bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability-Based Water Network Optimization for Steady State Flow and Water Hammer
Authors: Djebedjian Berge
Published: October 2008

The paper presents the reliability-based water network optimization by selecting the optimal pipe diameters for steady state flow and water hammer under hydraulic reliability. Hydraulic reliability is the probability that a water distribution system can supply consumers’ demands over a specified time interval under specified conditions. Thus, hydraulic reliability refers to the basic function of a water distribution system; conveyance of desired water quantities at desired pressures to desired locations at desired times. The evaluation of the hydraulic reliability of a network is achieved through stochastic simulation. In this study, the Monte Carlo simulation is used. The optimization method used in this study is the Genetic Algorithm (GA) which is a popular optimization choice for solving problems that are difficult for traditional deterministic optimization methods. The main advantage of GA is its ability to find the global optimum by using function values only. The GA is integrated with a hydraulic analysis solver, a Monte Carlo simulation program and a transient analysis program to improve the search for the optimal diameters under certain constraints. These include the minimum allowable pressure head constraints at the nodes for the steady state flow and the minimum and maximum allowable pressure head constraints for the water hammer. The approach was applied on a network and the transient flow is introduced to the water system by the pump power failure. The application of GA optimization tool to the case study demonstrates the capability of the Monte Carlo method and the genetic algorithm to find the optimal pipe. The technique of the optimal pipe diameter selection is very economical as the network design can be achieved without using hydraulic devices for water hammer control. This technique is not only crucial for the design and performance of water networks, but also effective in minimizing costs.
An Experimental and Analytical Investigation into the 3D Hot Bend of API 5L X65 Pipeline
Authors: Baek Jong-Hyun , Kim Young-Pyo , Kim Woo-Sik , Oh Chang-Kyun , Kim Yun-Jae , Seok Chang-Sung
Published: October 2008

Pipelines for natural gas transmission may be subjected to plastic deformation by an outside force such as ground subsidence, ground liquefaction, hot bending, cold bending and mechanical damage. Plastic deformation affects the tensile properties and fracture toughness. Tensile test, Charpy impact test and S-N fatigue test were conducted on an API 5L X65 pipe to investigate the mechanical properties of pipeline subjected to plastic deformation during 3D hot bend. Tensile and fatigue test revealed that yield strength, tensile strength and fatigue strength of the extrados of the 3D bend were higher than those of the intrados of the 3D bend. However, Charpy impact energy of the intrados of the 3D bend was higher than that of the extrados of the 3D bend. There is no variation of strain at the crown according to the numerical analysis to the 3D hot bend. The equivalent strain up to 19% shows in the side of the intrados of the 3D bend. The equivalent strain up to 15% displays in the side of the extrados of the 3D bend.
Improved Lateral Focusing for Thin-Walled Gas Pipelines Girth Welds Using Phased Arrays
Authors: Zhang Jinchi , Labbe´ Simon , Moles Michael
Published: October 2008

With the arrival of high strength, thinner walled pipe steels, improved defect sizing is becoming more critical. Repairs become more detrimental to the pipe material properties, and Engineering Critical Assessment requires better sizing as the pipes become thinner. Improved focusing is particularly relevant in the horizontal (circumferential) direction, to both minimize repairs and to more accurately characterize intermittent defects. This paper describes the development of an ultrasonic phased array specifically to improve focusing. Extensive computer modeling was performed to determine the optimum array for thin-walled pipes with mechanical focusing (i.e. a curved array) and various curvatures. The modeling showed that a 60 element, 1 mm pitch array with a 100 mm curvature in the passive aperture gave significant improvements over a standard array (60 elements, 1 mm pitch, unfocused). This curved array was manufactured and tested on a commercial calibration block with flat bottomed holes. The experimental results showed that the curved 1D array had significantly better focusing than the standard (unfocused) array, as expected. The curved array oversized flat-bottom hole reflectors by only ∼ 1 mm, instead of the 4–6 mm from the standard array. These curved arrays can be used on standard AUT systems with no modifications to the general mechanics or software.
Advanced Technologies for Spiral Welded Oil and Gas Line Pipes
Authors: Permyakov I. L. , Pumpyanskyi D. A. , Pyshmintsev I. Yu , Stolyarov V. I.
Published: October 2008

To obtain a higher strength in line pipes of diameter up to 1420 mm the controlled rolling of plates and coils or heat treatment of the product were applied. Metallurgical design based on purification, low carbon content, micro-alloying and controlled rolling has increased yield stress, ductility and low temperature behavior of the developed steels. Maximum homogeneous structure of the base metal and the weld joint, minimum residual stresses, which is beneficial for a better stress corrosion and fatigue resistance, were obtained through quench and tempering. Full scale tests have shown formed microstructure retards crack propagation from sharp defects notched in strip or plate end welds under both static and cyclic pipe loading. Combined laser–submerged are welding was tested for further improvement of properties of the end joints. Features of microstructure in weld, fusion and heat affected zone were studied. Advanced properties of the joints were found in laser welded steels but inherent high cooling rates must be reduced using different methods.
The Micro Structural Characteristic Parameters of High Grade Pipeline Steel and its Mechanical Properties
Authors: Zhang Xiaoli , Zhuang Chuanjing , Ji Lingkang , Feng Yaorong , Zhao Wenzhen , Huo Chunyong , Zhao Xinwei , Gong Shaotao
Published: October 2008

The microstructure of high grade pipeline steels, including X65, X70, X80, X100, were studied by SEM and EBSD, respectively. It was found that the microstructures of high grade pipeline steels were composed of lower bainite, granular bainite and acicular ferrite. The phases of kinds of pipeline steels were composed of Fe3C, retained austenite and ferrite. And their percentage content, grain size and its distribution were studied respectively also. These micro structural parameters were correlated to the mechanical properties of kinds of pipeline steels. Furthermore, all kinds of angles of grain boundaries were studied, and the relationship between the angles of grain boundaries and mechanical properties was obtained. It was shown that as the improving of the steel grade, the grain boundary including small angle and large angle increased. And only when grain boundary was greater than 15 degree, it was effective to the toughness behavior.
Manufacturing of X100 Pipes for the TAP Project
Authors: Hillenbrand Hans-Georg , Liessem Andreas , Grimpe Fabian , Schwinn Volker
Published: October 2008

The application of high strength steels like X100 are considered as an economical necessity in order to supply large volumes of gas over long distances in a competitive manner. The development of the grade X100 started more than 10 years ago and has progressed significantly. Therefore the focus of actual development and research work is focused on questions regarding the installation and the service behaviour of such high strength steels. In this context the TAP project has been launched by the ENI group in order to provide answers regarding the economic viability, the technological reliability and the real possibility of constructing high pressure pipelines with this newly developed steel grade. In this paper the manufacturing of line pipe in grade X100 for the TAP project including the two fibre reinforced crack arrestors will be summarized and the production results regarding strength and toughness we presented. Furthermore the analysis of tensile test results regarding the influence of specimen type, anisotropy and the effect of thermal treatment (low temperature ageing) on the stress-strain curve will be discussed.
Optimizing the Active Speed Control Unit for In-Line Inspection Tools in Gas
Authors: Rahe Florian
Published: October 2008

The simulation and optimization of an active speed control unit for an intelligent in-line inspection tool is presented. A simple model was developed describing the dynamics of such a tool in a gas pipeline. The dynamics are represented by a set of coupled differential equations incorporating tool velocity, pressure, differential pressure over the tool and bypass area. These equations were solved numerically by implementation in a simulation environment. Control rules for an active speed control unit were integrated in this model to simulate the effect of regulation activities on the reactions of the tool. The rules were chosen to represent the capabilities of a real unit (electronics and mechanics). The results of the simulation are compared with the behavior of a tool in a 40” gas pipeline and the regulation algorithm is optimized with respect to the capabilities of the existing control unit.
Emerging Techniques for Enhanced Assessment and Analysis of Dents
Authors: Dawson S. J. , Russell A. , Patterson A.
Published: October 2008

Dents can occur either during pipeline construction e.g., in the form of rock-induced dents or as a result of the handling and back-fill processes or in-service, e.g., excavator impact. If failure as a result of a dent is not immediate, it is possible that the induced dent and/or defect combination can deteriorate in service and cause failure at some time after the initial impact. Often incidents of dents go unreported and the challenge to the pipeline operator is the identification of those defects that may threaten the future integrity of the pipeline from those defects that are dormant and require no further action. Most commonly, ILI metal loss and geometry tools (and in some cases ILI crack detection tools) are used to detect and report the characteristics and dimensions of dent defects. The ILI tools can provide information on the location, shape of the deformation, the nature of the damage i.e., the association with other features (metal loss, cracks, long seam or girth welds). Indeed, dents are found in the majority (> 80%) of pipeline miles inspected; with more than 50% of pipelines containing 10 or more dents. Although the pipeline industry does recognize the potential threat from dents, much of the published guidance is limited to a combination of the nature of the damage (e.g., presence of metal loss, stress risers, location etc) and a simple depth-based assessment of the deformation. In the US, prescriptive rules of this type are in place to provide operators with the timescale for the investigation and remediation of different forms of dents. However, with unintentional releases still occurring in-service from dents (from both excavator impact damage and of construction origin) the current industry thinking and research supports the use of more advanced assessment techniques (beyond the depth-based rules). These enhanced assessment techniques make use of the detailed dent profile information obtained from high-resolution geometry tools and other supporting information on the presence and severity of stress risers from ILI tools. Indeed, the US regulations do allow operators an option to engage such techniques to re-evaluate the prescriptive timescales for certain dent categories. This paper describes two levels of enhanced dent assessment that can be utilized to rank dents in order of severity and to assess their significance and need for remediation and discusses their application supported by real case study information.
Rocker Pipes: A Solution for Differential Settlement Induced Distress in Pipeline
Authors: Wijeyesekera D. Chitral , Reginold J. Terence
Published: October 2008

Soil-pipe interaction studies leading to the evaluation of settlement of pipelines is not new. Nevertheless, pipeline failures still occur due to differential ground movements between a heavy yielding structure and a pipeline firmly connected to it. Such differential movements induce excessive stress concentrations in the pipeline. Plastics pipes fail as a consequence of such movements, though their flexibility can make them less vulnerable than rigid pipes. This paper presents two extreme case studies of failure; a 100mm diameter polyvinyl chloride (PVC) domestic sewer pipe and 2700mm diameter glass reinforced plastic (GRP) intake pipeline. By treating the pipelines as beams on elastic foundation, the magnitude and location of the maximum bending moments arising from yielding of the heavy structure can be determined. The provision of rocker pipe joints that entertain a permissible rotation helps to redistribute the bending moments to acceptable levels and thereby alleviate distress in the pipeline.
Considerations About the Urucu-Manaus Gas Pipeline Project
Authors: Villela Cla´udio Henrique Lobianco Garcia , Correia Luiz de Carvalho Dias
Published: October 2008

The main purpose of this job is to present the characteristics that influenced the elaboration of the Urucu-Manaus Gas Pipeline Project and the difference between this pipeline and other pipelines already installed on the Amazon region. In this project were emphasized the aspects related to the route definition, mapping technologies that had not been utilized in our pipeline projects, the crossing of vast flooded areas, requiring specific studies, as well the minimization of the environment impacts, in this case the existence of animal species present only in this region. Other differential factor was the Rio Negro crossing, where the pipeline will be installed in the riverbed. The know-how attained with this project consolidates ever so the activity of building pipelines in tropical forest regions.
Data Reconciliation Applied in a Transfer and Storage Terminal
Authors: Feldman Rafael Noac , Cruz de Oliveira Elcio
Published: October 2008

In a simply manner, data reconciliation is a mathematic treatment with propose of a better quality of the data in a process. Industrial processes typically have a large number of measured variables, which presents some degree of random errors and, less frequently, gross errors. In this text, in order to simplify the notation and terminology we classify all instrument and process errors in these two categories. Any significant systematic bias is included in the gross error category. Data reconciliation allows the measurements to be adjusted (“reconciled”) to satisfy process restrictions (mass and energy balances) and improve measurements quality. The results obtained by data reconciliation can also provide benefits in custody transfer issues. Custody transfer is the responsibility transfer during the storage and transportation of a measured refined product volume. Any loss or gain resulting in a non-trustful measurement is considered as the transportation company responsibility. Therefore, the work objective is to propose a data reconciliation methodology, in a process involving diesel oil custody transfer in a Transpetro’s terminal (Terminal of Sao Caetano do Sul), in order to evaluate and correct possible inconsistencies, besides to know a single measure that represents better the measurement system. In this study we will use data from static measurement in tanks, dynamic measurement in turbine and ultra-sonic device. A database will be obtained in two basic steps: process modeling and data reconciliation to consolidate the mass balance. The reconciled value shows us that there is a bias in the ultra-sonic meter and the turbine meter measurement is more reliable, as expected.
Comparison of Methods for Predicting Safe Parameters for Welding Onto In-Service Pipelines
Authors: Bruce William A. , Boring Matthew A.
Published: October 2008

When welding onto an in-service pipeline, to facilitate a repair or to install a branch connection using the “hot tapping” technique, there are two risks that need to be considered. The first is the risk of burnthrough, where the welding arc causes the pipe wall to be penetrated allowing the contents to escape. The second is the risk of hydrogen cracking that arises from the fast cooling rates that tend to be produced by the ability of the flowing contents to remove heat from the pipe wall. Various methods exist for predicting safe welding parameters for welding onto in-service pipelines with regard to the risk of both burnthrough and hydrogen cracking. This paper reviews these methods and presents a comparison of the results for a typical in-service welding application.
Semi-Automatic Gas-Less Process for Girth Welding X-80 Line Pipe
Authors: Narayanan Badri K. , Soltis Patrick , Quintana Marie
Published: October 2008

A new process (M2M™) to girth weld API Grade X-80 line pipe with a gas-less technology is presented. This process combines innovations in controlling arc length and energy input with microstructure control of the weld metal deposited to achieve high strength (over matching 550 MPa yield strength) and Charpy V-Notch toughness of over 60 Joules at −20°C. This paper will concentrate on the metallurgical aspects of the weld metal and the systematic steps taken to achieve high strength weld metal without sacrificing toughness. The development of an appropriate slag system to achieve the best possible microstructure for high toughness weld metal is discussed. The indirect effects of the slag system on the weld metal composition, which in turn affects the microstructure and physical properties, are detailed. In order to achieve sound weld metal without gas protection using a semi-automatic process, a basic slag system with minimal acidic components is used to improve the cleanliness of the weld metal without sacrificing weldability. In addition, a complex combination of micro-alloying elements is used to achieve the optimum precipitation sequence of nitrides that is critical for high toughness. The final part of this paper gives details about the robustness of this process to weld high strength pipe. The results show that this is a practical and unique solution for girth welding of X-80 pipe to achieve acceptable toughness and over a 15% overmatch in yield strength of X-80 pipe without sacrificing productivity.
Quantifying the Probability of Failure During the Pre-Commissioning Hydrotest
Authors: Cosham Andrew , Hopkins Phil , Spiekhout Jan
Published: October 2008

Failures during the pre-commissioning hydrostatic test of a newly constructed pipeline are rare, but occasionally they do occur. Structural reliability techniques can be used to estimate the probability of failure during the precommissioning hydrotest, and to investigate the sensitivity of the probability of failure to the test pressure. This paper describes a study of the probability of failure during the hydrotest, based on data for the BBL Pipeline. The BBL Pipeline is a 36 in. outside diameter, approximately 235 km long pipeline designed to export natural gas from the Netherlands to the UK. The definition of failure is limited to failure of the line pipe due to internal pressure loading. Failure of fittings (e.g. flanges, valves, etc.) is not considered. With this definition of failure, three different scenarios are considered: 1. Failure of defect-free pipe. 2. Failure of pipe containing a ‘workmanship’ defect (i.e. a defect in the pipe body or a weld that is acceptable to the relevant specifications or standards). 3. Failure of pipe containing a defect not acceptable to workmanship levels (e.g. a crack, or a dent on a weld). Defects larger than workmanship defects encompass defects that would not fail at the design pressure, but would fail at higher pressures, and ‘gross’ defects that would fail at very low pressures. It is difficult to estimate the probability of failure of such defects because it is highly dependent on the probability of these defects being present in the pipeline. Conversely, it is relatively straightforward to obtain a reasonable upper bound estimate of the probability of failure due to defect-free pipe or a workmanship defect. Consequently, in this study, only the probability of failure due to (1) or (2) has been calculated using structural reliability techniques. Inferences about (3) are drawn from the results of (1) and (2), and from historical data on hydrotest failures. It is shown that there is a hydrotest level below which the probability of failure is predicted to be zero. For defect-free pipe this is at least equal to the level of the mill test. In general, this hydrotest level depends upon factors such as: the ratio of the axial stress to the hoop stress in the mill test and the hydrotest, and the size of defects in the pipeline.
Considerations for Selecting Approaches to Estimate Lateral Spread Displacements for Assessing Pipeline Performance
Authors: Honegger Douglas G.
Published: October 2008

Liquefaction hazards, specifically lateral spread displacement resulting from liquefaction, are the most pervasive and often the most severe earthquake hazards to buried oil and natural gas transmission pipelines. While the potential threat of lateral spread displacements to buried pipelines has long been recognized, the availability of approaches and tools to assess the likelihood of liquefaction and estimate of the severity of the lateral spread hazard has improved significantly in the past 10 to 15 years. The most significant areas of improvements have focused on the development of probabilistic approaches, the use of alternatives to standard penetration tests such as cone penetrometer tests and shear wave velocity measurements, and methods to combine the results of dynamic site response analyses with what remains an empirical approach to liquefaction assessment. Approaches available for estimating lateral spread displacements can be generally divided into two categories, empirical methods and analytical methods. Empirical methods are generally limited to estimating the magnitude of lateral spread displacements at the ground surface and must rely upon judgment in defining ground displacements at depth, the size of the lateral spread, and the variation of lateral spread displacement both within and at the margins of the lateral spread zone. Current advanced analytical methods range from relatively simple mathematical analogs to finite element continuum models using either Eulerian or Lagrangian formulations. In addition, many researchers have developed specialty codes for assessing lateral spread displacement. As analytical methods have increased in complexity, there has been a commensurate increase in the cost to undertake these methods because of additional subsurface information requirements and the engineering effort to implement the analyses. Despite the significant advances in the ability to estimate lateral spread displacements, engineering assessment of pipeline performance for potential lateral spread hazards remains an approximate proposition requiring considerable judgment owing to practical limitations with respect to available information, modeling capabilities, and interpretation of modeling results. In many instances, these limitations raise questions regarding whether or not the added value provided by more sophisticated lateral spread modeling techniques justifies the substantial increase in costs. These questions are explored by comparing the advantages and constraints related to common approaches for estimating lateral spread hazard with respect to the ultimate goal of assessing the adequacy of a pipeline river crossing. The comparisons support a conclusion that the most advanced methods may not necessarily lead to a more reliable design solution.
Prediction of Environmentally Assisted Cracking on Gas and Liquid Pipelines
Authors: Been J. , Eadie R. , Sutherby R.
Published: October 2008

A model has been developed to predict crack growth on pipelines from environmentally assisted cracking in near-neutral pH environments (often-termed low-pH stress corrosion cracking (SCC)). The model is based on the results of cyclic loading experiments and is used in conjunction with pressure time variations in the pipeline determined from the operating SCADA records to predict the growth of an assumed existing crack in the pipe. The crack grows through different crack growth regimes, which are determined by the size of the pressure variations and the instantaneous crack dimensions. For a growing crack that experiences relatively high pressure fluctuations, as often encountered on liquid lines, reasonable crack growth predictions were made based on corrosion fatigue. An approach based on crack tip strain rate appears more suitable for the prediction of crack growth of small cracks and for cracks on gas lines with small pressure fluctuations. The model is designed so that the effect of stress intensifiers (like the long seam weld crown) that are often associated with these failures can be included. The model can be used in its present format for prioritizing inspections on both gas and liquid pipelines. Whereas predicted crack growth rates compare favorably with rates measured in the field, further work is required to incorporate additional mechanical and environmental effects, in particular to improve the prediction of small crack growth rates. Low crack velocities may be possible in the presence of small pressure fluctuations and low frequencies, but they may be less probable.
GIS-Based Seismic Hazard Mapping for Pipeline Integrity Management
Authors: Hitchcock Christopher , Nishenko Stuart , Lee Chih-Hung , Sun Joseph , Sundermann Sean , Zellman Mark , Givler Robert
Published: October 2008

Geographic information systems (GIS) technology enables sophisticated, numerical-based mapping of earthquake hazards, including liquefaction and landslide susceptibility, on a regional basis for pipeline systems. Existing earthquake hazard mapping was integrated with interpretation of topographic, geologic, hydrologic, and geotechnical data to update an earthquake hazard database for Pacific Gas & Electric Company’s California Gas Transmission (CGT), as part of the CGT Pipeline System Integrity program. The regionally consistent, map-based database covering CGT’s pipeline system in northern California allows for modeling of possible pipeline impacts from moderate to large earthquakes. GIS-based modeling that incorporates the hazard mapping is a powerful tool for planning and emergency response purposes. Specifically, near real-time models of possible pipeline damage locations can be derived from internet-based groundshaking records (USGS ShakeMap) produced after earthquakes. Scenario-based models of earthquake impacts from possible earthquakes can be used for planning purposes.
Colonization and Habitat Use by Marine Fish and Epifauna of the Gulfstream Pipeline Habitat Replacement Structures
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 the Gulf of Mexico, making landfall in Tampa Bay. Activities such as the installation of the pipe on the seafloor, the subsequent lowering of the pipe beneath the seafloor, and the mooring of construction vessels used in these processes were anticipated to disturb the seafloor and associated resources. Compensatory mitigation for project impacts to live hard-bottom was undertaken with the installation of habitat replacement sites consisting of either limestone boulder groupings or pre-fabricated reef modules. As part of the mitigation monitoring plan, Gulfstream has documented the success of the limestone’s placement and stability within the habitat replacement sites, monitored colonization by sessile epifauna, and censused the reef fish populations found utilizing the created habitat. The monitoring protocol includes diver collected still photography and Bohnsack point counts for fish. The created habitat provides a greater amount of habitat relief/complexity than natural hard/live bottom and is thriving in terms of both the recruitment of sessile epifauna and habitat use by a diverse demersal and commercially important fish community. Thus the limestone boulder and reef module areas created as part of the Gulfstream project appear to be a very successful means of habitat mitigation.
Valve Placement and Operation for Liquid Transmission Pipelines: A Risk Reduction Tool
Authors: Weir David A. , Kwan Vienna W. , Power Barry F.
Published: October 2008

The Intelligent Valve Placement (IVP) approach has been developed to incorporate risk (defined as likelihood × consequence) reduction techniques to identify optimum locations for sectionalizing (block) valves along existing or new petroleum transmission pipelines. This process aims to optimize valve placement based on risk reduction rather than current rule-of-thumbs and regulatory requirements. It may result in cost reduction and cost optimization through efficient valve placement while meeting required regulations. This approach incorporates risk through reduction of consequence, which is achieved by reducing the potential spill volumes and impact to sensitive areas in an iterative manner. With the use of consequence reduction strategies, this paper demonstrates that valve placement and operability decisions on both new or existing pipelines can be made to optimize the location of valves and provide for a safer pipeline. Although this process is highly consequence driven, there are opportunities to incorporate likelihood drivers. Equations have been developed that quantify consequence reduction and allow for determination of an optimal valve placement design. Application of this technique to pipelines in the United States is presented and the limitations of this method addressed. Although this technique is valid anywhere, this approach is in line with the requirement from the U.S. Department of Transportation to examine the placement of emergency flow restricting devices as per the High Consequence Area ruling and the requirements set forth by the Canadian Standards Association regarding remote operation of valves in Canada consistent with “extraordinary hazard” determinations.
Towards Permission to Construct Oilfield Facilities Without a Conventional Field Survey
Authors: Adam Steve , Sloan James
Published: October 2008

With the decreasing cost and ever increasing availability of digital information, visits to the field are being minimized. This is particularly evident in remote areas or regions where land access is difficult. For example, the possibility of using preliminary route alignment sheets built from digital engineering data for an application to construct a pipeline could provide cost and schedule savings as well as safety advantages over staging a preliminary field survey. A desktop-based approach which uses existing project data may be a valuable alternative, deferring the legal survey until after (or during) construction of each spread.
Transpetro Southeast Gas Security of Supply Study
Authors: Faertes Denise , Domingues Joaquim , Oliveira Luiz
Published: October 2008

The purpose of this paper is to present the study developed jointly by TRANSPETRO/Natural Gas Department and Det Norske Veritas in association with Jardine Asset & Risk Management Solutions (Jardine) from the United Kingdom. The study was carried out with the objective of evaluating the security of supply of the overall TRANSPETRO Southeast gas supply network in 2005, 2006 and 2007, that provide gas in the Southeast region of Brazil to thermo plants, to vehicles and to industrial and residential consumers. The occurrence of contract shortfalls imply in heavy fines for the suppliers. To provide best in class analysis, state of the art software was used in order to count on powerful tools to model the gas supply system and to quantify the availability and the efficiency of the overall network and of the individual components.
MOL’s New Pipeline Operations Supervision System
Authors: Szilassy Csaba
Published: October 2008

The MOL Group consists of refining and petrochemical companies from Hungary and Slovakia and with 2700 Km of pipeline, owns 11.4% of the European pipeline network. In 2002 the company began the replacement of the old SCADA pipeline operational management system and its wire based communication system. The new system utilizes intelligent field devices, redundant GPRS communication technology, and Intranet technology for visualization and control. The new system maintains all of the advantages of a traditional SCADA system. However, it applies key features which take it beyond the definition of a SCADA system, and thus has been given the name DIWICON (Distributed Intelligence Wireless Control). These additional features include central server based software, platform independent workstation access, unlimited number of users, no user based license fees, accessible from the field, easy expandability, and yet, it retains the standardized, modular, secure and functional nature offered by SCADA.
Evaluation of the Resistance of X120 Pipe to Mechanical Damage
Authors: Lucci Antonio , Mannucci Gianluca , Malatesta Giuliano , Biery Nicholas E.
Published: October 2008

High strength linepipe steels are being considered for several upcoming projects due to their potential to offer substantial savings through reduced wall thickness, particularly for high pressure designs. It is well known that mechanical damage from excavation activities is one of the most common causes of pipeline failure, however, little test data are available for higher grade steels. This paper presents the results of simulated excavator impacts on X120 pipe, and compares the results to those obtained on lower grade materials and to those predicted by computer simulations.
Godin Lake Trial: X120 Field Welding
Authors: Biery Nicholas E. , Macia Mario L. , Appleby Robert J. T. , Fairchild Doug P. , Hoyt Doug S. , Dorling David , Horsley David
Published: October 2008

In February 2004, ExxonMobil and TransCanada PipeLines, Limited (TCPL) cooperated to construct a 1.6 km long segment of X120 pipeline near Wabasca, Alberta. The line included numerous mainline and tie-in welds, and an extra section of pipe was constructed in the field for later destructive testing to assess the characteristics of field welds. This line represented the first field application of welding procedures and consumables developed specifically for X120. The technologies used performed well; productivity and weld repair rates were better than expected, and the properties of these welds made in challenging conditions compare well with development welds made under controlled “shop” conditions.
Cross-Weld Tensile Properties of Girth Welds for Strain-Based Designed Pipelines
Authors: Bowker J. T. , Gianetto J. A. , Shen G. , Tyson W. , Horsley D.
Published: October 2008

For strain-based designed pipelines it is important to understand the relative tensile properties of both weld metal and pipe material in the pipe axial direction. The evaluation of weld metal tensile properties has typically involved extracting all-weld-metal tensile samples in the direction of the weld. In this study an evaluation of the application of “waisted” tensile samples to generate data has been conducted. Initial studies focused on finite element analysis to generate geometry factors for a range of specimen configurations to correct for the level of stress triaxiality. These factors were then applied to samples extracted from X70 and X100 pipe material to establish the validity of this approach. It was shown that, regardless of the radius of waisted specimens, very good agreement was obtained between the geometry-factor-corrected stress-strain curves and those generated from standard test specimens at true strains above 0.02. To achieve a better agreement between the corrected and standard tensile curves in and around yield it was necessary to use samples with a large radius (9 mm) where the stress concentration was low. Finite element analysis provided supporting evidence with respect to the effect of stress concentration associated with different specimen radii on the yielding pattern. These waisted samples were used to measure the tensile properties in all-weld-metal and cross-weld-metal directions for an X70 double joint (DJ) weld and an X100 mechanized pulsed gas metal arc (P-GMA) weld. Waisted samples taken from the double joint weld on X70 with radii of 3 mm and 9 mm showed no difference with respect to their orientation. Once stress-strain behaviour was corrected for geometry, the curves were in excellent agreement with the standard test specimens above 0.01 true strain in the case of the sample of radius 3 mm and for the whole curve for the sample with radius 9 mm. An assessment of the X100 weld identified a small difference between all-weld-metal and cross-weld-metal directions, with the latter displaying a lower stress between yielding and 0.03 true strain. The use of waisted samples of larger radius generated much better agreement with the standard specimens associated with their lower stress concentration. Because of the finite weld width, consideration needs to be given to the extent to which the reduced section may extend beyond the weld and the potential effect of mismatch in strength.
Management of Pipeline Dents and Mechanical Damage in Gas Pipelines
Authors: Warman David J. , Johnston Dennis , Mackenzie John D. , Rapp Steve , Travers Bob
Published: October 2008

This paper describes an approach used by Duke Energy Gas Transmission (DEGT) to manage dents and mechanical damage as part of its overall Integrity Management Plan (IMP). The approach provides guidance in the process for evaluating deformation anomalies that are detected by high resolution magnetic flux leakage (HR-MFL) and multi-channel geometry in-line inspection tools, the process to determine which deformations will be selected for excavation, the process to conduct pipeline field excavations, assessments, and repairs for pipeline integrity purposes. This approach was developed, tested and fully implemented during pipeline integrity work over a two year program involving over 1,100 miles of HR-MFL and 900 miles of geometry in-line inspection. Integration of data from high resolution ILI tools (HR-MFL and multi-channel deformation tools) was used to identify and characterize dents and mechanical damage in the pipeline system. From subsequent field assessments and correlation with ILI results, the processes were refined and field procedures developed. The new guidance provided in the 2003 edition of ASME B31.8 was used as the governing assessment criteria.
Low-Constraint Back-Bend Test of High Strength Steels: Crack Driving Force Calibration
Authors: Liu Ming , Wang Yong-Yi
Published: October 2008

It has been well-established that the experimentally measured toughness of materials depends on the crack-tip constraint levels. Accurate assessment of the integrity of real structures requires that the laboratory tests be conducted at similar constraint levels as those experienced by the structures. Conventional laboratory tests are usually designed at high constraint levels to obtain “conservative” toughness values. However, pipelines usually experience low-constraint loads; therefore the assessment results using the conventional laboratory test data can be overly conservative. Back-bend specimen is designed as a low-constraint laboratory test. To obtain the fracture toughness from the test, it is necessary to develop a correlation between the crack driving force, i.e. the crack tip opening displacement (CTOD), and the overall load and displacement. A semi-analytical correlation equation for back-bend tests is presented in this paper. The equation is based on the slip-line theory which was originally developed for rigid-perfectly plastic materials under plane strain conditions. The equation has been extended to take account of the elasticity, yield strength, and strain hardening of the materials. The geometry factors such as the ligament thinning and finite thickness are also investigated. The predicted CTOD driving force by the correlation equation shows a good match with the finite element calculations for a wide range of material properties and specimen dimensions.
Stress Intensification and Crack Growth in the Presence of Dents on Pipelines
Authors: Been Jenny , Carroll Blair , Dinovitzer Aaron , Sutherby Robert
Published: October 2008

Historically, ruptures in near-neutral pH SCC environments on gas transmission pipelines have been associated with some kind of stress raiser, generally the long-seam weld, corrosion, or dents/gouges. The current work provides an assessment of the effect of dents on environmental cracking. A dent assessment model was combined with a recently developed crack growth rate model to simulate crack growth in high-stressed areas caused by the presence of a dent. The work suggests that unrestrained dents (indenter removed) provide higher stresses and result in faster crack growth than restrained dents (indenter held in place). A dent in a lower ductility, higher strength X-65 steel further promoted the formation of high stresses and crack growth. Small crack growth and crack growth on gas lines, when governed by a strain rate based crack growth mechanism, may be less sensitive to dent parameters than crack growth governed by corrosion fatigue. It should be noted that neither the dent assessment model nor the crack growth model have been fully validated. Further work using elastic-plastic Finite Element Analysis is needed to determine more accurately the extent of stress intensification of a crack growing in or near a dent.
Simplified Methods for Predicting the Stress-Strain Response of Hoop Wound Composite Reinforced Steel Pipe
Authors: Wolodko John
Published: October 2008

Fiber reinforced composite steel pipe is a potential alternative to conventional pipe materials, particularly for high pressure applications. While composite-steel hybrids offer a number of advantages, the design (or sizing) of the pipe requires the use of specialized analysis tools such as finite element modeling. The objective of this paper is to provide a series of closed-form equations which can be used to determine the stress-strain response for both the composite and steel components. Coupled with an appropriate failure criteria, these simple equations can be used for preliminary design and sizing purposes. Solutions are developed for fixed (restrained) ends and free (unrestrained) boundary conditions. Predictions are compared to advanced finite element models and experimental data to demonstrate their utility.
Comparison of Technologies for SCC Threat Validation and Assessment
Authors: Kariyawasam Shahani , Larios Jose , Colquhoun Iain
Published: October 2008

Recent incidents and consequent regulatory processes have increased awareness and concern regarding the threat of SCC (Stress Corrosion Cracking). Throughout the world research organizations and operators are building processes to both validate the presence of SCC and, where present, assess the pipeline for the SCC threat. SCC is not a concern in the majority of the pipelines, however for the pipelines that do have SCC it is one of the major threats leading more often to ruptures than leaks. Therefore validating the presence of SCC is an important step in threat management. Where SCC threat has not been discovered operators need to check for susceptibility and where susceptible validate the threat of SCC. The validation of SCC threat does not require all the measurement capabilities required to assess the pipeline once cracking is discovered. This paper describes the benefits and limitations of ILI inspection, direct assessment (SCCDA), and hydrostatic testing in terms of detection, false indication, classification, measurement accuracy of defect sizes, and life-cycle assessment. The technologies are critically reviewed and compared using quantitative probabilistic methodologies. Case studies are simulated to demonstrate how the different technologies perform to provide immediate and future integrity. The performance characteristics are discussed and combined to form a comprehensive crack management plan that can provide safety, regulatory compliance and related economies to the crack management process.
Mechanical Properties of Cold Bend Pipes
Authors: Sen M. , Cheng J. J. R. , Murray D. W. , Zhou J.
Published: October 2008

Cold bends are frequently required in energy pipelines in order to change the vertical and horizontal orientation of the pipeline route. They are produced by plastically bending a pipe joint in a cold bending machine, by creating a series of uniformly spaced kinks. This procedure acts to reduce the moment capacity and buckling strain of the pipe, and studying the changes in pipe properties caused by cold bending is valuable in assessing the level of this strength reduction. Accordingly, the initial imperfections and material transformations of five full-scale cold bend pipes were assessed in this research program. The imperfections were measured at several locations around the circumference of the specimens, along the entire bend length. It was determined that the distribution of imperfections was similar in shape to a sine function, and their amplitude ranged from 0.3 to 1.0 mm. Tension coupon tests were conducted on material from the intrados, extrados, and virgin material of the specimens. It was revealed that the extrados material exhibited an increase in yield strength due to work hardening, and that the intrados material demonstrated a reduction in yield strength due to the Bauschinger Effect. It was established that the imperfections, and material transformations in the specimens were predominantly unaffected by the kink magnitude or spacing that was employed during the cold bending procedure.