bluuebunny/crossref_metadata_2025 huggingface dataset:
ILI Performance Verification and Assessment Using Statistical Hypothesis Testing
Authors: Desjardins Guy , Reed Mike , Nickle Randy
Published: October 2008

Following an inspection, API 1163 recommends that operators verify the accuracy of the ILI measurements. This paper examines the performance of an ILI tool from two separate perspectives. The first question is whether the ILI tool’s performance meets expectations and contractual requirements. The second question is to what level of accuracy the ILI tool can be relied upon for making integrity related decisions. This paper develops a method of determining the number of excavations and the number of anomalies to be investigated in the field to verify and assess the accuracy of the ILI reported depths. The verification and assessment of the ILI accuracy are two separate questions, and each is addressed as a hypothesis testing procedure. The first hypothesis states that the tool meets expected and contractual standards. That hypothesis is tested against the excavation data. Its acceptance means that the excavation data is consistent with the expected accuracy of the tool, but it does not specifically verify that accuracy. A second hypothesis states that the tool fails to meet some level accuracy as stated by a tolerance and certainty level. That hypothesis is constructed so that when it is tested against the excavation data it is rejected. Its rejection means that the tool exceeds the stated level of accuracy with a high degree of confidence.
Advances in Feature Identification Using Tri-Axial MFL Sensor Technology
Authors: Miller Scott , Sander Frank
Published: October 2008

Pipeline operators have been using intelligent in-line inspection (ILI) tools as part of their pipeline integrity management systems for several decades now. A wide variety of ILI tools have been developed to serve a multitude of uses. Most notable is the detection, locating, and sizing of metal loss corrosion. Magnetic Flux Leakage Technology (MFL) was developed for that exact purpose, however over the years technology and innovation has vastly improved the capabilities of MFL tools. This paper contains a comparison of historical and current pipeline feature identification/classification capabilities for axial magnetizing MFL tools with Tri-Axial sensor technology. The pipeline features discussed include corrosion, mechanical defects, structural pipeline components, as well as the physical and magnetic parameters that affect accurate identification, location, and/or sizing. Some of these features have never been detected, identified, or reported in the past, and now constitute a significant portion of the training and testing procedure that occurs in the certification of a new MFL data analyst.
Ductile Fracture Control for High Strength Steel Pipelines
Authors: Fonzo Andrea , Meleddu Andrea , Demofonti Giuseppe , Tavassi Michele , Rothwell Brian
Published: October 2008

The determination of the toughness values required for arresting ductile fracture propagation has been historically based on the use of models whose resulting predictions can be very unreliable when applied to new high strength linepipe materials (≥X100) and/or different operating conditions. In addition, for the modern high strength steels a methodology for determining the material fracture resistance for arresting running shear fracture starting from laboratory data is still lacking. The work here presented (developed within a PRCI sponsored project) deals with the use of CSM’s proprietary PICPRO® Finite Element code to develop methodologies for ductile fracture propagation control in high grade steel pipes. The relationships providing the maximum crack driving force which can be experienced in a pipe operated at known conditions have been determined, for different types of gas. On the other side, an empirical relationship has been found to correlate the critical Crack Tip Opening Angle (CTOA) determined by laboratory testing, to the critical CTOA on pipe (which represents the material fracture propagation resistance) with the aid of devoted simulations of past full-scale burst tests. By comparing Driving Force and Resistance Force, ductile fracture control for high strength steel pipelines can be achieved.
A Historical Review of Pre-Commissioning Hydrotest Failures
Authors: Cosham Andrew , Eiber Robert J. , Owen Robert , Spiekhout Jan
Published: October 2008

The concept of proof testing engineering structures has its origins in antiquity. The pre-commissioning hydrostatic test (also known as the pre-service pressure test) has been an important part of the process of commissioning a newly constructed pipeline for over 50 years, since its beginnings in the 1950s in the USA. The purpose of the hydrotest is several-fold: to prove the leak tightness of the pipeline system at a pressure above the design pressure, as a strength (proof) test to identify (fail) defects and sub-standard pipe, and to prove a safety margin above the pipeline design pressure. Historical data, from PARLOC (Pipeline and Riser Loss of Containment), the OPS (Office of Pipeline Safety) 30 day Incident Reports, and the published literature on the number and causes of pre-commissioning hydrotest failures has been reviewed. The historical data covers onshore gas transmission pipelines in the USA and the UK, and gas and liquid pipelines in the North Sea. The data covers the period from 1952 to 2005, although there are significant gaps in the data (e.g. the OPS data for the USA does not report test failures after 1984). In this paper, the historical data is summarised over this period, by year, in terms of the number of failures per km, and trends in the frequency and type of failures are identified. Comparison of USA and UK experience, or onshore and offshore experience, is contentious because of the influences of different design codes, and local custom and practice. The USA and UK pipeline design code requirements for the hydrotest are summarised in the paper, and it is shown that some of the trends in the failure data may be explained by the differences between the codes. Failures during the hydrotest are rare, but occasionally they do occur. The general consensus is that failures during the precommissioning hydrostatic test are now less common, and that failures due to defective line pipe (rather than due to leaking fittings) are rare. The historical data supports this consensus, but it also highlights that it is largely based on anecdotal evidence rather than data and analysis, because information on test failures is not now routinely gathered and published. The results of the historical review demonstrate that understanding the causes and reasons for hydrotest failures is important for learning from past mistakes, and also for identifying those cases where it may be possible to dispense with a pre-commissioning hydrotest. Reliable historical data on hydrotest failures is necessary to quantify trends over time, and to understand the causes of failures. The pipeline industry as a whole is not coherently recording this data. It should be.
Scripting Real-Time Application Platform (RTAP) Panels: An Overview of the Terminal Swing Panel Project
Authors: Lewis Chris
Published: October 2008

Enbridge Pipelines remotely controls the flow of approximately two-thirds of Canada’s crude oil and refined products produced from the Western Canadian Sedimentary basin through the Enbridge mainline pipeline system. These various products divided into batches run though multiple terminal systems. Each terminal site is unique and requires a multitude of specialized control systems to maintain its various flow patterns. To efficiently control these terminals Enbridge operators use the custom built PROCYS SCADA system. This system contains a graphical user interface containing schematics and panels that allow operator view and control. As part of this system a subset of control panels were developed and labeled swing panels. Swing panels allow operators to safely and efficiency run product through the various systems within a terminal. Swing panels have been in successful operation for over 10 years, however their development and maintenance cycles were less than optimal for operators and SCADA support staff. For this reason the Enbridge Terminal swing panel system was redesigned. These second generation swing panels were designed to use XML input files and Perl scripting to allow for automated construction. By encapsulating terminal swings in XML the swing panels are easier to maintain and build. This re-design resulted in a system of more functional, usable, and maintainable swing panels. The following paper will discuss this project in more detail.
Fracture Arrest Assessment of Low Toughness Pipelines
Authors: Stephens Mark , Fuglem Mark , Sloterdijk Wytze
Published: October 2008

In support of the development of Fracture Control Plans for older pipelines, a probabilistic approach has been developed for evaluating the susceptibility of these potentially low toughness lines to ductile and/or brittle propagating fractures. In characterizing the fracture arrest capability of these lines, the methodology explicitly accounts for the uncertainties associated with imperfect fracture arrest models, the inherent variability in line pipe material properties, and the added uncertainty associated with estimates based on limited amounts of sample data. A PC-based software implementation of this methodology has been developed that can be used to first prescribe a fracture arrest criterion in terms of a target proportion of arrest joints, and to then estimate the likelihood that a given pipeline segment will meet this target value based on the available line-specific material toughness data. Where the prescribed fracture arrest criterion is not met, a scenario evaluation process can be employed to assess the value of collecting additional material toughness data. The scenario evaluation process involves estimating the likelihood that similar additional sample data will reduce the effects of sample size uncertainty to the point where the chosen fracture arrest criterion is satisfied. The results of this type of propagation susceptibility analysis are useful in assessing the implications of a possible line failure from both a business/financial perspective as well as a life safety perspective. The approach can be used to demonstrate that older existing lines satisfy the intent of current codes with regard to propagation resistance, or to determine the change in operating conditions necessary to achieve a target level of fracture propagation resistance.
Methodologies for Evaluating and Qualifying External Pipeline Coatings for Northern Pipelines
Authors: Papavinasam S. , Doiron A. , Panneerselvam T. , Lafrenie`re Y. , Attard M. , Derushie C. , Bouchard R. , Eagleson B. , Revie R. W. , Demoz A.
Published: October 2008

The design of coatings must be adequate to protect pipelines under long-term, severe environmental conditions, including the extreme climatic conditions that will apply in the North before the pipe is installed and operation begins. Practices and standardised methodologies for evaluating and qualifying pipeline coatings for application in northern pipelines are discussed. Results from laboratory and field experiments, carried out under the conditions to which coatings will be exposed during construction, are presented. Based on 1-year laboratory experiments in which samples were exposed to temperatures as low as −45°C and limited data from the field experiments, it is concluded that Canadian Standards Association (CSA) standards CSA Z662, CSA Z245.20 and CSA Z245.21 adequately cover evaluation of coatings for northern pipelines. However, in order to evaluate the effects of low-temperatures, the specimens should be exposed for at least 4 months. Coatings qualified by CSA Z245.21 (System B1 and B2) are less affected from exposure to low-temperatures than those qualified by CSA Z245.21 (System A1) and CSA Z245.20.
“Digital Pigging” as a Basis for Improved Pipeline Structural Integrity Evaluations
Authors: Hart James D. , Zulfiqar Nasir , Moore David H. , Swank Greg R.
Published: October 2008

This paper describes the application of “digital pigging” procedures for converting field measurements of pipeline geometry (e.g., top of pipe survey profiles), results from geometry pig surveys, or analytically generated pipeline centerline profiles into corresponding profiles of pipeline curvature and bending strain. Application of digital pigging procedures to pipeline elevation and/or inclination profiles developed from accelerometer based geometry pigs provides a basis for performing the additional calculations required to develop bending strain profiles which may not be a part of the geometry survey deliverable but are required for pipeline structural integrity evaluations. This paper presents examples of digital pig runs over analytical pipe centerline profiles to illustrate the important effects of feature length, pig length and curvature gage length. Comparisons of the results from digital pig runs over actual geometry pig data profiles and digital pig runs over the corresponding known analytical profiles will illustrate how basic pattern recognition concepts can be used as a basis for improved synthesis of real pig data signatures. This paper also presents examples of digital pigging calculations performed on geometry pig survey data that show how low-pass filtering can be used to reduce the effects of noise in the survey data as well as the influence of curvature gage length on the computed curvature/bending strain profiles.
Some Interesting Flow Characteristics of a Heavy Crude Pipeline
Authors: Wu Changchun , Cui Hongsheng , Zuo Lili
Published: October 2008

In this paper the hydraulic characteristics of a heavy crude pipeline were discussed in detail. The crude oil to be transported is very heavy and highly viscous, with the specific density as high as 0.965 (API degree is about 14.7) at 20°C and the kinematic viscosity as high as 920mm2/s at 50°C, and its viscosity increases sharply with decreasing temperature. Due to its poor flow-ability the heavy crude is to be heated in the heating-pumping stations of the heat-insulated pipeline during its pipelining process. It is interesting that the pipeline does not behave like a usual hot oil pipeline in two ways. First, given a heating temperature and a pressure drop for a section of the pipeline, the trial-and-error process to solve for the flow-rate of the section is likely to fall into the trap of an unstable flow-rate interval, in which the friction loss of a pipe section decreases with increasing flow-rate, just contrary to usual oil pipelines. Secondly, the flow of heavy crude through the pipeline is probably in the critical regime between laminar flow and turbulent flow, so it is possible that a proper flow-rate can not be found corresponding to some heating temperature and pressure drop of the pipeline. For a hot oil pipeline, the necessary condition for occurrence of an unstable flow-rate interval is to fix the discharge temperature of a heating station, additionally, a steep curve of viscosity versus temperature and good heat transfer condition between the pipeline and its surroundings will be activating factors. Based on the hydraulic calculations of Xinmei heavy crude pipeline at different flow-rates, the curves of friction loss versus flow-rate were plotted, from which the unstable flow-rate intervals may be determined. From the viewpoint of safe operation, the unstable flow-rate interval should be avoided. For the hydraulic calculations of an oil pipeline, a critical Reynolds number of 2000 is usually used to divide flow regimes into laminar and turbulent flow. Because of different friction factors determined respectively from laminar flow and turbulent flow for the Reynolds number 2000, for some values of friction loss of a pipe section, the corresponding flow-rates do not exist, in this case, the problem for finding out the flow-rate of a pipe section is not solvable. On the other hand, the critical Reynolds number is sensitive to many factors related to pipe flow, so for the stable operation of a pipe section, its Reynolds number should be far from the Reynolds number 2000.
Pipeline In-Service Fillet Weld Inspection Delay Time
Authors: Dinovitzer A. , Semiga Vlado , Pusseogda L. N. , Ironside Scott
Published: October 2008

Traditionally, in-service welding procedures have been developed to minimize the risk of hydrogen cracking by considering the weldment cooling rate and chemistry to control the susceptibility of the resulting microstructure. To further ensure that weld hydrogen cracks do not enter service, weldment inspection is completed. The BMT Hydrogen Diffusion and Cracking Model has been used to develop a means of conservatively estimating the delay time for hydrogen cracking in multi-pass welds. The hydrogen cracking delay time estimate is developed based upon the Time To Peak Hydrogen (TTPH) concept that is evaluated numerically considering the hydrogen diffusivity in the weldment. CSA Z662 indicates that the pipeline operator should delay weld inspection until the risk of cracking is over. This requirement includes a suggested delay time of 48 hours after weld deposition. The BMT Hydrogen Diffusion Model and TTPH concept were used to define conservative inspection delay times for pipeline repair sleeve end circumferential fillet welds deposited in-service. This paper describes the investigation results and the effect of variations in welding, environmental, material and pipeline characteristics on the recommended inspection delay time. These delay times are compared to those recommended by CSA Z662 to illustrate this novel approach to establishing weldment inspection delay times.
How to Optimize the Design of Mechanical Crack Arrestors
Authors: Wilkowski G. , Rudland D. , Rothwell B.
Published: October 2008

Ductile fractures in natural gas and other high-energy pipelines could be arrested by either toughness in the pipe body or by a crack arrestor device. Although numerous crack arrestor devices have been proposed and patented, the mechanical crack arrestor that surrounds the outside of the pipe (external sleeve type) is the most common type of arrestor. This paper presents an empirically based criteria developed for the optimization of the design of mechanical crack arrestors. The initial development was based on a significant number of steel sleeve crack arrestors with different radial spacings (with and without grouting) and axial lengths that had the same thickness and strength as the main-line pipe. That work was extended to circular cross-section (toroidal) arrestors with different mechanical connectors to eliminate the need for welding. These crack arrestor tests were on 152 and 304 mm (6 and 12-inch) diameter pipes pressurized with nitrogen, rich gas, and liquid carbon dioxide that produce radically different crack-driving forces. It will be shown that the arrestor size is related to the velocity of the ductile fracture as it enters the arrestor, i.e., the fracture velocity is a measure of the instability that needs to be overcome for arrest. A limited number of results from full-scale tests are also presented to validate the design guidelines from this project. Finally, it will be shown how the results could be expanded for composite arrestors.
Application of an Integrated Stress Analysis Method to Determine the Fitness-for-Purpose of Pipeline Fittings
Authors: Jandu Chas , Francis Antony , Verity Chris , Mustoe Andy
Published: October 2008

A primary design requirement for onshore pipelines is a need to demonstrate that hoop stress associated with the internal pressure loading is less than a prescribed allowable value. In addition to this management of the hoop stress (design factor) there is also a requirement to manage the magnitude of other stress components that may arise due to the interactive effects of soil friction and thermal gradients. It is quite a straight forward matter to determine the magnitude of such stress components using non-linear finite element techniques with the pipeline represented as a series of beam elements. A complexity arises when the pipeline contains fittings, such as bends and tees, since these components give rise to stress concentrations that cannot be addressed by simple beam elements. In some situations, it is possible to apply standard (handbook) values of the stress concentrations to the nominal stresses obtained from the beam element analyses and to assess the resulting stress levels against allowable values. However, stress concentration factors are not available for all components and in these situations the stresses can only be determined using 3D finite element analyses. The computational methods associated with these procedures have previously been undertaken in two stages. The first stage involved the determination of forces and moments, using beam elements, that act at the location of the fittings. The second stage involved the 3D finite element analysis with the previously computed forces and moments applied to the fitting. The process involved considerable effort and some accuracy was lost due to the approximate nature of the applied boundary conditions as described above. In order to mitigate both of these effects, AFAA have recently developed a method in which the two stages are integrated giving both a more accurate result, thus saving time and cost. The first part of this paper describes the modelling approach adopted by AFAA in some detail. Considerable focus is then given to the application of the technique. Working in close collaboration with Laing O’Rourke (UK), the technique was successfully applied to demonstrate the fitness-for-purpose of a number of hot-tap encirclement split-tees that were to be installed in close proximity on an operational pipeline. Both the installation procedure and subsequent operation were assessed in detail, taking account of the installation loads, pilot drill holes and the operational loads that would be encountered in the future. It was shown that installation process would not pose a threat to integrity of the existing pipeline and nearby components and that the system could be safely operated over the proposed design life period.
Effect of Reel-Laying Simulation on Mechanical Performance of Flowlines
Authors: Anelli Ettore , Tivelli Marco , Izquierdo Alfonzo , Quintanilla Hector
Published: October 2008

In this work, major efforts were devoted to a full understanding of the effect of the plastic deformation pattern which is typical of reeling on the in-service mechanical performance of quenched and tempered (Q&T) seamless pipes. This was performed by both laboratory multiple plastic straining cycle (MPSC) tests and full-scale reeling (FSR) trials. Different steel grades were investigated with and without aging after single deformation and MPSC/FSR. All materials showed similar deformation behavior. In MPSC tests and FSR trials, the direction of the last deformation step influenced the mechanical behaviour. Finishing with compression gave a slight reduction in YS, whereas subsequent aging gave a YS value similar to that in the as-received condition. Leaving the last step in tension, an increase in YS was observed and subsequent aging gave a further increase to a level similar to that of conventional tensile straining plus artificial aging. In terms of toughness properties (CVN energy, 50%FATT, CTOD) there was no significant effect of reeling plus aging process. Also girth welds were tested: no significant effect of reeling plus aging process was pointed out with respect to the as-received situation for both HAZ and weld metal. The behavior of deformed and aged material was explained in terms of work-hardening, Bauschinger and bake-hardening effects.
Variation of Flow Regimes in +2 Degree Inclined Wet Gas Environments and Drag Reduction
Authors: Kang Cheolho , More Parimal
Published: October 2008

Experiments were carried out to examine the study of flow patterns and the performance of drag reducing agents in a 40 m long, 10.16 cm diameter, + 2 degree inclined wet gas pipeline environments. Superficial liquid velocities ranging from 0.03 to 0.1 m/s and gas velocities from 2 to 10 m/s were investigated with the commercial DRA concentration of 0, 25 and 50 ppm. Light viscosity oil was used as the liquid phase and carbon dioxide was used as the gas phase. Variation of flow patterns in horizontal and +2 degree pipes are reported in this paper. The effect of inclinations on the pressure gradient is also presented. The stratified flow was dominant flow pattern in horizontal wet gas pipelines. However, for certain conditions, slug flow along with big wave forms was observed in 2 degree upward flow. The pressure gradient for 2 degree upward flow was higher than horizontal flow since the height of the liquid film was higher in case of upward flow. The pressure gradient decreased significantly as drag reducing agent was added in the pipeline. For slug flow in + 2 degree inclination, the pressure gradient reduction of 19 % was achieved for superficial liquid and gas velocities of 0.03 and 2 m/s at a flow improver concentration of 50 ppm. This was because the flow characteristics such as slug frequency and wave activity were changed with the addition of DRA.
Seamless Pipes of High Strength 100 KSI Grade
Authors: Anelli Ettore , Di Schino Andrea , Izquierdo Alfonzo , Quintanilla Hector , Cumino Giuseppe , Tivelli Marco
Published: October 2008

A joint industrial program (JIP), termed “Seamless 100 ksi weldable” was launched in order to address the complex design issues of high strength Q&T seamless pipes for ultra deep water applications. The JIP was split in two main phases, the first one devoted to the development and production of seamless pipes, with minimum yield strength of 90 ksi (620 MPa) to 100 ksi (690 MPa), and the second one to evaluate their field weldability. Phase I was recently completed. The role of chemical composition and Q&T process conditions on microstructure and precipitation was analyzed, together with relevant effects on strength and toughness, for both laboratory and industrial steels. The main microstructural features which control the strength-toughness combination of these high strength Q&T steel grades were identified and results were exploited for the set-up of a production route for pipelines and risers. The 100 ksi grade was achieved in 16 mm (0.630 in) and 25 mm (0.980 in) WT pipes. Phase II is in progress.
An Assessment of Hard/Live Bottom Epifaunal Community Structure Post-Construction of the Gulfstream Natural Gas Pipeline
Authors: Schmidt Jon A. , Ellsworth Steven W. , Brooks R. Allen , Bishop Darren F. , Bisett Mark G. , Aubele Michael C. , Watkins H. Ed
Published: October 2008

Gulfstream Natural Gas System, L.L.C. (Gulfstream) constructed a 36-inch-diameter pipeline in 2001 to transport natural gas from plants in Mississippi and Alabama to markets in central and southern Florida. The route of the marine portion of the pipeline originates from the shoreline of Mississippi and Alabama in Mississippi Sound and transverses a large portion of the Gulf of Mexico, making landfall in Tampa Bay. Activities such as the installation of the pipe on the seafloor and the mooring of construction vessels used in these processes were anticipated to disturb the seafloor and associated resources. Of particular concern during project permitting were areas of hard/live bottom habitat within the pipeline construction corridor. As part of the mitigation plan, Gulfstream has monitored post-construction disturbance and re-colonization of sessile epifauna into the disturbed pipeline, spoil mound, and anchor strike areas. Monitoring has been performed using ROV video and diver collected photograph transects. The mitigation plan defined impacted hard/live bottom recovery as achieving a metric of 80-percent similarity to unimpacted hard/live bottom areas (it was not stated if this similarity metric referred to percent cover or species composition). After completion of the 2005 monitoring effort, it was determined that percent cover and species composition recovery criteria have been achieved. Biotic cover was found to have been enhanced in the trench corridor, spoil mound, and visible anchor strike areas in comparison to unimpacted hard/live bottom areas. Although recruitment within impacted hard/live bottom areas was enhanced and a greater diversity of fauna was present, the actual community structure was not significantly different from undisturbed bottom. During project permitting, recovery of the biological community was predicted to take 100-years, however, it is evident that within less than five-years, the community structure has recovered in equivalence to unimpacted areas.
A Central Database Improves Pipeline Projects
Authors: Adam Steve
Published: October 2008

Pipeline projects see enormous benefit from using geospatial information systems since a pipeline will commonly cover large geographic distances. In doing so, terabytes of engineering, geotechnical, and environmental data can be generated for engineering and regulatory needs. A central database allows the project to organize this information and provide a single source of truth. In fact, the central database is as much a philosophy as it is computer infrastructure. This level of organization allows a project to properly manage change, thus ensuring data integrity and security. When data is reliable and secure, its full value can be realized during the pipeline planning stage and even further leveraged through construction and operation.
Structural Integrity Evaluation for the Analysis of Corroded Pipelines With Multiple Corrosion Defects
Authors: Andueza Alejandro , Pontual Thiago
Published: October 2008

The structural integrity evaluation of corroded pipelines is very important for the management of systems that are in operation in order to help managers in the important decision of repairing the line. The required models for the analysis of corroded pipelines with multiple corrosion defects are in many cases a hard task to be generated. This paper presents a new methodology for the generation of full 3D hex meshes for the analysis using the Finite Element Method. The algorithm, developed specifically for the analysis of corroded pipelines, makes the task of model generation with multiple corrosion defects easier and faster. Examples with one and two corrosion defects are presented using a linear-elastic material model and the corresponding results compared to the criteria established by ASME code sec. VIII div. 2. The same models are analyzed using ideal elastic-plastic material model in order to determine the minimum failure pressure for the corroded pipes. The numerical failure pressures obtained are also compared to the values obtained from DNV RP-F101 method for single defects and experimental results. Finally, a new repairing methodology that allows the continuous operation of the pipeline in a safer way is presented. This methodology can help managers in the undertaking of scheduling a full repair of the pipeline in a much more flexible way.
High Strength Consumables for High Dilution Submerged Arc Welding
Authors: James Matthew , Melfi Teresa , Katiyar Rajeev
Published: October 2008

Current requirements for high strength pipelines are placing extreme demands on welding consumables. These applications include strain based pipelines using X80 as well as traditionally designed pipelines using X100 and even X120 base materials. Traditional procedures used in the pipemills for both the seam weld and the jointer weld utilize a SAW process with very high dilution and high heat inputs. Existing consumables are not able to meet the minimum strength requirements under these conditions. A project was undertaken to develop an alloy system that could meet these requirements while still allowing the use of traditional welding processes. Testing results with this new consumable are presented and future work is described. This alloy system may also prove useful in other high dilution applications where high strength is required.
Towards Automated Control Centre Support: Intelligent Alarm Analysis
Authors: Pond Burke , Barlow Rick , Kamal Sooban
Published: October 2008

The operation of Enbridge’s pipeline system is continuously monitored by a leak detection system termed the Material Balance System (MBS). The MBS is not only a regulatory requirement; it helps minimize the financial and environmental damages that could result from an oil leak. A team of MBS experts provides 24/7 support to Enbridge’s control centre, which manages pipeline operations. When MBS predicts or detects any hydraulic abnormality in the pipeline, it alerts the operations’ staff. Though the operators do some basic analyses, such abnormal situations are usually referred to the support team. The idea of the intelligent alarm analyzer is to provide a tool to analyze and present the most probable cause of the alarm. The human knowledge of MBS alarm analysis is transferred into a soft knowledge base, which is then used in combination with the real-time data to analyze the alarm causes. Logic was developed to identify a group of alarms caused by a single reason, which was important from the performance point of view as a set of alarms can result from one event. In parallel, some basic rules were designed to implement the procedure for analyzing these alarms. A detailed study of some typical alarm scenarios was done to build an example knowledge base. The “event” triggers the alarm analyzer, which uses the real-time data and the knowledge base to go through an extensive series of logical evaluations and mathematical manipulations (called “tests”) to decide on the probable cause of the alarms. The next task was to combine the power of computational techniques and human understanding to implement possible scenarios. At this stage more complex and realistic rules have been developed to facilitate real-time alarm analyses. The paper will include an example scenario of how the tool could be applied to a production system. The alarm analysis system described in this paper is currently being tested for production use later this year. Once in production, additional tuning and refinement of the tool will be a continuing process.
Thermodynamically Consistent Anisotropic Plasticity Model
Authors: Lukyanov Alexander A.
Published: October 2008

The objective of the work presented in this paper is to consider the thermodynamically consistent anisotropic plasticity model based on full decomposition of stress tensor into generalised deviatoric part and generalised spherical part of stress tensor. Two fundamental tensors αij and βij which represents anisotropic material properties are defined and can be considered as generalisations of the Kronecker delta symbol which plays the main role in the theory of isotropic materials. Using two fundamental tensors, αij and βij, the concept of total generalised “pressure” and pressure corresponding to the volumetric deformation are redefined. It is shown that the formulation of anisotropic plasticity in the case of incompressible plastic flow must be considered independently from the generalised hydrostatic “pressure”. Accordingly, a modification to the anisotropic Hill criterion is introduced. Based on experimental research which has been published, the modified Hill (1948, 1950) criterion for anisotropic elasto-plasticity is validated. The results are presented, discussed and future studies are outlined.
Tensile and Toughness Properties of Pipeline Girth Welds
Authors: Gianetto J. A. , Bowker J. T. , Bouchard R. , Dorling D. V. , Horsley D.
Published: October 2008

The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.
Effective Use of Contract Administration Principals in Mitigating Claims Brought Pursuant to the Sarbanes Oxley Act
Authors: Wyse Donald D.
Published: October 2008

This paper considers the implications arising from a violation of Sarbanes Oxley when an officer does not rely upon a minimum level of contract administration controls when making biased statements concerning contingent liabilities in a company’s financial statements.
API 5L X80 ERW Pipes: TenarisConfab and Usiminas Development
Authors: Roza Juliana E. , Fritz Marcelo C. , Tivelli Marco A. , Silva Ronaldo C. , Miranda Lu´cio S. , Kojima Sergio S.
Published: October 2008

The utilization of high strength steels can decrease, both, installation and operation costs of a new pipeline, since the increase of mechanical resistance can reduce the pipe wall thickness and, consequently, the weight of the pipe. For this purpose, the manufacture of electric resistance welding (ERW) pipes is recent, and it comes as an opportunity for gas pipelines, mainly onshore projects. As a function of their larger productivity, ERW pipes are more economically attractive than those produced by seamless and SAW processes. TenarisConfab and Usiminas, through studies and investments in manufacturing processes, have been working to increase their skills, in order to supply API 5L X80 ERW pipes. The steel elaborated by Usiminas is low C, high Mn, Nb, V and Ti microalloyed, and with additions of Cr and Mo, aiming to produce hot rolled coils with acicular microstructure, achieved as a combination between its chemical composition and higher cooling rates after hot rolling. The results in φ18” (457 mm) × 0,469” (11,91 mm) pipes are presented in this article. High toughness values reached at very low temperatures suggest that X80 ERW pipes developed by TenarisConfab and Usiminas may be an excellent option of choice for onshore projects that request pipes in diameters up to 20” (508 mm) and thickness up to 0.500” (12.7 mm).
Validating the Threat of SCC With an Alternative, Economic and Reliable Method: SCCScreen™
Authors: Spencer Kevin , Kariyawasam Shahani , Hugger Achim
Published: October 2008

With ever-aging pipelines, the threat of SCC to pipeline operators has never been taken more seriously. High profile failures have prompted the USDOT to issue an advisory to operators of hazardous gas and liquid pipelines. The advisory, dated October 2003, requires pipeline operators to determine the susceptibility to SCC along their pipelines, and, to identify and manage SCC in segments where conditions indicating such susceptibility are found. CEPA recommendations provide guidelines to operators for the susceptibility assessments, validation and mitigation methods based upon the significance of the SCC found. Hydrotesting, SCCDA and In-Line Inspection (ILI) are traditional methods that can be used to validate the SCC threat. SCCScreen™ is an alternative threat validation method, which provides both a reliable and an economic option. Complying with both the USDOT SCC Advisory and CEPA recommendations, SCCScreen™ is the result of combining the latest ILI analysis techniques with historic SCC database and studies. Unique post ILI algorithms have been developed to target the signal characteristics intrinsic to SCC colonies. This reduction in data analysis effort enables a quick and economic answer to SCC threat validation. The use of proven Crack Detection ILI tools with an extensive database of crack detection history enables the quantification of its reliability. The methodologies are validated on over 20,000 Kms of crack detection data from the Ultrasonic Crack Detection (USCD) Tool. This paper describes the SCCScreen™ methodology from concept to reality. Validation of results will be demonstrated using previous inspection runs and more recent case studies.
Gas Pipeline Simulation: Use of a Single System for All Simulations
Authors: Scheerer Heribert , Midwinter Stewart
Published: October 2008

Simulation tools have been used for a long time in the gas pipeline industry to do things like system planning and training simulation, using both steady state and transient simulators. Companies have also tried using simulation models in real time environments, to do applications such as line pack management and leak detection, with less than great results. With the increased cost of energy, more importance has been placed on use of simulation to optimize the operation of gas pipelines. One of the biggest problems with using simulation in so many areas is that many different models from potentially different suppliers had to be used. This resulted in a high cost to implement and maintain several systems. This paper will show a simulation system that is capable of performing steady state and transient simulation, off-line and real time simulation, leak detection and optimization, all using a single modeling platform. Examples of field use of the system will show the benefits that can be realized.
History of Pressure Fluctuations Related to Severity of Near-Neutral pH SCC
Authors: Been Jenny , Fessler Raymond R. , Keane Sean , Kresic Walter
Published: October 2008

This paper describes a small exploratory study into the feasibility of predicting where near-neutral-pH stress-corrosion cracking (NN-pH SCC) would be more likely to occur based upon the history of pressure fluctuations in a pipeline. Such a correlation would be very valuable for prioritizing hydrostatic testing, in-line inspection (ILI), and direct assessment in addition to possibly suggesting a way to minimize the occurrence of SCC. The recent development of ILI tools that can find stress-corrosion cracks coupled with computerized SCADA and GIS systems provides an opportunity to make accurate assessments of the severity of SCC in a pipeline segment and to characterize the history of that segment. Previous work had shown the importance of strain rate and pressure fluctuations in promoting SCC. On that basis, Enbridge Pipeline, Inc. initiated a review of their system, which indicated that there appeared to be a strong correlation between SCC severity and magnitude and frequency of pressure fluctuations. Data from two other pipeline companies — one liquid and one gas — was obtained to see if the correlation was more broadly valid. It was determined that the correlation utilized by Enbridge was biased towards fatigue-type considerations. This suggests that the cracking on pipelines that demonstrate this correlation may involve a corrosion-fatigue mechanism in addition to, or instead of, traditional environment-sensitive SCC. Analysis of data from the other two companies was ambiguous, primarily because the available SCADA data covered only 1.25 years of recent operation. It also is possible that some effects of pressure fluctuations might have been masked by environmental effects and steel susceptibility. Consideration of such factors in addition to the inclusion of information on coating, pipe manufacturer, and geological features, would be expected to produce an even higher level of predictability.
Pressure-Containing Sleeve Alternatives
Authors: Lazor Robert B. , Bolton Brock , Florez Julian , Nieves Carlos
Published: October 2008

The work described in this paper was completed to assess the expected performance of various repair sleeve configurations on an NPS 30, Grade X70 pipeline. A total of ten sleeve variations were studied, and these included sleeve-on-pipe, sleeve-over-collar, and sleeve-over-double collar configurations. The comparisons were based on the stress results of axisymmetric finite element modeling of the sleeve geometries, and included examining sleeves with different thickness, models with and without a gap between the sleeve and the pipe, and cases in which the annulus between the sleeves and pipe were either pressurized or not pressurized. Complementary tasks involved with this work included the specification of recommended epoxy materials and steel grades for reinforcing sleeves. The results of the analyses are presented in terms of contour plots of stress at the maximum operating pressure of the pipe, showing the general stress distribution and indicating areas of stress concentration. This study demonstrates how the loads vary amongst the different sleeve types, and shows how variations in geometry and loading conditions between models affect the operating stresses.
ICDA Case Study: 43 Year Old Sour Gas Pipeline
Authors: Abels Theo , Bich Nguyen
Published: October 2008

A 42km/356mm diameter pipeline was built and commissioned in 1962 and is the primary source of sour gas to a sour gas processing plant. The pipeline has operated as a dehydrated sour gas/condensate pipeline, and was assessed as a candidate for an Internal Corrosion Direct Assessment (ICDA). This analysis came with the challenge of a lack of operational and inspection history. The decision was made to obtain as much history as possible by interviewing previous operators, and to perform an ICDA analysis based on this information. The ICDA analysis was performed by a technical specialist utilizing 1) wet sour gas corrosion methodology and 2) ICDA (critical angle) technology. The analysis was performed for one ICDA region. Nine assessment cases were identified as the operating criteria changed with time and each was assessed. On occasion the gas specifications had criteria below the minimum levels of influence, and analysis was also performed with these adjusted to force identification of potential internal corrosion locations. The results were presented identifying two locations of potential long-term corrosion, and one location susceptible to corrosion post 2000. Following a review of the ICDA analysis, it was felt that there was sufficient confidence to proceed with the direct assessments. The decision was taken to expose the three identified locations. The direct assessment at all three locations was performed using guided wave UT as the initial anomaly detector, and phased array UT was then utilized to confirm any anomalies, and was run along the bottom of the exposed line to confirm no anomalies were missed. The results of the NDE indicated no anomalies of more than 10%, and it was concluded that no significant internal corrosion of concern exists. The final phase of the ICDA (post assessment) concluded that the analysis was successful and that the ICDA project was a success. The re assessment intervals will be driven by any future changes in the transported product, and information obtained from on line corrosion monitoring.