bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementation of Reliability-Based Criteria for Corrosion Assessment
Authors: Adianto Riski , Nessim Maher , Kariyawasam Shahani , Huang Terry
Published: November 2018

In an era where pipeline safety is of paramount interest, vintage pipelines with corrosion have to be managed responsibly. Optimization of corrosion mitigation for these pipelines has a significant effect on the industry’s management systems and related costs. To help optimize the corrosion management process, reliability-based limit state design (LSD) corrosion assessment criteria have been developed for onshore pipeline as part of a joint industry project. The LSD approach is a simplified form of the reliability-based approach. It achieves risk or safety consistency within a certain tolerance, while utilizing a deterministic procedure that is easier to apply. The overall methodology and development of the criteria are described in a companion paper. This paper describes the application of the LSD corrosion criteria to real pipeline cases and evaluation of the results.

The performance of the LSD criteria, as determined by the number of corrosion repairs required, was compared to that of the CSA Z662 deterministic assessment criteria and the full probabilistic criteria used by TransCanada Pipelines Ltd. (TCPL) to determine if the criteria lead to practical solutions for real cases. The CSA criteria use safety factors that are not directly based on the risk level associated with the pipeline, while the TCPL criteria utilize pipeline-specific reliability targets. The comparison was conducted using a comprehensive set of TCPL pipeline cases that covered a wide range of diameters (NPS 6 to 42), hoop stress-to-SMYS ratios (0.4 to 0.8) and corrosion densities (0.625 to 6508 features per km). The results show that the LSD criteria perform similarly to the TCPL reliability-based criteria, and that both are generally less conservative than the CSA deterministic criteria.

The results demonstrate that the LSD criteria provide a simple and deterministic procedure that capitalizes on the benefits of more complex reliability analyses in eliminating unnecessary conservatism and focusing on the repairs required to achieve consistent safety levels for all cases. Thus, these criteria will enable operators to maximize risk reduction for the dollar spent.
Study of Safe Dig Pressure Level for Rock Dents in Gas Pipelines
Authors: Arumugam Udayasankar , Gao Ming , Krishnamurthy Ravi , Wang Rick , Kania Richard
Published: November 2018

Pipelines passing through hilly-terrain potentially have numerous rock dents. Some of them require further in-ditch investigation. However, in-ditch experience revealed elastic rebounding and re-rounding due to internal pressure that could cause cracking on dent outside surface when rock is removed even after following the commonly used pressure reduction by industry. Such OD-surface cracking in rock dent could pose safety issues to excavation crew and immediate integrity threat due to gas release. A preliminary research was performed to determine the required safe dig pressure level for rock dent excavation and address if there is a gap between the common industry practice for pressure reduction. This research could assist pipeline operators with setting a safe dig pressure level for rock dent excavation.

The research consists of four components. First, detail review of rock dents cracking experience during excavation has been performed and identified relevant parameters that contributed to OD-cracking. Then, performed several rock dent case studies with different dent depths, indenter sizes, internal pressures and developed criterion for OD cracking using Finite Element Analysis. Thirdly, a decision chart was developed for safe rock dent excavation and presented. Finally, full-scale denting tests with internal pressure was conducted to corroborate the safe dig pressure criterion and compared against FEA results. In this paper, all above components are presented with summary of findings and recommendations for future research.
Asset Integrity Management System Audits for the National Gas Company of Trinidad and Tobago
Authors: Brongers Michiel P. , Weichel Steven J. , Mohammed Rafer , Kissoon Amanda
Published: November 2018

In 2015 and 2017, Asset Integrity Management (AIM) System Audits were performed of a natural gas transmission and distribution company. The AIM systems were evaluated as part of a National Facilities Audit (NFA) for the Trinidad and Tobago T&T) Ministry of Energy and Energy Industries (MEEI) and for the company directly. To allow comparison of the company-sponsored audit with the NFA performed for the MEEI, the audit protocol and methodology used the same scoring system and benchmarking in both cases. This paper presents the results, divided as Notable Mentions and Opportunities for Improvement for the company. The findings are discussed in the context of the national oil & gas industry in Trinidad and Tobago, and the long-term vision and efforts of the company to improve its AIM performance.
Colonial Scout: A Powerful Web Map Solution Designed As the Data Messenger for Colonial Pipeline Company
Authors: James Eric H.
Published: November 2018

Colonial pipeline’s asset data management team maintains large volumes of data, CAD facility drawings, and historical records. Organizing and encapsulating this data has been a historical challenge. Frequent requests for data relevant to individual projects was time-consuming and laborious. Colonial Scout was designed to be a simple self-help tool that allows employees to locate data quickly. Further, it was constructed to provide a one-stop shop for accessing Colonial data in its most current and up to date forms. Design of the Colonial Scout application took approximately six months to complete. The final result is an intuitive web map application connected to a versioned enterprise geodatabase. Within the application, relevant tools interact with live data, providing immediate access to Colonial’s most up to date information. Integration with FME server, adept document management and Esri’s ArcGIS enterprise have advanced colonial scout’s efficiency in locating data. These software products enhance colonial scout’s power as a help-yourself product for accessing current information through means of helpful data visualization. Colonial Scout is the go to source for alignment sheets, CAD drawings, property and easement records, locating tank assets, and Colonial’s 5,500 miles of pipeline assets. Users also have the ability to download data in a variety of file formats for project specific analysis and reports. Colonial Scout has significantly reduced the number of work orders related to searching for data, drawings and records. Employees are better informed by acquiring the latest information and no longer rely on outdated paper hardcopies. Colonial Scout is an innovative and expandable solution for Colonial’s ever-growing data needs.
Understanding Quantitative Performance of Large Standoff Magnetometry in Detecting Live Gas Pipeline Anomalies With Stress Estimation
Authors: Xu Tianzong (David)
Published: November 2018

Large standoff magnetometry (LSM) is an emerging non-intrusive, above-ground, passive geo-magnetization flux leakage measurement technology to detect pipeline features or anomalies associated with elevated stresses. Although many promising field trial results have been reported in the past, its overall performance still has not reached sufficient consistency and reliability. This paper presents PG&E’s effort in gaining some fundamental understanding of the current LSM technology and its qualitative & quantitative performance. Specifically location accuracy of girth weld, casing end, dent and landslide damage is analyzed with references to inline inspection (ILI) and excavation data. In addition, basic physics of LSM stress quantification is examined using references of a full-scale finite element stress analysis on selected plain dents. The outcomes indicate advanced global navigation satellite system (GNSS) tool plus capability of identifying girth weld are important to achieve good anomaly location accuracy especially as LSM tends to report more indications than other inspection technologies in current practice. The LSM stress estimation and its comparison to pipe’s specified minimum yield strength (SMYS) may be only good quantitatively within magneto-elastic regime where localized stress concentration zones (SCZs) are under elastic stress loading only and without presence of residual plastic stress.
System Wide Risk Assessment in the 21st Century: TransCanada’s Approach
Authors: Tomic Aleksandar , Huang Terry , Kariyawasam Shahani
Published: November 2018

The US regulations and Canadian standards require that a System Wide Risk Assessment (SWRA) be performed for all pipelines. Typically, an annual SWRA is performed by operators and used to identify high risk sections. Appropriate identification of these high risk sections is expected to avoid significant failures, particularly in higher consequence locations. With current heightened public awareness levels and related regulatory oversight even a failure, such as a rupture, with relatively low safety and environmental consequences is considered undesirable. Post failure analysis often examines SWRA results to investigate if SWRA is identifying such locations appropriately. Are SWRAs developed with the intention of avoiding these failures? How can we ensure SWRA achieves these expectations?

This paper examines the purpose of SWRA and takes a data driven approach to critically assess its effectiveness. In the 21st century, where vast amounts of data are being generated through inspections, patrolling, monitoring, and management systems, TransCanada’s approach seeks to leverage all the evidence or leading indicators of high risk and imminent failures. However, data and subject matter expert opinions are not perfect and complete. Understanding these limitations and inadequacies, yet optimizing in the face of them, requires an honest representation of reality with considerations to limits of applicability and probable blind spots, together with clear decision-making to achieve a well-defined purpose.

This paper will describe the six-year evolution of a quantitative SWRA approach with a built in continuous improvement cycle. Examples of learning from failures, assessments, and analytical studies and how they were incorporated into the SWRA are demonstrated. Also the development of meaningful risk targets and their applications are explained. The particular details for scenarios where risk criteria have been exceeded in both high consequence and low consequence locations are examined and interpreted such that maintenance teams can address issues appropriately. The value of bringing all relevant data to a common risk platform is also demonstrated. In the 21st century, where data availability will only increase, appropriate holistic incorporation of these multiple data sets is critical to identify where multiple threats interact. Depending on how likelihood of failure and the consequences of failure are combined, the resultant risk could potentially be high (i.e. different risk measures). Therefore, it is important to cover all risk measures that are relevant and develop criteria that govern these risk measures.

The implementation of a holistic SWRA to make the best optimized decisions possible is demonstrated in practical situations where inputs are imperfect and vast data sets need to be combed for meaningful indicators.
A Canadian Operator Based Framework for Pipeline Pressure Tests: Lessons Learned
Authors: Robertson Nicole-Lee M. , Campbell Bob
Published: November 2018

Commissioning pressure tests are a critical life-of-asset record. Successfully achieving an acceptable pressure test can be challenging both at an execution and documentation perspective. This paper aims to assist in streamlining the approach to pipeline commissioning pressure tests between operators to increase efficiency and drive consistency across the pipeline industry. Key lessons learned from the planning stages through to the quality control turnover are highlighted. Lessons learned, respective to pressure tests, include: road map of Canadian regulations, tabulated equipment requirements, suggested instrumentation setup, template checklist for test plans, outlined company to contractor responsibilities, as well as a proposed internal process to manage and accept completed tests.
Geohazard Management Approach Within Safety Case
Authors: Zapata Dario , Pederson Ingrid , Keane Sean
Published: November 2018

Safety case is utilized within the Enbridge Pipeline Integrity Management Program as a means to provide evidence that the risks affecting the system have been effectively mitigated (LeBlanc, et al. 2016). The safety case is an independent, evidence-based assessment based on system integrity management processes applied across all pipelines. This paper describes the process in which safety case methodology was implemented to manage geohazard threats. The benefits of assessing geohazard and other integrity threats will also be discussed. The safety case report documents the opportunities to address the identified problems in addition to the relationship between hazards, implemented controls, and associated susceptibility.

To demonstrate that adequate safety controls for geohazard threats have been incorporated into the operational and maintenance phase of the pipeline system, the geohazard management component of the safety case was assessed using a bowtie diagram. The results gave visibility to the geohazard program and its effectiveness. Predefined safety performance metrics with probabilistic and deterministic criteria are evaluated to confirm the geohazard program’s continued effectiveness.

Results from the safety case assessment identify opportunities for improvement and provide a basis for revision to maintenance, assurance and verification programs. Ultimately the assessment demonstrates that geohazard threats in the pipeline system are being recognized and assessed. The assessment provides evidence that adequate resources and efforts are allocated to mitigate the risk and identifies continuous improvement activities where needed. The safety case report generated as the final portion of an integrity management framework demonstrates risk is as low as reasonably practicable (ALARP).
Understanding Inverse Fracture: A Comparison of Results of Drop Weight Tear Tests and Partial Gas Tests
Authors: Erdelen-Peppler Marion , Kalwa Christoph , Völling Alexander
Published: November 2018

For a safe operation of gas pipelines, the prevention of propagating brittle facture is one of the most important requirements. To evaluate the transition temperature of a propagating fracture, the Drop Weight Tear (DWT) Test was developed in the 60s. Fracture surfaces of DWT specimens have been shown to correspond well to the fracture surface of a pipe exposed to a propagating fracture at a certain temperature. Historically, there have always been observations of the fracture initiating in a ductile manner in the DWT test. Nevertheless, the most widely used test standard rules out such behavior, known as inverse or abnormal fracture. As an option to prevent ductile initiation, an alternative notch is proposed. While this might have served in the earlier days, high toughness steels of today are known to provide a high resistance against crack initiation and are therefore prone to inverse fracture, even when making use of the suggested alternative notch. Other, non-standard notch types have been investigated and discussed in literature, amongst these the static pre-crack and brittle weld notch.

Observations of the DWT test, especially comparing material showing non-inverse and inverse behaviour, show delayed crack initiation resulting in large deflection when the specimens are inverse. This high degree of pre-deformation of the material will have an adverse influence on the material performance by the time the crack propagates into it. This implies that the appearance of inverse fracture is a test effect in the laboratory test, and not an inherent material property, leading to the question if such DWT test results still correspond to the behavior of pipes. If the correlation is shown to be valid, the brittle initiation requirement as such becomes questionable.

This study summarises investigations of different notch types in DWT tests. West Jefferson tests that have been conducted to verify the correlation to shear area fraction in DWT tests. The investigation revealed that ductile initiation could not be reliably suppressed. While neither Chevron nor static pre-crack specimen lead to any reduction of the occurrence of inverse fracture, test series of brittle weld specimens did have a higher number of valid specimens. Interestingly, the results of valid, non-inverse specimens and invalid, inverse specimens showed no shift in transitional behavior. Correspondingly, both valid and invalid specimens showed a good representation of the pipe behaviour in the upper transition region.
Pipeline Dent Fatigue Crack Leak Rate for Liquids Pipelines and the Application to Release Consequence Assessment
Authors: Tiku Sanjay , Piazza Mark , Semiga Vlado , John Binoy , Dinovitzer Aaron
Published: November 2018

Pipeline design and integrity management programs are employed to ensure reliable and efficient transportation of energy products and prevent pipeline failures. One of the failure modes that has received attention recently is pipeline fatigue due to pressure cycling in liquid pipelines, promoting through wall cracking and the release of product. Being able to estimate the leakage rate and/ total release volume are important in evaluating the consequence of developing a through wall crack, operational responses when incidents occur, and remedial action strategies and timelines. Estimates of leak rates can be used in pipeline system threat and risk assessment, evaluation of leak detection system sensitivity, development of Emergency Response Plans and strategies, and post-event evaluation.

Fracture mechanics techniques consider the response of crack-like features to applied loading such as internal pressure, including estimation of crack mouth opening. Considering the differential pressure across the pipe wall and the crack opening area, estimated from the crack mouth opening, the flow of fluid through the crack can be conservatively estimated. To understand the conservatism of this analytical estimate of leakage rate, full-scale testing has been completed to evaluate the leakage rate through dent fatigue cracks of differing lengths under a range of internal pressures, and compare the empirical measured results to the analytical/theoretical estimates. The test procedure employed cyclic internal pressure loading on an end-capped pipe with a dent to grow fatigue cracks through the pipe wall thickness. Once a through wall crack was established, the internal pressure was held constant and the leakage rate was measured. After measuring the leakage rate, cyclic loading was employed to grow the crack further and repeat the leakage rate measurement with the increased crack length.

The results of this experimental trial illustrate that the tight fatigue crack resulted in a discontinuous relationship between leakage rate and pipe internal pressure. Measureable leakage did not occur at low pipe internal pressures and then increased in a nonlinear trend with pressure. These results illustrate that a liquid pipeline with a through wall fatigue crack operating at a low internal pressure, or one having taken a pressure reduction, can have low leakage rates. The data and results presented in this paper provide a basis for an improved understanding and describing the leakage rate estimates at pipeline fatigue cracks, and providing insights into leakage rates and how to conservatively estimate them for fatigue crack consequence evaluation.
Validation of Computed Tomography Technology for Pipeline Inspection
Authors: Piazza Mark , Burns Timothy H. , Medford James , Shie Taylor
Published: November 2018

Pipeline operators rely extensively on in-line inspection (ILI) systems and other forms of non-destructive examination (NDE) as the basis for meeting the continual assessment requirements to evaluate pipeline integrity. The verification of ILI prediction accuracy involves correlating ILI data to direct inspection/assessment information using traditional NDE methods such as Ultrasonic Testing (UT), Phased Array Ultrasonic Testing (PAUT), and Electromagnetic Testing (ET). Substantial effort has been taken to establish and consider measurement tolerances for ILI systems, but not as much attention has been placed on understanding the tolerances of NDE technologies. Through studies conducted by Pipeline Research Council International, Inc. (PRCI) these NDE methods have been shown to have inconsistencies and inaccuracies in sizing and characterizing pipe wall and weld seam crack-like anomalies. Effectively managing the uncertainty in NDE measurements and selection of the appropriate technologies for anomaly verification is as important to continuous improvement in pipeline integrity management programs as ILI tool tolerance.

A primary goal for pipeline operators is to develop field-ready NDE methods for full volumetric characterization of pipeline anomalies. The inability of traditional NDE methods to accurately provide a three-dimensional (3D) image of a pipe wall features in the field leads to critical decisions being made based on imprecise tools, with layers of conservatism being included in the analysis for both NDE and ILI measurements. The lack of precision often leads to conservative and therefore excessive repair digs, unnecessary pipe replacements, and in some cases hydrostatic pressure testing of the pipeline to verify the system integrity.

This paper presents the results of a research project that includes comparative analysis of seam anomaly characterization data from an ILI system, traditional NDE inspection, Computed Tomography (CT), and metallurgical results. CT is the only current method that has shown consistency in providing accurate 3D profile measurements of an anomaly comparable to destructive testing and direct measurement of anomaly characteristics. The CT results presented in this paper represent the potential for field ready inspection capabilities as the data were obtained from full circumference measurement of pipe samples rather than plate samples, which have typically been studied in prior analysis of CT methods. Obtaining accurate data on anomaly dimensions is critical to understanding and improving the application of ILI and NDE data to drive integrity decisions. Improved results in the field will lead to improved decision-making to protect the environment and public safety.
Fracture Toughness Testing and its Implications to Engineering Fracture Mechanics Analysis of Energy Pipelines
Authors: Limon Sergio , Martin Peter , Barnum Mike , Pilarczyk Robert
Published: November 2018

The fracture process of energy pipelines can be described in terms of fracture initiation, stable fracture propagation and final fracture or fracture arrest. Each of these stages, and the final fracture mode (leak or rupture), are directly impacted by the tendency towards brittle or ductile behavior that line pipe steels have the capacity to exhibit. Vintage and modern low carbon steels, such as those used to manufacture energy pipelines, exhibit a temperature-dependent transition from ductile-to-brittle behavior that affects the fracture behavior. There are numerous definitions of fracture toughness in common usage, depending on the stage of the fracture process and the behavior or fracture mode being evaluated. The most commonly used definitions in engineering fracture analysis of pipelines with cracks or long-seam weld defects are related to fracture initiation, stable propagation or final fracture.

When choosing fracture toughness test data for use in engineering Fracture Mechanics-based assessments of energy pipelines, it is important to identify the stage of the fracture process and the expected fracture behavior in order to appropriately select test data that represent equivalent conditions. A mismatch between the physical fracture event being modeled and the chosen experimental fracture toughness data can result in unreliable predictions or overly conservative results. This paper presents a description of the physical fracture process, behavior and failure modes that pipelines commonly exhibit as they relate to fracture toughness testing, and their implications when evaluating cracks and cracks-like features in pipelines.

Because pipeline operators, and practitioners of engineering Fracture Mechanics analyses, are often faced with the challenge of only having Charpy fracture toughness available, this paper also presents a review of the various correlations of Charpy toughness data to fracture toughness data expressed in terms of KIC or JIC. Considerations with the selection of an appropriate correlation for determining the failure pressure of pipelines in the presence of cracks and long-seam weld anomalies will be discussed.
Application of In-Line Inspection and Failure Data to Reduce Subjectivity of Risk Model Scores for Uninspected Pipelines
Authors: Beauregard Yannick , Woo Aaron , Huang Terry
Published: November 2018

Pipeline risk models are used to prioritize integrity assessments and mitigative actions to achieve acceptable levels of risk. Some of these models rely on scores associated with parameters known or thought to contribute to a particular threat. For pipelines without in-line inspection (ILI) or direct assessment data, scores are often estimated by subject matter experts and as a result, are highly subjective. This paper describes a methodology for reducing the subjectivity of risk model scores by quantitatively deriving the scores based on ILI and failure data.

This method is applied to determine pipeline coating and soil interaction scores in an external corrosion likelihood model for uninspected pipelines. Insights are drawn from the new scores as well as from a comparison with scores developed by subject matter experts.
Pipeline Open Data Standard (PODS) Next Generation Data Model
Authors: Veenstra Peter C. G.
Published: November 2018

The Pipeline Open Data Standard (PODS) Association develops and advances global pipeline data standards and best practices supporting data management and reporting for the oil and gas industry. This presentation provides an overview of the PODS Association and a detailed overview of the transformed PODS Pipeline Data Model resulting from the PODS Next Generation initiative.

The PODS Association’s Next Generation, or Next Gen, initiative is focused on a complete re-design and modernization of the PODS Pipeline Data Model. The re-design of the PODS Pipeline Data Model is driven by PODS Association Strategy objectives as defined in its 2016–2019 Strategic Plan and reflects nearly 20 years of PODS Pipeline Data Model implementation experience and lessons learned.

The Next Gen Data Model is designed to be the system of record for pipeline centerlines and pressurized containment assets for the safe transport of product, allowing pipeline operators to:

• Achieve greater agility to build and extend the data model,

• respond to new business requirements,

• interoperate through standard data models and consistent application interface,

• share data within and between organizations using well defined data exchange specifications,

• optimize performance for management of bulk loading, reroute, inspection data and history.

The presentation will introduce the Next Gen Data Model design principles, conceptual, logical and physical structures with a focus on transformational changes from prior versions of the Model. Support for multiple platforms including but not limited to Esri ArcGIS, open source GIS and relational database management systems will be described. Alignment with Esri’s ArcGIS Platform and ArcGIS for Pipeline Referencing (APR) will be a main topic of discussion along with how PODS Next Gen can be leveraged to benefit pipeline integrity, risk assessment, reporting and data maintenance. The end goal of a PODS implementation is a realization of data management efficiency, data transfer and exchange, to make the operation of a pipeline safer and most cost effective.
A Case Study on Potential SCC Management Using 10-Inch EMAT ILI
Authors: Henderson Scott , Ector Jeff , Kirkwood Mike
Published: November 2018

Environmentally assisted cracking (EAC), more specifically, stress corrosion cracking (SCC) has been a pipeline integrity concern since the 1960s. However, there were not many options for pipeline operators to effectively manage this threat on gas and liquid pipelines. SCC and other crack type defects have become a threat which is more widely understood and can be appropriately managed through in-line inspection (ILI). The two primary technologies for crack detection, developed in the 1990s and early 2000s respectively, are ultrasonic (UT) and electromagnetic acoustic transducer (EMAT). Although EMAT was originally developed to find SCC on gas pipelines, it has proven equally valuable for crack inspections on liquid pipelines.

A case study with a gas and natural gas liquid (NGL) operator, ONEOK Inc. (ONEOK) demonstrates the effectiveness of using EMAT ILI to evaluate the potential threat of crack and crack-like defects on a 48 mile (77.2 km), liquid butane pipeline. By utilizing both 10-inch (254 mm) multiple datasets (MDS) technology and 10-inch (254 mm) EMAT ILI tools, ONEOK proved the effectiveness of ILI to identify critical and sub-critical crack and crack-like defects on their pipeline.

This paper will present on the findings from the two technologies and illustrate the approaches taken by the operator to mitigate crack type defects on this pipeline.
An Update to the Recommended UKOPA External Interference Frequency Prediction Model and Pipeline Damage Distributions
Authors: Goodfellow Graham , Lyons Chris , Turner Susannah , Gray Fraser , Joyce Simon
Published: November 2018

The United Kingdom Onshore Pipeline Operators Association (UKOPA) was formed by UK pipeline operators to provide a common forum for representing operators interests in the safe management of pipelines. This includes providing historical failure statistics for use in pipeline quantitative risk assessment and UKOPA maintain a database to record this data.

The UKOPA database holds data on product loss failures of UK major accident hazard pipelines from 1962 onwards and currently has a total length of 21,845 km of pipelines reporting. Overall exposure from 1952 to 2016 is 927,351 km years of operating experience with a total of 197 product loss incidents since 1962. The low number of failures means that the historical failure rate for pipelines of some specific diameters, wall thicknesses and material grades is zero or statistically insignificant. It is unreasonable to assume that the failure rate for these pipelines is actually zero.

In addition to product loss incidents, the UKOPA database contains extensive data on measured part wall damage that did not cause product loss, unlike the European Gas Incident data Group (EGIG) database, which also includes the UK gas transmission pipeline product loss data. The data on damage to pipelines caused by external interference can be assessed to derive statistical distribution parameters describing the expected gouge and dent dimensions resulting from an incident. Overall external interference incident rates for different class locations can also be determined. These distributions and incident rates can be used in structural reliability based techniques to predict the failure frequency due to external interference for a given set of pipeline parameters.

The current distributions of external interference damage were derived from data up to 2009 and presented as Weibull distributions for gouge depth, gouge length and dent depth. Analysis undertaken for the COOLTRANS CO2 pipeline project, undertaken by National Grid in the UK, has identified several improvements to the recommended UKOPA approach to external interference failure frequency prediction. This paper summarises those improvements and presents updated damage distribution parameters from data up to 2016.
Girth Weld Strength Matching Effect on Tensile Strain Capacity of Grade X70 High Strain Line Pipe
Authors: Tajika Hisakazu , Sakimoto Takahiro , Handa Tsunehisa , Ikeda Rinsei , Kondo Joe
Published: November 2018

Recently high grade pipeline project have been planned in hostile environment like landslide in mountain area, liquefaction in reclaimed land or the frost heave in Polar Regions. Geohazards bring large scale ground deformation and effect on the varied pipeline to cause large deformation. Therefore, strain capacity is important for the pipeline and strain based design is also needed to keep gas transportation project in safe. High grade steel pipe for linepipe tends to have higher yield to tensile (Y/T) ratio and it has been investigated that the lower Y/T ratio of the material improves strain capacity in buckling and tensile limit state. In onshore pipeline project, pipe usually transported in 12 or 18m each and jointed in the field. Girth weld (GW) is indispensable so strength matching of girth weld towards pipe body is important.

In this study strain capacity of Grade X70 high strain pipes with size of 36″ OD and 23mm WT was investigated with two types of experiments, which are full scale pipe bending tests and curved wide plate tests.

The length of the specimen of full scale bending tests were approximately 8m and girth weld was made in the middle of joint length. A fixed internal pressure was applied during the bending test. Actual pipe situation in work was simulated and both circumferential and longitudinal stress occurred in this test. Test pipes were cut and welded, GTAW in first two layer and then finished by GMAW. In one pipe, YS-TS over-matching girth weld (OVM) joint was prepared considering the pipe body grade. For the other pipe, intentionally under-matching girth weld (UDM) joint was prepared. After the girth welding, elliptical EDM notch were installed in the GW HAZ as simulated weld defect. In both pipe bending tests, the buckling occurred in the pipe body at approximately 300mm apart from the GW and after that, deformation concentrated to buckling wrinkle. Test pipe breaking locations were different in the two tests. In OVM, tensile rupture occurred in pipe body on the backside of buckling wrinkle. In UDM, tensile rupture occurred from notch in the HAZ. In CWP test, breaking location was the HAZ notch. There were significant differences in CTOD growth in HAZ notch in these tests.
Optimization of Averaging Window Length and Alarming Hold Time in Volume Balance RTTM Leak Detection to Minimize False Alarms and Spill Volume
Authors: Learn Shawn , Shahidi Ehsan
Published: November 2018

Reliability and sensitivity are two main performance metrics of leak detection systems as defined by API 1130 [1]. Proper thresholding scheme is one of the primary factors in having a sensitive and reliable leak detection system with timely detection. In RTTM leak detection, if not dealt with properly, severe pipeline pressure transients can degrade the performance of the leak detection system. One of the common basic methods of reducing the effect of pressure transients is using moving averaging windows; having looser thresholds on the shorter averaging windows, while maintaining tighter thresholds on the longer ones. The thresholds are typically set to meet the API 1149 [2] curve for the pipeline. While the post-processing of filtered data and alarm assessment has been explored via different methods such as sequential probability ratio test, to the authors’ knowledge, there is currently no systematic way of selecting the averaging windows to minimize false alarms prior to the post-processing of the average-filtered data. Moreover, to be able to maintain tight thresholds, especially in shorter averaging windows, one of the common methods is to apply dynamic thresholds, i.e. temporarily expanding thresholds when transients occur. While effective in some scenarios, the main disadvantage of this method is that the imbalance caused by a transient may not clear until the entire averaging window period is passed. This causes either extended periods of degraded performance, or more false positives. This paper utilizes an alarming hold time (also referred to as alarm persistence [3]) to remedy this problem where the averaging window length is reduced while maintaining detection time and sensitivity. To find the optimal set of threshold values, hold times, and averaging window lengths, a Particle Swarm Optimization (PSO) is performed. The ‘fitness function’ of the optimization algorithm is designed to minimize total spill volume for leak scenarios and have minimum false alarms for no-leak scenarios. The former is achieved via setting the objective function to the spill volume and the latter is enforced via applying constraints to the optimization algorithm. For no-leak scenarios, the historical operational data of a pipeline system is used. For leak scenarios, the historical data is modified by introducing a bias in the inlet volume of the section to simulate a leak. The result of the PSO provides a set of alarming parameters, threshold value, averaging window length, alarm hold time, and clearing threshold that provide the minimum false alarm rate and spill volume for different detectability ranges. The optimization method proposed in this paper can be applied to any mass or volume balance-based leak detection system that utilizes moving averaging windows. However, the leak detection parameters found with this method depend on the pipeline system.
Burst Pressure of Pipelines With Corrosion Anomalies Under High Longitudinal Strains
Authors: Zhou Honggang , Wang Yong-Yi , Stephens Mark , Bergman Jason , Nanney Steve
Published: November 2018

Existing corrosion assessment models were developed and validated under the assumption that internal pressure was the principal driver for burst failure and that longitudinal strain levels were low. The impact of moderate to high levels of longitudinal strain on burst capacity had not been explicitly considered.

This paper summarizes work performed as part of a major effort funded by the US Department of Transportation Pipeline and Hazardous Materials Safety Administration (DOT PHMSA) aimed at examining the impact of longitudinal strain on the integrity of pipelines with corrosion anomalies. This paper focuses on the burst pressure of corroded pipes under high longitudinal strains. It is known that longitudinal tensile strain does not reduce the burst pressure relative to that of pipes subjected to low longitudinal strains. Therefore, existing burst pressure models can be considered adequate when the longitudinal strain is tensile. However, longitudinal compressive strain was found to lead to a moderate reduction in burst pressure. Numerical analyses were conducted to study the effect of longitudinal compressive strain on the burst pressure of corroded pipes. A burst pressure reduction formula was developed as a function of the longitudinal compressive strain.

Full-scale tests were conducted to confirm the findings of the numerical analysis. Guidelines for assessing the burst pressure of corroded pipes under high longitudinal compressive strains were developed from the outcome of numerical analysis and experimental tests. The guidelines are applicable to different types of corrosion anomalies, including circumferential grooves, longitudinal grooves and general corrosion.
Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents
Authors: Zhu Xian-Kui , Wang Rick
Published: November 2018

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results.

To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.
Effects of ultrasound-guided suprascapular nerve pulsed radiofrequency on chronic shoulder pain
Authors: Ergonenc Tolga , Beyaz Serbulent Gokhan
Published: November 2018

Aim: Pulsed radiofrequency (PRF) therapy has become increasingly popular in the treatment of chronic shoulder pain due to its long duration of action and non-destructive method. The aim of the study was to reveal the effects of PRF therapy of the suprascapular nerve (SSN) under ultrasound guidance (UG) in patients with chronic shoulder pain on both shoulder pain and function.Material and methods: This study included 74 patients diagnosed with at least one of the following: adhesive capsulitis, rotator cuff syndrome and impingement syndrome of shoulder. The PRF therapy of the SSN under UG was performed in those patients with a reduction of 50% or more Visual Analog Scale (VAS) score and those that reported healing in the active range of motion (AROM) in the diagnostic SSN block. The resting, motion and sleeping shoulder pain assessments of the patients were done with VAS score. The shoulder joint function was assessed with the Shoulder Pain and Disability Index (SPADI) questionnaire and the AROM of the joint was measured using a goniometer.Results: In 70 of the 74 patients a 50% or more reduction was found in the VAS score with diagnostic SSN block. After the PRF therapy of the SSN, the 15thday, 1st month, 3rd month, and 6th month follow-up VAS averages, SPADI averages and the flexion, internal rotation, external rotation, and abduction values were statistically significantly lower than the baseline values (p<0.05).Conclusion: This study is the largest series in the literature evaluating the efficacy of PRF therapy of the SSN under UG and has shown that pain canbe controlled quickly, for a long period of time, using ultrasound guided PRF therapy of the SSN in chronic shoulder pain.
Visibility of MRI prostate lesions on B-mode transrectal ultrasound
Authors: Steinkohl Fabian , Luger Anna Katharina , Pichler Renate , Bektic Jasmin , Rehder Peter , Lebovici Andrei , Aigner Friedrich
Published: November 2018

Aim: Prostate biopsies are usually done with transrectal ultrasound (TRUS) in B-mode (B TRUS) but multiparametric MRI (mpMRI) is the gold imaging standard for the visualization of clinically significant prostate cancer (PCa), since a lowPCa detection rate is reported for B TRUS. The aim of this study was to assess the visibility of MRI lesions on B TRUS and to determine which factors may influence the visibility on B TRUS.Material and methods: 142 men with 148 lesions reported on mpMRI underwent a B TRUS/mpMRI fusion targeted biopsy of the prostate and were included in this retrospective study. During the biopsy, images were obtained and stored in the institution’s PACS. These images were reviewed by two radiologists to determine, whether an mpMRI lesion was or was not visible on B TRUS.Results: Overall 92 from 148 mpMRI lesions (62.2%) were visible on B TRUS. The location of the lesion in the prostate, the PIRADS classification of the lesions and the size of the lesion had no significant influence on the visibility on B TRUS. Only the prostate volume had a significant influence on visibility: in smaller prostates significantly more lesions were visible on B TRUS than in large glands (p+0.041; 45.1 ml vs 54 ml).Conclusion: The use of newer high-end ultrasound units as well as experience gained from fusion biopsies enables us to see 62.2 % of all suspicious mpMRI lesions on B TRUS. B TRUS images merit a thorough examination during a conventional biopsy setting.
Differential diagnosis of gallbladder ascariasis debris: the added value of contrast enhanced ultrasound with high frequency transducer
Authors: Dong Yi , Mao Feng , Cao Jiaying , Zhang Qi , Yang Daohui , Wang Wen-Ping , Dietrich Christoph F
Published: November 2018

Ascariasis debris of the gallbladder is a very rare incidental or symptomatic presentation. Ascaris debris has a pseudotumorous appearance and may be confused with neoplasia. The aim of the current retrospective study is to investigate the value of contrast enhanced ultrasound (CEUS) for the differential diagnosis of ascariasis debris and neoplasia of the gallbladder.Material and methods: Conventional B-mode ultrasound (BMUS) and CEUS were performed for solitary echo-rich gallbladder lesions. Analysis of the CEUS enhancement pattern of the lesions was conducted according to the current EFSUMB guidelines. Two radiologists assessed the CEUS enhancement patterns in consensus. The final gold standard was surgery with histological examination or imaging follow-up.Results: A total of 9 patients with final diagnoses of gallbladder ascariasis debris were included. As a control group 26 solitary hyperechoic gallbladder lesions without shadowing were included as a control group. The typical zigzag morphology with multiple echogenic parallel lines without shadow were detected inside the lumen of the gallbladder in 6 patients. After injection of 2.4 ml ultrasound contrast agents, all hyperechoic gallbladder ascariasis debris lesions showed no enhancement. All patients in the control group with similar BMUS morphology showed contrast enhancement.Conclusions: Real time visualization of contrast enhancement without radiation exposure is one of the main advantages of CEUS over other diagnostic modalities to differentiate ascariasis debris in the gallbladder from enhancing neoplasia. Thus, surgery and other interventions and their complications could be avoided.
New connections: Taking advantage of bias
Authors: Foley John F.
Published: November 2018

Biased chemokine receptor agonists and antagonists that target specific signaling pathways may provide therapeutic benefit.