bluuebunny/crossref_metadata_2025 huggingface dataset:
SAWL 485 for 48” Offshore Application in Thickness up to 41 mm
Authors: Schwinn Volker , Parunov Alexander , Bauer Ju¨rgen , Stepanov Pavel
Published: July 2009

Vyksa Steel Works (VSW), part of United Metallurgical Company (OMK), has manufactured a trial batch of large diameter pipes for subsea pipelines in accordance with the DNV-OS-F101 standard and the specification of the Nord Stream project. The plates were produced by Dillinger Hu¨tte (DH). The batch included 1,220 mm (48″) diameter pipes of steel grade SAWL 485 (X70) with a wall thickness of 33 mm and 36 mm. All the requirements were met and OMK/VSW became Russia’s and the CIS’s first qualified producer of subsea pipes in accordance with DNV-OS-F101. In order to meet these high-class property requirements for thick wall pipes a successful development program was performed. The development program is outlined and the test results are explained. As a further consequence of the successful qualification work VSW became one of the two suppliers for the world’s largest and first 48″ diameter pipe subsea pipeline project (Nord Stream). Pipes will be supplied for the most sophisticated segment with wall thicknesses of 30.9 mm, 34.6 mm and even 41.0 mm. Results of manufacturing procedure qualification testing (MPQT) and start of production are presented.
Compressive Strain Limits of High-Strength Linepipes
Authors: Suzuki Nobuhisa , Zhou Joe , Toyoda Masao
Published: July 2009

Regression formulas are developed in order to predict the critical compressive strain of X80 linepipes subjected to pure bending. The regression formulas were derived using an analytical solution and two conversion functions. The analytical solution was previously proposed to calculate the critical compressive strain of a pipe subjected to axial compression, where hardening properties are taken into account. The original analytical solution was rewritten to include a strain-hardening exponent. Two conversion functions are defined to connect two critical compressive strains of a pipe under different loading conditions. One is a pressure-effect conversion function which connects two critical compressive strains of a pipe without and with internal pressure, respectively. The other is a compression-bending conversion function which also connects two critical compressive strains of a pressurized pipe which is subjected to compression and bending. The regression formulas were obtained using the improved analytical solution and the two conversion functions. The regression formulas yield good agreement with FEA results especially for high-strain linepipes.
On the Design of an Operator Training Simulator in a South African Pipeline Network
Authors: Liebenberg Marais , Magalha˜es Claudia C. , Bueno David Eduardo G. P.
Published: July 2009

Pipeline operating companies require skilled employees to operate their pipeline network with safety and meeting the customer’s nominations, seeking to reduce costs and preserve the environment. A useful pipeline operational functionality designed to train, qualify and certificate operators to perform those tasks successfully is the Operator Training Simulator (OTS). OTS reproduces operational scenarios without the necessity of being inside the control room, allowing the trainee to simulate daily operational routines such as pumps startup/shutdown, valves opening/closing, slack line prevention, leak identification and others. This work presents a detailed description of an Operator Training Simulator to be employed in a South African pipeline network, comprising around 2500km of pipes handling multi-products and crude oils. The designed OTS shall allow the trainee to have exactly the same environment the operator has at the control room, including machines, screens and functionalities like Leak Detection as well as Batch/Pig Tracking. Two modes of OTS operation are cited: an offline and an online one. The offline mode performs any simulation from a configured offline scenario. On the other hand, online mode allows the trainee to see actual real time data on a passive mode (without interfering with real operation). Besides, it can get a desirable real time scenario and continue from that point in an offline way, i.e. loading a start state scenario. Finally, it shall be presented and discussed the interaction between the OTS and the ability to reproduce local station operational sequences. The gain obtained with such interaction, as well as the consequent introduced complexity, is also commented.
SCC Integrity Management for a Gas Pipeline Using a Combined Approach EW ILI, Calibration Excavation and FAD Analysis
Authors: Gao Ming , Kania Richard , Garth Clint , Krishnamurthy Ravi , Sen Millan , Fairbrother Stuart
Published: July 2009

Gas pipeline operators face significant challenges with respect to quantifying and managing SCC in gas pipelines. Following SCCDA excavations, SCC was found on one of TCPL’s gas pipelines. A combined approach was then introduced to manage SCC, which consists of comparison of two consecutive Elastic Wave Inspection Runs prioritization of excavations, refinement of ILI tool sizing performance, and remediation using a Fracture Mechanics based FAD (Failure Assessment Diagram) methodology. The overall process from the ILI inspections to crack growth comparison, as well as integrity assessment and rehabilitation has demonstrated the effectiveness of the approach for SCC integrity management. In this paper, the history of the subjected pipeline segment is described. The concept of the approach is presented. The process of applying the approach to manage the pipeline integrity is outlined with examples for demonstration. The potential of utilizing this approach and process to other pipelines and crack detection ILI tools in gas pipelines in terms of POI, sizing, and excavation is discussed.
Revised Corrosion Management With Reliability Based Excavation Criteria
Authors: Kariyawasam Shahani , Peterson Warren
Published: July 2009

For decades, TransCanada Pipelines has used inline inspection (ILI) to manage the threat of corrosion on gas pipelines. Immediate integrity was addressed using rupture pressure ratio and leak criteria, and future integrity was addressed using a growth assessment. However, a review of excavations based on predictions of defect growth shows that few excavations actually lead to repairs. This study investigated the areas of undue conservatism in both the integrity assessments and the excavation criteria. All aspects of the immediate and future integrity assessment based on ILI were examined. All relevant uncertainties were accounted for in calculating the reliability of the pipeline. A new basis of defining excavation criterion was established based on a reliability assessment and calibration. This criterion was validated against previous ILI based excavations which reveal the features that actually required repair. The criterion was also compared to reliability based criteria recommended in Annex O of the CSA Z662 which gives guidelines for Reliability Based Design and Assessment. This paper addresses the practical limitation of data and presents methods for extracting best information from available data. Case studies that demonstrate the application of the revised assessment method and criterion are also discussed.
Internet-Oriented Method of Reliability Analysis of On-Shore Pipelines With Growing Defects
Authors: Timashev S. A. , Malyukova M. G. , Polouian L. V. , Bushinskaya A. V.
Published: July 2009

The results of a holistic study are presented dedicated to developing an Internet-based reliability and remaining life assessment for on-shore main pipelines with growing defects. The reliability analysis is carried out using five types of failure pressure models. Two types of limit state functions are used. The limit state functions (LSF) are comprised of nine parameters that are considered as random variables (RVs). These RVs describe the pipe and defect geometry, rate of axial and longitudinal corrosion, strength properties of the pipe wall material, operating pressure. The main reliability analysis is conducted using the Gram-Charlier-Edgeworth (GCE) method of expansion of the limit state function, which can be considered as a generalization of the FOSM and the Taylor series expansion methods, as it is capable of using arbitrary probability density functions (PDF) and takes into account the third and the fourth central moments of the non-Gaussian PDFs. Five types of PDFs are used in the analysis. The Monte Carlo simulation method was used for verifying the results obtained by the G-C-E method. The reliability of each cross-section of the pipe containing a defect is calculated, as well as the reliability of a pipeline segment or the pipeline as a whole. Sensitivity is investigated of pipeline reliability to the above nine parameters and their statistical characteristics (PDFs), which describe pipeline and defect geometry, corrosion rates, pipe wall material properties and operation mode. The expected number and volume of repairs are calculated using some values for the ultimate permissible pipeline failure probability. Comparative study on the computer time needed for calculation of reliability by the G-C-E and the M-C methods is conducted in relation to their applicability for remote Internet usage. A brief description is given of the Internet-based software that implements the described above technology.
Enhancement of Collapse Resistance of UOE Pipe Based on Systematic Exploitation of Thermal Cycle of Coating Process
Authors: Liessem Andreas , Groß-Weege Johannes , Zimmermann Steffen , Knauf Gerhard
Published: July 2009

The present paper discusses recent results of an ongoing study on the effect of thermal treatment on collapse strength of cold formed pipes, for instance those following the UOE production route. It has been recognized that thermal treatment as encountered during thermal cycle of pipe coating processes may compensate the reduction of compressive yield strength owing to cold plastic deformation induced during forming. This effect has been systematically analyzed. Enhancement of collapse resistance exploiting the thermal cycle of coating process was studied based on experimental evidence, Finite Element simulations as well as theoretical analysis. It is herein shown that appropriate thermal treatment manifests itself positively with respect to compressive yield strength, leading to significantly improved collapse pressures. As a result fabrication factors of one and even higher may be applicable.
The Practical Application of Fracture Control to Natural Gas Pipelines
Authors: Widenmaier K. A. , Rothwell A. B.
Published: July 2009

The use of high strength, high design-factor pipe to transport natural gas requires the careful design and selection of pipeline materials. A primary material concern is the characterization and control of ductile fracture initiation and arrest. Impact toughness in the form of Charpy V-notch energies or drop-weight tear tests is usually specified in the design and purchase of line pipe in order to prevent large-scale fracture. While minimum values are prescribed in various codes, they may not offer sufficient protection in pipelines with high pressure, cold temperature, rich gas designs. The implications of the crack driving force arising from the gas decompression versus the resisting force of the pipe material and backfill are examined. The use and limitations of the Battelle two-curve method as the standard model are compared with new developments utilizing crack-tip opening angle and other techniques. The methodology and reasoning used to specify the material properties for line pipe are described and the inherent limits and risks are discussed. The applicability of Charpy energy to predict ductile arrest in high strength pipes (X80 and above) is examined.
Development of a Multi-Pass Weld Transverse Cracking Test
Authors: Pussegoda L. N. , Begg D. , Lazor R.
Published: July 2009

Transverse weld metal cracking has been occasionally observed in girth welds on large diameter thick wall pipelines that utilize high strength steels. The cracks are typically in the last one or two layers of the weld, and are not necessarily surface-breaking cracks. These cracks are a serious concern as they are parallel to the pipe axis, an orientation that is perpendicular to the hoop stress due to pipeline operation. Weldability tests have been developed or modified in recent years that were intended to specifically examine the tendency for cracking in multipass welds. Test methods are somewhat similar in that a multilayer full-thickness weld is deposited in a restrained (or self-restrained) weld joint, followed by examination to determine the occurrence of cracking after a specified delay period. The primary objective of this study has been to develop a test method that can then be used to compare the incidence of cracking to hydrogen-induced cracking prediction methods (for example delay time), also allowing one to develop welding conditions that would avoid cracking of field welds during pipeline construction. This could be achieved in two ways; a) determining delayed cracking time, and b) assessing the effects of pre-heat and interpass temperature. The test has been successful in producing transverse cracks in the top layers of the fill passes, similar to the cracking that has been observed on thick weldments in high strength steels. The test has been instrumented to assess the restraint level and also to attempt to detect cracking. The cracking has also been detected by UT and subsequent sectioning.
Deformation Behavior Prediction of X80 Steel Line Pipe and Implication on High Strain Pipe Specification
Authors: Chen Hongyuan , Ji Lingkang , Gong Shaotao , Gao Huilin
Published: July 2009

The use of strain based design in pipeline technology has been widely discussed during the last decade for pipelines in harsh environment. In such cases pipelines should be designed based on strain criterion. Strain based design poses a number of challenges, particularly on pipe size and material properties. This paper presents preliminary studies on prediction of buckling strain and buckling mode for X80 high-strain line pipe by finite element methods based on full-scale test. The effects of several parameters such as internal pressure, material properties pipe size and geometric imperfection, were investigated to predict the critical strain for 48″ diameter line pipe under compression and pure bending with 12MPa internal pressure. Material parameters of a specification for high strain line pipe were analyzed to promote its application in the 2nd West-East pipeline of China National Petroleum Corporation.
An Analysis of the Stresses Incurred in Pipe During Laying Operations
Authors: Scott C. , Etheridge B. , Vieth P.
Published: July 2009

It is common practice during the construction of underground pipelines that pipe sections are welded together at surface level and then lowered into a pre-dug trench. Lowering of the pipeline into the trench incurs bending and/or torsional stresses that are not typically considered during the design of the pipeline. Current industry guidelines recommend the pipelines be lowered into the trenches with care in order to avoid cracking of the pipe, or yielding that could lead to residual stresses and distortion. There are currently no formal guidelines on how to minimize these stresses, or estimates of the magnitude of stresses associated with these operations. The stresses incurred during the laying of pipe can be estimated using simple beam bending and torsion equations. One can simplify the analysis by assuming the pipeline is either a cantilever with a given load or deflection at one end, or, a beam with given loads, deflections and rotations at both ends. The choice of boundary conditions influences the calculated stresses, and can be considered appropriate for different pipe laying operations. If a pipeline is moved laterally during the laying operations one must consider the associated torsional stresses. The combination of bending and torsional stresses will lead to different stress states on different sides of the pipe, some of which may result in cracking or yielding. The goal of this work is to develop a framework for estimating the stresses incurred in pipe during laying operations, as a function of pipe length, deflection, diameter and wall thickness. This will allow guidelines to be developed that will allow construction crews to ensure that pipelines are laid with minimal damage. A variety of analyses has been considered during the course of this work and is presented in this paper. It is expected that discussion of these analyses with industry representatives will lead to improved construction protocols.
Development of a Low Application Temperature FBE Coating
Authors: Pratt Jennifer K. , Mallozzi Meghan L.
Published: July 2009

Fusion bonded epoxy (FBE) coatings have been used on pipelines as protection against corrosion for over 40 years. They have been used as a stand-alone product in single layer systems and as a primer in dual and three layer systems. To achieve optimal performance, current FBE products require application temperatures in excess of 230°C for single layer systems and 200°C for three layer systems. The introduction of high strength steels such as X80, X100 and X120 for use in pipeline construction has presented a challenge to the industry in terms of the availability of suitable coating systems. High strength steels (particularly grades X100 and greater) cannot withstand pre-heat temperatures in excess of 200°C. Exposure to the high heat required when coating with a typical FBE product results in the degradation of some of the key properties of these high strength steels. This paper will discuss the development and performance of a new generation FBE coating that can be applied at temperatures as low as 180°C for single layer systems and as low as 150°C for multi-layer systems. Performance of this new product will be compared to one of the best performing commercially available FBE products applied at 240°C.
Geotechnical Activity and Third-Party Damages
Authors: Peixoto Luiz Felipe M. , Sousa Angelo J. P.
Published: July 2009

This article presents an accident that took place at a Petrobras Transporte S.A. - TRANSPETRO pipeline right-of-way (ROW), involving one of its pipes: ORSUB (Southern Bahia diesel, gasoline and LPG 360km Φ10″/Φ8″ pipeline). Basically, the mentioned occurrence shows the influence of collapses in third-party constructions in TRANSPETRO facilities’ integrity. The event in Bahia consisted in the exposure of 70m of the pipeline, caused by a dam breach from a private property nearby. Due to the failure, the water from the reservoir streamed through the terrain, dragging and destroying whatever it came across (small houses wrecks, torn trees and crops were found along the water track), reaching the pipeline ROW around 700m from its origin, in a narrow rocky valley, hence gaining power and speed, and swept away the soil that covered the pipe, provoking a 70m long, 2m deep and 5m across opening. The fact that the water ran along the pipe and did not hit it perpendicularly led to minor damages. The consequences, whether it happened otherwise, would be much more serious, especially in an environmental way, as this happened within the limits of a cocoa and banana farm, with a creek not even 10m away. A number of irregularities were found in the dam wreck, such as under dimensioned valve and intake structure and the lack of a spillway were the main reasons that caused the breach. Major events like this bring to attention the fact that some farmers build their own dams (within the limits of their properties) with no expertise on the matter whatsoever and often without any professional assistance. This represents a tremendous jeopardy for almost everything existing downstream the dam, such as crops, cattle, houses and people. After the dam rupture, the geotechnical engineers from TRANSPETRO started a study which mapped 35 dams only in ORSUB ROW neighbourhood, at least 3 of them were classified as critical. A hydrodynamic simulation, based on the accident described here, is being developed, so the engineers can predict what might happen to the pipeline ROW and, in a worst case scenario, to the pipe itself, whether another dam failure occurs.
Nano-Technology for Improved Dual Layer Performance
Authors: Mallozzi Meghan , Kehr J. Alan
Published: July 2009

Fusion bonded epoxy (FBE) powders and liquid resins are commonly used for corrosion protection of steel pipeline and metals used in the oil, gas and construction markets. The FBE coating should have excellent physical properties to minimize damage during transit, installation and operation. Damage to the coating leads to higher potential corrosion sites on the metallic surface and could ultimately lead to a decrease in service life. During transportation, cinders and grit can get between pieces of the coated substrate so the coating should have superior penetration and abrasion resistance. During installation, the coating should have good impact resistance from back fill or handling equipment. Often the coated substrate is bent during installation, for example to fit the contour of the land, and should be flexible enough to prevent damage to the coating. Once in operation, the coating can be exposed to water and other chemicals and should have good resistance to these chemicals and good cathodic disbondment. There are several ways that have been used conventionally to attempt to make a FBE coating more resistant to mechanical damage. In one conventional approach, the thickness of the overall coating is increased to provide added absorption of impact and abrasion. However, as the thickness of the coating increases the flexibility of the coating decreases. Another conventional approach to enhance damage resistance is to add an abrasion resistant overcoat that has a high filler loading to increase abrasion resistance and decrease impact damage. As with the thicker coatings, higher filler loadings can dramatically decrease the flexibility of the FBE coating. As mentioned above, flexibility of the coating is very important during installation and must be tolerant to bending. Currently available damage resistant coatings force the user to compromise between toughness and flexibility. This paper will present a novel FBE coating system using nano-technology that would incorporate damage resistance AND flexibility.
Development of Optimized Weld Metal Chemistries for Pipeline Girth Welding of High Strength Line Pipe
Authors: Fiore Susan R. , Gianetto James A. , Hudson Mark G. , Vaze Suhas , Khurana Shuchi , Bowker John T. , Dorling David V.
Published: July 2009

The primary objectives of this program were to provide a better understanding of the factors that control strength and toughness in high strength steel girth welds and to develop optimized welding consumables and welding procedures for high strength pipelines. The initial work on the program involved developing cooling rate models so that optimized weld metal compositions for high-strength pipelines could be developed, ensuring that the ideal balance of strength and ductility, together with tolerance to process variations and resistance to hydrogen cracking is achieved. The model, which was developed under a companion program, uses a two-dimensional finite element approach. Complete details can be found in Reference [1]. The model predicts the cooling rates during various weld passes in narrow groove welding of X80 and X100 pipes. Using this model, along with experimental datasets, a neural network model was developed which has been used to predict weld metal properties for various weld metal compositions. Based on the predictions, eight target compositions were selected and were manufactured by one of the team partners. The results of mechanical property testing showed that it was possible to develop weld metal compositions which exceeded the target yield strength of 820 MPa and also provided excellent toughness (>50J at −60°C). It was also found that the weld metal yield strength measured close to the ID of the pipe was significantly higher than that which was measured closer to the OD of the pipe. Complete mechanical property results, including results for round-bar and strip tensiles, CVN impact toughness, microhardness and more, are presented.
Development of a Hybrid Laser Arc Welding System for Pipeline Construction
Authors: Begg D. , Beynon G. , Hansen E. , Defalco J. , Light K.
Published: July 2009

The construction costs for a northern pipeline will represent approximately half of the project costs and will be extremely challenging with much of the work being carried out in harsh winter conditions at temperatures, as low as −55°C. The welding costs are a major component of the overall construction costs and industry continues to seek future generation pipeline welding technologies to achieve additional improvements in productivity and enable significant cost savings. The current state-of-the-art welding processes for onshore pipelines involve mechanized gas metal arc welding (GMAW). The dual tandem pulse GMAW process provides the greatest productivity to date with four welding arcs operating simultaneously on each welding carriage. Based on the progression of laser welding technology, it is highly likely that the next generation of automated pipeline welding equipment will be built around hybrid laser arc welding (HLAW). The primary objective of this project is to develop, test, and validate a “field ready” HLAW system for full circumferential girth welding of large diameter (NPS30 and above) high strength pipe. The system is based on both robotic and direct clamp-on platforms where potential applications include double jointing operations in pipe mills and as well for onshore and offshore pipeline construction projects. The pipe grades evaluated include both X80 and X100, with wall thicknesses of 10.4mm and 14.3mm, respectively. Lab trials include high speed root pass, high speed root pass with laser assisted GMAW for fill and cap passes, and, single pass complete joint penetration girth welding. This paper discusses the approach to the development of the HLAW system, however at the time the paper was submitted no mechanical testing or system validation trials had been completed. It is expected results will be available for the conference presentation.
Innovative Technology to Identify, Map and Plan for the Management and Integrity of Pipeline Assets
Authors: Smith Mark A. , Ward Linda M.
Published: July 2009

The need to develop an accurate, autonomous, and economical pipeline mapping system capable of use within a wide range of pipeline sizes, configurations, operating pressures and specific uses was accomplished, resulting in the manufacture of a series of unique inertial-based smart probes. This paper reviews the innovative technology developed to identify, map and plan for the management and integrity of pipeline assets through use of the smart probe technology. Today’s owners and operators of the world’s pipeline infrastructure are faced with competitive pressures and regulatory constraints which are creating increasingly stringent demands to manage our pipeline assets in an efficient and responsible manner. Billions of dollars will be spent over the next 20 years to rehabilitate the world’s infrastructure and oil and gas pipeline systems. “Out of sight – out of mind” no longer applies. Now, more than ever, pipeline owners and operators need solid information to plan for the challenges of tomorrow.
Underwater Habitat Clamp (UHC): An Innovative Partnership in Underwater Pipeline Repair
Authors: Berge Mark , Birdsall Lance , Erickson Adam , Vernon Tanya
Published: July 2009

We present a hybrid solution (UHC) for multi-parameter underwater pipeline repair. The UHC project involved three phases 1) initial assessment and temporary repair 2) design of novel solution taking consideration of all parameters and 3) implementation. The resulting vessel enables repairs on pipelines 6″ to 36″ in diameter and to depths of up to 33′, under one atmosphere of pressure or in a true hyperbaric environment. In the project, the UHC was lowered into position, hydraulically clamped around a pipeline, sealed to the pipeline, counterweighted to negate buoyancy, and pumped dry yielding a submerged dry habitat; equipped with leg support from the river bottom and anchor attachment points to compensate for current. Two manways extend to the surface of the water. Air movers, rescue and other equipment are installed and the UHC is occupied by confined space trained personnel, welding technicians and inspectors. The pipeline was then repaired with no compromise in integrity or need to take the pipeline out of service.
LDS Trials: A Dedicated Tool to Enable Realistic Leaks and Measure the Relevant Variables
Authors: Baptista Renan Martins , Dittz Carlos Henrique S. , dos Santos Ramon Pereira , Fernandes Renato , Fracasso Paulo , Almeida Rui
Published: July 2009

Certificate a LDS is a complex task. It deals with parameters specified by international acknowledged norms (e. g. the ones of API [1][2] such as reliability, sensitivity and accuracy, usually put in a contract, and audited in a SAT (Site Acceptance Test). The two most important ones respectively, reliability (the most important one) and sensitivity: The first deals with the ability of the system reliably detect any type of leakage, without false alarms, and also without allowing any leak undetected. The second effectively measures the price to detect a leak in terms of accumulated leaked fluid volume up to detection, and the limits of the system (essentially the minimum detectable leak). This paper describes a hardware testing tool (here called a leak trial skid/station) to be used in leak trials, as well as a related testing procedure. The tool is designed to generate both slow and immediate leaks and measure, track (in real time) and record the most important variables like pressure, temperature and flow rate, at the leaking point. Its usage was initially conceived for a gas pipeline, but can be adapted to be used in a liquid one as well. Finally, a procedure for a gas trial is also approached, in a way to profit from the main designed elements and this way provide the core elements requested by the certification process.
Dealing With Uncertainty in Pipeline Integrity and Rehabilitation
Authors: Mora Rafael G. , Murray Alan , Paviglianiti Joe , Abdollahi Sara
Published: July 2009

Determining the ongoing fitness for service of an energy transmission line, whether in response to an incident, or as part of a due diligence review involves conducting an engineering assessment. Many pipeline standards and regulations refer to such assessments without providing much detail as to their expected extent or proof of adequacy. This lack of clarity creates difficulties for both the pipeline operator and its governing regulatory body. This paper discusses measurement, modeling, and interpretation errors that could affect the validity of integrity assessments. As a first phase of this development, the paper introduces a case study that identifies the uncertainty effects of in-line inspection accuracies during the criticality assessment of reported metal loss anomalies that could fail by leak or rupture., Some technical approaches are proposed on how to deal with uncertainty in the development of integrity verification and rehabilitation programs when using in line inspection data.
Predicting the Brittle-to-Ductile Transition Temperatures for Surface Cracks in Pipeline Girth Welds: It’s Better Than You Thought
Authors: Wilkowski Gery , Rudland David , Shim Do-Jun , Horsley David
Published: July 2009

A methodology to predict the brittle-to-ductile transition temperature for sharp or blunt surface-breaking defects in base metals was developed and presented at IPC 2006. The method involved applying a series of transition temperature shifts due to loading rate, thickness, and constraint differences between bending versus tension loading, as well as a function of surface-crack depth. The result was a master curve of transition temperatures that could predict dynamic or static transition temperatures of through-wall cracks or surface cracks in pipes. The surface-crack brittle-to-ductile transition temperature could be predicted from either Charpy or CTOD bend-bar specimen transition temperature information. The surface crack in the pipe has much lower crack-tip constraint, and therefore a much lower brittle-to-ductile transition temperature than either the Charpy or CTOD bend-bar specimen transition temperature. This paper extends the prior work by presenting past and recent data on cracks in line-pipe girth welds. The data developed for one X100 weld metal shows that the same base-metal master curve for transition temperatures works well for line-pipe girth welds. The experimental results show that the transition temperature shift for the surface-crack constraint condition in the weld was about 30C lower than the transition temperature from standard CTOD bend-bar tests, and that transition temperature difference was predicted well. Hence surface cracks in girth welds may exhibit higher fracture resistance in full-scale behavior than might be predicted from CTOD bend-bar specimen testing. These limited tests show that with additional validation efforts the FITT Master Curve is appropriate for implementation to codes and standards for girth-weld defect stress-based criteria. For strain-based criteria or leak-before-break behavior, the pipeline would have to operate at some additional temperature above the FITT of the surface crack to ensure sufficient ductile fracture behavior.
Exploring to Predict Pipeline High-PH SCC Crack Growth Rates
Authors: Song Fengmei
Published: July 2009

A mathematical model was developed that enables the prediction of crack growth rate (CGR) of high pH stress corrosion cracking (SCC) of buried steel pipelines. The goal of developing the model is to use it to understand the relative CGRs of SCC-susceptible locations along a pipeline, so that a more reliable prioritization of these locations for direct examination becomes possible. The model, in its current status, was used to predict CGRs using two methods, with the anodic current density at the crack tip being expressed by: (1) the anodic polarization curve, and (2) the Butler-Volmer equation. The merits and shortcomings of these two methods were analyzed. The former method tends to yield large CGRs, while the latter has the flexibility to predict low CGRs. Even though the high pH chemistry in the disbonded region outside of a crack is often associated with a concentrated carbonate and bicarbonate solution buffer, the model predicted that when the CGRs are large, the predicted chemistry and potential at the crack tip can vary significantly with time, while they are somewhat stable when the CGRs are small.
A Novel Two-Phase Gas\Liquid Slug Flow Measurement System Using a T-Junction Separator and Ultrasonic Measurements
Authors: Khalifa Khalifa M. , Sanderson Mike L.
Published: July 2009

Over the last decade, the development and deployment of in-line multiphase flow metering systems has been a major focus worldwide. Accurate measurement of multiphase flow in the oil and gas industry is difficult because it occurs in wide range of flow regimes and multiphase meters do not generally perform well under the intermittent slug flow conditions which commonly occur in oil production. A novel ultrasonic multiphase metering concept has been proposed and investigated which measures the flow rates of the liquid and gas phases from ultrasonic measurements made in two different flow regimes – partially separated and homogeneous — in the same measurement system and fuses the data from the different flow regimes to obtain improved overall measurement accuracy. The system employs a partial gas/liquid separation using a T-junction configuration and a combination of Doppler and cross correlation. The partially separated flow regimes uses ultrasonic cross correlation measurement for the liquid flow measurement which has gas entrained within it. The homogeneous regime employs ultrasonic Doppler method. This approach has been tested on water/air flows on a 50mm facility in the Department of Process and Systems Engineering. The liquid and gas flowrate measurements using the proposed techniques were compared with a reference measurement and good agreements between these two measurements were obtained with error ranging from ± 2% and 10%, respectively. Such a performance offers the potential for an in-line multiphase flowmeter with improved performance.
Development of a Highly Efficient Diesel Engine Boiler System With a Secondary Combustor
Authors: Lee D. H. , Cha Y. S. , Lee J. S. , Lee D. K. , Park H. J. , Bae G. Y.
Published: July 2009

We have developed a highly efficient boiler system using the 930 cc diesel engine. In this system, the co-generation concept is utilized in that the electric power is produced by the generator connected to the diesel engine, and waste heat is recovered from both the exhaust gases and the engine itself by the finned tube and shell & tube heat exchangers. A specially designed secondary combustor is installed at the engine outlet in order to completely reignite the unburned fuel from the diesel engine, thereby improving a system’s efficiency as well as reducing air pollution due to exhaust gases. It is found that the total efficiency (thermal efficiency plus electric power generation efficiency) of this system reaches maximum 94.4% which is about 20% higher than the typical diesel engine boiler system currently being used worldwide.
Case Study on the Remaining Life Analysis of a Power Generation Valve
Authors: Peters Daniel T. , Jones Eric , Berasi Mario
Published: July 2009

Many components in power plants are nearing the end of their useful life. Management of cracking in these components can be critical to the successful management of many power plants. The work here presents a case study of a success story of the analysis of one of these components. The paper here discusses the study of a valve that was originally scheduled for replacement during a recent outage. The work comprised of the examination and accurate sizing of the cracking inside the valve, stress analysis using cutting edge modeling for quick turn around, and advanced creep-fatigue life prediction calculations to give accurate predictions regarding the remaining life of the component. The project culminated in the ability of the valve, with proper care and monitoring to be continued in service for many years and eliminating the need to extend the previous outage.
Rotor Welding: TVA Experience
Authors: Best H. G. , Koss M. E.
Published: July 2009

TVA has a fleet of 59 units with 187 large steam fossil turbine rotors, 68 fossil generators, and 27 auxiliary turbine rotors, in-service. The original equipment manufacturers (OEM) rotors have three designs some welded, others are shrunk on disk, but the majority of the rotors are mono-block. TVA has worked with OEM’s, third parties, and with-in TVA to perform weld repairs on rotors. Rotor Problems requiring welding: 1. Journal/gland damage due to lubrication failure and/or wear. 2. Attachment area damage due to cracks or distortion. 3. Attachment area due to changes in design. In the TVA fleet there are approximately 20 rotors that have been welded. Most of these have been successfully operated, but there have been 3 failures of welded rotors that will be discussed. Allen Fossil Plant Unit 3 Intermediate Pressure–Low Pressure Single Flow Turbine Rotor: In 1992 this rotor had a failure of the Curtis Stage. The decision was made to have the rotor welded and change the number of blades. Westinghouse (the OEM) performed the design and weld repair. In 2000 the unit experienced vibration, the unit was disassembled, and the weld repair had failed at the fusion line. An investigation of the failure revealed the weld had not been located at the designed location and the actual location of the weld was in a high stress area. Gallatin Fossil Plant Unit 4 High Pressure Turbine Rotor: TVA designed an upgrade to the Rateau Stage to change from axial entry to a tri-pin attachment. This required the welding of the disk. During welding, with a third party, cracks resulted that extended into the base material. This failed and additional base material was removed before welding. After 8 years of operation the rotor experienced vibration, the unit was inspected, and the weld was found with creep cracks in the heat affected zone (HAZ). An investigation of the failure revealed the expanded weld build-up relocated the HAZ into a high temperature, high stress region of the rotor. Widows Creek Fossil Plant Unit 7 Boiler Feed Pump Turbine Rotor: The rotor experienced stress corrosion cracking (SCC) of the fifth stage during operation in 2003. The rotor was weld repaired and returned to service in 2006. After 5 months of operation the rotor experienced vibration, was inspected, and the welded fifth stage and the sixth stage had experience SCC failures.
Gas Turbine Part Load Performance Testing: Comparison of Test Methodologies
Authors: Schmitt Thomas P. , Clement Herve
Published: July 2009

Current trends in usage patterns of gas turbines in combined cycle applications indicate a substantial proportion of part load operation. Commensurate with the change in operating profile, there has been an increase in the propensity for part load performance guarantees. When a project is structured such that gas turbines are procured as equipment-only from the manufacturer, there is occasionally a gas turbine part load performance guarantee that coincides with the net plant combined cycle part load performance guarantee. There are several methods by which to accomplish part load gas turbine performance testing. One of the more common methods is to operate the gas turbine at the specified load value and construct correction curves at constant load. Another common method is to operate the gas turbine at a specified load percentage and construct correction curves at constant percent load. A third method is to operate the gas turbine at a selected load level that corresponds to a predetermined compressor inlet guide vane (IGV) angle. The IGV angle for this third method is the IGV angle that is needed to achieve the guaranteed load at the guaranteed boundary conditions. The third method requires correction curves constructed at constant IGV, just like base load correction curves. Each method of test and correction embodies a particular set of advantages and disadvantages. The results of an exploration into the advantages and disadvantages of the various performance testing and correction methods for part load performance testing of gas turbines are presented. Particular attention is given to estimates of the relative uncertainty for each method.
Technical and Economic Feasibility of a 5 MW Solar Photovoltaic (PV) Power Plant on Kauai, Hawaii
Authors: Lee Kenneth K.
Published: July 2009

This study presents the results of an initial assessment of the technical and economic feasibility of a 5 megawatts (MW) net Solar Electric Photovoltaic (PV) power plant on the Island of Kauai, Hawaii. It analyzes three potential PV based designs of the solar power plant — single-axis tracking flat plate, fixed flat plate, and two-axis tracking concentrating photovoltaics (CPV) based on the solar insolation on Kauai. Greenhouse gas (GHG) avoided, energy production projection, capital costs, operation & maintenance (O&M) costs, and the levelized cost of energy (LCOE) of each PV design is developed for comparison. Regardless of the PV technology, the following factors may position solar PV power plant as a competitive alternative to conventional fossil-powered power plant: • Recent technology advances have occurred in concentrating solar collectors increasing overall efficiency; • Use of renewable energy can lead to reduced greenhouse gas (GHG) emissions; • Fossil fuels (e.g. natural gas and oil) retail prices are near record highs, increasing electricity rates. The assessment results show that single-axis tracking flat plate PV system are best suited for sites in Kauai as they accommodate the intermittent cloud cover of the region while following the sun from dawn until dusk as it crosses the sky.
CFD Study on Vermiculite Injection System Optimization in a Cyclone-Fired Boiler
Authors: Yu Guanghui , Swanson Larry , Zhou Wei , Moyeda David , Rossow Joshua
Published: July 2009

Boilers firing low-rank coal generally experience high levels of slagging and fouling. To help manage convective pass fouling, various additives or conditioners can be injected into the boiler furnace high temperature region as physical disruptors of slag deposits, exhibiting a varying density or gas evolution, which physically breaks up slag or as chemical modifiers of the ash to increase its softening temperature. Vermiculite is one additive that has been applied with success; however, it is important to ensure that the injected material is placed in the most heavily slagged and fouled areas. The purpose of this study was to evaluate the effectiveness of a vermiculite injection system installed on a large cyclone-fired boiler and to identify improvements in the injection system that would permit more effective treatment of the areas of interest. During the study, a million-cell full boiler combustion model was developed. Typical features of the furnace flow and temperature field were obtained. Considering the particular operating conditions and features of the upper furnace flow field (biased gas velocities and rotational flow), optimized injection schemes were proposed. This study shows the usefulness of applying CFD to solve slagging and fouling issues for coal-fired boilers.
Improving Boiler Reliability Through NDT
Authors: Gowatski Shawn
Published: July 2009

TesTex, Inc. has worked with numerous utilities that experienced Boiler Tube Failures in areas such as water walls, superheaters, reheaters, etc. In this presentation we will discuss specific areas of a given boiler describing what problems (failures) the units were experiencing and what solutions were implemented. We will also discuss various failure mechanisms for boiler tubing, the causes, and various Non-Destructive Testing (NDT) methods used to locate and identify these flaws. Some specific case studies of boiler tube failures are listed below. Xcel Energy-Valmont Station, Boulder, CO Boiler: This 166mw Coal Fired Boiler was experiencing water wall tube failures due to corrosion cells and hydrogen damage. This unit has been inspected with Low Frequency Electromagnetic Technique (LFET) four times over the last seven years. This unit has gone from experiencing tube failures every two weeks to only having 1–2 failures per year. Western, PA Power Plant: This 835 MW Coal Fired Boiler was experiencing reheater tube failures due to oxidation pitting in their horizontal sections. Sections of this reheater were inspected with the Low Frequency Electromagnetic Technique using Low Profile scanners to access the bottom half of the tubes in the horizontal sections. Several flaws were found and repairs were made. Similar inspections were also performed in the plant’s other two boilers where no defects were found. These inspections helped the plant locate and make repairs to flawed regions in the boilers. Their run-time between boilers tube failures has risen significantly.