bluuebunny/crossref_metadata_2025 huggingface dataset:
Cycle-by-Cycle Air-to-Fuel Ratio Calculation During Transient Engine Operation Using Fast Response CO and CO2 Sensors
Authors: Prucka Robert G. , Filipi Zoran S. , Hagena Jonathan R. , Assanis Dennis N.
Published: July 2013

Stringent engine emission regulations highlight the importance of proper engine control during transient operation. In recent years, fast emissions analyzers that measure CO and CO2 simultaneously have allowed for fast air-to-fuel ratio (AFR) calculation under steady-state engine operation. However, using a steady-state methodology to calculate AFR under transient conditions can lead to significant data interpretation errors. This research introduces an experimental cycle-by-cycle AFR calculation routine developed for transient operation using cycle-resolved CO2 and CO analyzers. Need for the new technique arises when the composition of recycled exhaust gases vary significantly from expected post-combustion products corresponding to the true in-cylinder AFR. This condition commonly occurs when AFR is changed from one cycle to the next. The peak difference between the new method and traditional methods is demonstrated to be in the range of 0.1 relative air-to-fuel ratio points, or approximately 10%. These results are for low dilution conditions where the new method should show minimal difference as compared to traditional methods. If residual gas fraction levels were increased the difference in corrected to uncorrected results would become even greater, motivating the use of the new method in high-dilution engines.
Hydrotreated Renewable Jet Fuel Ignition Delay Performance in a Military Diesel Engine: An Experimental and Modeling Study
Authors: Cowart Jim S. , Fischer Warren , Hamilton Len J. , Caton Patrick A. , Sarathy S. Mani , Pitz William J.
Published: July 2013

In an effort towards predicting the combustion behavior of a new fuel in a conventional diesel engine, Hydrotreated Renewable Jet (HRJ) fuel was first run in a military diesel engine across the entire speed-load operating range. Ignition delay was characterized for this fuel at each operating condition. Next, a HRJ surrogate fuel was developed in order to predict the combustion performance of this new renewable fuel. A chemical ignition delay was then predicted across the speed-load range using a detailed chemical kinetic mechanism model based on an 8-component surrogate representative of HRJ. The modeling suggests that rich fuel-air parcels developed from the diesel spray are the first to ignite. The chemical ignition delay results also show decreasing ignition delays with increasing engine load and speed just as shown by the empirical data. A moderate difference between the total and chemical ignition delays was then characterized as a physical delay period which scales inversely with engine speed. The approach used in this study suggests that the ignition delay and thus start of combustion may be predicted with reasonable accuracy allowing for the analytical assessment of the acceptability of a new fuel in a conventional engine.
Advanced Aftertreatment System Development for a Locomotive Application
Authors: Park Paul W. , Downey Markus , Youngren David , Bruestle Claus
Published: July 2013

For the first time in the locomotive industry, an advanced exhaust aftertreatment system for a locomotive application was successfully demonstrated to reduce nitrogen oxides from 6.46 g/kW·hr to 1.21g/kWhr to meet the needs of local NOx reduction requirements for non-attainment areas.

Five 2,240 kW (3,005 horsepower) PR30C line-haul repowered Progress Rail locomotives were equipped with diesel oxidation catalyst and selective catalytic reduction technologies to accumulate more than 27,000 hours in total in revenue service.

Full emissions performance including carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter was conducted at Southwest Research Institute on a regular basis to measure the change of emissions performance for two selected locomotives.

The emissions performance of the aftertreatment system did not show any degradation during 3,000 hours operation. After 3,000 hours operation, 0.13 g/kW·hr carbon monoxide (89–91% reduction), 0.027 g/ kW·hr hydrocarbons (91% reduction), 1.08–1.21 g/ kW·hr nitrogen oxides (81–83% reduction) and 0.05–0.08 g/ kW·hr particulate matter (38–58% reduction) were measured on the line-haul cycle. The baseline emissions levels of the engine are within Tier 2 EPA locomotive limits. The newly developed close loop control software successfully controlled targeted nitrogen oxides reduction with minimum ammonia slip during the locomotive emission cycle tests.
Analysis of the Lubrication Regimes at the Small End and Big End of a Connecting Rod of a High Performance Motorbike Engine
Authors: Bertocchi Luca , Giacopini Matteo , Dini Daniele
Published: July 2013

In the present paper, the algorithm proposed by Giacopini et. al. [1], based on a mass-conserving formulation of the Reynolds equation using the concept of complementarity is suitably extended to include the effects of compressibility, piezoviscosity and shear-thinning on the lubricant properties. This improved algorithm is employed to analyse the performance of the lubricated small end and big end bearings of a connecting rod of a high performance motorbike engine.

The application of the algorithm proposed to both the small end and the big end of a con-rod is challenging because of the different causes that sustain the hydrodynamic lubrication in the two cases. In the con-rod big end, the fluid film is mainly generated by the relative high speed rotation between the rod and the crankshaft. The relative speed between the two races forms a wedge of fluid that assures appropriate lubrication and avoids undesired direct contacts. On the contrary, at the con-rod small end the relative rotational speed is low and a complete rotation between the mating surfaces does not occurs since the con-rod only oscillates around its vertical axis. Thus, at every revolution of the crankshaft, there are two different moments in which the relative rotational speed between the con-rod and the piston pin is null. Therefore, the dominant effect in the lubrication is the squeeze caused by the high loads transmitted through the piston pin. In particular both combustion forces and inertial forces contribute to the squeeze effect.

This work shows how the formulation developed by the authors is capable of predicting the performance of journal bearings in the unsteady regime, where cavitation and reformation occur several times. Moreover, the effects of the pressure and the shear rate on the density and on the viscosity of the lubricant are taken into account.
Non-Iterative Finite Element Scheme for Combined Annular-Thrust Porous Aerostatic Bearings Analysis
Authors: Khan Polina V. , Hwang Pyung
Published: July 2013

The key points of method derivation and a numerical example for bearing with three dimensional air flow are presented.
Local Adaptive Multi-Grid Control Volume Method for the Air Bearing Problem in Hard Disk Drives
Authors: Li Liping , Bogy David B.
Published: July 2013

A new local adaptive grid-generating algorithm is developed and integrated with the multi-grid control volume method to simulate the steady state flying condition of air bearing sliders in HDDs (Hard Disk Drives) accurately and efficiently. Two sliders are used to demonstrate the applicability of this method. The results show that this new local adaptive grid-generating method improves substantially the stability and efficiency of the simulation scheme.
Experimental and Numerical Investigation of the High-Speed Instability of Aerodynamic Foil Journal Bearings for Micro Turbomachinery
Authors: Somaya Kei , Yamashita Toru , Yoshimoto Shigeka
Published: July 2013

Foil bearings have been attracting considerable attention for their applications to micro turbomachinery, such as blowers and compressors, because of their excellent stability at high speeds and durability in high-temperature environments. This paper investigates experimentally and numerically the high-speed instability of a rotor supported by small aerodynamic foil journal bearings. Two types of foil journal bearings were prepared: a first-generation bump-type foil bearing and a dimple-type foil bearing; these consist of a top foil and a support foil with bumps or dimples, respectively. The dynamic characteristics of a support foil using the frequency response and the threshold speed of instability at high speeds were measured experimentally. Furthermore, the numerical threshold speed of instability was obtained using the nonlinear orbit method. It was confirmed experimentally and numerically that a 6 mm diameter rotor with a mass of 4.7 g supported by either of the two types of foil journal bearing treated in this paper could rotate stably at speeds of more than 760,000 rpm.
The Role of Effective Collaboration in the Advancement of EMAT Inline Inspection Technology for Pipeline Integrity Management: A Case Study
Authors: Sutherland Jeff , Tappert Stephan , Kania Richard , Kashammer Karlheinz , Marr Jim , Mann Andrew , Rosca Gabriela , Garth Clint
Published: July 2013

Over the past three years there has been increasing industry interest and profile regarding the role and pipeline integrity management potential of EMAT crack inspection technology in the Oil & Gas pipeline industry.

This paper outlines the stages and results of the effective collaboration of a major pipeline operator and a service company to advance the true predictive performance of the EMATScan Gen III crack inspection technology.

The paper will also summarize and provide examples of lessons-learned from this collaboration across all stages of EMAT based SCC integrity management program.

The paper will similarly outline ongoing work in progress regarding the assessment of the ILI data relative to hydro-testing equivalency, detection of injurious defects and the related analysis and reporting improvements made over the past three years.
Natural Gas Compressor Operation Optimization to Minimize Gas Turbine Outboard Bleed Air
Authors: Botros K. K. , Golshan H. , Sloof B. , Samoylove Z. , Rogers D.
Published: July 2013

Gas turbine (GT) engines employed in natural gas compressor stations operate in different modes depending on the power, turbine inlet temperature and shaft speeds. These modes apply different sequencing of bleed valve opening on the air compressor side of the engine. Improper selection of the GT and the driven booster compressor operating conditions can lead to larger bleed losses due to wider bleed valve openings. The bleed loss inevitably manifests itself in the form of higher overall heat rate of the GT and greater engine emission. It is therefore imperative to determine and understand the engine and process conditions that drive the GT to operate in these different modes. The ultimate objective is to operate the engine away from the inefficient modes by adjusting the driven booster compressor parameter as well as the overall station operating conditions (i.e. load sharing, control set points, etc.). This paper describes a methodology to couple the operating conditions of the booster compressor to the modes of GT bleed valve opening (and the subsequent air bleed rates) leading to identification of the operating parameters for optimal performance (i.e., best overall efficiency and minimum CO2e emission). A predictive tool is developed to quantify the overall efficiency loss as a result of the different bleed opening modes, and map out the condition on the gas compressor characteristics. One year’s worth of operating data taken from an existing compressor station on TransCanada Pipelines’ Alberta system was used to demonstrate the methodology. This station employs GE-LM1600 gas turbine driving a Cooper Rolls-RFBB-30 centrifugal compressor. The results from the analysis conclusively indicate that there are operating regions on the gas compressor map where losses due to bleed valves are reduced and hence lower CO2 emissions, which presents an opportunity for operation optimization.
Research on Burst Tests of Pipeline With Spiral Weld Defects
Authors: Chen Jian , Feng Qingshan , Wang Fuxiang , Zhang Hailiang , Song Hancheng
Published: July 2013

On some old long distance transmission pipelines of PetroChina some severe spiral weld defects existed. These weld defects were found to be from a lack of penetration and lack of fusion during pipe manufacturing. To avoid possible failure accidents, tri-axis magnetic flux leakage (MFL) in-line inspections were performed on some certain pipelines. A large quantity of spiral weld defects were detected in the inspections and their sizes were reported, some of them with large depth and large length along the spiral weld seam. However, there is no applicable engineering critical assessment (ECA) method for this kind of defects up to now. Assessment methods provided in BS7910:2005 and other codes are only applicable to assess flaws in cylinder oriented axially or circumferentially. Projection processing must be used to utilize these methods for spiral flaws. Three other different assessment methods for spiral defects in linepipe were proposed by Mok et al., Fu and Jones, and Bai et al. separately. But these methods were originally developed for spiral corrosion and have not been proved to be applicable for spiral weld defects on the old pipelines of PetroChina. In this paper’s work, several burst tests of pipeline with spiral weld defects were carried out. Different projection assessment methods based on BS7910:2005 were conducted as well as the spiral corrosion assessment methods proposed in previous studies. Predicted results were compared with burst tests and analyzed in this paper. As a conclusion of comparison, the axial projection method based on BS7910:2005 was suggested to assess this kind of spiral weld defects despite of its conservatism.
Soil Restraint Against Lateral and Oblique Motion of Pipes Buried in Dense Sand
Authors: Roy Kshama Sundar , Hawlader Bipul
Published: July 2013

This paper investigates the soil restraint against lateral and oblique motion of pipes buried in dense sand. A series of two- and three-dimensional finite element analyses are performed for pure lateral and combined axial-lateral relative pipeline/soil displacement. The commercially available finite element software package ABAQUS/Standard is used in numerical analysis. The analyses are performed for two burial depths. The numerical model is verified by comparing with model test results available in the literature. The built-in Mohr-Coulomb model in ABAQUS is used for modeling the soil. It is shown that an advanced soil constitutive model might be required for better modeling of pipe/soil interaction behavior.
Crack Arrest Testing of High Strength Steels
Authors: Hasenhütl Andre , Erdelen-Peppler Marion , Kalwa Christoph , Pant Martin , Liessem Andreas
Published: July 2013

Fracture propagation is a major concern for the safe operation of gas transmission pipelines. Ductile fracture resistance, which is required according to line pipe standards, is commonly assessed by Charpy impact testing. If fracture occurs during pipe operation, fracture propagation is required to appear in ductile manner. The prerequisite for this is the demonstration of sufficient shear fracture in the BDWT test and minimum required Charpy impact energy. A combination of both requirements ensures avoidance of brittle fracture as well as control of ductile fracture propagation. The experimental chain of evidence and the Battelle-Two-Curve (BTC) model which is the most widely applied model to predict resistance against fracture propagation have been developed on basis of welded pipes of grade ≤ X70. The model has been calibrated against test data obtained from pipes with Charpy impact energy values below 100 J. In recent years, new material concepts were developed to increase material strength and material toughness. On the one hand, increase in material toughness, which is evaluated by Charpy impact testing, is often achieved by an increase in crack initiation resistance. On the other hand, crack propagation resistance, which is determined by BDWT testing with an instrumented striker, can remain on the same level. Increased material toughness and crack initiation resistance can be manifested by incomplete fracture of Charpy impact specimens in the upper shelf (ductile fracture). Actual Charpy impact test standards for metallic materials do not coincide with each other regarding the validity of Charpy energy of unbroken specimens. Increased crack initiation resistance also affects fracture initiation mechanism in BDWT tests, leading to invalid test results according test standards. Invalidity can be expressed by inverse fracture appearance. To avoid inverse fracture, crack initiation energy can be reduced by changing notch type and therefore changing the constraint in the root of the notch. BDWT test standards also do not agree with each other concerning allowable notch types. While the pressed notch type is the preferred one for low toughness steels and the Chevron notch type for higher toughness steels according some test standards, other test standards allow only for a pressed notch type. Being semi-empirical by nature, the BTC concept strongly depends on the input parameters derived from different material tests. Changing test conditions can have a direct impact on the assessment results.
A New Method for Reducing Diffusible Hydrogen in Weld Metal
Authors: Fiore Susan , Barhorst Steve , Amata Mario , Bundy Joe
Published: July 2013

The effect of hydrogen on weld metal and weld heat-affected zones (HAZ) has been well established over many years. The potential for hydrogen-assisted cracking increases as the strength of the steel increases. High fuel costs have driven the need for lower weights in the transportation and shipbuilding industries, and increased regulations have driven the need for higher safety factors in the pipeline industry. As a result, many industries are requiring higher and higher base metal strengths. The push for higher strength steels has resulted in an increased demand for ultra-low hydrogen welding consumables and processes.

Manufacturers of flux-cored arc welding (FCAW) electrodes have generally attacked the problem of weld metal hydrogen through the use of raw materials that react with hydrogen to take it out of solution, by baking the wires in-process, and by using special drawing techniques and lubricants to minimize hydrogen pick-up. Unfortunately, many of the potential solutions result in electrodes that have poor operability, wire feeding problems, and/or increased welding fume.

Hobart Brothers has recently developed a method of producing very low-hydrogen weld deposits, which utilizes fluorine-containing gas compounds in the weld shielding gas. The modified shielding gas has no effect on the weld metal properties or the operation of the welding electrodes. This paper provides details of the method, along with test results that have been achieved using a number of flux- and metal-cored electrodes representing a variety of American Welding Society (AWS) classifications.
Corrosion Metal Loss Interaction From In-Line Inspection and How it Can Affect the Calculated Failure Pressure
Authors: Smart Lucinda , McNealy Richard , Haines Harvey
Published: July 2013

In-Line Inspection (ILI) is used to prioritize metal loss conditions based on predicted failure pressure in accordance with methods prescribed in industry standards such as ASME B31G-2009. Corrosion may occur in multiple areas of metal loss that interact and may result in a lower failure pressure than if flaws were analyzed separately. The B31G standard recommends a flaw interaction criterion for ILI metal loss predictions within a longitudinal and circumferential spacing of 3 times wall thickness, but cautions that methods employed for clustering of ILI anomalies should be validated with results from direct measurements in the ditch. Recent advances in non-destructive examination (NDE) and data correlation software have enabled reliable comparisons of ILI burst pressure predictions with the results from in-ditch examination. Data correlation using pattern matching algorithms allows the consideration of detection and reporting thresholds for both ILI and field measurements, and determination of error in the calculated failure pressure prediction attributable to the flaw interaction criterion. This paper presents a case study of magnetic flux leakage ILI failure pressure predictions compared with field results obtained during excavations. The effect of interaction criterion on calculated failure pressure and the probability of an ILI measurement underestimating failure pressure have been studied. We concluded a reason failure pressure specifications do not exist for ILI measurements is because of the variety of possible interaction criteria and data thresholds that can be employed, and demonstrate herein a method for their validation.
Value of Additional Valves on Existing Low Vapor Pressure Liquid Pipeline
Authors: Li Yanping , Weir David A.
Published: July 2013

API 1160 (Managing System Integrity for Hazardous Liquid Pipelines, 2001) and the Pipeline Risk Management Manual (3rd edition, by W. Kent Muhlbauer) are among the very few publications that have sections addressing the value of adding valves on existing liquid pipelines. These sections cite two references: the California State Fire Marshal Hazardous Liquid Pipeline Risk Assessment 1993 and the Safety of Interstate Liquid Pipelines: An Evaluation of Present Levels and Proposals for Change 1987.

This paper reviews and challenges valve placement considerations established in API 1160 and the Pipeline Risk Management Manual (3rd edition) including check valve inspection issues, valve leaks or malfunction, etc. The cost and benefit of additional valves on existing liquid pipeline systems are discussed. This paper calls for the need for further work or a collaborative study of the value of additional valves on existing liquid pipeline systems.
FE Analysis of Temperature Field of PQF Mandrel
Authors: Li Xinwen , Tu Yanfeng , Guo Yun
Published: July 2013

The PQF (Premium Quality Finishing) tube mill has been the most technologically advanced continuous-rolling tube mill so far. The mandrel is one of the main tools for processing in PQF, the temperature distribution and variation of which is the basis of studying the abrasion and defect generation of mandrels. Finite element method is applied to obtain the temperature field of every phase and the temperature history in PQF rolling tube 28CrMo57. The results show that the surface nodes are always in high temperature while the temperature of internal nodes almost maintains original value; the surface temperature of the mandrel changes dramatically, and the temperature reduction rate reaches 160°C/s between the 1# stand and the 2# stand; the average temperature of the whole mandrel rises fastest in the 1# stand, whereas the rate of rise slows down considerably in the subsequent phases. After comprehensive consideration of simulation results and failure mechanism of the mandrel, some suggestions on prolonging mandrel life are presented.
Development and Implementation of an Operational Risk Management Framework Aligned With ISO 31000
Authors: Weir David , Urra Susan
Published: July 2013

The International Standards Organization (ISO) standard 31000 (Risk Management – Principles and Guidelines) provides guidance on the development of a systematic approach to managing risk within an organization. Using ISO 31000 as a guide, Enbridge Pipelines has enhanced its existing release-focused risk-informed decision-making approach and risk management process. The development of this enhancement has involved engagement of all levels of management and staff, and has required consideration of corporate cultural change, staff communication and training, development of performance measures, and management reporting.

This paper provides a high level overview of the ISO 31000 standard as it pertains to its use in the development of the Enbridge Pipelines operational risk management framework, the roadmap for implementation of the framework, and discusses the challenges, successes, learnings, and early results of implementing the framework in a large multi-national pipeline company.
Validation of EMAT Technology for Gas Pipeline Crack Inspection
Authors: Kania Richard , Klein Stefan , Marr Jim , Rosca Gabriela , Riverol Elvis SanJuan , Ruda Rahim , Jansing Nikola , Beuker Thomas , Ronsky N. Daryl , Weber Ralf
Published: July 2013

The use of the Electro-Magnetic Acoustical Transducer (EMAT) technology for crack detection by In-Line Inspection (ILI) tools has increased over the last few years. Rigorous validation of the technology leading from the initial application of EMAT inline inspection tools through to determining Probability of Detection (POD) and Identification (POI) has contributed to improved confidence and reliability. EMAT results are being utilized to determine SCC valve section severity, to review and modify hydrostatic test schedules and intervals and could potentially be implemented as a viable alternative to hydrostatic testing.

This paper describes the development of an EMAT ILI based program and the related validation process applied by the vendor, pipeline operator and in-ditch personnel. This process is illustrated by demonstrating the performance of the EMAT tool in two 20″ diameter natural gas pipelines which have a documented history of SCC. The tool identified hundreds of features in the two pipelines which were validated both in the ditch and via detailed anomaly sizing.
An Update to the UKOPA Pipeline Damage Distributions
Authors: Goodfellow Graham , Turner Susannah , Haswell Jane , Espiner Richard
Published: July 2013

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 22,370 km of pipelines reporting. Overall exposure from 1952 to 2010 is of over 785,000 km years of operating experience with a total of 184 product loss incidents during this period. 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.

However, unlike the European Gas Incident data Group (EGIG) database, which also includes the UK gas transmission pipeline data, the UKOPA database contains extensive data on measured part wall damage that did not cause product loss. The data on damage to pipelines caused by external interference can be assessed to derive statistical distribution parameters describing the expected gouge length, gouge depth and dent depth resulting from an incident. Overall 3rd party 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 3rd party damage for a given set of pipeline parameters.

The UKOPA recommended methodology for the assessment of pipeline failure frequency due to 3rd party damage is implemented in the FFREQ software. The distributions of 3rd party damage currently used in FFREQ date from the mid-1990s. This paper describes the work involved in updating the analysis of the damage database and presents the updated distribution parameters. A comparison of predictions using the old and new distributions is also presented.
Enbridge Cost and Schedule Contingency Assessments
Authors: Schoenhardt Matthew , Pardais Vachel , Fortin Cheryl , Kitson Brent , Hanzel Jay
Published: July 2013

All capital projects have an element of risk and uncertainty. In today’s business environment this requires more than just simply adding 10 percent contingency to the cost estimate to cover off project unknowns. Before sanctioning a project for hundreds of millions of dollars, Board of Directors need to know what possible cost and schedule outcomes exist in order to safe-guard shareholders’ investments. Contingency assessments must be:

• Risk-based

• Project Specific

• Repeatable

• Defendable

• Cost effective

Six years ago, Enbridge grappled with these issues and realized it needed to adopt a new method of assessing both cost and schedule contingencies. After evaluating options, Enbridge set upon developing an in-house parametric modeling solution for its contingency assessment needs.

This paper will:

• Identify various options for assessing contingency

• Review the Enbridge process

• Demonstrate the value of a simplified risk register

• Identify required data inputs

• Illustrate calibration and accuracy of assessments

• Discuss business advantages of parametric modelling
Research on Oil and Gas Station Integrity Management System
Authors: Zheng Honglong , Ai Muyang , Zhou Lijian , Li Mingfei , Wang Ting , Zhang Huabing , Chen Jian
Published: July 2013

As a preventative management mode, integrity management which is significantly effective is now applicable in modern industry. Based on the successful application of integrity management for the pipeline, managers expect an extension of the integrity management program for the oil and gas stations such as pumping stations, so as to make the best arrangement of resources and guarantee the safety of station facilities. The differences between station integrity management system in China and abroad are analyzed. It is claimed that the oil and gas station integrity management is more difficult and complicated in China. An integrity management program is developed for the oil and gas stations in China. The authors summarily introduce the station integrity management framework, and determine the processes and elements of management. For the main parts of the stations are plenty of facilities, the authors attempt to carry out the management on each category of facilities in particular. According to the characteristics and working status, field facilities can be classified into three categories: static facilities, dynamic facilities, and electrical instruments. For all these facilities, integrity management approach consists of five steps: data collection, risk assessment, integrity assessment, repair & maintenance, and performance evaluation. Station integrity management system comprises five aspects: system documents, standards & specifications, supporting technologies, management platforms and applications. This paper should be considered as a reference for the oil and gas station integrity managers in the future.
One Design Method of Pipeline in Mined-Out Area
Authors: Zhang Zhenyong , Lei Tong
Published: July 2013

With the rapid development of oil and gas pipeline construction, there are more and more pipelines have to pass through the mineral deposits area. The surface cracking, subsidence and collapse will be occurred commonly because of the underground goaf after exploitation in mineral deposits area, and pipelines’ safety is faced with hidden troubles. In order to solve the contradiction between the pipeline construction and minerals mining, some research on design method of pipeline in mined-out area was carried out. The goaf subsidence prediction is constituted of subsidence influence factors analysis, surface deformation law analysis and surface deformation forecast. Pipe stress analysis includes stress influence factors analysis and stress model analysis. Combining the pipeline influence factors with the forecasted surface deformation, the pipeline stress analysis model could be built. This paper describes methods developed for the ground surface displacement prediction and the mechanical model of the pipeline/ soil interaction, and some application examples in china.
Continued Microstructure and Mechanical Property Performance Evaluation of Commercial Grade API Pipeline Steels in High Pressure Gaseous Hydrogen
Authors: Stalheim Douglas , Boggess Todd , Bromley Darren , Jansto Steve , Ningileri Shridas
Published: July 2013

In spite of current world economic climates, recognition that alternative energy sources to the traditional fossil fuels has to be explored and understood. One potential energy source being researched and developed is hydrogen gas. Currently the most economical method of transporting large quantities of hydrogen gas is through steel pipelines. It is well known that hydrogen embrittlement has the potential to degrade steel’s mechanical properties when hydrogen migrates into the steel matrix. Consequently, the current pipeline infrastructure used in hydrogen transport is typically operated in a conservative fashion. This operational practice is not conducive to economical movement of significant volumes of hydrogen gas as an alternative to fossil fuels.

The degradation of the mechanical properties of steels in hydrogen service is known to depend on the microstructure of the steel. Understanding the levels of mechanical property degradation of a given microstructure when exposed to hydrogen gas under pressure can be used to evaluate the suitability of the existing pipeline infrastructure for hydrogen service and guide alloy and microstructure design for new hydrogen pipeline infrastructure. To this end, the microstructures of relevant steels and their mechanical properties in relevant gaseous hydrogen environments must be fully characterized to establish suitability for transporting hydrogen.

Previously data from a US Department of Energy/private sector funded project to evaluate four commercially available pipeline steels alloy/microstructure performance in the presences of gaseous hydrogen was presented in 2010. Interest in this previous work from industry and the ASME B31.12 Hydrogen Piping and Pipeline Systems codes and standards committee resulted in additional funding for continued evaluation of additional pipeline steel alloys/microstructures in the presences of gaseous hydrogen. Samples from API grades X52 (1960’s and current vintage designs), X70 (1980’s and current vintage) and X80 along with various samples from an X52 induction bend pipe and one pressure vessel steel A516 Gr 70 are being evaluated. Microstructural characterization, fracture toughness and fatigue testing in the presence of gaseous hydrogen at 800 psig and 3,000 psig are being conducted.

This paper will describe the fracture toughness results achieved to date on various commercially available pipeline steels used in the existing North American pipeline infrastructure in the presence of gaseous hydrogen at pressures relevant for transport in pipelines. Microstructures and fracture toughness performances will be compared between these in this study along with those published previously. In addition, recommendations for future work related to gaining a better understanding of steel pipeline performance in hydrogen service will be discussed.
Simulation of Liquid-Gas Replacement in Commissioning Process for Large-Slope Crude Oil Pipeline
Authors: Chen Yuanyuan , Gong Jing , Li Xiaoping , Zhang Nan , He Shaojun , Liu Jianfeng , Liu Yuwei , Wu Jiawen
Published: July 2013

Pipeline commissioning, which is a key link from engineering construction to production operation, is aim to fill an empty pipe by injecting water or oil to push air out of it. For a large-slope crude oil pipeline with great elevation differences, air is fairly easy to entrap at downward inclined parts. The entrapped air, which is also called air pocket, will cause considerable damage on pumps and pipes. The presence of it may also bring difficulties in tracking the location of the liquid head or the interface between oil and water. It is the accumulated air that needed to be exhausted in time during commissioning.

This paper focuses on the simulation of liquid-gas replacement in commissioning process that only liquid flow rate exists while gas stays stagnant in the pipe and is demanded to be replaced by liquid. Few previous researches have been found yet in this area. Consequently, the flow in a V-section pipeline consisted of a downhill segment and a subsequent uphill one is used here for studying both the formation and exhaustion behaviors of the intake air. The existing two-fluid model and simplified non-pressure wave model for gas-liquid stratified flow are applied to performance the gas formation and accumulation. The exhausting process is deemed to be a period in which the elongated bubble (Taylor bubble) is fragmented into dispersed small bubbles. A mathematical model to account for gas entrainment into liquid slug is proposed, implemented and incorporated in a computational procedure. By taking into account the comprehensive effects of liquid flow rate, fluid properties, surface tension, and inclination angle, the characteristics of the air section such as the length, pressure and mass can be calculated accurately. The model was found to show satisfactory predictions when tested in a pipeline. The simulation studies can provide theoretical support and guidance for field engineering application, which are meanwhile capable of helping detect changes in parameters of gas section. Thus corresponding control measures can be adopted timely and appropriately in commissioning process.
Experimental Study on Blockage of Gas Hydrate Slurry in a Flow Loop
Authors: Lv Xiaofang , Yu Da , Li Wenqing , Shi Bohui , Gong Jing
Published: July 2013

Hydrate formation and blockage in long deepwater pipelines has long been a trouble for offshore petroleum production. Consequently, understandings of the procedures as well as influencing factors of hydrate blockage are key points to make reasonable flow assurance strategies. Thus two series of experiments have been conducted in a high-pressure hydrate flow loop newly constructed by multi-phase flow research group in China University of Petroleum (Beijing). One of the systems consists of water and CO2, while the other one includes water, diesel oil and natural gas. The relative time of hydrate blockage has been studied by varying pressure and flow rate for both two systems. The dimensions of hydrate particles in fluid during plugging are also investigated. The results indicate that the influencing factor exerts a similar effect on the relative time for the different systems. Besides, the sizes of particles in the fluid would change significantly due to hydrate formation.
Tomography of Inclined SCC Cracks in Australian Gas Pipelines
Authors: Gamboa Erwin , Zadow Luke
Published: July 2013

Stress Corrosion Cracking (SCC) in pipeline steel occurs when an aggressive environment and tensile stresses act on a susceptible microstructure. Typically, SCC in gas pipelines tends to travel perpendicular to the hoop stresses in the through wall direction. Studies conducted on the TransCanada pipeline where a rupture had occurred revealed the incidence of SCC cracks whose crack path deviated at an angle from the normal. These inclined cracks have also been found in a pipeline in Australia which has lead to an increased need to better understand inclined SCC. This paper, based on the Australian pipeline, investigates the incidence rate, morphology, and observed interactions of inclined SCC in the Australian pipe.
Probabilistic Fitness-for-Service Assessment of Pipeline
Authors: Semiga Vlad , Dinovitzer Aaron
Published: July 2013

Fitness for service assessments of oil and gas pipelines, conducted either at the design stage or to evaluate an indentified anomaly, are generally carried out in a deterministic manner based on conservative estimates of the required input parameters.

The following paper presents a probabilistic Fitness-for-Service (FFS) assessment approach which can be used in a risk based pipeline integrity management program. The probabilistic assessment utilizes an Advanced Monte Carlo simulation based approach and the fracture mechanics techniques described in BS 7910. The paper presents an overview of the basic approach and provides a demonstration of its capabilities in terms of estimating the risk of failure (or probability of failure) associated with a pipeline over time, due to the presence of a crack like flaw. The paper also discusses the sources of data and inherent assumptions used to model various input parameters required for a typical FFS analysis carried out according to BS 7910.
Remaining Life Assessment of ERW Flaws: A Case Study
Authors: Cazenave Pablo , Tandon Samarth , Tinacos Katina , Gao Ming , Katz David C. , Limon Sergio , Van Hook Michael
Published: July 2013

Recent failures in seam weld pipe have raised concerns within the pipeline industry over the integrity of such welded pipe. Low-Frequency (LF) Electric Resistance Welded (ERW) pipe manufactured prior to 1970, in particular, can be susceptible to failures caused by hook cracks, lack of fusion and other planar defects should the weld area exhibit low toughness.

Integrity management regulations and Pipeline operators are evaluating potential methodologies to address and mitigate the LF-ERW seam weld threat. A program has been initiated at Williams Northwest Pipeline GP (NWPGP) to address the integrity management of its pre-70s ERW pipelines.

In this case study, as part of an overall integrity management program, a hydrostatic test and fatigue analysis based methodology for addressing the LF-ERW seam weld threat is presented. The methodology was applied to 15 pre-1970’s natural gas pipelines. The results and findings are summarized in terms of the integrity threat mitigation and maintenance strategies.
Extension of a Material Model for Pipeline Steels
Authors: Hart James D. , Zulfiqar Nasir , Zhou Joe , Adams Keith
Published: July 2013

Pipeline steel stress-strain curves obtained from tension and compression testing of longitudinally and circumferentially oriented specimens of the pipe wall can be significantly different e.g., the pipe material is anisotropic. The anisotropic behavior can result from the manufacturing process (e.g., due to cold expansion of UOE pipe) and can also be influenced by strain aging effects (e.g., due to heated application of pipe coating materials). As described in previous work, the Mroz multilinear kinematic hardening plasticity theory has the ability to accurately model different types of anisotropic pipe material behavior including relatively “sharp” uniaxial circumferential tension response and relatively well-rounded uniaxial longitudinal tension and compression response. The stress-strain curve fitting is accomplished by essentially selecting the sizes and initial positions of elliptical von Mises yield functions in stress-space.

A previously developed and published 8-parameter model is well-suited for fitting a matched pair of longitudinal tension (LT) and hoop tension (HT) stress-strain curves as might typically be available from a strain-based pipeline design project. Fitting a pair of “target” LT-HT stress-strain curves is accomplished using a “2-root” fitting procedure where the roots correspond to locations where the yield functions intercept the stress axes in two-dimensional (longitudinal-hoop) stress space. In this paper, the previously described 8-parameter/2-root fitting procedure is extended to a 10-parameter/3-root fitting procedure for situations where a matched “triple” of pipe steel stress-strain curves are available (e.g., LT, HT and longitudinal compression or LC). This extension allows for analysis of strain-based design conditions using an analytical pipe steel, which provides an accurate representation of the uniaxial longitudinal and circumferential stress-strain response of the pipeline material. This paper reviews the 8-parameter/2-root fitting procedure and outlines the extension to the 10-parameter/3-root fitting approach including example application.
Bayesian Model for Calibration of ILI Tools
Authors: Al-Amin M. , Zhou W. , Zhang S. , Kariyawasam S. , Wang H.
Published: July 2013

The Bayesian methodology is employed to calibrate the accuracy of high-resolution ILI tools for sizing metal-loss corrosion defects on pipelines by comparing the field-measured depths and ILI-reported depths for a set of static defects, i.e. defects that are recoated and ceased growing. The measurement error associated with the field-measuring tool is found to be negligibly small; therefore, the field-measured depth is assumed to equal the actual depth of the defect. The depth of a corrosion defect reported by an ILI tool is assumed to be a linear function of the corresponding field-measured depth subjected to a random scattering error. The probabilistic characteristics of the intercept and slope in the linear function, i.e. the constant and non-constant biases of the measurement error, as well as the standard deviation of the random scattering error are then quantified using the Bayesian methodology. The proposed methodology is able to calibrate the accuracies of multiple ILI tools simultaneously and quantify the potential correlations between the accuracies of different ILI tools. The methodology is illustrated using real ILI and field measurement data obtained on two pipelines currently in service.
Maximizing MFL ILI Sizing Confidence and Accuracy Using High-Resolution Field Measurement Data
Authors: Yeung Patrick , Sporns Ryan , Clouston Stuart , Coleman Grant A. , Miller Scott , Mieila Cristin
Published: July 2013

Magnetic Flux Leakage inspection tools are generally calibrated on a series of manufactured defects. This has been shown to give good results on a wide range of defects in varying wall thicknesses, velocities and pipeline conditions. Significant improvements in sizing performance can be achieved if sizing algorithms can be optimized on high resolution field data with low uncertainty that more closely reflects the actual line specific corrosion dimensions and profiles. The effects of defect profile can be significant to the MFL signal response. In order to achieve this goal, very high resolution and accurate field measurement techniques are needed to map the combined profile of a significant number of corrosion defects. This paper discusses a process for developing high performance sizing algorithms that consistently better industry standards for MFL sizing performance in areas of high density or complex corrosion in both oil and gas pipelines through the incorporation of high resolution laser scan technology. Complex corrosion may be considered as an area wherein individual corrosions interact together such that they no longer behave as a single corrosion and the MFL response experiences a superposition of leakage signals. A review of the methodology will be discussed and the results demonstrated through case studies from both Enbridge Pipelines Inc. and TransCanada Pipelines Ltd. where high-resolution field data was used as the basis for sizing model optimization.