bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circumferential Compression Material Characterization for Pipe Collapse Load Prediction
Authors: Meijer Garret , Kaiser Trent 
Published: July 2013

Pipe collapse limits are controlled by circumferential compressive material response. In addition to yield strength and elastic modulus, elastic-plastic transition and plastic collapse performance of thick-wall pipes also depends on the character of yielding and post-yield hardening. Accurate characterization of all these properties is necessary to obtain a reliable estimate of collapse load. Common standardized material test methods provide convenient means to acquire basic mechanical properties (i.e., yield strength, elastic modulus and elongation) under laboratory conditions (i.e., room temperature and relatively rapid loading). However, these test methods include specimen preparation, such as pipe-wall straightening, and rapid strain rates that are known to impact material response, particularly in the yield transition and post-yield regimes that are important to elastic-plastic collapse. Therefore, these common laboratory techniques are useful for providing an index of material properties, but their simplified methodologies can have a significant impact on the accuracy of collapse performance estimates.
This paper describes a circumferential compressive material testing technique, developed to complement strain-based design in the energy industry, used to demonstrate differences in pipe material response measured from circumferential compressive tests and standard axial tensile tests. This technique avoids straightening the pipe wall by plastic deformation that leads to artificial rounding of the measured stress-strain yield behavior. Strain controlled loading is used to reveal yield behaviors that may be impacted by changing strain rates under stroke and load control testing.
Accurate circumferential compressive material characterization improves the identification of yield and anisotropic behaviors (tension-compression and axial-circumferential) that arise from material processing, pipe manufacturing and subsequent loading. The impact of the material response is illustrated in a numerical pipe collapse simulation that directly incorporates the measured stress-strain behavior. The impact of yield strength, stress-strain yield shape and post-yield hardening are explored. Using the measured stress-strain behavior and collapse simulation results, the sensitivity of collapse load predictions to material behavior is discussed and the requirement for accurate circumferential compressive and in-situ material characterization is demonstrated.
Variable Frequency Drive Applications and Their Electrical Protection Scheme for Liquids Pipelines
Authors: Ramirez Oscar , Yu Ting 
Published: July 2013

Motor and pump units can start either directly across the line (utility) or through a VFD. If the power system is weak (high impedance and relatively low available MVA), the result will be limitations on the maximum size of motor that may be started directly across the line. Currently some available power systems are not capable of starting large motors across the line and therefore VFD systems are required.
A VFD can be used for starting purposes or to operate a motor/pump unit (unit) continuously. Liquids pipelines have been using VFDs for unit starting purposes and for pressure control while either one of the units connected to the VFD or while there is a dedicated VFD per unit.
One VFD can be used to operate all the units. The VFD starts the motor, ramps it up, and synchronizes it with the utility to switch the motor from VFD operation to utility operation. The VFD follows the same sequence with the next unit. The VFD also switches the motor from utility operation to VFD operation. With pumps in series, one unit can remain connected to the VFD for pressure control in liquids pipelines.
Each unit can also be controlled by a dedicated VFD, allowing independent control of each unit for start-up and speed control. Both single VFD or dedicated VFD per unit offer advantages. Benefits of using a single VFD for all units are cost savings for some applications, a backup start across the line when allowed by the power system, and station pressure control. The benefits of a dedicated VFD per unit application include more flexibility in flow and pressure control, ease of expansion without interrupting existing operations for an extended period, energy efficiency, and redundancy.
Motor protection schemes for the above two VFD applications are discussed and compared in this paper. In order to maintain a safe and reliable pipeline system, comprehensive motor protection functions are provided to the pump unit. Although the principles are the same, there are some differences between the two motor protection applications.
For a dedicated VFD per unit application, the VFD protection/control circuitry normally provides motor protection because the motor is always connected to the VFD. RTDs over-temperature protection is not typically a standard feature of VFDs, however, it can be provided by proper PLC programming or the VFD incoming feeder protection relay.
Development of Pipeline Integrity Performance Indicators for Canadian Energy Pipelines
Authors: Reed Mike , Lee Rachel , Coote Bob 
Published: July 2013

In 2004, in response to a number of internal and external drivers, the Pipeline Integrity Working Group (PIWG) of the Canadian Energy Pipeline Association (CEPA) undertook to develop pipeline integrity performance indicators. The PIWG wished to create indicators that would assist in reporting performance to regulatory stakeholders and provide its member companies with a means of comparing their respective integrity performance with the performance of their peers in the industry.
The development of meaningful performance indicators is not as straightforward as it might appear. The performance indicator analysis and reporting has evolved since the initial report prepared in 2004, and now trends in the indicators are emerging that can be used to improve understanding of the issues and successes related to pipeline integrity management.
This paper describes development of the CEPA pipeline integrity performance indicators including:
• Stakeholder expectations;
• Characteristics of the CEPA performance indicators;
• The steps in development the performance indicators;
• Key elements;
• Data collection;
• Data analyses;
• Reporting;
• Significant modifications;
• Issues; and
• Next steps.
Compressive and Tensile Strain Capacities of 48” X80 Line Pipes
Authors: Tajika Hisakazu , Igi Satoshi , Sakimoto Takahiro , Endo Shigeru , Tsuyama Seishi , Muraoka Ryuji , Arakawa Takekazu , Suzuki Nobuhisa 
Published: July 2013

This paper presents the results of experimental studies focused on the strain capacity of X80 linepipe. A full-scale bending tests of X80 grade, 48″ high-strain linepipes pressurized to 60% SMYS were conducted to investigate the compressive strain limit and tensile strain limit. The tensile properties Y/T ratios and uniform elongation of the pipes had variety. Three of four pipes are high strain pipes and these Y/T ratios are intentionally low with manufacturing method. One of these high-strain pipe was girth welded in its longitudinal center to investigate the effect of girth weld to strain capacity. The other was set as a conventional pipe that have higher Y/T ratio to make comparative study.
The compressive strain limit focused on the critical strain at the formation of local buckling on the compression side of bending. After pipe reaches its endurable maximum moment, one large developed wrinkle and some small wrinkles on the pipe surface during bending deformation were captured relatively well from observation and strain distribution measurement. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation/propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and rupture in the base material at the tension (opposite) side of the local buckling position.
Simulation of the Response of Buried Pipelines to Slope Movement Using 3D Continuum Modeling
Authors: Fredj Abdelfettah , Dinovitzer Aaron 
Published: July 2013

Pipeline integrity is affected by the action of external soil loads in addition to internal fluid pressure. External soil loads can be generated by landslides or at sites subject to ground subsidence, heave or seismic effects. Under these varied conditions of ground movement potential pipeline safety involves constraints on design and operations. The design processes includes developing an understanding of strains that could be imposed on the pipe (strain demand) and strain limits that the pipe can withstand without failure. The ability to predict the pipeline load, stress or strains state in the presence of soil restraint and/or soil displacement induced loading is not well described in design standards or codes of practice.
This paper describes the ongoing work involved in a study investigating the mechanical behavior of buried pipelines interacting with active landslides. Detailed pipe-soil interaction analyses were completed with a 3D continuum SPH method. This paper describes the LS-DYNA numerical modeling process, previously developed by the authors, which was refined and applied to site-specific conditions. To illustrate the performance of the modeling process to consider a translational slide, additional numerical model validation was completed and is described in this paper. These comparisons illustrate that good agreement was observed between the modeling results and experimental full scale trial results.
Sample results of the application of the validated 3D continuum modeling process are presented. These results are being used to develop generalized trends in pipeline response to slope movements. The paper describes both the progress achieved to date and the future potential for simplified engineering design tools to assess the load or deformation capacity requirements of buried pipelines exposed to different types of slope movement.
The Effect of Low Sulfur Content on the Weldability of Linepipe Steel
Authors: Cameron Kimberly K. , Pettinger Alfred M. 
Published: July 2013

Over time, the demand for high-strength linepipe has increased significantly. One of the challenges for developing higher strength linepipe has been maintaining an appropriate level of fracture toughness, yield to tensile strength ratio, and weldability. Fortunately, significant progress has been made in the production of high strength line pipe steel. A major improvement in steel making has been the utilization of secondary steel treatments to refine the steel and accurately control alloy additions to achieve a higher level of steel cleanliness. In particular, these refining treatments have enabled the achievement of extremely low sulfur levels.
For most purposes, restricting sulfur content is desirable to help prevent a reduction in mechanical properties such as fracture toughness of the steel. Fortunately, steelmaking and desulfurization technologies have advanced to the point where pipeline steel with sulfur contents less than the requirements by API 5L are available on a large scale.
Extremely low sulfur contents, however, can lead to other problems when welding steels. These weldability problems are related to the fact that sulfur is a known surface active agent for steels. Low sulfur concentrations lead to a reversal of the Marangoni convection in the weld pool, which is responsible for the large differences in weld penetration on otherwise identical steels. Additionally, when welding heats of unmatched sulfur concentrations, the arc will tend to deviate towards the low sulfur heat and axially shift the root of the weld if one of the heats was below a critical value for the sulfur content and the other was above this value.
Although this phenomenon has been primarily observed in stainless steels, the increasing ability to produce linepipe steel with extremely low sulfur contents has led to the possibility that this phenomenon could also occur in low carbon pipeline steels. One pipeline system utilizing cellulosic consumables for shielded metal arc welding (SMAW) of X70 steel with sulfur contents an order of magnitude below that permitted by API 5L and with widely varying sulfur contents shows evidence of this effect. The profiles of the welds in this system exhibited a tendency for lack of penetration, asymmetric weld roots, and concave welds.
One approach to ameliorate this would be the specification of a lower permissible amount of sulfur.
Evaluation of Anisotropic Pipe Steel Stress-Strain Relationships Influence on Strain Demand
Authors: Hart James D. , Zulfiqar Nasir , Zhou Joe 
Published: July 2013

Buried pipelines can be exposed to displacement-controlled environmental loadings (such as landslides, earthquake fault movements, etc.) which impose deformation demands on the pipeline. When analyzing pipelines for these load scenarios, the deformation demands are typically characterized based on the curvature and/or the longitudinal tension and compression strain response of the pipe. The term “strain demand” is used herein to characterize the calculated longitudinal strain response of a pipeline subject to environmentally-induced deformation demands. The shape of the pipe steel stress-strain relationship can have a significant effect on the pipe strain demands computed using pipeline deformation analyses for displacement-controlled loading conditions. In general, with sufficient levels of imposed deformation demand, a pipe steel stress-strain curve with a relatively abrupt or “sharp” elastic-to-plastic transition will tend to lead to larger strain demands than a stress-strain curve with a relatively rounded elastic-to-plastic transition. Similarly, a stress-strain curve with relatively low strain hardening modulus characteristics will tend to lead to larger strain demands than a stress-strain curve with relatively high strain hardening modulus characteristics. High strength UOE pipe can exhibit significant levels of anisotropy (i.e., the shapes of the stress-strain relationships in the longitudinal tension/compression and hoop tension/compression directions can be significantly different). To the extent that the stress-strain curves in the different directions can have unfavorable shape characteristics, it follows that anisotropy can also play an important role in pipeline strain demand evaluations.
This paper summarizes a pipeline industry research project aimed at evaluation of the effects of anisotropy and the shape of pipe steel stress-strain relationships on pipeline strain demand for X80 and X100 UOE pipe. The research included: a review of pipeline industry literature on the subject matter; a discussion of pipe steel plasticity concepts for UOE pipe; characterization of the anisotropy and stress-strain curve shapes for both conventional and high strain pipe steels; development of representative analytical X80 and X100 stress-strain relationships; and evaluation of a large matrix of ground-movement induced pipeline deformation scenarios to evaluate key pipe stress-strain relationship shape and anisotropy parameters. The main conclusion from this work is that pipe steel specifications for high strength UOE pipe for strain-based design applications should be supplemented to consider shape-characterizing parameters such as the plastic complementary energy.
Routing Analysis in a Heavily Dissected Jungle Environment
Authors: Morrison Ian F. , O’Leary Dennis , Piraux Olivier , Harris Rob , Dauphin Raphaël 
Published: July 2013

The selection of a pipeline route is of great importance in minimizing the levels of construction and maintenance cost and in determining the outcomes of reliability, environmental impact, social impact and development timeframe. The decision of choosing one route over another must be informed by the correct balance between significant variables using a structured and transparent process, arriving at repeatable results.
Predictable outcomes depend on knowing what information is important in a particular context and utilizing information with a known level of accuracy. Each step in the process of refining a design and cost estimate is a function of the effort put into engineering design as well as the accuracy of the inputs. Knowing what information is required and how to get that information quickly and economically is key to meeting cost and time goals in the pipeline development process.
Finding “the best” route varies from being a simple process in agricultural table lands, to a very complex process in rugged, remote, ecologically sensitive lands on the development frontier. In this paper the authors describe the process that was used in a heavily dissected jungle environment in a remote area of Northern Peru. Constraints included a very limited footprint for construction and operations, steep unstable slopes, continually varying grades and terrain types and a large number of water crossings.
Issues that are discussed in this paper include: decision making for data acquisition and applicable remote sensing technology, terrain analysis tools, routing methodology, integration of construction methodology with terrain elements and route optimization and decision making processes.
Factors Affecting the Generation of High-pH Environments Required for Stress Corrosion Cracking (SCC)
Authors: Yan Li , Worthingham Robert , King Fraser , Been Jenny 
Published: July 2013

A series of seven experiments have been performed to investigate the effects of various environmental and operational parameters on the generation of high-pH SCC environments under disbonded permeable coating. The parameters investigated include:
• the rate of CO2 generation;
• direct CO2 production in the disbonded region under the coating;
• preferential gas-phase transport of CO2;
• the magnitude of the cathodic current density; and
• simulated trapped water composition.
In general, the total carbonate/bicarbonate concentrations of the simulated trapped water increased with:
• increased CO2 flow rate;
• direct production of CO2 under the disbonded coating;
• increased cathodic current density; and
• rapid gas-phase transport of CO2 through holidays above the level of the solution.
Ca2+ and Mg2+ cations in groundwaters could buffer the solution in the disbondment at a range of pH 8 to 9 lower than the pH required for the occurrence of high pH SCC. Formation of insoluble carbonate minerals was detected in the simulated disbondment and in the coating with solutions rich in Ca2+ and Mg2+. However, the presence of poorly soluble Ca2+ and Mg2+ cations did not affect the total carbonate/bicarbonate concentration in the inner cell.
These observations suggest that environments conducive to high-pH SCC are more likely to occur under the following circumstances:
• in regions where the CO2 generation rate is higher, typically wetter and warmer locations;
• for coating systems or in regions where there can be microbial activity under the disbonded coating;
• in areas where the pipe is not permanently below the water table and where the coating has defects or holidays; and
• in areas with a history of higher cathodic current density (which generally results in higher carbonate/bicarbonate concentration) and periodic loss of cathodic polarization.
How New Vintage Line-Pipe Steel Fracture Properties Differ From Old Vintage Line-Pipe Steels
Authors: Wilkowski G. , Shim D.-J. , Hioe Y. , Kalyanam S. , Brust F. 
Published: July 2013

Newer vintage line-pipe steels, even for lower grades (i.e., X60 to X70) have much different fracture behavior than older line-pipe steels. These differences significantly affect the fracture control aspects for both brittle fracture and ductile fracture of new pipelines.
Perhaps one of the most significant effects is with brittle fracture control for new line-pipe steels. From past work brittle fracture control was achieved through the specification of the drop-weight-tear test (DWTT) in API 5L3. With the very high Charpy energy materials that are being made today, brittle fracture will not easily initiate from the pressed notch of the standard DWTT specimen, whereas for older line-pipe steels that was the normal behavior. This behavior is now referred to as “Abnormal Fracture Appearance” (AFA). More recent work shows a more disturbing trend that one can get 100-percent shear area in the standard pressed-notch DWTT specimen, but the material is really susceptible to brittle fracture. This is a related phenomenon due to the high fracture initiation energy in the standard DWTT specimen that we call “Abnormal Fracture Behavior” (AFB). This paper discusses modified DWTT procedures and some full-scale results. The differences in the actual behavior versus the standard DWTT can be significant. Modifications to the API 5L3 test procedure are needed.
The second aspect deals with empirical fracture control for unstable ductile fractures based on older line-pipe steel tests initially from tests 30-years ago. As higher-grade line-pipe steels have been developed, a few additional full-scale burst tests have shown that correction factors on the Charpy energy values are needed as the grade increases. Those correction factors from the newer burst tests were subsequently found to be related to relationship of the Charpy energy values to the DWTT energy values, where the DWTT has better similitude than the Charpy test for fracture behavior (other than the transition temperature issue noted above). Once on the upper-shelf, recent data suggest that what was once thought to be a grade correction factor may really be due to steel manufacturing process changes with time that affect even new low-grade steels. Correction factors comparable to that for X100 steels have been indicated to be needed for even X65 grade steels. Hence the past empirical equations in Codes and Standards like B31.8 will significantly under-predict the actual values needed for most new line-pipe steels.
Overcoming Technical Limitations in Identifying and Characterizing Critical Complex Corrosion
Authors: Kariyawasam Shahani , Yeung Patrick , Clouston Stuart , Hurd Geoffrey 
Published: July 2013

In 2009 a pipeline within the TransCanada pipeline system experienced a rupture. As this pipeline was already under a rigorous In Line Inspection (ILI) based corrosion management program this failure led to an extensive root cause analysis. Even though the hazard causing the failure was microbiologically induced corrosion (MIC) under tape coating, the more troubling question was “Why had the severity of this anomaly not been determined by the ILI based corrosion management program?” This led to an investigation of what key characteristics of the ILI signals resulting from areas of “complex corrosion” are more difficult to correctly interpret and size and furthermore where the line condition is such that manual verification is needed. By better understanding the limitations of the technology, processes used, and the critical defect signal characteristics, criteria were developed to ensure that “areas of concern” are consistently identified, manually verified and therefore the sizing is validated at these potentially higher risk locations.
These new criteria were applied on ILI data and then validated against in-the-ditch measurements and a hydrotest. This process in conjunction with optimization of ILI sizing algorithms enabled the operator to overcome some of the known challenges in sizing areas of complex corrosion and update its corrosion management process to improve the detection and remediation of critical defects. This paper describes this investigation of the failure location, development of the complex corrosion criteria, and the validation of effectiveness of the criteria.
The criteria are focused on external corrosion and have been currently validated on pipelines of concern. Application to other lines should be similarly validated.