bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Operator’s Perspective on Fracture Control in Dense Phase CO2 Pipelines
Authors: Barnett Julian , Cooper Russell 
Published: November 2016

Carbon Capture and Storage (CCS) is an approach to mitigate global warming by capturing and storing carbon dioxide (CO2) from large industrial emitters. Pipelines will play a significant role in the transportation of CO2 in CCS projects. National Grid has an interest in this, and has carried out research to investigate the requirements for the safe design and operation of CO2 pipelines.
CO2 pipelines are susceptible to long running fractures which are prevented by specifying an adequate pipe body toughness to arrest the fracture. There is no existing, validated methodology for setting pipe body toughness for pipelines transporting dense phase CO2 with impurities. The methods for estimating the pipe body toughness are semi-empirical so full scale fracture propagation tests are required to validate and extend these methods.
As part of a major research programme into pipeline transportation of dense phase CO2, National Grid conducted two full scale fracture propagation tests using 900 mm diameter pipe in 2012. The tests demonstrated that the current natural gas practices for setting pipe body toughness was incorrect and non-conservative for dense phase CO2 pipelines. National Grid recognises the importance of understanding fracture arrest as it required to ensure design code compliance, impacts on pipeline design and provides reassurance to stakeholders.
As the results of the two tests cannot be used directly to set the toughness requirements for a specific project pipeline, a third full scale test was necessary to confirm the fracture arrest capability of the pipe for the proposed pipelines.
A third full scale fracture propagation test was conducted in July 2015. A propagating ductile fracture was initiated and successfully arrested in linepipe representative of that to be used on the proposed project.
Improved Pipeline Integrity Management by Using Multiple ILI Technologies
Authors: Chan Peter , Liu Kaiwen 
Published: November 2016

The most common methods currently available for detecting cracks and linear features in pipelines are Ultrasonic Crack Detection (USCD) ILI and Electromagnetic Acoustical Transducer (EMAT) ILI. A third ILI technology using Spiral MFL with hard spot detection capability has also showed capability for detecting linear features within deformations that are not readily detectable by USCD or EMAT tools.
Any measurement technology, including ILI and field NDE tools, has a range of accuracy and detection capability. This paper analyzes and compares the performance of these ILI tools against the measurements obtained from field investigations. It will be shown that each technology has its own limitations, and features detected by one tool could be missed by the other tool.
Consequently, until one existing or new ILI technology has demonstrated its ability to catch all the features within its stated specification, employing multiple ILI technologies is an effective method to compensate for the weaknesses of any one particular ILI tool and ensure a higher level of safety for pipelines. An additional benefit of running multiple ILI tools is the opportunity for providing feedback of dig results to the different ILI vendors which could help them improve their own tool detection and sizing capabilities.
Development of Pipeline Sleeve End Fillet Weld Stress Intensity Factor and Reference Stress Solutions for Fatigue and Failure Assessment
Authors: Semiga Vlad , Dinovitzer Aaron , Eshraghi Amin , Lazor Robert 
Published: November 2016

Pipeline defects such as cracks, dents and corrosion often require permanent pressure retaining repairs. Full encirclement metallic repair sleeves with fillet-welded end connections to the pipeline are often used for this purpose. In-service failures have occurred at pressure retaining sleeves as a result of defects associated with the sleeve welds, such as hydrogen-induced cracks, undercut at the fillet welds and inadequate weld size. At present, accurate quantitative fitness for service assessments for circumferential defects in a sleeve fillet welds are difficult to carry out due to a lack of detailed stress intensity factor (SIF) solutions for finite length cracks.
The primary objective of the project presented in this paper [1] was to develop flaw acceptance criteria which will fill gaps in the available Engineering Critical Assessment procedures for metallic sleeve repairs on all grades of pipelines. SIF solutions for finite length sleeve-end fillet weld toe and root cracks were generated and used to develop parametric equations suitable for carrying out defect assessments. These equations can be used in the assessment of fatigue crack growth and/or fracture using failure assessment diagram (FAD) methods at sleeve end fillets alongside the results developed for other structural geometries in national standards. The equations were developed based on detailed finite element (FE) analyses of a wide range of sleeve end fillet weld cracking scenarios to estimate the SIFs at both the deepest point and the surface breaking point along the crack front.
ILI-to-Field Data Comparisons: What Accuracy Can You Expect?
Authors: Ellinger Matthew A. , Bubenik Thomas A. , Moreno Pamela J. 
Published: November 2016

Det Norske Veritas (U.S.A.), Inc. (DNV GL) prepared this paper in order to study the expected accuracy of in-line inspections (ILI) as a function of year, depth (both reported and field measured), and length, amongst other factors. DNV GL has access to a significant amount of data that span many different pipeline operators, ILI vendors, inspection years, and inspection technologies. DNV GL is well suited to complete this study as a result of our access to these various data sets.
Over 3,000 individual comparisons of ILI and field depths and lengths spanning from 2010 through 2015 from 11 operators and 68 line segments were compiled to meet the objectives of this paper. Inspection technologies include axial magnetic flux leakage (MFL), ultrasonic wall thickness (UTWT), spiral MFL, and circumferential MFL.
Based on the analyses conducted in this paper, the following conclusions were generated.
• Axial MFL and UTWT inspections show significant improvements over the last several years.
• Axial MFL inspection systems are capable of meeting a depth accuracy of +/−10% of the wall thickness with 80% certainty, but this has not always been the case. UTWT inspection systems are capable of meeting a higher depth accuracy.
• Axial MFL inspection systems report more pits and circumferential grooves than UTWT systems. This could suggest UTWT systems are less sensitive to pits and circumferential grooves than axial MFL systems.
• Both axial MFL and UTWT inspection systems routinely under call defects with field measured depths greater than 50 to 80% of the wall thickness. This is contrary to a widely held notion that ILI is conservative for deep defects.
• ILI reported defect lengths do not correlate well to field measured defect lengths. In general, field measured defect lengths are greater than ILI reported defect lengths.
• Depth accuracy tends to decrease slightly for very short defects (less than 1-inch) and for very long defects (greater than 40-inches).
Based on these conclusions, the authors make the following recommendations:
• Pipeline operators should dig more than the deepest reported defects to better understand the accuracy of the inspection tools being used and to determine whether deeper anomalies are being under called.
• Pipeline operators should consider methods for evaluating change in corrosion depth from ILI survey to ILI survey to lessen the dependence on the accuracy of the ILI tools. This should include a raw data signal analysis in order to determine whether the general morphology (metal loss length and width) are changing between ILI surveys.
• ILI reported defect lengths should be used in conjunction with field measured defect depths (if available) when performing failure pressure calculations.
• Additional accuracy, especially for deeper defects, may only come with new tool developments. Industry support of such developments will be required to bring them to fruition.
Improved Pipeline Dent Integrity Management
Authors: Tiku Sanjay , Eshraghi Amin , Semiga Vlad , Torres Luis , Piazza Mark 
Published: November 2016

Pipeline dents can be developed from the pipe resting on rock, a third party machinery strike, rock strikes during backfilling, amongst other causes. The long-term integrity of a dented pipeline segment depends upon parameters including pipe geometry, indenter shape, dent depth, indenter support, secondary features, and pipeline operating pressure history at and following indentation. US DoT and other standards include dent repair and remediation criteria broadly based upon dent depth, dent location (top or bottom side), pressure cycling (liquid or gas), and dent interaction with secondary features (weld, corrosion, cracks). These criteria are simple and easily applied, however, they may not direct maintenance appropriately and be overly conservative or, in some cases, unconservative.
Previous IPC papers have discussed the full-scale dent fatigue testing and dent modelling efforts to support integrity management criteria development by collecting material and structural response during dent formation and pressure loading. The present paper will present the results of this extensive dent structural and fatigue life numerical simulation program using a validated finite element (FE) analysis process. The paper describes the numerical simulation technique, as well as, the development of the novel engineering tool for integrity management, eliminating the need for numerical simulation of individual dent features to assess the relative integrity threat they pose.
The development of the engineering tool presented in this paper considers the dent formation, re-rounding and through life response to pressure fluctuations to evaluate the fatigue life of dent features. The results of these analyses are used to develop fatigue life trends based on dent shape, restraint condition and operating pressure. These trends were used to develop models to predict dent relative severity and life based upon ILI inspection dent shape data for single peak dents. Dent shape has also been used to determine the restraint condition of a dent and its influence on the dent feature fatigue life. The tools were developed to address many of the uncertainties inherent in existing regulatory repair and remediation criteria. Current and future applications of the integrity assessment model are described along with recommendations for further development and testing to support pipeline integrity management, industry guidelines and standards.
The results of this research will be of use in improving integrity management decisions and support further development of industry guides and standards. As such the information presented in this paper will be of interest to pipeline operators, integrity management specialists, in-line inspection (ILI) organizations and regulators. The recommendations presented in this paper may be used to influence the direction of pipeline standards in their direction in the disposition of dent features.
Evolution of Linepipe Manufacturing and its Implications on Weld Properties and Pipeline Service
Authors: Wang Yong-Yi , Horsley David , Rapp Steve 
Published: November 2016

Pipe grade is a dominant parameter in a pipeline’s service life. Critical decisions on the design, construction, and maintenance of pipelines are made on the basis of pipe grade. The implied assumptions or expectations are that pipes of the same grade would behave similarly and the experiences with a particular grade can be applied to all pipelines of the same grade. This simplification does not adequately take into account the other characteristics that are not represented by pipe grade, but can play a critical role in the safe and economical operation of pipelines. For instance, the evolution of steel-making processes and advancements in field welding practice can lead to significant differences in weld behavior among pipes of the same nominal grade.
Most of the design, construction, and maintenance practices in the pipeline industry were established before the extensive use of modern control-rolled and microalloyed steels. With the exception of a few isolated research projects, the impacts of the fundamental changes in the steel metallurgy in modern microalloyed steels have not been systematically examined and understood. For instance, these steels may have very low strain-hardening capacity as a result of the TMCP process and may be subject to high levels of heat-affected zone (HAZ) softening due to their ultra-low carbon low-hardenability steel chemistry. HAZ softening reduces the longitudinal pipe strain capacity of girth welds, and low strain-hardening can potentially have a negative impact on tolerance to anomalies such as corrosion or mechanical damage.
This paper starts with a brief review of linepipe manufacturing history with a focus on the chemical composition and rolling practices that directly affect the mechanical properties and the response to welding thermal cycles. The characteristics of linepipes made from modern microalloyed steels are contrasted with those made from vintage hot-rolled and normalized steels. The resulting mechanical properties of these two types of materials in the presence of welding thermal cycles are presented, and compared in terms of their behavior.
The consequence of the weld characteristics is shown using examples of girth welds subjected to longitudinal strains. The implications of the pipe and weld characteristics on the design, field girth welding, and maintenance of pipelines are highlighted. Future directions and best practices in linepipe alloying and manufacturing strategies, linepipe specifications, field girth welding, and building strain-resistance girth welds are briefly described. It is emphasized that assessing the performance of pipelines based on their grades has fundamental shortfalls, and that gaps in codes and standards can lead to unexpected outcomes in pipeline integrity. In the long-run, revising relevant codes and standards is necessary to ensure consistent and reliable applications of new materials in the entire industry.
AIV and FIV in Pipelines, Plants, and Facilities
Authors: Harper Chris B. 
Published: November 2016

Acoustic-induced vibration (AIV) and flow-induced vibration (FIV) are two common phenomena that can lead to vibration-induced fatigue failures in piping systems. Pipeline facility managers, operators, designers, and engineers are faced with identifying and mitigating the risks of AIV and FIV to avoid catastrophic instances of vibration-induced fatigue failures in their facilities. This paper identifies common challenges to conventional AIV/FIV analyses methods, and discusses advanced techniques available to address these challenges.
Acoustic-induced vibrations are caused by the sound energy created by flow through pressure reducing devices like valves or restrictive orifice plates. This sound energy can cause the piping wall to vibrate, thus exciting, and possibly damaging, any nearby small-bore branch connections. Flow-induced vibrations are caused by pulsations induced by flow past dead legs in piping systems. These pulsations can create shaking forces that cause vibrations of piping, vessels, and equipment. The two phenomena will be compared and contrasted, while offering simple tips and best practices in identifying, evaluating, and solving these two common flow-induced issues.
A field case study utilizing pulsation and vibration measurements between a line heater and inlet separator for a gas plant will be presented and discussed. The case presents an opportunity to investigate mainline and small-bore piping AIV/FIV risks in plants, provides example data of clear AIV and FIV phenomena, and identifies complex situations that require more rigorous analysis. Advanced techniques for analyzing and solving complex issues that are commonly found in piping systems will be explored. Further, the case highlights the benefits of early screening and preventive considerations of upset conditions when dealing with flow-induced pulsation and vibration issues.
In this paper, the reader will gain an increased understanding of the importance of AIV/FIV in maintaining integrity of their facilities, and be provided with tools and knowledge to mitigate any risks that may be encountered.
Rational Stress Limits and Load Factors for Finite Element Analyses in Pipeline Applications: Part III — Elastic-Plastic Load Factor Development
Authors: Dotson Rhett , Alexander Chris , Iyer Ashwin , Gourlie Al , Kania Richard 
Published: November 2016

In this paper, a methodology is presented to develop load factors for use in elastic-plastic assessments of pipelines and their components. The load factors are based on the pipe material properties and the ASME pipeline code’s design margin for the service and location of the pipeline installation [1, 2]. These codes are recognized by 49 CFR 192 and 195 [3, 4].
Minimum required load factors for internal pressure loads can be derived analytically based on design equations from the ASME B31 piping codes and minimum material requirements for API 5L line pipe [6]. Once the load factor is established for a particular case, the elastic-plastic methodology may be used in the Finite Element Analysis (FEA) of pipelines and related components. This methodology is particularly useful in the assessment of existing systems when linear elastic numerical analysis shows that local stresses may exceed the elastic design limits.
Two case studies are presented showing analyses performed with Abaqus [5], a commercial, general purpose FEA software package. The first case study provides an assessment of a large diameter elbow where the stress on the outer fibers of the intrados exceeded the longitudinal stress limits from B31.8. The second case study examines an assessment of a tee connection where the stresses on the ID exceeded the yield strength of the component. In addition to the case studies, the paper also presents the results of a full-scale test that demonstrated what margin was present when the numerical calculations were based on specified minimum properties.
This paper is not intended to revise or replace any provision of B31.4 and/or B31.8 [1, 2]. Instead, it provides the means for calculating load factors that can be used with an elastic-plastic analysis approach in a manner that provides the same design margins as the ASME B31 codes. The approach described in this paper is intended for use in the detailed FEA of pipelines and their associated components.
Finite Element Modeling and Quantification of Mechanical Damage Severity in Pipelines
Authors: Zhu Xian-Kui , Leis Brian N. 
Published: November 2016

Mechanical damage is one of the major threats to oil and gas transmission pipeline integrity, which has been the case now for decades. Although much work has been done in that context, due to the complexity of its effects mechanical damage severity remains difficult to quantify. Thus, work continues to better understand the failure mechanism and develop the means to screen damage severity.
The present paper adopts a validated elastic-plastic finite element analysis (FEA) model to simulate mechanical dents in pipelines and to quantify the effects of damage through a broad parametric study. This considers the need for three-dimensional FEA models and the effects of FEA element type, soil constraint condition, indenter type, pipeline grade and initial pipe pressure on dent response. The FEA model is also used to assess the minimum wall thickness for which a dent has the minimal effect on pipeline integrity. Finally, application of the proposed FEA model is illustrated by successfully predicting the failure behavior of a dent in a full-scale fatigue test involving a modern pipeline steel.
A Novel Approach to Leak Sensitivity Testing of Computational Pipeline Monitoring Systems for Hydrocarbon Liquid Pipelines With Hydraulic Simulators
Authors: Hung Daniel , Mokamati Satya 
Published: November 2016

In the operation of hydrocarbon liquid pipelines, Computational Pipeline Monitoring (CPM) systems are used for software based leak detection. When installed, CPM systems must meet the regulatory requirements such as API 1130 in the USA and CSA Z662 in Canada. API RP 1130 provides several methods that can be used to test a CPM system: forced parameter testing, simulated leak test (SLT), and fluid withdrawal testing (FWT).
Leak tests are performed to establish and verify the leak detection capabilities of the installed CPM system and in some cases test the response of the personnel. One of the primary interests in leak testing is the realism or hydraulic accuracy of the leak signature, in order that the reported leak sensitivity results of the test are reflective of the real performance of the CPM system.
Simulated leak tests (SLT’s) use an offline pipeline model to generate hydraulically accurate data which can be fed into the CPM model. SLT’s provide the most flexible and hydraulically accurate solution to simulating leaks, compared to some of the other API RP 1130 compliant test methods. SLT’s do not have leak location restrictions and also correctly models the flow and pressure hydraulic signature of a leak.
The paper outlines a novel approach and method to leak simulation, based on its size and shape of the leak hole. This method can be used to represent various sizes of a leak, ranging from a pin hole to a large rupture along the seam. Implementation of the method in a simulator developed with commercial software is discussed. The results of the simulation, namely the hydraulic signatures from the simulated leak and the CPM response, are compared with the widely used leak simulation method using a constant leak rate. Finally, possible applications of this method are considered.
Comparisons of the Humoral and Cellular Immune Responses Induced by Live Attenuated Influenza Vaccine and Inactivated Influenza Vaccine in Adults
Authors: Hoft Daniel F. , Lottenbach Kathleen R. , Blazevic Azra , Turan Aldin , Blevins Tamara P. , Pacatte Thomas P. , Yu Yinyi , Mitchell Michelle C. , Hoft Stella G. , Belshe Robert B. 
Published: November 2016

ABSTRACT
Both live attenuated influenza vaccines (LAIV) and inactivated influenza vaccines (IIV) induce protective immunity against influenza. There is evidence that LAIV induces superior protection in children, whereas IIV may induce superior protection in adults. The immune mechanisms responsible for these differences have not been identified. We previously compared LAIV and IIV in young children of 6 to 36 months of age, and we demonstrated that while both induced similar hemagglutination inhibition (HAI) antibody responses, only LAIV induced significant increases in T cell responses. In the present study, 37 healthy adult subjects of 18 to 49 years of age were randomized to receive seasonal influenza vaccination with LAIV or IIV. Influenza virus-specific HAI, T cell, and secretory IgA (sIgA) responses were studied pre- and postvaccination. In contrast to the responses seen in young children, LAIV induced only minimal increases in serum HAI responses in adults, which were significantly lower than the responses induced by IIV. Both LAIV and IIV similarly induced only transient T cell responses to replication-competent whole virus in adults. In contrast, influenza virus-specific sIgA responses were induced more strongly by LAIV than by IIV. Our previous studies suggest that LAIV may be more protective than IIV in young children not previously exposed to influenza virus or influenza vaccines due to increased vaccine-induced T cell and/or sIgA responses. Our current work suggests that in adults with extensive and partially cross-reactive preexisting influenza immunity, LAIV boosting of sIgA responses to hemagglutinin (HA) and non-HA antigenic targets expressed by circulating influenza virus strains may be an important additional mechanism of vaccine-induced immunity.