create two challenges for an operator’s crack management program: they can reduce the fatigue life of the seam weld due to an increased stress concentration; and they create an unexpected geometry which challenges crack in-line inspection tools. The combination of these challenges can create a situation where a seam weld flaw can propagate at a higher rate without being detected by in-line inspection technologies, increasing the risk of failure. It is therefore prudent for operators to understand where they may have anomalous seam weld geometries and adjust their crack management plan accordingly.

This paper outlines the approach taken by TC Energy to leverage existing datasets to quantify anomalous seam weld geometries, and more specifically rooftopping, on pipe following an incident. Several different in-line inspection technologies were investigated to quantify the presence of rooftopping, with various levels of success. One of the most promising approaches involved sensor stand-off data of an ultrasonic wall thickness measurement technology. The technology was initially pulled through a calibration spool in which rooftopping was artificially introduced. Through collaboration between the TC Energy and NDT Global, an algorithm was developed to not only detect, but also size the levels of rooftopping within the pipeline. The results of the excavation program found that the technology could adequately detect rooftopping. The absolute sizing of rooftopping is an area of focus for future improvements; however, the ability to detect rooftopping allows for a better understanding of the pipeline system and adds another level of data integration which TC Energy has used to improve their liquids crack management program.