bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitigation of Groundwater-Dominated Lakebed Playas Crossed by the Ruby Pipeline, Utah and Nevada
Authors: Keaton Jeffrey R. , Jermyn John J.
Published: April 2011

The Ruby Pipeline is a 42-inch diameter pipeline that will transmit natural gas 675 miles from Opal, Wyoming, to Malin, Oregon. The pipeline alignment crosses landforms designated as playas at several locations in Utah and Nevada. Federal agencies reviewing environmental documents requested mitigation based on the concept that playas collect and hold rainwater on impervious clay bottoms for long periods of time, and that an open-cut trench could drain ephemeral lakes by penetrating impervious clay bottom soil layers and permanently alter the surface water hydrology of the playas. Trench plugs, segregation of excavated impervious soil, limited construction right-of-way, impervious backfill, and construction during the ‘dry’ season were the recommended mitigation measures, presumably to reduce the potential for surface water collected on the playa to drain into the subsurface through a trench cut across the playa. The surface-water hydrology concern may pertain to playa environments in semiarid areas such as the southern High Plains of the United States, notably northern Texas. The playas crossed by the Ruby Pipeline are lakebeds of major ancient lakes (Lake Bonneville in Utah, and Lake Lahontan and Lake Meinzer in Nevada) that were hundreds of feet deep and occupied extensive, topographically closed drainage basins. These lakebed playas are dominated by shallow groundwater. Surface water collects on the playa surfaces but is not responsible for playa formation or preservation. The water tends to be salty in lakebed playas in Utah and Nevada compared to fresh water in the ephemeral playa lakes in northern Texas. This brief case history describing playas dominated by groundwater instead of surface water may help advance the understanding that mitigation useful for surface-water dominated playas is not needed for groundwater-dominated playas. Geotechnical investigation included soil borings, test pits, laboratory testing, and surface geophysical surveys (seismic refraction and refraction microtremor [ReMi] methods).
Corporate Standardization Initiatives and Integrated Management System: The Case of Transpetro’s Oil Pipelines and Terminals Standardization Program
Authors: de Almeida Maria Fatima Ludovico , Labrunie Charles , de Arau´jo Dario Do´ria
Published: April 2011

This paper presents the implementation by Petrobras Transporte S.A. - Transpetro of its Oil Pipelines and Terminals Standardization Program (PRONOT) within the scope of the “Integrated Management System” (IMS). This program, launched in 2006 in the regions where the company operates, aims at standardizing all of its oil pipeline and terminal operations. Its implementation was planned in two phases: (i) the first, already successfully concluded, refers to pipeline operations, industrial maintenance and right-of-way activities management; and (ii) the second, initiated in 2009, encompasses cross-sectional activities including health, safety and environment (HSE); training and development of oil pipeline workforce; communication with stakeholders; oil pipeline integrity; and engineering project requirements. The documental structures of Transpetro IMS and PRONOT are described and represented graphically to emphasize the intentional alignment of the standardization process carried out by the Oil Pipelines and Terminals Unit to the corporate IMS, based upon national and international literature review and through practical research focusing on the best international practices.
Analytical Approach for Buckling Resistance of UOE Linepipe With Orthogonal Anisotropy Under Combined Loading
Authors: Tsuru Eiji , Agata Jun , Nagata Yukinobu
Published: April 2011

UOE linepipes have orthotropic work hardening in which the longitudinal (L-) stress vs. strain (SS) curve is different from the circumferential (C-) one. The anisotropy is emphasized by the thermal aging during the anti-corrosion coating. However, there are few studies on the effect of the circumferential mechanical properties on the compressive strain limit required in strain-based design (SBD). This paper describes the combined effect of SS curves in L- and the C-direction on the buckling resistance using the newly developed yield function to model the orthogonal anisotropy. The coupon tests after thermal aging during the anti-corrosion coating indicate that the L-SS curve can maintain the round-house type while the long yield point elongation (YPE) appears on the C-SS curve. Using these mechanical properties, FE-models demonstrate that YPE in the C-direction reduces the compressive strain limit for pipes with high diameter/thickness (D/t) under high internal pressure. Hence, SS curves in the C-direction should be considered for more reliable prediction of the buckling resistance required in long distance gas pipelines.
Heavy Wall Seamless Line Pipe X70–X80 for Sour Service Applications
Authors: Konrad Joachim , Toma Diana , Rohden Volker , Kubla Guido
Published: April 2011

The continued shift of exploration and production to deep water fields will require the industry to develop alternative pipe solutions to cope with the challenging demands of these exploration regions. Because of the complexity of exploration conditions in deep water fields, e.g. high pressures, low temperature and sour reservoirs, higher grades and heavier wall thickness in combination with low temperature toughness and suitability for sour service are required. The Vallourec&Mannesmann Tubes’s alloying concept for line pipe steels based on low carbon concept [1] was extended to grades X70 and X80 with wall thicknesses up to 75mm. In this paper the latest results on industrial studies on high strength heavy-wall steels manufactured by seamless hot rolling and subsequent quench and temper treatment are presented. The work is a part of the development program for high performance heavy wall seamless pipes for special applications such as J-lay collars, buckle arrestors and risers. Mechanical properties, advanced metallographic examinations, results of the sour service resistance and weldability are reported.
Weld Metal Hydrogen Cracking in Transmission Pipelines Construction
Authors: Sarrafan Sheida , Malek Ghaini Farshid , Rahimi Esmaeel
Published: April 2011

Developments of high strength steels for natural gas pipelines have been in the forefront of steelmaking and rolling technology in the past decades. However, parallel to such developments in steel industry, the welding technology especially with regards to SMAW process which is still widely used in many projects has not evolved accordingly. Decreasing carbon equivalent has shifted the tendency of hydrogen cracking from the HAZ to the weld metal. Hydrogen cracking due to its complex mechanism is affected by a range of interactive parameters. Experience and data gained from field welding of pipeline construction projects indicated that weld metal hydrogen cracking is related to welding position as it occurs more in the 6 o’clock position of pipeline girth welds. In this research an attempt is made to open up the above observation in order to investigate the contributory factors such as welding position and welding progression in terms of diffusible hydrogen and possibly residual stress considerations. It was observed that transverse cracks produced in laboratory condition may not be detected by radiography. But, the higher tendency for cracking at 6 o’clock position was confirmed through bend test. It is shown that more hydrogen can be absorbed by the weld metal in the overhead position. It is shown that welding progression may also have a significant effect on cracking susceptibility and it is proposed that to be due to the way that weld residual stresses are developed. The observations can have an important impact on planning for welding procedure approval regarding prevention of transverse cracking in pipeline girth welds.
DNV Recommended Practice for Design and Operation of CO2 Pipelines
Authors: Johnsen Kim , Helle Kaare , Torbergsen Lars Even , Eldevik Fro̸ydis
Published: April 2011

A unified Recommended Practice (RP) for safe and reliable design, construction, testing, operation and maintenance of steel pipelines for transmission of CO2 has been developed through the CO2PIPETRANS Joint Industry Project (JIP). Particular challenges related to CO2 streams as a medium are identified and guidance’s provided to meet these challenges both considering compliance with the pipeline standards and issues related to public acceptance and safety. The RP applies to pipelines for large scale transmission of CO2 and is intended as a supplement to existing recognized standards for both onshore and submarine pipelines.
Effect of Geometry, Material and Pressure Variability on Strain and Stress Fields in Dented Pipelines Under Static and Cyclic Pressure Loading Using Probability Analysis
Authors: Al-Muslim Husain Mohammed , Arif Abul Fazal M.
Published: April 2011

Mechanical damage in transportation pipelines is a threat to its structural integrity. Failure in oil and gas pipelines is catastrophic as it leads to personal fatalities, injuries, property damage, loss of production and environmental pollution. Therefore, this issue is of extreme importance to Pipeline Operators, Government and Regulatory Agencies, and local Communities. As mechanical damage can occur during the course of pipeline life due to many reasons, appropriate tools and procedures for assessment of severity is necessary. There are many parameters that affect the severity of the mechanical damage related to the pipe geometry and material properties, the defect geometry and boundary conditions, and the pipe state of strain and stress. The main objective of this paper is to investigate the effect of geometry, material and pressure variability on strain and stress fields in dented pipelines under static and cyclic pressure loading using probabilistic analysis. Most of the published literate focuses on the strain at the maximum depth for evaluation which is not always sufficient to evaluate the severity of a certain case. The validation and calibration of the base deterministic model was based on full-instrumented full-scale tests conducted by Pipeline Research Council International as part of their active program to fully characterize mechanical damage. A total of 100 cases randomly generated using Monte Carlo simulations are analyzed in the probabilistic model. The statistical distribution of output parameters and correlation between output and input variables is presented. Moreover, regression analysis is conducted to derive mathematical formulas of the output variables in terms of practically measured variables. The results can be used directly into strain based design approach. Moreover, they can be coupled with fracture mechanics to assess cracks, for which the state of stress must be known in the location of crack tip, not necessarily found in the dent peak. Furthermore, probabilities derived from the statistical distribution can be used in risk assessment.
Remedial Measures to Tame the Frost Heaves at Gas Distribution Stations in West-East Gas Pipeline
Authors: Deng Daoming , Wang Xiaoping , Li Kai , Jiang Yongtao , Gong Jing
Published: April 2011

The first West-East Gas Pipeline, running from the Tarim Basin gas fields in Xinjiang to the Yangtze River Delta area in China, is an 1016-mm-dia, 3900-km-long pipeline, the design capacity and pressure of which are 12 billion cubic meters annually and 10 MPa respectively. The whole pipeline was put into commercial operation on Oct. 2004, and the distribution stations suffered from frost heaves due to subfreezing gas temperatures, with obvious uplifts of valves from the bases, upheavals of the ground, and cracks of the paved surfaces and fence walls, and deformations of gas pipelines. From the commission on, the demand on gas in the downstream market was booming, and the company strove to upgrade the throughput to 17 billion cubic meters annually by building new gas compressor stations, so the more serious frost heaves are expected at the regulator stations. As we know, gas-fueled heaters can effectively tackle the frost heaves, but the difficulty of land acquisition, and more expensive CAPEX and OPEX limit the installation of the gas-fueled heaters. In this paper, various types of measures to cope with the frost heaves are compared and analyzed. Based on the geotechnical survey of field soils, theoretical calculations and actual data, soil replacement schemes with a water migration control technique are developed and successfully applied at different gas distribution stations with different water tables. The schemes are simple to use, and are cost-effective. When the remedial actions with this scheme are conducted, no interruptions of service are required. Furthermore, a large sum of expense is saved in comparison with the gas-fueled heaters.
An Overview of Recent Initiatives in Preventing Damage to Energy Pipelines
Authors: Hall Sam , Fischer Steve
Published: April 2011

Over the past 20 years, excavation damage has caused approximately one-third of energy pipeline incidents resulting in fatalities or in-patient hospitalizations in the U.S. While excavation damage to pipeline facilities has declined in recent years, reducing excavation damage to energy pipelines remains a top priority for the United States. The Pipeline and Hazardous Materials Safety Administration (PHMSA) of the U.S. Department of Transportation is undertaking several initiatives to reduce excavation damage to energy pipelines. This paper summarizes several of these initiatives, including: PHMSA’s strong support of the 1999 Common Ground Study, the Common Ground Alliance (CGA), and the continued development of damage prevention best practices for all damage prevention stakeholders; the documentation of State damage prevention programs to understand where programs can be strengthened; support of State damage prevention programs in the form of funding and other assistance to states for implementation of the “nine elements” of effective damage prevention programs; a focused damage prevention research and development program; the coordination of the Pipelines and Informed Planning Alliance (PIPA), which is an effort to develop and foster the use of recommended practices for local land use in the vicinity of transmission pipelines; and the development of a rule for federal enforcement of damage prevention laws when appropriate. PHMSA believes comprehensive damage prevention programs are essential to energy pipeline safety and must have the right balance of incentive and enforcement for preventing damage to pipelines.
Evaluation of Fracture Toughness of X100 Pipe Steel Using SE(B) and Clamped SE(T) Single Specimens
Authors: Park Dong-Yeob , Tyson William R. , Gianetto James A. , Shen Guowu , Eagleson Robert S.
Published: April 2011

J-resistance testing using a single-specimen unloading compliance technique has been performed on single-edge-notched tension (SE(T)) specimens of X100 pipe steel base material at room temperature and at −20°C, using a procedure developed at CANMET. J-resistance testing using single-edge-notched bend (SE(B)) specimens according to ASTM E1820 was also conducted for comparison. The specimens included two nominal through-thickness pre-crack aspect ratios (a/W = 0.25 and 0.5). The results show that shallow-cracked (a/W∼0.25) bend and tension specimens produce higher resistance curves than deeply-cracked (a/W∼0.5) specimens; ductile propagation was observed at both temperatures. Resistance curves are slightly higher at −20°C than at room temperature for both bending and tension, especially for shallow-cracked specimens. Crack length predicted from unloading compliance of crack mouth opening displacement for the SE(T) specimens was validated by optical measurement of initial crack length (ao) and final crack extension (Δa>1.0 mm) after heat-tinting, as per ASTM E1820. Predicted crack growths show acceptable agreement with measured values in all cases. The effect of side-groove depth on the resistance curve and straightness of the crack front was briefly investigated. For both bending and tension, resistance curves for 10% (total) side-grooved specimens were close to those from plain-sided specimens when other testing conditions, such as precrack and testing temperature, were the same, whereas 20% (total) side-grooved specimens showed lower toughness. It was occasionally observed that the crack grew faster at the side for 20% side-grooved bend and tension specimens, resulting in a crack front of concave curvature. For 10% side-grooved specimens a rather straight crack front or slightly faster crack growth in the middle of the specimen (convex curvature) was observed.
Development of a Non-Contact Hydrogen Sensor for Coated Pipeline Steel Weldments
Authors: Koenig Kamalu , Lasseigne Angelique N. , Olson David L. , Jackson Joshua E. , King Robert H. , Mishra Brajendra
Published: April 2011

Only a few parts per million of hydrogen are needed to produce detrimental results in higher strength pipeline steels. The cost of removal and subsequent replacement of a pipeline coating is high; thus a working hydrogen detector for field measurements must operate through the pipeline coating. An in-field sensor must utilize technology that provides rapid (or real-time) non-contact nondestructive measurements. Nondestructive low frequency impedance measurements can be used to determine hydrogen content in operating pipeline steel and weldments as well as through structural coatings. Low frequency impedance measurements have been correlated to hydrogen content in pipeline steel both in the laboratory and in the field. The use of real-time low frequency impedance measurements to monitor hydrogen content in coated steel weldments is presented.
Technical Challenges of Heavy Wall HFW Pipe Production for Bord Ga´is E´ireann Pipeline Project
Authors: O’Dwyer Paul , Tazedakis Athanasios , Boothby Peter
Published: April 2011

The recently constructed Bord Ga´is E´ireann, Curraleigh West to Midleton pipeline runs due north from the Midleton compressor station near the city of Cork in Southern Ireland. The 47.5 km, 610mm outside diameter pipeline, comprises over 30 km of 9.5 mm and 17 km of 19.1 mm wall thickness L450MB (X65) grade pipe. The pipe for the project was produced by Corinth Pipeworks (CPW), at its state of the art HFW pipe mill at Thisvi, Greece and represents a first in terms of the quantity of 19.1 mm L450MB (X65) HFW pipe produced by the mill for a specific project. The paper outlines the engineering approach adopted for the pipeline before describing in detail the production challenges faced by the pipe mill in successfully completing this demanding pipe order. Production of the 9.5 mm wall thickness pipe was not anticipated to present any particular difficulties. However, the principal concern associated with the manufacture of the 19.1 mm pipe was that the combination of wall thickness and strength level was toward the upper end of the commercially supplied wall thickness-strength combinations for HFW produced linepipe, particularly as the actual strength of the starting coil was well above the minimum specified level for L450MB (X65). In addition, to accommodate the demanding drop weight tear test (DWTT) toughness requirement the chemical composition of the 19.1 mm coil strip was above the permitted limits of the parent pipe standard EN 10208-2 [1] for the elements Cu & Ni, and the yield to tensile ratio was also above the 0.87 maximum level required by EN 10208-2 for L450MB (X65) grade pipe. Potential risks were therefore identified prior to production and mitigated by several methods detailed in the paper, including for example; increased initial production test frequency, close monitoring during pipe production, duplicate testing to verify mill results, identification of potential construction issues and weldability testing. A summary of production experience including statistical data for the production of both 9.5 mm and 19.1 mm pipe is presented. Also covered are the results of a supplementary investigation which makes a further assessment of the influence of the welding and heat treatment cycles on the final pipe properties. The paper concludes by referring to the overall successful construction phase of the project.
Challenges in Joining Thermoset Composite Piping
Authors: Parashar Avinash , Mertiny Pierre
Published: April 2011

The aim of this paper is to examine solutions and challenges related to joining thermoset composite piping. Fiber reinforced polymers (FRP) have been used in piping systems for more than 40 years. Higher specific mechanical properties and corrosion resistance of FRP make them a potential candidate for replacing metallic piping structures. Despite the advantages associated with FRP, their application is still limited due to, in part, unsatisfactory methods for joining composite subcomponents and inadequate knowledge of failure mechanism under different loading conditions. Adhesively bonded joints are attractive for many applications since they offer integrated sealing, minimal part count and do not require pipe extremities with complex geometries such as threads or bell and spigot configurations. So far, the majority of work reported in the technical literature on adhesively bonded pipe joints is concerned with lap joints employing wrapping techniques to produce overlap sleeve connections. More recently, a joining technique was proposed that replaces the wrapping technique with filament-wound overlap sleeve couplers that are adhesively bonded to the pipe extremities. In the present article, various joining techniques for FRP piping through adhesive bonding are discussed, and damage mechanisms under different loading conditions are examined.
Probabilistic Assessment of ILI Metal Loss Features
Authors: Chan Peter D. , Webster David
Published: April 2011

In-line inspection (ILI) gives pipeline operators a snapshot of the condition of their pipelines. Unfortunately, accuracy limitations exist with all ILI tools. It is therefore judicious for pipeline operators to support their pipeline integrity maintenance planning by employing Probability of Exceedance (POE) methodology that accounts for the inexact nature of the ILI data. A new method is needed that can be used to assist pipeline operators make rational and defensible integrity decision when faced with very poor pipeline conditions with numerous interacting metal loss defects. The normal method of using RSTRENG with Monte Carlo Simulation (MC) for probabilistic assessment of corroded pipeline pressure is unsuitable and unmanageable. The new method employs DNV-RP-F101 with Point Estimate Method (PE) and the MC to efficiently apply the POE methodology to severely corroded pipelines.
Pipeline Design: Are Current Pipe Standards Adequate?
Authors: Haswell Jane , Boothby Peter
Published: April 2011

The paper commences by identifying the basic pipeline design criteria for onshore gas transmission pipelines by reference to the UK Institution of Gas Engineers and Managers (IGEM) TD/1 code “Steel Pipelines and Associated Installations for High Pressure Gas Transmission”. Amendments incorporated into the recently updated Edition 5 of that document are then highlighted together with appropriate justification for the adopted changes. The current status of pipe standards & specifications, (i.e. the practical interpretation of pipeline design criteria) is then summarised highlighting specific gaps and anomalies that raise cause for concern. Issues specific to different pipe types and grades are covered raising the question; do current pipe standards adequately address the necessary technical requirements bearing in mind the intended pipeline service application? Areas of concern discussed in detail by reference to specific examples include intrinsic weld geometry concerns in high frequency welded pipe, the absence of a reduction of area requirement for transverse weld tensile tests, pipeline construction & operation concerns associated with poor weld bead geometry in spiral pipe, variable flattening test behaviour in high frequency welded pipe and the supply of multiple alloy types within a single pipe order. The above examples are illustrated graphically in the paper where appropriate by photographs taken at the time of pipe production and testing.
Oblique Field Magnetic Flux Leakage Inline Survey Tool: Implementation and Results
Authors: Simek James , Ludlow Jed , Tisovec Phil
Published: April 2011

InLine Inspection (ILI) tools using the magnetic flux leakage (MFL) technique are the most common type used for performing metal loss surveys worldwide. Based upon the very robust and proven magnetic flux leakage technique, these tools have been shown to operate reliably in the extremely harsh environments of transmission pipelines. In addition to metal loss, MFL tools are capable of identifying a broad range of pipeline features. Most MFL surveys to date have used tools employing axially oriented magnetizers, capable of detecting and quantifying many categories of volumetric metal loss features. For certain classes of axially oriented features, MFL tools using axially oriented fields have encountered difficulty in detection and subsequent quantification. To address features in these categories, tools employing circumferential or transversely oriented fields have been designed and placed into service, enabling enhanced detection and sizing for axially oriented features. In most cases, multiple surveys are required, as current tools do not incorporate the ability to collect both data sets concurrently. Applying the magnetic field in an oblique direction will enable detection of axially oriented features and may be used simultaneously with an axially oriented tool. Referencing previous research in adapting circumferential or transverse designs for inline service, the concept of an oblique field magnetizer will be presented. Models developed demonstrating the technique are discussed, shown with experimental data supporting the concept. Efforts involved in the implementation of an oblique magnetizer, including magnetic models for field profiles used to determine magnetizer configurations and sensor locations are presented. Experimental results are provided detailing the response of the system to a full range of metal loss features, supplementing modeling in an effort to determine the effects of variables introduced by magnetic property and velocity induced differences. Included in the experimental data results are extremely narrow axially oriented features, many of which are not detected or identified within the axial data set. Experimental and field verification results for detection accuracies will be described in comparison to an axial field tool.
A Mathematical Model Developed to Predict the Chemistry and Corrosion Rate in a Coating Disbonded Region of Variable Gap
Authors: Song Fengmei
Published: April 2011

A model is developed to predict the chemistry, corrosion potential and rate of pipeline steels in a coating disbonded region. The gap of the disbonded region is assumed to vary with distance from the holiday. The effect of this gap variation on the chemistry and corrosion rate in the coating disbonded region is not well understood and investigated in this study through modeling. The preliminary model results suggest that overall, the variation of the disbondment gap with distance has an insignificant effect on the pH, corrosion potential and rate in the disbonded region. This may be explained as that unlike some conventional crevice corrosion often associated with a large cathode-to-anode area ratio, the area ratio here is rather relatively small and the pH commonly falls in the neutral or alkaline range. Within this pH range, even if the pH varies within a few units across the crevice length, the variation of the crevice corrosion rate is not significant. In this paper, the fundamental principles used for the model, some key model results and practical implications of the results are reported and discussed.
A Probabilistic Model for Predicting Internal Corrosion Threat in Dry Natural Gas Pipelines
Authors: Song Fengmei , McFarland John , Bichon Barron , Huyse Luc , King Fraser , Perry Laurie
Published: April 2011

A probabilistic model is developed in this work to predict the internal corrosion (IC) threat due to water condensation in dry natural gas pipelines. The model involves the understanding of tariff limits (TLs) for water and other corrosive species in natural gas; a consensus definition of an extremely unlikely condition for IC threat; a statistical analysis of field operating temperature, pressure, and water content (WC) data from a number of operators; and a known but modified relation of the saturated WC vs. operating temperature and pressure. By setting the limit of the probability of water condensation at 2% of the time that the pipe surface is wet, the maximum WC allowed in the natural gas can be determined for any given temperature and pressure. Practical operating charts have been developed for guiding pipeline operators to understand and minimize IC threats in dry gas (DG) pipelines. This paper presents the probabilistic modeling approach and discusses some model results.
Transient Evaluation for LPG and Oil Pipelines
Authors: Meliande Patricia , do Nascimento Elson Antonio , Fernandes Lacerda Rogerio
Published: April 2011

Nowadays, anticipating and controlling transient response is a critical design activity for ensuring both safety and integrity of the operational subsea system. Predicting transient effect, commonly known as surge pressure, is of high importance for offshore industry. In order to determine the installation of protection equipments to avoid surge pressure effects, the operational teams have raised concerns, whether the system is adequately designed to protect the subsea system against possible surge pressures during the event of sudden closure of a valve. Researches, referred to transient effects, explain that is necessary to evaluate the system performance under current and desired operating conditions. The main goal of this paper is to predict the surge pressure during unforeseen closure valves at Refrigerated LPG and Gasoline (C5+) pipeline systems. In these systems the valves are located downstream the flowlines. Detailed computer modeling attempts to simulate the complex interactions between flowline and fluid, aiming at providing efficient flowline system integrity. These models are based on Transient Methodology which is defined for a set of nonlinear partial differential equations that relate fundamental variables with pressure head and flow velocity. The solution of differential equations has been carried out by Finite Difference Method that transforms these equations into characteristic equations. These can be accurately solved through high-speed digital computers. Flowmaster, Chicago, USA, was the software used to develop the analysis models. The software offers an advanced graphical interface to build networks and resultant graphics. The results from Flowmaster have been validated through a defined methodology that applies the Characteristics Method based on Wylie and Streeter assumptions. Simulations considering the fluid as gasoline have shown a sudden damping of pressure wave when the valve closure time was 10 seconds, leading to the restoration of the initial flow conditions. The analysis using the Method of Characteristics, however, does not exhibit this sudden damping, although a gradually reduction of fluctuations around the initial pressure are observed. The transient analysis through Flowmaster for Refrigerated LPG leads to a pressure envelope that shows a change of the flow direction triggering a cyclical process until the restoration of the initial operational conditions.
A Precipitation-Induced Landslide Susceptibility Model for Natural Gas Transmission Pipelines
Authors: Finley Jason P. , Slayter David L. , Hitchcock Chris S. , Lee Chih-Hung
Published: April 2011

Landslides related to heavy rainfall can cause extensive damage to natural gas transmission pipelines. We have developed and implemented a geographic information system (GIS) model that evaluates near real-time precipitation-induced landslide susceptibility. This model incorporates state-wide precipitation data and geologically-based landslide classifications to produce rapid landslide risk evaluation for Pacific Gas & Electric Company’s (PG&E) gas transmission system during winter rain storms in California. The precipitation data include pre-storm event quantitative precipitation forecasts (QPF) and post-storm event quantitative precipitation estimates (QPE) from the United States National Oceanic and Atmospheric Administration (NOAA). The geologic classifications are based on slope, susceptible geologic formations, and the locations of historic or known landslide occurrences. Currently the model is calibrated using qualitative measures. Various scientists have developed large landslide databases with associated rainfall statistics to determine rainfall thresholds that trigger landslides. With a sufficient number of landslides, we can more precisely determine minimum rainfall thresholds using similar methods.
Enhanced Leak Detection Risk Model Development
Authors: Harron Lorna , Barlow Rick , Farquhar Ted
Published: April 2011

Increasing concerns and attention to pipeline safety have engaged pipeline companies and regulatory agencies to extend their approaches to pipeline integrity. The implementation of High Consequence Areas (HCAs) has in particular had an impact on the development of integrity management protocols (IMPs) for pipelines. These IMPs can require that a risk based assessment of integrity issues be applied to specific HCA risk factors. This paper addresses the development of an operational risk assessment approach for pipeline leak detection requirements for HCAs. A detailed risk assessment algorithm that includes 25 risk variables and 28 consequence variables was developed for application to all HCA areas. The significant likelihood and consequence factors were chosen through discussions with the Leak Detection Risk Assessment Model Working Group and subject matter experts throughout Enbridge. The leak detection algorithm focuses on sections of pipe from flow meter to flow meter, as these are the locations that impact the leak detection system used by Enbridge. Each section of pipe is evaluated for likelihood, consequence and risk. When a high or medium risk area has been identified, an evaluation of potential Preventive and Mitigative (P&M) measures will be undertaken. A P & M Matrix has been developed to identify potential mitigation strategies to be considered for higher risk variables, called risk drivers, in the model. The matrix has been developed to identify potential risk mitigation strategies to consider for each variable used in the HCA Leak Detection Risk Assessment. The purpose of the matrix is to guide the user to consider actions identified for variables that drive the risk for the particular location. Upon review of the matrix, the user determines feasibility of the risk mitigation strategies being considered to identify an action. The paper will describe the consultative process that was used to workshop the development of this algorithm. Included in this description is how the process addressed various methods of leak detection across a wide variety of pipelines. The paper closes with “development challenges” and future steps in applying operation risk assessment techniques to mainline leak detection risk management.
A New Approach to Essential Welding Variables in Girth Welding of High Strength Pipe Steels
Authors: Rajan V. B. , Chen Y. , Quintana M.
Published: April 2011

In the narrow groove joints typically used for mechanized GMAW girth welding of high strength pipe, weldment properties are controlled by a large number of variables. The groove geometry, the bevel offset distance, the pass sequence and number of passes, the heat input per pass, the preheat and interpass temperatures, single vs. dual torch configuration, and the chemical composition of the consumable and the base pipe can all have an effect on the weldment properties. Determining the primary and secondary variables that control mechanical properties is a daunting task. Use of an integrated thermal-microstructural model has allowed virtual experiments to be conducted by varying the aforementioned welding variables to identify the primary and secondary drivers that control thermal behavior, microstructural evolution and ultimately weld and HAZ mechanical behavior. Outputs from this model have been used to correlate the essential process variables with weld hardness.
Portable Laserscan for In-Ditch Dent Profiling and Strain Analysis: Methodology and Application Development
Authors: Arumugam Udayasankar , Tandon Samarth , Gao Ming , Krishnamurthy Ravi , Hanson Ben , Rehman Hamood , Fingerhut Martin
Published: April 2011

Traditionally, the pipeline industry and government regulations used a depth based assessment criteria to identify and prioritize dents in the order of severity. This depth based criteria had limitations and could potentially underestimate dent severity. In recent years, strain parameter has been used to characterize dent severity in a pipeline. Dent strain analysis requires dent profile information. In-Line Inspection (ILI) caliper tools provide both longitudinal and circumferential dent profiles that can be used to evaluate strain. However, no comparable technologies are available for in-ditch dent profile measurement. The currently used profile-gauge technology only measures dent profile through its deepest point, which may not capture the maximum strain in the dent and could result in underestimating the severity. A recent study showed that LaserScan 3D mapping technology provides an accurate dent 3D profile that can easily be extracted for “point-to-point” strain analysis and is an ideal tool for verification of ILI performance. Furthermore, LaserScan 3aD mapping accurately measures other associated anomalies such as gouge and metal loss. Most importantly, the advantage of employing dent LaserScan is that strain analysis can be conducted at the excavation site and simultaneously, strain based mitigation decision can be made in real time. In this paper, a portable LaserScan 3D mapping technology for measurement of dents and dents associated with other anomalies in pipelines is introduced. Fundamentals of the technology are briefly discussed in terms of accuracy, resolution and appropriateness for pipeline application. Examples of 3D mapping for dent and dent with other anomalies are presented. Extraction of dent profile and subsequent strain analysis are further demonstrated.
Broad Perspectives of Girth Weld Tensile Strain Response
Authors: Wang Yong-Yi , Liu Ming , Weeks Timothy , Richards Mark , McColskey David , Horsley David
Published: April 2011

Tensile strain capacity (TSC) is a critical component of the strain-based design of pipelines. TSC is affected by a number of material parameters, such as the strain hardening rate, weld strength mismatch, and toughness. Girth weld high-low misalignment, internal pressure, and flaw size are additional influential parameters. The impact of those parameters can be rationalized by fracture mechanics principles and is supported by an increasingly large library of experimental test data. A number of predictive TSC models are under development. One of the most significant challenges in the development of these models is the scatter of experimental test data. As more test data are collected with specially arranged precision instrumentation, it is become apparent that the scatter of test data is a matter of true material response. It is, therefore, critical to see beyond the scatter and understand the overall material behavior in the development and validation of TSC models. This paper highlights the material behavior observed in a large number of large-scale experimental tests. The material response is then classified into different categories to assist the understanding of the experimental data scatter and rationalize the trends expected from test data.
ILI Tool Tolerance and Repeatability Effect on Corrosion Growth Rates
Authors: Coleman Grant A. , Miller Scott J.
Published: April 2011

The knowledge of the rate at which corrosion grows in a given pipeline could be used to determine the time between inspections, find hot spots of high corrosion growth, and possibly prevent catastrophic failure of the pipeline. For these reasons many pipeline companies employ some method to calculate the growth between inspections years apart. This calculation may be on two sets of inspection data from different vendors using different technologies. This paper discusses normalization of data which is necessary for a fair data comparison. Growth rates are calculated for the normalized data for the complete population of anomalies, as well as individual anomalies. Analysis of tool tolerance and repeatability is then used to put the results into perspective.
Enhanced Apparent Toughness Approach to Tensile Strain Design
Authors: Liu Ming , Wang Yong-Yi , Long Xin
Published: April 2011

Tensile strain design is an essential element of the overall strain-based design methodology. This paper focuses on the apparent toughness approach and introduces the concept of apparent CTOD resistance curve (CTODR). The determination of apparent toughness, CTODA, from the apparent CTODR is demonstrated. The prediction of tensile strain capacity (TSC) using the CTODA and the traditional tangent method is conducted. Similar results are obtained from both approaches. The value of apparent CTODR is found to be relatively insensitive to the amount of flaw growth after some limited initial growth. This insensitivity allows the determination of CTODA at the small amount of flaw growth. This feature establishes the connection between CTODA and initiation-based toughness. Further work is under way to apply these findings.
Influence of Remanent Magnetization on Pitting Corrosion in Pipeline Steel
Authors: Espina-Herna´ndez J. H. , Caleyo F. , Hallen J. M. , Lo´pez-Montenegro A. , Pe´rez-Baruch E.
Published: April 2011

These days, in-line inspections based on the magnetic flux leakage (MFL) principle are routinely used to detect and size metal loss and mechanical anomalies in operating oil and gas pipelines. One of the characteristics of the MFL technology is that after the inspection, the pipeline wall shows a remanent magnetization. In this work, the influence of the magnetic field on pitting corrosion in pipeline steel is studied. Pitting corrosion experiments have been carried out on samples of an API 5L grade 52 steel under a magnetization level of the same order of magnitude of the remanent magnetization in the pipeline wall after the MFL inspection. The samples were magnetized using rings of the investigated steel. The closed magnetic circuit configuration used in this study survey guaranteed that the samples kept the same magnetization level during the complete duration of the conducted experiments. This experimental setup was used in order to reproduce the conditions observed in MFL-inspected pipelines in which the magnetic field was confined to the pipe wall thickness. Immediately after magnetization, the investigated samples were subjected to pitting by immersing them in a solution with dissolved Cl− and SO42− ions. The pitting experiments were conducted for exposure times of 7 days. Non-magnetized specimens were used as control samples. The depths of the pits induced in the investigated samples were measured using optical microscopy. The maximum pit depth of each sample was recorded and used to conduct extreme value analysis of the pitting process in the magnetized and non-magnetized specimens. The results of this investigation indicate that the magnetic field confined within the pipeline wall has a significant influence on the pitting corrosion process. The statistical assessment of the pitting corrosion data collected during this study shows that the magnetic field reduces the average depth of the pit population. It also reduces the extreme pit depth values that can be predicted from the maximum values observed in the magnetized samples, with respect to the non-magnetized control samples. Scanning electron microscopy observations show that the magnetic field alters the pit morphology by increasing the pit opening (mouth). It is shown that the observed reduction in the pit depth when a magnetic field is confined to the volume of the corroding material can be explained based on the behavior of the paramagnetic corrosion products under the influence of the local magnetic field gradients produced inside and within the immediate vicinity of stable pits.
Large Scale Experimental Data for Improved Strain-Based Design Models
Authors: Stephens Mark , Petersen Randy , Wang Yong-Yi , Gordon Robin , Horsley David
Published: April 2011

This paper provides an overview of a large-scale testing program that is associated with an ongoing, joint government/industry funded research program, which is intended to advance the state-of-the-art in strain-based design as it pertains to the tensile capacity of girth welds in steel pipelines. The testing program has exercised a number of parameters that are known to have a significant impact on tensile strain capacity including: the effects of internal pressure, the strain hardening characteristics of the pipe body and weld material, the degree of weld strength overmatch and the location of the assumed flaw. This paper describes the type of tests performed and the instrumentation plan; it also provides a summary and discussion of the results obtained to date.
Technical Forums as a Tool for Implementing and Learning About Standard Operating Practices
Authors: de Almeida Maria Fatima Ludovico , Santiago Adilson , Ribeiro Kassandra Senra , Arruda Daniela Mendonc¸a
Published: April 2011

This paper describes the experience of Transpetro’s Oil Pipelines and Terminals Unit regarding an institutionalized knowledge management (KM) process of systematically promoting technical forums focused on: (i) pipeline and terminal operations; (ii) industrial maintenance; and (iii) right-of-way activities management. This empirical work adds evidence that in the model of cooperative and communicative knowledge management it is necessary to motivate staff to provide the company with their tacit knowledge and to take a proactive part in knowledge management processes, particularly in technical forums. Within this KM perspective, technical forums have been held by Transpetro for the following purposes: (i) to discuss the main barriers and challenges the Oil Pipelines and Terminals unit has to face in the coming years; (ii) to share and disseminate good practices concerning oil pipeline and terminal activities; (iii) to discuss new processes, methods and equipment developments with potential application in business and operational processes; (iv) to establish action plans concerning the main challenges, barriers and opportunities; (v) to disseminate Research and Development (R&D) projects in course, new procedures, methods and equipments and (vi) to promote integration among forum attendees. The two year-experience in Transpetro’s Oil Pipelines and Terminals Unit revealed that technical forums have been an important instrument for cooperative and communicative knowledge management, according to evaluations from 173 attendees.