bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Stress-Strain Response of an Axial X100 Girth Weld Under Tensile Loading Using Digital Image Correlation
Authors: Adeeb Samer , Horsley Dave , Yan Junhui , Sutton Michael A. , Reynolds Anthony P.
Published: October 2008

An important design, construction and maintenance concern for pipelines is the integrity of flaws in the girth welds. Numerous fitness for purpose codes are available to assess weld flaws, many of which were calibrated with reference to wide plate test data. Often, wide plate tests are conducted on girth welded pipe in the as-received condition, i.e. without application of a pipeline coating. The area adjacent to the weld is thus subjected to a thermal cycle due to the heat generated from the welding process. In some pipe materials this thermal cycle might be sufficient to induce strain aging. It is not clear how the welding process changes the behaviour of the area next to the weld. The results of such wide plate experiments are very important in assessing the acceptable flaws in a girth weld under a strain-based design. Therefore, it was important to understand the extent of the aging, specifically the stress-strain behaviour on either side of the girth weld. This paper presents results of cross-weld tensile tests, which utilized a two-dimensional digital image correlation (DIC) technique to determine displacement, and thus infer strain. The local strains were mapped to global stress to obtain local constitutive properties every 12.5mm along the length of the specimen. The DIC test results were very consistent and were also similar to results obtained from standard circumferential tensile tests at corresponding locations. The strength of the specimens, as defined by the relative strength of their stress-strain curves, was found to be highest in the girth weld region, to drop in the HAZ, and then to reach a plateau in the base metal. It was also shown that strain localization in one of the HAZ regions was clearly visible during the loading process and the near-HAZ regions had a stress-strain response with a yield stress value higher than the base metal. This behaviour was observed at 12.5mm away from the girth-weld centerline in both the transverse and longitudinal directions. The reason for this slight change of behaviour can be attributed to the effect of heating supplied to this part during welding (strain aging). The described DIC technique is very promising in obtaining local strain fields within very small areas of the tested specimens.
Pipeline Integrity Management Made Simple
Authors: Bolsover Andy , Hansen Eric
Published: October 2008

Over the years, new regulations, safety and environmental concerns from the public have emphasized the requirement for pipeline owners to demonstrate and document the safe operation of their facilities. In Europe, the “Seveso 2” regulation has mentioned pipelines in the requirement for safety and integrity management of hazardous facilities. What were originally technical issues related to inspection and maintenance have now been wrapped up in the general concept of pipeline integrity management. The safety of pipelines has indeed become a social accountability issue at Corporate level for every Operator. Bureau Veritas has been involved since its inception in the conformity assessment, the certification of facilities and organisations and has developed a vast experience in the field of QHSE and Regulatory compliance. Based on this experience, Bureau Veritas is developing a practical approach to Pipeline Integrity Management, providing guidelines and methodologies for operators. The paper describes a performance-based and risk-based approach to Pipeline Integrity Management. The approach includes: assessment of the condition of facilities (through audits and inspections), performing risk analysis and engineering criticality assessments, drawing up the priority list of further inspections, interventions, repairs and maintenance, assisting and advising in the selection of the appropriate methodologies and tools, controlling the execution of such inline inspections, cathodic protection surveys, safety systems upgrades, maintenance and repair works. Bureau Veritas has also developed calculation criteria to interpret inspection data and to advise on fitness for service of the facilities to prioritize the repair works.
New Developments for the Description of Oil Leakages by Advective Migration From Submarine Pipelines
Authors: Baptista Renan Martins , Machado Ricardo Antonio Francisco , Quadri Marintho Bastos , Bolzan Ariovaldi , Nogueira Andre´ Lourenc¸o , Lopes Toni Jefferson
Published: October 2008

The significant growing in offshore operations increases the risk of a pipeline rupture, even considering the high standards of safety involved. Throughout a submarine leakage, four different amounts of oil may be accounted. The first one is the oil volume released until the leakage detection. The second one is the volume leaked throughout mitigation initiatives (e.g. pump shut-down and valve closure). The third parcel is the amount released by gravitational flow. Finally, the fourth and last amount of oil is released due to the water-oil entrainment, generally known as advective migration. Normally, a considerable amount of oil is released in this step. It begins just after the internal pipeline pressure becomes equal to the external one. The present work continues to introduce a mathematical alternative approach, based on the theories of perturbation and unstable immiscible displacement, to accurately estimate the leakage kinetics and the amount of oil released by the advective migration phenomenon. Situations considering different holes sizes and thickness were tested experimentally and through simulations. Additional experiments were accomplished using smooth and rough edge surfaces, besides different slopes (using the horizontal plane as reference). Those experiments permitted a preliminary evaluation of the importance of these factors. The results obtained with the model showed good agreement with experimental data in many situations considered.
Effect of Grade on Ductile Fracture Arrest Criteria for Gas Pipelines
Authors: Wilkowski G. , Rudland D. , Xu H. , Sanderson N.
Published: October 2008

Several different criteria have been proposed over the years to predict the minimum toughness for arrest of an axial propagating crack for natural gas pipelines. The initial ones were empirically based. The Battelle Two-Curve Method (TCM) was subsequently developed and was somewhat less empirical. The TCM is still used frequently today. Nevertheless, all of these criteria use the Charpy energy as a measure of the material’s ductile fracture resistance. As higher-grade steels have been developed, it has been found from full-scale tests that a multiplier was needed on the predicted minimum Charpy arrest energy value as calculated from the original TCM. Several researchers have also suggested that a correction factor was needed on the Charpy energy as the Charpy energy value increased above a certain level. This was a nonlinear correction factor that essentially showed that as the Charpy energy value surpassed a certain level, the effective energy for ductile fracture arrest is less than the total energy from the Charpy test. This paper presents background information on several of these toughness correction factors, as well as statistical analyses of full-scale pipe burst tests on 186 lengths of X60 to X100 grade pipes using these methods. The results show the effects of grade level on not only the original TCM predictions, but also several other modifications for high Charpy energy levels. Additionally, a method has also been developed where the DWTT energy was used instead of the Charpy energy in the Battelle TCM. The results of the statistical analyses showed that all the Charpy-energy-based criteria required an increasing correction factor as the grade level increased. The one DWTT energy criterion was statistically constant with grade level. This difference between the Charpy criteria and the DWTT criterion was traced back to a changing relationship between the Charpy and DWTT energy values as the grade of the steel increases.
Metal-Cored Welding GMAW Consumables Development for Girth Welding of X-100 Pipe
Authors: Rajan Viadyanath , Hartman Dennis
Published: October 2008

Metal-cored wire electrodes with different compositions were used to make girth weld joints at a heat input of 0.7–0.8 kJ/mm. Design of experiments methodology was used to create a response surface primarily in carbon (C), manganese (Mn) and nickel (Ni) space in steel containing molybdenum (Mo), titanium (Ti), and boron (B) additions. This allowed the modeling of all-weld-metal yield strength, tensile strength and Charpy impact toughness as a function of weld metal composition. Results indicated that weld metal yield and tensile strengths have a linear dependence on the %C, %Mn and %Ni content of the weld. The Charpy impact toughness behavior at −20° C was more complex, initially showing a dependence on %C and %Ni in small scale trials, and subsequently showing a dependence on the %oxygen (O) and %Mn content in full scale production trials. These results can be combined for graphical optimization of the response surface to identify regions in weld metal composition that contain the desired weld metal yield, tensile and Charpy impact toughness for design of metal-cored wire electrodes for the welding of X-100 pipe. These results and their implications for design of girth welds in X-100 pipe are presented in this study.
Evaluation of Hydrogen Cracking in Weld Metal Deposited Using Cellulosic SMAW Electrodes
Authors: Fiore Susan R. , Boring Matthew A.
Published: October 2008

In a previous study of the limitations of cellulosic coated electrodes, it was found that arc length has a pronounced effect on carbon, manganese, and silicon recovery in welds made using these electrodes. The effect of arc length could not explain the extremely rich compositions observed in a series of cracked girth welds that were analyzed, however. Subsequent investigation demonstrated that it was possible to effectively double the manganese concentration and triple the silicon concentration when using cellulosic-coated electrodes with low moisture contents in the coatings. A variety of multipass weld metal cracking tests were reviewed and a test method that can be performed as part of a procedure qualification/material qualification test to determine appropriate preheat/interpass temperatures was developed. This paper describes the results of a follow-on program funded by Pipeline Research Council International (PRCI) and the US Department of Transportation. The objectives of the program were to further define the conditions that can lead to hydrogen cracking in weld metal deposited using cellulosic coated electrodes, in terms of operator preference (arc length), electrode properties, power supply selection, and materials handling, and to develop welding and safe handling guidelines to prevent weld metal hydrogen cracking. Cellulosic coated electrodes were procured from several manufacturers. Initially, they were checked for weld metal chemical composition in the as-received and dried conditions. The coating moisture of each electrode in each condition was also determined. Some of the electrodes were selected for additional testing in the as-received, dried and re-hydrated conditions. Pipe sections were welded with each electrode in each condition, using both a short arc length and a medium arc length. Weld metal testing included tensile testing, bend testing and weld metal chemical analysis. In the second phase of this program, additional welds were made with two of the electrodes using different power sources. Electrodes were also exposed to conditions intended to simulate actual weather conditions from around the world, in an effort to produce guidelines for maximum exposure times at the various conditions.
Probabilistic Assessment of Minor Mechanical Damage
Authors: Vieth Patrick H. , Maier Clifford J. , Harper William V. , Johnson Elden , Neogi Bhaskar , Baskurt U. J. , Beckett Alan
Published: October 2008

In-line inspection (ILI) of the Trans Alaska Pipeline System (TAPS) using high resolution metal loss tools indicated 77 locations with suspected minor mechanical damage features (MDF). The tools used are able to detect the presence of a suspected feature, and measure indented dimensions, but are insufficient to detect the presence of cracks or gouges needed to reliably assess feature severity based solely on the ILI data. Excavations of 42 sites deemed most severe provided important field data characterizing residual deformation dimensions, the occurrence of gouges or cracks, and allowing a reliable field assessment of defect severity. Upon completion of the excavations, 35 possible MDF locations remained unexcavated. An engineering evaluation was undertaken to assess whether or not these remaining minor MDF pose a threat that is significant enough to warrant excavation. Multiple assessment methods were utilized including deterministic, probabilistic, and risk assessment methods. The probabilistic assessment of 35 unexcavated MDFs was performed using PCFStat; or Pressure Cycle Fatigue Statistical Assessment, which uses Monte Carlo simulation to estimate remaining fatigue life. PCFStat performs 1,000’s of simulations for each case where the input parameters are randomly selected from expected distributions. Of particular importance is the fatigue environment of the location. The results of the probabilistic assessment were used to estimate the potential for failure of remaining MDFs. The results suggest that 25 of 35 unexpected damage features had a POF of less than 10−4 over the remaining expected pipeline life cycle and thus are unlikely to fail. Alyeska considered a combination of probabilistic, deterministic and risk assessment results to decide on the actual locations to be examined. The results of probabilistic analysis also were found to support the outcome of the operator’s risk-based evaluation process.
Quantitative Risk Assessment: Underground Natural Gas Storage Facilities
Authors: Wickenhauser Patrick L. , Wagg Brian T. , Barbuto Fausto A.
Published: October 2008

TransGas undertook a risk-ranking project for storage facilities as the first step in the process of evaluating the financial and life-safety risk associated with the eight storage facilities that they operate in Saskatchewan, Canada. Based on this analysis, two salt cavern storage facilities were selected for a quantitative risk assessment. The most cost-effective maintenance actions for each cavern were determined as follows: Fault trees were prepared for all of the identified failure scenarios. Several unique computer models were developed to predict the failure rates of the events identified in the fault trees and the consequences associated with both sub-surface and atmospheric releases from the storage facilities. Both life-safety and financial risk were considered in the analysis. For each of the caverns, a number of potential maintenance scenarios were selected that address the dominant failure causes. Life-safety risk was assessed first and compared to the TransGas tolerance. A cost optimization analysis was then carried out in which the total expected future cost associated with each maintenance option was amortized over the benefit period and compared to the total expected future cost associated with the current maintenance practice. The paper describes the risk analysis and cost optimization approach and provides case study examples of the caverns analyzed and the recommendations reached in each case.
Applying Gurson Type of Damage Models to Low Constraint Tests of High Strength Steels and Welds
Authors: Liu Ming , Wang Yong-Yi
Published: October 2008

Pipelines experiencing displacement-controlled loading need to have adequate strain capacity. Large tensile strain capacity can only be achieved when the failure processes are ductile. In ductile failure analyses, the strain capacity may be determined by two approaches. The first approach uses the conventional fracture mechanics criteria, such as the attainment of the critical crack tip opening displacement, to assess the onset of the crack propagation. The other approach uses damage mechanics models in which the onset and propagation of cracks are controlled by the nucleation, growth, and coalescence of voids in the material. The damage mechanics models can provide some insights of the ductile failure processes as they have more physical mechanisms built in the constitutive model. In this paper, the Gurson-Tvergaard-Needleman (GTN) model is applied to two types of low-constraint tests: curved wide plates and back-bend specimens. The wide plate test is considered more representatives of full-scale pipes than the conventional laboratory-sized specimens, but requires large-capacity machines. The back-bend test is a newly developed low-constraint laboratory-sized test specimen. A relatively simple approach to determine the damage parameters of the GTN model is discussed and the transferability of damage parameters between those two test types is also analyzed.
Validation of Sleeve Weld Integrity and Workmanship Level Development
Authors: Lazor Robert , Bolton Brock , Dinovitzer Aaron
Published: October 2008

Full encirclement repair sleeves with fillet-welded ends are often used as permanent repairs on pipelines to reinforce areas with defects, such as cracks or corrosion. In-service failures have occurred at reinforcing sleeves as a result of defects associated with the sleeve welds, such as hydrogen-induced cracks and undercut at the fillet welds, inadequate weld size, and sleeve longitudinal seam ruptures. This work was undertaken to support the development of tools for sleeve design and for conducting an engineering assessment to determine the tolerable dimensions of flaw indications at full encirclement repair sleeves. In particular, the project was intended to validate the stresses estimated using finite element analysis (FEA) models against actual in-service loading conditions experienced at reinforcing sleeves. The experimental work focused on the collection of full-scale experimental data describing pipe and sleeve strains for the following field and laboratory conditions: • Strains induced by sleeve welding, • Strains induced by pressurization of the sleeved pipe, • Strains induced by pressurization of the sleeved pipe and the annulus between the pipe and sleeve. Finite element models of the field and laboratory sleeved pipe segments were developed and subjected to the same applied loading conditions as the full-scale sleeved pipe segments. Comparisons of the measured strains against those estimated using FEA were completed to determine the ability of the models to predict the behaviour of the sleeved pipe segments. Comparisons were made to illustrate the relative strain levels and deformation trends, the accuracies of the strain predictions and trends in changes with pressure, the differences in behaviours between tight and loose fitting sleeves, and the effects of pressurizing the annulus between the pipe wall and sleeve. The analysis of the field data and FEA modeling predictions led to several conclusions regarding to use of numerical models for predicting sleeved pipe behaviour and weld flaw acceptance: • FEA results demonstrated behaviours that were consistent with full scale data, • Trends in the FEA predicted strains agreed with the full-scale data, • FEA models describing the effects of gaps between the pipe and sleeve and annulus pressurization agreed with field experience and engineering judgment, • Evaluation of the significance of root and toe flaws can be completed by extending the models validated in this work.
Modeling Damage Prevention Effectiveness Based on Industry Practices and Regulatory Framework
Authors: Chen Qishi , Davis Kimbra , Parker Curtis
Published: October 2008

Managing actual or perceived risk in today’s environment is the concern of every industry and government. For oil and gas pipelines, prevention of mechanical interference by excavation equipment is one of the most effective ways to reduce incidents and to manage operating risk. A common technique used to manage reliability, risk and safety is the fault tree method. In general terms, a fault tree model identifies important events and combinations of events, with respect to system reliability, to estimate the likelihood of system failures. When applied to damage prevention, the fault tree forms a logical representation of the manner in which the combined fault effects associated with individual prevention measures could lead to a hypothesized failure of an operator’s damage prevention program. The model presented in this paper considers performance factors such as signage, patrols, one-call practices, excavation techniques, public awareness programs and new damage prevention technologies.
Characterization of Mechanical Damage Through Use of the Tri-Axial Magnetic Flux Leakage Technology
Authors: Co Vanessa , Ironside Scott , Ellis Chuck , Wilkie Garrett
Published: October 2008

Management of mechanical damage is an issue that many pipeline operators are facing. This paper presents a method to characterize dents based on the analysis of the BJ Vectra Magnetic Flux Leakage (MFL) tool signals. This is an approach that predicts the severity of mechanical damage by identifying the presence of some key elements such as gouging, cracking, and metal loss within dents as well as multiple dents and wrinkles. Enbridge Pipelines Inc. worked with BJ Services to enhance the knowledge that can be gained from MFL tool signals by defining tool signal subtleties in dents. This additional characterization provides information about the existence of gouging, metal loss, and cracking. This has been accomplished through detailed studies of the ILI data and follow-up field investigations, which validate the predictions. One of the key learnings has been that the radial and circumferential components of the MFL Vectra tool are highly important in the characterization and classification of mechanical damage. Non-destructive examination has verified that predictions in detecting the presence of gouging and cracking (and other defects within dents based on tool signals) have been accurate.
Automatic Detection of Pipeline Components in Radiographs for Corrosion Monitoring
Authors: Felisberto Marcelo K. , Schneider Guilherme A. , Centeno Tania M. , de Arruda Lucia V. R.
Published: October 2008

This paper introduces new techniques to support industrial radiographic inspection, aiming at automatic corrosion monitoring in pipeline systems. Using the methodologies we proposed, pipeline components to be inspected are automatically detected in the radiographic image, their wall thicknesses are measured and parameters for corrosion detection are computed. For the automatic detection and recognition of pipeline components, we developed a new method that uses image matching techniques in conjunction with genetic algorithms. For measuring the pipe wall thicknesses we used image segmentation techniques based on the analysis of image line profiles. As a result, analysis of pipeline radiographs for corrosion monitoring can be automatically performed, improving the reliability and speed of the inspection process.
Long Range Hot Oil Pipeline Leak Detection and Location Technique Based on Negative Pressure Wave
Authors: Li Yibo , Sun Liying , Jin Shijiu , Wang Likun , Tan Dongjie
Published: October 2008

Negative pressure wave (NPWs) technique is an effective method for oil leakage detection and location. However, conventional negative pressure wave technology failed to be applied to leakage location in China directly. China’s crude oil has to be transmitted over heating because of its high viscosity, high wax and high solidifying point. In this paper, conventional location method of instantaneous pressure wave was analyzed and techniques were developed to overcome the defects. Since temperature of the oil would drop continuously during transmission, temperature drop influence on physical characteristics of the crude oil and propagation velocity of pressure wave was studied in detail. In order to achieve high precision, wavelet transform algorithm was adopted to define inflexion of negative pressure wave when it propagates along the pipe, and wavelet threshold denoising technique was used to separate the characteristic inflexion of negative pressure wave when calculating the leak position. The problem of false alarms was solved by application of eigenvector indexes method. On the basis of that, a new oil leakage detection and location system was developed for hot oil transmission pipeline. In China, SCADA (supervisory control and data acquisition) system was installed on most oil transmission pipeline to monitor operational parameters for long range crude oil or product oil pipeline. Because it acquires pipeline operational parameters from the existing SCADA system, the cost and complexity of the new system was greatly reduced. The earliest leak detection and location system which installed on a hot oil transmission pipeline in PetroChina 5 years ago is still working well. It responds to leakage (1.5% of the total fluid) within 2 minutes and location error is less than 2% of the pipeline length between the two stations.
A Quantitative Approach to Tensile Strain Capacity of Pipelines
Authors: Wang Yong-Yi , Liu Ming , Horsley David , Zhou Joe
Published: October 2008

Tensile strain rupture is an ultimate limit state. A limit state is stated in generic terms of “load” and “resistance” or alternatively termed “demand” and “capacity.” The “demand” of tensile rupture limit state is mostly related to displacement-controlled loading, such as that induced by frost heave, landslide, and seismic activities. The “capacity” is most often controlled by girth weld tensile strain limits, as girth welds tend to be the weakest link in pipelines experiencing high tensile strains. The tensile strain limits of girth welds are affected by a large number of factors: tensile and toughness properties of the pipe and weld, weld geometry, stress state, defect size and location. Consequently, closed-form solutions for tensile strain limits of girth welds do not yet exist in codes and standards. PRCI and TransCanada have funded a number of projects in recent years to develop fracture-mechanics-based procedures aimed at quantitative determination of girth weld tensile strain limits. The results of these projects, along with the reviews and examination of available experiment data by the authors, have culminated in a set of recommended procedures that enable the quantitative determination of the tensile strain capacity of pipelines. The required input parameters, formulae for the computation of tensile strain limits, limits of applicability, and suggested methods of applications are specified in the proposed procedures. This paper covers the technical basis of the procedures. Particular emphasis is placed on the validation of these procedures. The limitations of the procedures and future directions of improvements are suggested. It is believed that these procedures may lay the initial groundwork towards the eventual code implementation of a comprehensive set of tools for quantitative strain-based design of pipelines.
Laboratory Simulation of Hydrostatic Test in Near-Neutral pH Soil Environments
Authors: Chen Weixing , Sutherby Robert
Published: October 2008

Hydrostatic testing is the principle method for managing stress corrosion cracking (SCC) of natural gas transmission pipelines. The long-term benefit of such testing relates to the stress margin between testing and operation and the effect of overstress on the surviving population of sub critical defects. This research was initiated to understand the response of these subcritical cracks of varied dimensions to hydrostatic testing in typical soil electrolytes that are conducive to SCC. More than 10 laboratory hydrostatic simulations have been conducted in this investigation. The results obtained provide insight into such issues as whether there will be crack advances during the hydrostatic test and the effect of hydrostatic testing on the subsequent growth of surviving cracks during service.
Effects of Geometry, Temperature, and Test Procedure on Reported Failure Strains From Simulated Wide Plate Tests
Authors: Wang Yong-Yi , Liu Ming , Chen Yaoshan , Horsley David
Published: October 2008

Wide plate test is a valuable tool in the assessment of pipeline girth weld integrity. It has been used for welding procedure qualification and for the validation of theoretically based defect assessment procedures. Although the general form of the test has remained largely unchanged over the years, the size of the test specimen, strain measurement, and test procedure, has had some variations. The influence of these variables has not been adequately examined. While this might be acceptable for tests targeted for stress-based design in which a general pass/no-pass answer is desired, the requirements for data accuracy and consistency for strain-based design are much higher. Understanding the variability of the test data is critical for high strain applications. This paper examines the effects of test geometry, mainly the length to width ratio, on the reported failure strains, assuming material’s failure process remains the same. The influence of different strain measdurement procedures, such as the location and gage length of LVDTs (Linear Variable Displacement Transducer), is assessed for different materials and weld strength mismatch levels. The other consideration is the influence of temperature fields on the cold test data. The postulated cold tests use either local cooling at the location of the weld defect or uniform cooling. In the case of local cooling, the gage length of the LVDTs covers materials of different temperatures. Consequently the reported failure strains are affected by the distribution of the temperature fields. The effects of the temperature fields on the reported tensile failure strains are examined.
Evaluation of Leak/Rupture Limit for Axially Through-Wall Notched Line Pipes Using J-Integral Resistance Curve
Authors: Kawaguchi Shinobu , Hagiwara Naoto , Rudland David L. , Wilkowski Gery M.
Published: October 2008

This paper investigated the applicability of the differential function of J-integral Resistance (J-R) curves, that is, dJ/da to predict the leak/rupture limit on X65 and X80 line pipes. The leak/rupture limit depended on the J-R curves of line pipes and was estimable using the dJ/da approach irrespective of the levels of the Charpy impact energy. It is noted that the dJ/da approach enables us to evaluate the leak/rupture limit of pipelines having a high Charpy impact energy, to which the Charpy impact energy-based equation is inapplicable.
Analysis of Non-Coplanar the Pressurized Laminations in X52 Steel Pipes by Non-Linear by Finite Element
Authors: Gonza´lez Jorge Luis , Morales Alfredo
Published: October 2008

Hydrogen induced cracking is of great interest in the mechanical integrity assessment of sour gas pipelines. Multiple stepwise cracks with internal pressure called laminations are often observed in pipelines and their interaction and coalescence may significantly affect the residual strength of the pipes. In this work, the interacting fields of non coplanar pressurized laminations in the wall of a pipe under pressure are analyzed by non-lineal finite element, considering an isotropic hardening law and the real tensile properties of the X52 steel. The results are presented as the evolution of the stress fields in the interlaminar region as a function of the pressure inside the laminations. It is found that for two approaching stepwise laminations the critical pressure follows a hyperbolic type law, thus the effect of the lamination length is principal for greater lengths and for shorter lengths the effect is minimum. The critical pressure is defined as pressure inside the lamination that causes plastification of the interlaminar region.
Operator Assessment of ILI Defects
Authors: Ferguson Kevin W.
Published: October 2008

With the age of the original Panhandle Eastern Pipeline (PEPL) Company pipelines, it’s not a matter of if anomalies will be found when an ILI tool is run, it’s a matter of how many and how severe. When a final report is received from an ILI vendor, burst pressures are typically calculated using Modified B31G, 0.85dL. The results can seem unmanageable, but success has been had doing further assessments on some anomalies without excavating them all. This assessment has been developed and performed by PEPL on three sets of Tuboscope ILI data and one set of Baker Hughes CPIG data. The method to be discussed was first employed in 2002. It provides a more accurate characterization of the defect and provides the company the ability to more effectively allocate resources. Efforts have been made to review the color scan of a vendor’s raw High Resolution Magnetic Flux Leakage (HRMFL) data, and perform an assessment using Effective Area Analysis without excavating hundreds of anomalies that prove no threat to the pipeline. This assessment is done by hand on the computer and in many cases returns a burst pressure higher than that calculated using Modified B31G, 0.85dL. The following is a case study that shows how multiple defects have been assessed prior to excavation in an attempt to more accurately characterize the defect, and allow for a better allocation of resources. Digs have been performed to validate the process, and the results will be discussed.
Measuring the Remaining Strength Factor of a Steel-Adhesive-Repair System
Authors: Rosas M. A. , Vieira R. D. , Freire J. L. F.
Published: October 2008

A new repair-reinforcement system to be utilized on pipeline showing external metal loss was developed and tested by employing scaled models in order to verify the system’s effectiveness in reestablishing pipeline structural integrity. The repair system is composed of pre-curved thin layers of steel lamina, which are set in place on the external metal loss defect area of a pipe and cemented in place with epoxy resin. Hydrostatic burst tests were performed on three types of pipe specimens: with metal loss defects, without metal loss defects and with metal loss defects but repaired with the new system. Strain gages were used to monitor elastic and plastic strains during the tests. Test results, burst pressures and pressure-strain curves were compared using simple analytical equations that were developed to determine the number of thin steel layers to be used in the system and to model the behavior of each tested specimen. The investigation reached the conclusion that the simple analytic equation is effective for determining the required repair thickness and its number of layers, that the repair system reconstructs pipe integrity and that it should be further investigated as to applying it while the pipeline is still in operation.
An Automated Leak Detection and Location System in a Brazilian Liquid Ammonia Pipeline
Authors: Ceciliato Emir , Magalha˜es Claudia C. , Bueno David G. P.
Published: October 2008

Liquid ammonia is the basis of a variety of products, ranging from fertilisers, important intermediate chemical raw material (such as nitric acid and ammonium hydroxide), cosmetics, up to explosives. It is a very toxic product, requiring special care when transported. This paper shall present an automated leak detection system (i. e., without human intervention for shutting pumps down) for a short (approximately 6 kilometres long), 6 inch., liquid ammonia pipeline located at the city of Cubata˜o, state of Sa˜o Paulo, Brazil, within the bounds of a fertiliser producer. The pipeline runs from a Terminal (which is a port) down to a fertiliser complex, where the ammonia is used as raw material to produce ammonium nitrate. There is approximately 3.5 km of buried pipes, as well as 2.5 km of aerial ones. A special set of insulation layers is coating pipeline segments in order to keep ammonia in an undercooled temperature (and showing an undercooled liquid behaviour, as a consequence). The selected leak detection system is based on statistical concepts, using the SPRT (Sequential Probability Ratio Test) sampling technology. The main idea is to establish an automated procedure in which the LDS is capable of sending an alarm signal directly to the SCADA, to shut down pumps, without human intervention. The system architecture is covered, as well as the details on the pipeline hydraulics and ammonia transport properties (especially density and viscosity). Finally, initial field trials data are provided and analysed.
Evaluating the Reliability and Sensitivity of a Leak Detection System on a Liquid Pipeline
Authors: Twomey Michael
Published: October 2008

Detecting leaks in a liquid pipeline is not the most difficult task for a leak detection system (LDS); detecting leaks without giving false leak alarms is the main challenge. An operator will have trouble identifying a real leak if he has to sift through many false alarms. Therefore pipeline leak trials should test the reliability (number of false alarms) of a leak detection system as well as its ability to detect real leaks. This paper reviews how a number of pipeline operators tested their leak detection systems with simulated leaks, verifying the reliability as well as the sensitivity of their new leak detection systems. These simulated leaks were introduced by removing product from the pipeline by bleeding. The paper also outlines a simple table based on the API 1155 guidelines to evaluate software based leak detection systems that can be used as part of the bid evaluation process to hold the leak detection vendor accountable to deliver the performance promised in his bid proposal. This paper high-lights some of the performance limitations to watch for when selecting and testing an LDS, For example; will a pipeline leak detection system detect the quoted minimum leak if the normal operations include transients? Does the system block leak alarms to reduce frequent false alarms? Are the leak detection times based on the time it takes to declare a “Leak Warning” or on the time it takes to declare a “Leak Alarm”? Finally, the paper discusses how to perform more realistic leak tests.
Methodology of ROW Maintenance and Control in Bolivia-Brazil Gas Pipeline
Authors: Jorge Kemal V. , Souza Ananias F.
Published: October 2008

The Bolivia-Brazil Gas Pipeline runs 2,593 kilometers in Brazil, from the border of Bolivia to the consumer industries in the south of Brazil. This document presents the maintenance control methodology implemented in the first seven years of operation that helped to improve the R.O.W. stabilization and the integrity of the pipeline, focused in the central-west Brazilian spread. It presents the several methods of surveillance used, and the collection and processing of the vast amount of data, as well as the repair and maintenance planning and control system. It also presents the efforts taken to develop an awareness program, which is substantially important to the integrity of the R.O.W. and the Pipeline.
The Use of Geographic Information System to Managing Results of ILI (Inline Inspections) and Repairs in Transpetro’s Pipelines
Authors: Amado Ulisses Dias , Freitas Carlos
Published: October 2008

It is quite significant the effort given by firms to utilize all of the GIS potential. The GIS is more than a mapping information system, it is a powerful management device that should be explored to add value to firm’s management efforts. It is by fact that with the advances in new information technology, aligned with the facilities of the Internet has significantly contributed to push forward GIS projects into big firms. GIS has also become the new aim to software suppliers worldwide. TRANSPETRO has been investing heavily in geo-processing technology to guarantee a technological competitive edge. The firm believes that Geographical Information Systems will be an important contributor to the improvement of its management efforts on their terminals and pipeline network. The use of intelligent tools (smart pig) for inspections of pipelines’ integrity (ILI inspection) has been intensified by those advanced technologies observed in this specialized activity. In general, right after the reports of the inspections, the results are analyzed thoroughly by qualified professionals in this area. These specialists are responsible for attesting the results supplied by consultants that execute the inspection in the fields. Those reports and results are constantly checked by field correlations involving a number of inspection teams. Once accepted, the database is carefully analysed through technical criteria involving the severity of the defects indicated in the internal and external surfaces of the pipeline. The use of GIS tools for this kind of analysis is extremely important because it also allows specialist to analyze every kind of geographical data, such as rivers and sensitive environmental areas, among others. When those tests are finally finished a repair order is sent to the field professionals. Once again, the use of GIS is extremely important for support those locations of interference areas as well as the planning of the interventions in the roads, channels or points to be repaired. All of those actions, defects analyzed and the field applications are perfectly managed by the GIS technology, storing all of those strategic information in the database of Transpetro’s specialists. In this paper we intend to present the applications of this technology that analyzes the intelligent tools (smart pig) results in the field works with the GIS developed by Transpetro.
Combined Quantitative In-Line Inspection of Pipelines for Metal Loss and Cracks
Authors: Beller Michael , Uzelac Neb I. , Barbian Alfred
Published: October 2008

As awareness about pipeline integrity grows, so does the need for accurate and reliable inspection methods to provide operators with precise and reliable data for performing advanced integrity assessment calculation and optimizing maintenance processes. Until recently, the inspection of a pipeline for metal loss and cracks necessitated two separate inspection runs with two separate tools. This paper will introduce a range of advanced in-line inspection (ILI) tools that incorporate abilities to be used for quantitative metal loss and wall thickness as well as crack inspections. These tools, utilizing ultrasound technology, make use of a new generation of electronics and an entirely new design of the sensor carrier to enable metal loss and crack inspection surveys in a single run. The paper will explain the physical principle used, introduce the tool technology, present a case study and discuss the advantages to the pipeline operator.
Simulation Pipeline Control Systems for Operator Training
Authors: Basnett David John
Published: October 2008

Most pipeline simulations are primarily concerned with performance of the pipeline, and the modeler typically assumes an idealized model of the control systems. The modeler assumes that control devices operate instantaneously and perfectly. This assumption is sufficient for a wide range of engineering simulation tasks, but inadequate for simulations used to training pipeline operators. For training purposes it is important that the software provides a “virtual pipeline” that responds in the same manner as the real pipeline. The simulator should model the delays and interactions of the control system as well as the hydraulics of the pipeline. This paper describes how a generic control capability was added to an existing liquid simulation package to provide a more realistic training simulation for several applications including crude oil and multi-product pipelines. The paper will discuss the practical lessons learned from these simulations of the full control systems for pipeline training systems. The potential drawbacks of the method chosen will also be addressed.
Owner–Construction Contractor Risk Sharing for Major Oil and Gas Projects in Emerging Economies
Authors: Calvin David , Spence Sheila
Published: October 2008

The increasing global demand for energy will continue to necessitate the construction of large oil and gas infrastructure. With the exploitation of economic reserves in OECD countries largely in decline, the opportunities available for multinational oil companies and construction contractors are increasingly presenting themselves in non-OECD nations where the nature of non-technical risk is less predictable and less well understood. This paper attempts to outline areas of non-technical risk which should be considered in the formulation of the contracting strategy for large development and infrastructure projects. The non-technical risks described within this paper are a direct result of experiences obtained during the construction and early operations of the BTC and SCP pipelines, from 2003 to the present date. Methods by which these non-technical risks can be recognized and possibly managed will be put forward to ensure that the financial and reputation interests of both the owner and construction contractor can be protected during the execution phase of the project, where the potential for loss is the greatest.
Mechanic, Metalurgic and Factografic Characterization of a Composite of Microalloyed Steel (API X65) Cladded With Austenitic Stainless Steel (AISI 308L)
Authors: da Cunha Carlos R. , Strohaecker Telmo R.
Published: October 2008

In some offshore structures, pipes with good mechanical resistance and internal surfaces that have also good corrosion resistance are necessary. To associate these properties, one possibility is to make a cladding process in the pipe. To evaluate this kind of composite, a pipe (API X65) was clad with stainless steel (ASTM 308L) by GMAW process and sectioned in several specimens for different analyses. The work starts qualifying the quality of the composite with bending tests. The load that was recorded in this test was the guide to three-point-fatigue tests that gave us the possibility to plot an S-N curve. The tension was the most tensioned point in the specimen. To verify the metallographic conditions of both materials and the interface, metallographic analyses with a transversal cut in the specimens and hardness test across the composite were accomplished. The fatigue tested specimens were submitted to fracture analyses to know how the failure occurs. These analyses contain photos of the specimen’s fracture - showing the origin of the failure, a metallographic of the specimen’s interface to check undesired microstructures that could cause a failure and micrographs of the most tensioned point of the specimen to check the initial failure mechanism. The results in the following work show a good way of cladding process.
Monitoring and Prediction of Pipe Wrinkling Using Distributed Strain Sensors
Authors: Chou Z. L. , Cheng J. J. R. , Zhou Joe
Published: October 2008

As exploration of energy resources develops further into the remote Canadian North, pipeline construction is being pushed further into the unknown. The new pipeline construction in the North has generated a great need for understanding and predicting the behaviour of pipelines under harsh northern environmental conditions. Continuous real-time monitoring technology using distributed strain sensors has become a possible method for monitoring the performance of these pipelines in the field. The aim of this research is to find the correlation between the distributed strains along the line pipes and the local buckling (wrinkling) of these pipes, and to study the contribution of these distributed strains to the detection of initial wrinkle of buried pipelines. Both experiments and finite element analyses (FEA) concluded significant findings in the current research. Conventional strain gauges and advanced Brillouin Scattering fibre optic sensors (BSFOSs) were employed in the experimental programs. BSFOSs can measure the distributed strains spacing as close as 50 mm along the line pipes, so that these sensors can detect the wrinkle location along the monitored pipeline. The distributed strains measured from the BSFOSs and from conventional strain gauges in longitudinal direction are presented in this paper. The methodology for detecting the initiation of pipe wrinkling and finding the optimal positions of installation of the distributed sensors are proposed.