bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Pattern Measurements by µ-PIV in the Microchannels of a Heat Exchanger and Solutions to the Particle Fouling Problem
Authors: Heinzel V. , Jianu A. , Sauter H.
Published: December 2008

Preliminary experimental results of measuring velocity fields of a transparent liquid flow in a closed circuit, through a 100 μm deep flat cell with heat exchanger microchannel elements are presented. The resolution and possible errors of the microscopic particle image velocimetry system are discussed in relation with the evaluation results. Particle fouling phenomenon, which proved to be the main difficulty in performing velocity field measurements in microchannels in the past, are widely overcome by techniques which avoid or limit it. The test object, which is aimed at being exposed to real technical conditions (pressures up to 0.6 MPa leading to flow velocities up to 15 m/s, as well as temperatures up to 100°C), was up to now operated at a Reynolds number of about 5. The obtained information allows for starting the test loop upgrade.
High Frequency AC Electrospraying of Dielectric Liquids
Authors: Yeo Leslie Y. , Lastochkin Dimitri , Chang Hsueh-Chia
Published: December 2008

A new high-frequency (> 10 kHz) AC electrospray phenomenon which behaves distinctly to DC electrosprays is investigated. Unlike DC electrosprays, the drops do not emanate from the usual well-defined Taylor cone-jet and carry no net charge. Instead, the meniscus vibrates at a resonant frequency associated with its capillary-inertia vibration time, periodically ejecting drops with dimensions of order 10 μm under the action of the Maxwell-Wagner electric stress at the meniscus tip. Above a crossover frequency, the polarization and direction of the Maxwell force reverses and an apparent electrowetting effect is observed. A simple lubrication model is used to generate spatio-temporal evolution profiles for the stretched liquid meniscus tip as a function of the Maxwell-Wagner stress and a capillary number. From a self-similar scaling technique, the meniscus is shown to advance as t1/2.
Performance Predictions of MEMS-Based Nozzles at Moderate or Low Temperatures
Authors: Wang Moran , Li Zhixin
Published: December 2008

Performance of MEMS-based nozzles at moderate and low temperatures is numerically analyzed using the direct simulation Monte Carlo method. Considering the intermolecular attractive potential due to low temperature, the generalized soft sphere collision model is introduced. The Larsen-Borgnakke model for the generalized sphere model is used to model the energy exchange between the translational and internal modes. The results for nozzle flows at an initial temperature of 300 K show that the temperature behind the throat is quite low and the intermolecular attractive potential cannot be ignored. Different working conditions in two-dimensional nozzles are simulated using the present method, including exit pressure, inlet pressure, initial temperature, nozzle geometry, and gas species. The effect factors on the nozzle performance are analyzed. A 3D nozzle flow simulation shows the increased surface-to-volume ratio which leads to high viscosity dissipation cause a much lower flow characteristic and performance comparing with the 2D case.
Multistage Viscous Micropumps
Authors: Abdelgawad M. , Hassan I. , Esmail N. , Phutthavong P.
Published: December 2008

The viscous micropump consists of a cylinder placed eccentrically inside a microchannel, where the rotor axis is perpendicular to the channel axis. When the cylinder rotates, a net force is transferred to the fluid due to the unequal shear stresses on the upper and lower surfaces of the rotor. Consequently, this causes the surrounding fluid in the channel to displace towards the microchannel outlet. The simplicity of the viscous micropump renders it ideal for micro pumping, however, previous studies have shown that its performance is still less than what is required for various applications. The performance of the viscous micropump, in terms of flow rate, pressure head and efficiency, may be enhanced by implementing more than one rotor into the configuration. The present study will numerically investigate the performance of various configurations of the viscous micropumps with multiple rotors, namely the dual-horizontal rotor, the triple-horizontal rotor, the symmetrical-dual-vertical rotor, and the 8-shaped dual-vertical rotor. The development of drag force with time, as well as the viscous resisting torque on the cylinders were studied. In addition, the corresponding drag and moment coefficients were calculated. Results show that the symmetrical-dual-vertical rotor configuration yields the best efficiency, and generates the highest flow rate. The steady state performance of the single-stage micropump was compared with the available experimental and numerical data, and was found to be in very good agreement. This work provides a foundation for future research on the subject of fluid phenomena in viscous micropumps.
Study on Joule-Thomson Micro-Cooler
Authors: Naganuma K. , Takata Y. , Kubota H. , Takahashi K.
Published: December 2008

An experimental model of Joule-Thomson micro-cooler has been fabricated on silicone wafer of 39mm×15.5mm in size. The micro-cooler uses ethylene as the refrigerant and it works in the pressure range between 2.3MPa and 0.1MPa. The micro-cooler consist of condenser, evaporator and capillary tube. Flow passage of the refrigerant was fabricated by etching process. Peltier device was used to pre-cool and condense the refrigerant. Temperature decrease by 3K was obtained at maximum flow rate of 3mg/s.
Faradaic AC Micro-Pumps and Mixers With Orthogonal Electrodes
Authors: Ben Yuxing , Lastochkin Dmitri , Chang Hsueh-Chia
Published: December 2008

A new electrolyte AC micro-pump and mixer design based on Faradaic reaction polarization is investigated. The non-uniform AC electric field generated by electrode reaction polarizes the electrode surface, exerts a net electric force on the polarized layer and drives a net AC electro-osmotic flow of the electrolyte on the planar microelectrodes. At large electric potentials (>10V) and frequencies of 100 kHz to 1MHz, the flow direction is shown to be opposite to (previously reported) AC pumps due to capacitive charging. Moreover, the velocity has an exponential dependence on the applied electric potential due to the reaction and is hence an order of magnitude higher than the velocity driven by capacitive charging, which has a quadratic dependence. Theoretical analyses demonstrating the possibility of this Faradaic mechanism and some preliminary experimental results are presented.
Analysis of Electroosmotic Flow in a Microchannel Packed With Microspheres
Authors: Kang Y. J. , Yang C. , Huang X. Y.
Published: December 2008

The electroosmotic flow in a microchannel packed with microspheres under both direct and alternating electric fields is analyzed. In the case of the steady DC electroosmosis in a packed microchannel, the so-called “capillary model” is used, in which it is assumed that a porous medium is equivalent to a series of intertwined tubules. The interstitial tubular velocity is obtained by analytically solving the Navier-Stokes equation and the complete Poisson-Boltzmann equation. Then using the volume averaging method, the solution for the electroosmotic flow in a single charged cylindrical tubule is applied to estimate the electroosmosis in the overall porous media by introducing the porosity and tortuosity. Assuming uniform porosity, an exact solution accounting for the electrokinetic wall effect is obtained by solving the modified Brinkman momentum equation. For the electroosmotic flow under alternating electric fields in a cylindrical microchannel packed with microspheres of uniform size, two different conditions regarding the openness of channel ends are considered. Based on the capillary model, the time-periodic oscillating electroosmotic flow in an open-end microchannel in response to the application of an alternating electric field is obtained using the Green’s function approach to the Navier-Stokes equation. When the two ends of the channel are closed, a backpressure is induced to generate a counter flow, resulting in a new zero flow rate. Such induced backpressure associated with the counter-flow in a closed-end microchannel is obtained analytically by solving the transient modified Brinkman momentum equation.
Modeling of the Flow and Heat Transfer in Micro Heat Pipes
Authors: Sobhan C. B. , Peterson G. P. (Bud)
Published: December 2008

The fluid flow and heat transfer characteristics of micro heat pipes are analyzed theoretically, in order to understand the physical phenomena and quantify the influence of various parameters on overall thermal performance of these devices. A one-dimensional model is utilized to solve the governing equations for the liquid/vapor flow and the heat transfer in the heat pipe channel. Variations in the liquid and vapor cross-sectional areas along the axial length of the heat pipe are included and the equations are solved using an implicit finite difference scheme. Appropriate models for fluid friction in small passages with varying cross-sectional areas have been incorporated to yield the axial distribution of the meniscus radius of curvature and the velocity, temperature and pressure in both the liquid and the vapor phases. Using this information, the effective thermal conductivity of the micro heat pipe is modeled, and parametric studies are performed by changing the heat load and cooling rate. The results of the analysis are discussed and compared with other theoretical models and experimental results found in the literature. By so doing, this analysis provides greater insight into the physical phenomena of flow and heat transfer in micro heat pipes and identifies a methodology for optimizing the design of these devices.
Liquid Distribution in the Axial Direction of an Inclined Triangular Micro Heat Pipe
Authors: Sugumar D. , Kiong Tio Kek , Venkatesh B. , Eng Chong Kuan
Published: December 2008

Micro heat pipes (MHPs) are, essentially, miniature heat transfer devices which use phase change to transfer thermal energy. In recent years, there have been numerous proposals for their applications in cooling electronic devices. In this paper, the axial liquid distribution of a triangular MHP is investigated for the case of inclined orientation. The study is limited to the case of positive inclination, whereby the condenser section is elevated from horizontal position. In this case, the inclusion of gravity renders the governing equation unsolvable analytically, and the 4th order Runge-Kutta method has been selected to solve it numerically. The results show that for a horizontally oriented MHP, so that the effect of gravity can be neglected, the liquid distribution along the axial direction increases monotonically from the minimum value at the evaporator end to the maximum at the condenser end. However, if the MHP is positively inclined, the axial distribution of the liquid phase is changed qualitatively. While the liquid distribution still increases monotonically starting from the evaporator end, it reaches its maximum value not at the condenser end but at a certain point in the condenser section, beyond which the liquid distribution decreases monotonically. Moreover, as the angle of inclination is increased, the maximum-distribution point moves further away from the condenser end. This maximum point, where potentially flooding will first take place, results from the balance between the effects of gravity and the heat load on the MHP, the former having the propensity to move all the liquid from the condenser towards the evaporator while the latter the tendency to place more liquid in the condenser section. As the liquid distribution assumes its greatest value at the maximum point, a throat like formation appears there. This formation is detrimental to the performance of an MHP, because it hinders, and at worst may block, the axial flow of the vapor phase.
A Mean-Field Free-Energy Approach to Lattice Boltzmann Method for Liquid-Vapor and Solid-Fluid Interfaces in Micro and Nanofluidics
Authors: Zhang Junfeng , Li Baoming , Kwok Daniel Y.
Published: December 2008

We presented a lattice Boltzmann method (LBM) using a mean-field representation of the free energy for fluid systems. This free-energy approach provides more realistic contact angles and fluid density profiles near the vicinity of an impenetrable wall, which cannot be easily obtained by other LBM schemes. Our method was tested against various criteria and the results are in good agreement with those from thermodynamics and molecular dynamics considerations. This mean-field approach to LBM can have important implication on studies where the solid-fluid interactions are crucial to fluidic behaviors.
Joule Heating Induced Thermal and Hydrodynamic Development in Microfluidic Electroosmotic Flow
Authors: Tang G. Y. , Yang C. , Chai C. J. , Gong H. Q.
Published: December 2008

Joule heating is present in electrokinetically driven flow and mass transport in microfluidic systems. Specifically, in the cases of high applied voltages and concentrated buffer solutions, the thermal management may become a problem. In this study, a mathematical model is developed to describe the Joule heating and its effects on electroosmotic flow and mass species transport in microchannels. The proposed model includes the Poisson equation, the modified Navier-Stokes equation, and the conjugate energy equation (for the liquid solution and the capillary wall). Specifically, the ionic concentration distributions are modeled using (i) the general Nernst-Planck equation, and (ii) the simple Boltzmann distribution. These governing equations are coupled through temperature-dependent phenomenological thermal-physical coefficients, and hence they are numerically solved using a finite-volume based CFD technique. A comparison has been made for the results of the ionic concentration distributions and the electroosmotic flow velocity and temperature fields obtained from the Nernst-Planck equation and the Boltzmann equation. The time and spatial developments for both the electroosmotic flow fields and the Joule heating induced temperature fields are presented. In addition, sample species concentration is obtained by numerically solving the mass transport equation, taking into account of the temperature-dependent mass diffusivity and electrophoresis mobility. The results show that the presence of the Joule heating can result in significantly different electroosomotic flow and mass species transport characteristics.
TAP Project
Authors: Spinelli Carlo Maria , Marchersani Furio
Published: December 2008

International gas market development is towards very long transportation distances (3000–6000 km); the only suitable onshore technology to conjugate economics, large amount of gas conveyed and possibility to exploit remote gas fields appears to be the Very High Pressure (P > 14 MPa), Very High Strength Steel (Steel grade X100 API 5L [1] equivalent) option. Eni Group is going to sponsor a 3 years long project, called TAP (Trasporto gas Alta Pressione) [High Pressure gas Transportation] aimed to demonstrate: • economic evaluation; • technology reliability; • real possibility to build Very High Pressure Pipeline. The project itself is framed into five logical areas: • Evaluation of the applicability of alternative technological solution in extreme enterprise; • Technological innovation, mainly within Eni Group; • FEED (Front End Engineering Development) for strategic route gas pipeline and comparison with LNG option; • Demonstrative construction of a High Strength Steel (X80) pipeline section on Snam Rete Gas Network in Italy; • Demonstrative construction of a Very High Strength Steel (X100 API equivalent) provisioning pilot section pipeline. To achieve this object Eni has involved: • Eni Gas & Power Division as Business Developer; • Snamprogetti as Technology Developer; • Aquater, Enidata, Enitecnologie, Saipem, Snam Rete Gas as specific item expertises; • CSM and Universita` di Bergamo as high qualified partners for lab and full scale testing; • Pipe steel makers and coating producers as fundamental partners to develop new solutions. TAP, within Eni Group, is the final step of a long development research and innovation activity started 8 years ago with two explorative “Long distance pipeline High Grade Steel” projects on Very High Strength Steel performances (strength, toughness, weldability) carried out mainly with the support of Snam, Snamprogetti and Saipem. TAP final goal is to collect, transfer, develop all the possible technological solutions to be ready for building “The pipeline network for Very High Pressure Transportation”.
Evaluation of the Ability of the Steel Compression Reinforcement Sleeve to Repair Active Internal Corrosion Defects
Authors: Smyth Robert J. , Spitzmacher Derek K.
Published: December 2008

It is assumed that active internal corrosion will eventually develop into through wall defects, if not mitigated. An ongoing long-term test is being performed to determine if the technology associated with the “Steel Compression Reinforcement Repair Sleeve” (Petrosleeve) is applicable for repairing active internal corrosion. In January 2002, four anomalies were manufactured into a section of NPS 20 (508mm) pipe to simulate through-wall defects. A steel compression reinforcement sleeve was installed using the standard installation procedure. The pipe section was pressurized with hydraulic fluid and instrumentation installed to record pressure and temperature at selected intervals. To date, no hydrocarbon leakage has been noted. Manual pressure release and thermal variance has resulted in pressure variance from nil to 6,728 kPa. The average internal pressure has been in the range of 5,500 kPa. This paper reviews the technology, testing procedure, and results of the application. The test is ongoing and is planned to continue for an extended period of time (ie. long-term test).
The Pros and Cons of Training Simulator Configurations
Authors: Wike Andrew
Published: December 2008

Pipeline operator training simulators have been used in control centers for more than two decades. They present control center managers with an unparalleled opportunity to ensure their staff are properly equipped with the skills to handle normal and, perhaps more importantly, abnormal pipeline operations. In the U.S. the Operator Qualification (OQ) rule has mandated that control center staff (among others) demonstrate their skills as a prerequisite to being allowed to operate the pipeline, and as the OQ rule evolves, it seems inevitable that it will be used as a template for legislation in other countries. Simulation is cited in the OQ rule as one of the approved mechanisms for demonstrating proficiency, and is the most effective method for exposing staff to abnormal conditions in a safe, controlled environment, and pipeline operator training simulators provide that environment. How that environment is configured will directly affect: • the results that an operating company might expect by incorporating a simulator into a pipeline operator training or qualification program; • the usefulness and acceptance of the simulator; • the initial and the on-going cost of maintaining the simulator. This paper serves to illustrate the spectrum of different configurations, highlighting the pros and the cons of each. The aim is to provide a broad understanding of what goals can be satisfied by each configuration, and the relative costs of each.
Quantitative Evaluation of Indirect Inspection Reliability and Pipeline Reliability Based on Statistical Methods
Authors: Mihell James N. , Coleman David , Sporns Ryan
Published: December 2008

To support an External Corrosion Direct Assessment (ECDA), Indirect Inspections were performed on a 44 km section of NPS 6 extruded polyethylene coated natural gas pipeline. Based on previous investigations of the pipeline, external corrosion defects were known to have occurred at coating holidays. Such holidays can often be detected using current voltage gradient surveys and close interval surveys. Two successive ACVG surveys over the pipeline were preformed. In addition, Close Interval Survey data were considered in order to complete the Indirect Inspection dataset. Statistical analysis methods were developed and employed against the data generated from these surveys so that the following objectives could be met: 1. Assess the reliability of the Indirect Inspection technique in terms of its ability to locate coating holidays and hence, its ability to locate potential corrosion features; and, 2. Assess, in quantitative terms, the reliability of the pipeline in terms of its potential for failure, and quantitatively establish the impact that the Indirect Inspection and dig program had in improving that reliability. In completing the first objective, duplicate survey results were compared with Direct Examination results. The statistical analysis provided a means of estimating technique reliability, which was conservatively estimated at 96%. Subsequent evaluation of factors affecting technique reliability indicated that the density of indications and consistency of applying the Indirect Inspection technique had a bearing on the overall reliability. The second objective was completed by applying the results of the Indirect Inspection reliability study to a statistical analysis of corrosion incidence data and corrosion size distributions that were derived from the Direct Examination data. Pipeline reliability was quantitatively expressed as a function of year of operation and the reliability of the Indirect Inspection technique. For the case examined, the Indirect Inspection techniques that were applied were found to increase pipeline reliability by approximately an order of magnitude.
Integrity Analysis for Dents in Pipelines
Authors: Leis Brian N. , Forte Thomas P. , Zhu XianKui
Published: December 2008

Incident analyses over the last several decades consistently show that outside force is the largest single cause of reportable incidents for the hazardous-liquid- and gas-transmission pipeline systems throughout the world. This paper addresses outside-force incidents due to “acts of man” leading to mechanical damage in the form of dents. As such incidents are significant worldwide, there are worldwide efforts to prevent future incidents, and develop approaches to manage this threat. This paper evaluates the criticality of dents in a more general framework than acceptable dent depth used in codes. This analysis is done with reference to typical line pipe mechanical properties, as well as less know parameters like true -fracture ductility and fracture-initiation toughness. Analyses results characterize severity and rank criticality as a function of dent type in reference to the general PRCI model for mechanical damage. Results are presented that show current code-acceptance criteria for dents are over conservative in general, sometimes significantly, particularly for plain dents. Full-scale test data are introduced to support the analytical results. Results are also presented to assist in evaluating the utility and accuracy of ILI deformation tools, and their calibration with reference to measured field dent size.
Dynamic Modeling of Non-Isothermal Gas Pipeline Systems
Authors: Abbaspour Mohammad , Chapman Kirby S. , Keshavarz Ali
Published: December 2008

Natural gas systems are becoming more and more complex as the usage of this energy source increase. Mathematical models are used to design, optimize, and operate increasingly complex natural gas pipeline systems. Researchers continue to develop unsteady mathematical models that focus on the unsteady nature of these systems. Many related design problems, however, could be solved using steady-state modeling. Several investigators have studied the problem of compressible fluid flow through pipelines and have developed various numerical schemes, which include the method of characteristics, finite element methods, and explicit and implicit finite difference methods. The choice partly depends on the individual requirements of the system under investigation. In this work, the fully implicit finite difference method was used to solve the continuity, momentum, energy, and equations of state for flow within a gas pipeline system. The particular solution method described in this paper does not neglect the inertia term in the conservation of momentum equation. It also considered the compressibility factor as a function of temperature and pressure, and the friction factor as a function of the Reynolds number. the fully implicit method representation of the equations offer the advantage of guaranteed stability for a large time step, which is very useful for the gas industry. The results show that the effect of treating the gas in a non-isothermal manner is extremely necessary for pipeline flow calculation accuracies, especially for rapid transient processes. The results indicate that the inertia term plays an important role in the gas flow analysis and cannot be neglected from the calculation.
Laboratory and Field Investigations of the Performance of HPCC Coatings
Authors: King Fraser , Been Jenny , Worthingham Robert , Rubie Grant
Published: December 2008

Three-layer FBE-polyolefin coatings offer the promise of good adhesive and corrosion properties from the FBE layer coupled with resistance to mechanical damage from the outer polyolefin layer. TransCanada Pipelines have been investigating the long-term behaviour of High Performance Composite Coating (HPCC) using a combination of laboratory testing and field trials. In the laboratory, panels of HPCC were subjected to standard CD disbondment testing following a two-stage degradation process. The degradation process, designed to simulate field exposure, involved impact damage followed by exposure to either a hot-water soak (60°C), or to microbiologically active soil with and without the application of CP. Following exposure, the duplicate panels were subject to 28-day CD disbondment tests to determine the extent of damage caused by the combination of impact and soil/hot water exposure. In the field, a section of HPCC coating was excavated and examined after 11 years service. In addition to visual inspection, the coating was examined in situ using a newly developed impedance technique EISPlus. This technique is a development of earlier EIS techniques and allows the dielectric properties of the coating to be determined in addition to the impedance of the solution-filled pores. EISPlus provides an improved sensitivity for high-impedance coatings, such as FBE, HPCC, and polyolefin tape. Furthermore, since it is a dry technique, rapid measurements can be made on coatings exposed to field conditions allowing the in-service performance to be determined. Results of both the laboratory testing and field EISPlus measurements are presented and the long-term performance of the coating discussed.
Managing Projects for Life Cycle Success: Perfecting the Process
Authors: Jenkins Andrew , Babuk Tom , Mohitpour Mo
Published: December 2008

Managing projects for long-term success requires a focus more on process than on technique. Whereas traditional project managers may apply certain well-defined abilities or skills to the task of bringing a project to physical completion on-time and on-budget, development of the “perfect” project requires a much broader perspective. Excellence at every phase of development must be pursued, from concept through to continuous operation. Discipline in process and ruthlessness in execution are key.
Leak Detector Pig for Oil Pipelines
Authors: Camerini Daniel Almeida , von der Weid Jean Pierre , Camerini Cla´udio Soligo , Maia Carlos Eduardo
Published: December 2008

The leakage detector pig was created with the purpose of detect and locate leakages in a preventive way. The fast detection of small leakages decreases the probability of larger leakages. By means of a differential pressure system based on pressure data acquired through the pig’s running, using pressure sensors installed on the pig’s vessel, small leakages are identified and its positions registered. This allows a quick intervention at the identified location. The working principle is based on the pressure difference caused by the leakage, which is read by the sensors. The polyurethane cups responsible by the pig’s propulsion are of a special kind capable of sealing a constant volume of product among them. So, when the pig passes through a leakage, the pressure in the middle drops compared to those in front and hear, generating a characteristic signal thus permiting identification. The first prototype was tested intensively at laboratory facilities, and in a test pipeline showing excellent results locating precisely all the simulated leakages. Defects from different sizes with different flow where simulated and measured. This work has the objective to present the tool, its potential, the test results, to discuss its efficiency in detect and locate leakages and the possibilities for the future.
INSAR Monitoring of the Alaska Pipeline Following the November, 2002 Earthquake
Authors: Rabus Bernhard , McCardle Adrian , Johnson Elden
Published: December 2008

Repeat pass interferometry using synthetic aperture radar satellites (INSAR) has been used to measure small movements of the earth’s surface associated with both natural and man-made activities. On November 3, 2002, an earthquake measuring 7.9 on the Richter scale struck Alaska along the Denali fault in the vicinity of the Trans-Alaska pipeline crossing. Images from the RADARSAT 1 satellite were acquired both before and after the earthquake and have been analyzed using a variety of techniques, including INSAR, to: • Illustrate various change detection techniques relevant to pipeline structures and natural features of interest (e.g. slopes and glaciers). • Detect and measure subtle earth movement and evaluate the accuracy and operational usefulness by comparing with ground control. The results show increasing land surface deformation near the pipeline crossing at the fault line, and indicate a maximum displacement of 19 feet. Independent ground truth surveys have confirmed the accuracy of these measured displacements. These results demonstrate that radar satellite observations can successfully be used to detect and assess potential threats to the integrity of pipelines. The benefits include: • Accurate measurements of deformation down to the millimeter level. • Remotely monitoring features without extensive groundwork. • Large spatial extent of two-dimensional InSAR monitoring rather than single point monitoring with GPS. • Cost-effective method to observe potential hazards along pipeline right of way. • Ability to “go back in time” for baseline information through the use of archived satellite images.
Finite Element Modeling of Ductile Tearing of Pipeline-Steel in Cracked Plates
Authors: Chen Yu , Lambert Steve
Published: December 2008

The purpose of this work was to develop a three-dimensional finite element model to simulate ductile tearing in pipeline-steels. The measured load versus displacement histories for single edge notch tension (SENT) and surfaced-cracked wide plate specimens, both made of X-70 pipeline-steel plates and subject to tensile load, were numerically predicted using the proposed damage model. In the numerical model, progressive damage was restricted to a predetermined ductile tearing zone. The material damage behaviour in this tearing zone was described in terms of a Gurson-Tvergaard (G-T) isotropic constitutive model, which accounts for micro-void nucleation and growth. The criterion for the onset of void coalescence was determined via the Thomason criterion. Experimentally measured load-displacement histories for all specimens were accurately reproduced by the proposed model, irrespective of different plate width, thickness and crack configurations. The numerical predictions were in good agreement with experimental test data in terms of both the maximum load and the corresponding displacement at maximum load. The proposed damage model was also used to numerically estimate the effect of crack growth on maximum load for these cracked specimens. The results in this paper demonstrate the potential of the proposed damage model as an engineering tool for analyzing ductile tearing in application to defect assessment of surface cracked pipes.
Inline Inspection Decisions and Results Using an Integrated Technology for a Baseline Inspection Program on a Large Diameter High Pressure Gas Transmission and Interconnect System
Authors: Westwood Stephen , Bhatia Arti
Published: December 2008

The Alliance Pipeline System consists of 2664 Km of NPS 36 high pressure transmission pipeline and 339 Km of NPS 42 high pressure transmission pipeline. The mainline systems are connected by lateral and interconnect pipeline sections ranging in diameter from NPS 4 to NPS 24. The pipeline system extends from northeast British Columbia to Illinois. The Trans border nature of the pipeline means that it needs to satisfy both the Canadian and US regulatory requirements related to pipeline integrity management. Part of the approval process for the pipeline system was that it had to be inspected on a regular basis with a baseline inspection program to be initiated upon start-up of the pipeline system in 2000. This paper outlines some of the unique challenges the high pressure transmission pipeline presented to both the operator and the inline inspection (ILI) vendor in developing a successful in line inspection program. It discusses the vendor selection criteria used by the pipeline operator and the design process undertaken by the ILI Vendor to meet the requirements of this unique pipeline system. By the end of 2004, the mainline sections in Canada and the US will have been inspected as well as most of the smaller diameter interconnect and lateral system. Results are presented from the ILI inspection of both the high pressure system and the smaller diameter system. While the inspections have used Magnetic Flux leakage (MFL) Technology to detect metal loss features, the use of integrated technology in particular the inertial navigation system aboard the vendor’s inspections tools has allowed geometric features to be detected as well. Lessons learned from both the operator and the ILI Vendor will be presented on the execution of the inline inspection program as well as discussion on ways of ensuring that the ILI process goes smoothly and if not how to address these concerns.
An Industry Consensus Standard for Pipeline Personnel Qualification: ASME B31Q
Authors: Moore Daron , Selig Bernd J.
Published: December 2008

The pipeline industry and its regulators have been collectively working on the qualification of pipeline personnel for more than 20 years. The U.S. Pipeline Safety Act of ’02 required the U.S. Office of Pipeline Safety of the Department of Transportation to develop standards (protocols) for Operator Qualification to properly inspect pipeline companies’ Operator Qualification programs. During the first half of 2003, OPS developed protocols as inspection standards for use by OPS field inspectors to audit existing OQ programs that must conform to existing regulations. The pipeline industry supported the development of the protocols. During this process, industry and the regulators developed a longer term strategy for Operator Qualification that would resolve outstanding issues that had not yet been resolved. The strategy will be described in this presentation. Part of that strategy included the development, on an expedited basis, of an industry consensus standard for Operator Qualification. ASME agreed to sponsor and develop this standard. This paper will discuss ASME B31Q – Pipeline Personnel Qualification, its development process, issues the team had to address and how they resolved these issues. It will describe the major elements of the standard. The path the industry and the regulator are taking to address personnel qualification to ensure safe, reliable operation of gas and liquid pipelines will be described. B31Q development started in August of 2003 and is expected to be completed by the end of 2004. The latest update on the standard and its implementation will be presented at the Conference.
Comparison of the Performance of Commercial Flow Improvers in Wet Gas Horizontal Pipelines
Authors: Kang Cheolho , More Parimal P. , Jepson William Paul
Published: December 2008

There is a conspicuous absence of flow improver work for wet gas pipeline environments. The tests were carried out in a 44 m long, 10.16 cm diameter, industrial scale multiphase flow loop with a wide range of superficial liquid and gas velocities ranging from 0.03 to 0.1 m/s and 4 to 10 m/s, respectively. Oil with a viscosity of 2 cP and carbon dioxide were used as the liquid and gas phases, respectively. Two commercial oil soluble flow improvers (FI-1 and FI-2) were used for the tests. This paper discusses the comparison of the performance of these flow improvers in wet gas pipelines. FI-1 and FI-2 were able to decrease the pressure gradient in most of the cases. At the same superficial liquid velocity, the pressure gradient reduction increased with an increase in the superficial gas velocity. This was due to the increase in turbulence level at the liquid and gas interface. At superficial liquid and gas velocities of 0.1 and 10 m/s, FI-1 showed a maximum effectiveness of 13% with the reduction of pressure gradient from 86 to 75 Pa/m. Whereas, FI-2 achieved the maximum effectiveness of 25% as the pressure gradient decreased to 65 Pa/m at the same conditions. Flow improver-2 showed a better performance than Flow improver-1 at all conditions. The decrease in the height of the liquid film was accompanied with spread of the liquid film around the pipe circumference with the addition of both the flow improvers. The changes in the height of the liquid film were more significant with FI-2 than FI-1. At certain superficial gas velocities, it was seen that a transition in flow pattern occurred from wavy to smooth stratified flow with the addition of both the flow improves. This was because the flow was much smoother at the gas-liquid interface with flow improvers.
The Merluza Gas Pipeline: A Complete Multiphase Flow Analysis Coupling Pig Launching With Pressure Constrained Survival Analysis
Authors: Baptista Renan Martins , Guedes Maricato Andre´ Luiz
Published: December 2008

This work describes the requirements and comments the results of a set of pipeline flow numerical simulations, for the offshore Merluza wet gas pipeline, located at Santos Basin, state of Sa˜o Paulo, Brazil. The work was conceived under the two-phase flow domain, and has used a well known commercial two phase flow numerical simulator. This pipeline is somewhat singular when compared to the average wet gas pipeline, as there is a considerable amount of condensate being carried, requiring a frequent launching of pigs. Besides, the capacity request at the pipeline’s tail is variable, even though it fits to an approximate stable cycle of demand. This cycling nature has required a survival analysis, for both packing and drafting operations, accounting for sometimes four pigs within the line, at the same time. Additionally, there is a pressure constraint downstream to the pipeline, due to the operational limits of the slug catcher, turning compulsory to have the survival cycle adjusted, in order to fully commit to this restriction. Finally, the results obtained with the simulation fits properly to the measured operational data, and allows the operational programmer to optimize the launching of pigs, as well as to take advantage of the maximum pipeline capacity.
Stress Corrosion Cracking of X70 Pipeline Steel in Near-Neutral pH Soil Solution
Authors: Fang B. Y. , Wang J. Q. , Han E.-H. , Zhu Z. Y. , Ke W.
Published: December 2008

Stress corrosion cracking behavior of X70 pipeline steel was studied using slow strain rate tests (SSRT) and cyclic loading at high R and low frequency in a nearneutral pH soil solution saturated with 5% CO2+95% N2. The soil was from Xinjiang Uygur Autonomous Region where the Chinese West-East natural gas transmission pipeline started. Electrochemical tests including a potentiodynamic polarization technique and electrochemical impedance spectrum (EIS) were also conducted in order to analyze the effect of the concentration of bicarbonate, bubbled gas and the addition of chloride ion on the polarization behaviors. The results of SSRT showed that transgranular stress corrosion cracking (TGSCC) occurred in Xinjiang soil solution. Crack initiation was associated with pitting, inclusion and streamline of rolling. The susceptibility to SCC increased with the decrease of the applied electrochemical potential and strain rate. Cyclic loading tests with smooth specimens showed that some cracks initiated after certain cycles and cracking mode was transgranular. Under the cyclic loading of high R and low frequency, the crack propagation rate (CPR) of precracked specimens did not increase at some region of stress intensity factor range (ΔK), which showed that the crack propagation process was dominated by SCC. The results of the electrochemical tests showed that the polarization behaviors were influenced greatly by the concentration of bicarbonate, bubbled gas and the addition of chloride ion. Low concentration of chloride ion in bicarbonate could cause the elimination of passivity and SCC behavior to that in near-neutral pH soil solution.
Numerical Studies of Pipeline Uplift Resistance in Frozen Ground
Authors: Liu Bill , Moffitt Karen , Nixon J. F. (Derick) , Zhou Joe , Xiao Yuxing
Published: December 2008

A buried pipeline is subject to a variety of internal and external loads, one of which is the load induced by relative movement between the pipeline and the surrounding soils. Frost heave is one of the potential mechanisms that induce the relative movement for buried pipelines of chilled gas. The magnitude of the loads due to frost heave depends upon the amount of heaving and the load-displacement characteristics of the surrounding frozen soils, i.e., the uplift resistance of the soils. Under the sponsorship of Pipeline Research Council International (PRCI), laboratory uplift tests have been carried out to study the load-displacement characteristics of a frozen soil. In parallel, a series of laboratory geo-mechanical tests were conducted to define stiffness, tensile strain limits and time-dependent features of the frozen soil. A numerical model, using the geo-mechanical properties of the frozen soil as input parameters, has been developed. The numerical model is intended to be used as a tool primarily for sensitivity analyses and scaling of the results of the laboratory uplift tests to field operations, which are anticipated to have pipe diameters in a range of 5 to 10 times of the laboratory tests. A description of the numerical model is provided in the paper. The load-displacement relationships and failure mechanisms represented in the numerical model are compared with the measurements and observations made during the laboratory uplift tests (quantitative data on uplift resistance are considered proprietary and will not be presented, but detailed data may be obtained from technical publications of PRCI). After being calibrated, the numerical model can be used for sensitivity analyses, and also potentially used as a design tool for pipelines in discontinuous permafrost.
Public Issues Associated With Planning a Large Diameter Pipeline in a Multi-Use Urban Corridor
Authors: Buszynski Mario E.
Published: December 2008

The lack of foresight by municipalities and others in preserving corridors for utilities means that there are increasingly fewer opportunities to locate linear facilities in large urban centers such as the City of Toronto. In those corridors that do exist, there are competing land uses that make it difficult to accommodate any new use. Many of these land uses are directly related to the people living adjacent to and in the vicinity of the corridors. In 2003, the Ontario Energy Board approved new “Environmental Guidelines for the Location, Construction and Operation of Hydrocarbon Pipelines and Facilities in Ontario”. The Guidelines include specific new requirements for planning pipelines in urban areas. Among other things, these new requirements involve the identification of indirectly affected landowners and a more detailed analysis of public issues and how they were resolved. Through the use of a case study, this paper identifies the public issues that were encountered in planning the location of a NPS 36 (Nominal Pipe Size 914 mm or 36 inch diameter) natural gas pipeline through residential neighbourhoods in the City of Toronto and the Town of Markham. It also describes how the public involvement requirements contained in the Ontario Energy Board’s new guidelines were incorporated into the planning process. The case study begins with a rationale for the study area selected. A description of the public issues follows. The techniques used to address these issues and the success of the public involvement program that identified 180 directly affected and 3,200 indirectly affected landowners is documented. The study results illustrate that it is possible to plan a right-of-way through an urban corridor in such a manner as to satisfy the general public, be compatible with existing development, conform to the new Ontario Energy Board Guidelines and minimize the amount of remedial work required to mitigate the impacts occurring on and adjacent to the right-of-way.
Evaluation of the Suitability of X100 Steel Pipes for High Pressure Gas Transportation Pipelines by Full Scale Tests
Authors: Demofonti G. , Mannucci G. , Hillenbrand H. G. , Harris D.
Published: December 2008

In order to increase the knowledge necessary for the utilisation of grade X100 steel pipes, and to consolidate preliminary indications regarding the safe level of toughness required to control the ductile fracture propagation event within X100 gas pipeline, an ECSC-Demonstration Project, (DemoPipe), partially sponsored by EPRG, has been performed (2001–2004) using TMCP X100 pipes with a diameter of 36”. The project examines the problems of building a new high grade steel on-shore gas pipeline, with special emphasis given to the issues of the field welding technologies and selection of consumables, girth weld defect tolerance, field cold bending, and the fracture propagation behaviour in a high-pressure natural gas pipeline. In order to achieve these stated aims, a dedicated programme of laboratory and full scale tests was included in the project. This paper presents a summary of some of the results obtained, together with a discussion regarding their applicability to future X100 pipelines.
Cost of Risk and Its Affect on Integrity Management
Authors: Laughlin Shawn
Published: December 2008

Pipeline Integrity Management is a growth industry. Much of the material published in the last few years has been directed at reducing maintenance cost by accepting and managing some level of risk. Risk is typically established by complex statistical calculations based on available data. These methods work well when both the accuracy and confidence of the data used in the calculations are very high. These methods work less well when the data is less accurate and can sometimes lead to underestimating both the degree of risk and its associated cost. This paper is a general review of the industry practice of determining risk and its cost. This paper reviews published specifications (accuracy and confidence) of in-line-inspection tools with regard to the use of this indirect data as a basis for complex calculations to determine acceptable risk. This paper argues that current tool specifications make determination of actual risk difficult. According to published papers and documents, the industry uses discounted cash flow models that consider only the cost of repairs and the cost of ILI inspection as the basis for management decisions on maintenance and scheduling of inspection and repair activities. This paper argues that the risk accepted under these models has a quantifiable cost commensurate with the accuracy of the data used in the risk assessment process and level of risk acceptable to the Operator. This paper argues that the cost of risk is sometimes underestimated.