See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/223417529 Review of pipeline integrity management practices Article in International Journal of Pressure Vessels and Piping · July 2010 DOI: 10.1016/j.ijpvp.2010.04.003 CITATIONS 67 READS 3,088 2 authors: Some of the authors of this publication are also working on these related projects: Machining of MMCs View project H. A. Kishawy University of Ontario Institute of Technology 139 PUBLICATIONS 1,473 CITATIONS SEE PROFILE Hossam A.Gabbar University of Ontario Institute of Technology 179 PUBLICATIONS 607 CITATIONS SEE PROFILE All content following this page was uploaded by Hossam A.Gabbar on 17 July 2014. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
International Journal of Pressure Vessels and Piping 87 (2010) 373e380
Contents lists avai
International Journal of Pressure Vessels and Piping
journal homepage: www.elsevier .com/locate/ i jpvp
Review
Review of pipeline integrity management practices
Hossam A. Kishawya, Hossam A. Gabbar b,*a Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (UOIT), 2000 Simcoe St. N., Oshawa ON L1H 7K4 ON, Canadab Faculty of Energy Systems and Nuclear Science, University of Ontario Institute of Technology (UOIT), 2000 Simcoe St. N., Oshawa ON L1H 7K4 ON, Canada
a r t i c l e i n f o
Article history:Received 13 July 2009Received in revised form13 April 2010Accepted 30 April 2010
0308-0161/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.ijpvp.2010.04.003
a b s t r a c t
Pipeline integrity is the cornerstone of many industrial and engineering systems. This paper providesa review and analysis of all aspects related to pipeline integrity. Pipeline threats are explained andfailures are classified. Design practices are discussed using pressure criteria. Inspection techniques arestudied and used as a basis for describing the corresponding integrity assessment techniques, which arelinked with integrity monitoring and maintenance criteria. Finally, pipeline integrity managementsystem design is presented using activity models, process models, and knowledge structures. The paperwill be useful for further development of automated tools to support pipeline integrity management.
� 2010 Elsevier Ltd. All rights reserved.
1. Introduction
Pipelines function as blood vessels serving to bring life-neces-sities such as water or natural gas and to take away life waste likesewage. And they are considered to be the most favored mode oftransportation of gas/liquid in large quantities. Many of the pipe-lines were built by specific companies to transport commodities totheir customers in their respective territories. Furthermore, pipe-line companies must continue to operate profitably, and thuspipelines are interconnected at national and global level. Thenetwork of pipelines indisputably out-rates other transportationmodes such as truck/train due to its cost effectiveness, convenience,high land use efficiency, higher reliability, higher degree of safetyand security and environmental friendliness over great distances.
However, as pipeline infrastructures represent a high capitalinvestment and pipelines must be free from the risk of degradationwhich could cause environmental hazards and potential threats tolife, pipeline integrity design, monitoring andmanagement becomevery crucial. For example, improper design of storm sewers canthreaten lives, such as drowning children or even adults swept intoor fallen into a storm sewer without a grate. Improper maintenanceof natural gas pipelines threatens property and life from explosionand fire resulting from pipeline leaks or rupture. Furthermore,highly dangerous gases or liquids, such as cyanide, and highlyradioactivewastes, such as those existing in nuclearweapons plantspose a high risk to theworkers of those plants, and to the neighbors
ar).
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of such plants. They must be designed and operated with extremecare. Leaks or ruptures of such pipes must be prevented at all costs.
“Pipeline integrity” connotes the concepts of failure prevention,inspection and repair, and it also includes products, practices andservices that help operators maximize their assets. With entireeconomies built on reliable pipeline, its integrity is receiving moreattention than ever from the very composition of its tubularstructure to the high-tech ways of building, modeling, managing,monitoring and repairing. It begins at the project conception stageand allows for risk mitigation and long-term optimized perfor-mance to be built into the final design.
This articlewill brief on typical threats faced bypipeline integrityand techniques widely used in management and monitoring.
1.1. Pipeline integrity threats
With many kilometers of the pipeline buried in dirt orsubmerged in water and with coatings that can range in thicknessfrom a few microns to several metres, there are many categories ofthreats to pipeline integrity:
� Material and construction defects, e.g. defective longitudinalpipe seam, pipe body or joint welds;
� Mechanical damage from construction, maintenance or third-party excavation;
� Incorrect operation;� Corrosion,creep and cracking mechanisms;� Device failures and malfunctions;� Earth forces such as earthquakes, land slips or telluric currentsand weather related threats such as high winds, rough seas orcold/hot temperatures.
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Due to the varied forms of threats, there appears to be a trend innot only thinking defensively but also in taking an aggressiveposition toward safety and asset optimization. In order to keep upwith the demands of regulations, economics and applications, thereliability of the pipeline begins with the quality of the line pipeused. Companies constructing new pipelines have an array ofmaterials and coatings at their disposal that were not available justa few years ago. Advances in metallurgy give pipe manufacturersthe ability to fine-tune alloys to meet the most demanding condi-tions, including high-temperature/high-pressure, arctic and sourapplications.
However, even with these technology advances, it is stillimportant to have a robust pipeline integrity management system.It is a process for assessing and mitigating pipeline risks in order toreduce both the likelihood and consequences of incidents.
1.2. Pipeline integrity management
Recent pipeline failures, as shown in Fig. 1, have resulted in theU.S. Department of Transportation issuing regulations that aim atenhancing pipeline integrity management through inspection,testing and analysis of pipelines that run through or near highconsequence areas [1]. Pipeline integrity management consists ofpipeline assessment, inspection, defect and repair, and mainte-nance. However, based on different types of pipes, the integritymanagement focuses on different aspects of the system. High-pressure pipes, for example, are those where the internal pressureof the pipe is so high that the prime attention of the management isto ensure the safety of the pipelines from bursting or leaking. Mostlong-distance petroleum and natural gas pipelines belong to thiscategory. Low-pressure pipes where the internal pressure is so low,focus should be posed on governing the external loads. Most sewerpipes and culverts belong to this category. For intermediate-pres-sure pipes especially those with large diameters and relatively thinwalls are subjected to large external loads and earthquakes or othernatural disasters.
Alexander [2] developed to present ideas associated with thedevelopment of an Engineering-Based Integrity Management
Fig. 1. Recent failure of pip
Program (EB-IMP) which based in part on the principles embodiedin the API 579 Fitness for Service document. At its core, API 579makes use of a three-level assessment process to evaluate thefitness for service of a particular component or system. There areother models like 5-M approach and Model developed by Canadianassociation of petroleum producers (CAPP).Generally each pipelineintegrity management program shall contain the followingcomponents [3]: (1) a process for identifying the pipeline segmentsand failure mode that could affect a high consequence area; (2)a baseline assessment plan; (3) an analysis that integrates allavailable information about the integrity of the entire pipeline andthe consequences of a failure; (4) criteria for repair actions toaddress integrity issues raised by the assessment plan and infor-mation analysis; (5) a continual process of assessment and evalu-ation to maintain pipeline integrity; (6) identification of preventiveand mitigation measures for protecting the high consequence area;(7) methods to measure the program’s effectiveness; and (8)a process for the review of integrity assessment results and forinformation analysis.
Experience shows that properly designed, inspected andmaintained pipelines can continue safely serving the needs fordecades. That’s why pipeline operators use a combination of directassessments, hydrostatic testing and internal inspection tools forensuring the safe and reliable delivery of world’s most vital naturalresource.
2. Pipeline integrity design
Based on different type of pipes, there are special designconsiderations involved:
2.1. High-pressure pipes
For higher-pressure pipes effect of temperature change has to beconsidered. For pipelines with rigid supports, the pipe is restrainedby the supports to expand lengthwise. If significant temperaturechanges occur, due to either weather change or cooling followinghot welding of a restrained pipe during repair, high stresses can be
H.A. Kishawy, H.A. Gabbar / International Journal of Pressure Vessels and Piping 87 (2010) 373e380 375
generated in the pipe to cause the pipe to break, buckle, or bendexcessively, or destroy the supports.
For pipelines not supported uniformly and when a lateral loadexists, pipe bending is another factor that needs to be consideredwhen designing for a high-pressure pipeline. Any lateral loadapplied to the pipe, including its ownweight, causes the pipe to sagor bend between adjacent supports. Such bending causesa moment at any cross section of the pipe, which in turn generatesa bending tensile stress. The maximum bending stress happens atthe location of maximum bending moment, which most oftenhappens at the mid-span, and at the outer face or edge of the bend.The stress is a tension on the outer part of the bend, andcompression on the inner side of the bend. Such bending stressescan also happen to buried pipelines when the bedding or groundsupport for a portion of the buried pipe is lost due to scouring,earthquake, or ground settlement. Pipe bending affects pipelinedesign in another important way. The flow in a pipe can producevery large forces on pipe bends and responsible for corrosion anderosion, especially when the fluid pressure is high. This requirescareful design of thrust blocks, which are usually heavy reinforcedconcrete structures, to resist such thrusts.
2.2. Low-pressure pipes
For low-pressure pipes, analysis and design are focused on soilproperties, soilepipe interaction, installation (bedding) method,and the rigidity of the pipes.
The design of low-pressure or non-pressure pipes is focused onexternal instead of internal loads. Especially important to thedesign of these pipes is the earth load, which depends on theproperties and conditions of the soil. Meanwhile, the soil-pipeinteraction is highly complicated by the fact that the system isstructurally indeterminate. This means that the forces and stressesbetween the soil and the pipe cannot be determined from usingonly statics and dynamics (Newton’s laws). The stiffness propertiesof the pipe and of the soil must also be included in the analysis.Further complicating the matter is the fact that the soil propertiesvary both with space and time; they are three-dimensional andunsteady. Due to such complexity, most analyses of soilepipeinteraction are semi-empirical relying on many simplifyingassumptions and experimental data.
Based on the stiffness properties of the pipes, the design shoulddistinguish between rigid and flexible pipes. For the rigid pipesystems, integrity design includes the following steps [3]: (1)determine the earth load; (2) determine the live load by usingempirical data; (3) combine the earth load with the live load, byadding them together; (4) select the type of construction, anddetermine the corresponding bedding factor; (5) determine thesafety factor from standards or codes (if no standards exist on safetyfactor, use a minimum of 1.5); and (6) select the pipe strength.
As for flexible pipes, when a pipe of circular cross section isunder earth load from above. This force deforms the pipe into anelliptical shape. Such deformation and deflections are to be referredto as ring deformation and ring deflections, respectively. Such largedeflections reduce the cross-sectional area of the flow, and createpotential risks in the transportation of fluids and obstacles intesting. Other factors accompanying with rigid pipes and high-pressure pipes include buckling, earthquake loads, and stresscaused by thermal expansion, which should also be considered inthe design of flexible pipes.
3. Pipeline inspection management
The purpose of integrity assessment management is to ensurethat the material, practices, and inspection tools used to maintain
a safe pipeline are state-of-the-art. An assessment process usuallyincludes developing a pipeline integrity assessment managementplan, gathering information, conducting risk assessment andprioritizing utilizing risk-ranking software.
Proper inspection is the key to safe and reliable pipeline oper-ations. Some inspecting methods include: pigging, hydro-testing,and external corrosion direct assessment (ECDA) and internalcorrosion direct assessment (ICDA), and some of which are brieflyintroduced as follows [3e6]:
3.1. Smart pigs
“Smart Pigs” are cylinder-shaped electronic devices used by theoil pipeline industry to detect loss of metal and in some casesdeformations in the pipeline. Inserted into the pipeline andpropelled by the flowing liquid, smart pigs record certain physicaldata about the pipeline’s integrity (e.g. location of reduced pipewall thickness, dents, etc.) as it moves through the pipeline. Eval-uation of smart pig data allows the pipeline operator to makeintegrity decisions about the pipeline and to find and mitigatepotential problem areas before they become a problem.
Since their development in the 1960s, smart pigs have under-gone several generations of technological advancements. As smartpig technology has evolved, pipeline operators have required theuse of specialized “smart pigs.” Specialized smart pigs have evolvedinto three types: metal loss tools, crack detection tools and geom-etry tools.
3.1.1. Metal loss tools (corrosion tools)
A. Magnetic flux leakage (MFL): This tool induces a magnetic fieldto the pipe. As it travels, it locates and records magnetic fluxanomalies in the pipe. The recorded magnetic flux data isconverted information that provides an indication of metal lossin the pipe. There are two types of these tools, high resolutionMFL and standard resolution MFL. The main differencebetween the two is in the number of sensors and the amount ofresolution. Most MFL tools can determine the location ando’clock position of the metal loss anomaly and detect ifa corrosion anomaly is internal or external to the pipe wall. Italso provides data of each corrosion anomaly including itslength and maximum pit depth, which allows for calculation todetermine the pipe’s remaining strength. MFL pigs are gener-ally capable of detecting corrosion greater than 20% of the pipewall thickness in depth, although actual indication reportingvaries by smart pig vendor and corrosion anomaly configura-tion. However, axially-oriented flaws such as stress corrosioncracking, selective seam corrosion and axial gouges are difficultto detect with MFL pigs.
B. Ultrasonic: Also called a “UT tool,” this tool provides similarphysical pipe data as the MFL tool, but it uses ultrasonic tech-nology. The UT tool transmits an ultrasonic pulse into the pipewall and directly measures its thickness. Since this technologyrequires a clean pipe wall, it is generally not used for certainpipelines such as crude lines with a paraffin build-up. There arealso wall-thickness limitations with the UT tool. It works wellwith heavy-wall pipe, but not as well with thin-wall pipe, and itis not as widely used as the MFL tool.
3.1.2. Crack detection toolsThese are the more recent addition to the pipeline operator’s
suite of integrity assessment tools. Some of these technologies arefairly new and still developing:
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A. Ultrasonic crack detection: This tool generates an ultrasonicsignal into the pipe wall that is reflected off the internal andouter surfaces of the pipe. If a crack is detected, the signalreflects back along the same path of the tool. Since a “liquidcoupling” is required between the sensors and the pipe wall,this tool works only with liquid pipelines.
B. Transverse magnetic flux leakage: This evolving technologymagnetizes the pipe wall around its circumference to detectcracks, such as longitudinal seams cracks and longitudinalseam corrosion. This tool is similar to the standard MFL toolmentioned above; however, the induced magnetic field is ina transverse or perpendicular direction. This tool also haslimitations e cracks must have sufficient width, or gap, to bedetected, and the severity of the crack is not determined.
C. Elastic wave tool: This evolving technology operates by sendingultrasounds in two directions along the pipeline to locate andsize longitudinally oriented cracks and manufacturing defects.
Fig. 2. Pipeline excavation to examine the external coating and assess corrosion [6].
Fig. 3. Sample pipeline elevation profile [12].
3.1.3. Geometry toolsThe purpose of geometry tools is to gather information about
the physical shape, or geometry, of a pipeline. Geometry tools areprimarily used to find “outside force damage,” or dents, in thepipeline. However, they can also generally detect and locatemainline valves, fittings, and other appurtenances. As with all inlineinspection tools, these tools have limits on their use and in theextent of results obtained. The two main types of geometry toolsutilize the same principle:
A. Caliper tools: This tool utilizes a set of mechanical fingers orarms that ride against the internal surface of the pipe or useelectromagnetic methods to detect dents or deformations
B. Pipe deformation tools: This tool operates the same as a calipertool, but it also utilizes gyroscopes to provide the o’clockposition of the dent or deformation in the pipe. This tool cangenerally provide pipe bend information as well.
3.2. Mapping tools
This tool can be utilized in conjunction with other toolsdescribed above to provide global positioning system (GPS) corre-latedmapping of the pipeline and other physical location data, suchas for valves and other appurtenances.
3.3. Long range guided wave inspection
The Guided Wave technology screens the piping which is inoperation, insulated and even be buried to inspect metal lossfeatures such as corrosion and erosion. Long range guided waveswith frequency less than 100 kHz are used tomap the corrosion anderosion in the pipes.
3.4. Hydrostatic testing
Hydrostatic testing is used to conduct strength tests on newpipes while in the manufacturing process, as well as at thecompletion of pipeline installation in the field prior to being placedin service. Hydrostatic testing is also used, at times, for integrityassurance after a pipeline is in operation. Hydrostatic tests aregenerally the preferred integrity assessment method when thepipeline is not capable of being internally inspected or if defects aresuspected that may not be detectable by internal inspection smartpigs. The hydrostatic test establishes the pressure carrying capacityof a pipeline and may identify defects that could affect integrityduring operation. Testing is done to a pressure that is greater than
the normal operating pressure of the pipeline. This providesa margin of safety. The test stresses the pipeline to a predeterminedpercentage of its specified minimum yield strength, and the test isgenerally held for eight hours. If stress corrosion cracking is sus-pected, the test pressure may be increased to 100% to 105% ofspecified minimum yield strength or higher for 30 min to an hour[3]. Axial flaws such as stress corrosion cracking, longitudinal seamcracking, selective seam corrosion, long narrow axial (channel)corrosion and axial gouges are difficult to detect withMagnetic FluxLeakage (MFL) pigs and are better detected with a hydrostatic test.Hydrostatic testing requires the ability to acquire large quantities oftest water, which in some areas may be difficult. Once used, the testwater may contain trace quantities of petroleum products, whichmay require treatment of the water prior to discharging or disposal.Finally, hydrostatic testing requires the pipeline to be out of servicefor a period of time thus potentially curtailing the availability ofgasoline, jet fuel, diesel fuel, crude oil, and/or home heating oil atthe delivery point.
4. Pipeline assessment methods
4.1. External corrosion direct assessment
Since only about 50% of pipelines are conventionally piggable,direct assessment was developed as an alternative to internal
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inspection tools and pressure testing [6e8]. It is a proactiveprocedure that prevents and detects external corrosion defectsbefore they grow to a size that damages the pipe’s structuralintegrity. ECDA is usually a four-step process for assessing theintegrity of a section of pipeline:
� Pre-assessment� Indirect inspections� Direct examination� Post-assessment
The pre-assessment involves data collection and visualization,determination of the feasibility of direct assessment, identification ofECDA regions and calculation of the probability of failure of thepipeline. The indirect inspection is to perform over-the-groundsurveys for the severity of coating faults, other anomalies and areaswhere potential corrosion exists. The direct examination includesanalyzing the indirect inspection data and determining which indi-cations are most severe. Fig. 2 [6] shows an excavation to examinea pipe for external corrosion. Finally, during the post-assessment, thedata collected from the direct examination and indirect inspectionare analyzed, and the overall effectiveness of the ECDA process isevaluated and the interval reassessment is established.
4.2. Internal corrosion direct assessment
Internal corrosion attack is one of the more serious agingmechanisms in pipeline systems that transport gaseous material.Internal corrosion can cause either a penetration of the gascontainment boundary that results in a leak or a decrease instructural strength that results in a catastrophic failure. For the safeand reliable operation of these pipeline systems, it is important todetect the location and quantify the amount of internal corrosionthat occurs before they reach critical conditions. There are threeapproaches to control internal corrosion: CAPP RecommendedPractices, ICDA approach, and 5-M approach.[9] CAPP recom-mended approach is most complete in nature but it is quantitativein nature on other hand 5-M approach (Modeling, Mitigation,
Fig. 4. IDEF0 based activity model for
Monitoring, Maintenance and Managements) has not been appliedin practically. ICDAmethods have been ratified for dry gas pipelinesand some are currently being developed for liquid petroleum andwet gas to meet the need for the assessment of pipeline integritywith respect to likelihood of internal corrosion [10e13]. As a directassessment, the process of ICDA is similar to that of ECDA. Thepurpose of ICDA is to determine areas of high potential for waterhold-up in a pipeline system. The basis of the analysis is on loca-tions where the inclination angle of the pipeline exceeds the criticalangle. Inclination angle is simply the changing elevation as a func-tion of the linear distance along the line. To determine the incli-nation angle of the pipeline, the pipeline’s elevation profile must beunderstood. The pipeline elevation profile can be obtained usingseveral means: visually interpreted directly from alignment sheets,using GPS survey information, or automatically generated usinga GIS tool, as shown in Fig. 3 [14]. Once the inclination angle isdetermined, the basic procedure of ICDA is as follows [14]:
� Determine the first location along the pipeline with an incli-nation angle that exceeds the critical angle.
� If all inclination angles exceed the critical angle, then choosethe angle of highest inclination.
� Examine the target location(s). If no corrosion is found, thendownstream corrosion is unlikely.
� Examine locations that have the highest inclination angles toprovide integrity information.
5. Pipeline integrity monitoring and maintenance
Pipeline integrity monitoring includes a variety of measures tomonitor the condition of the pipeline including its immediateenvironment, in order to determine or prevent damage to the pipeand its associated equipments, maximize the efficiency and safetyof the pipeline, minimize potential accidents and service inter-ruptions due to pipeline neglect, and safeguard company and publicinterests.
The following is a partial list of conventional measures thatshould be included in pipeline integrity monitoring [3].
Fig. 5. Proposed process model for pipeline integrity management.
H.A. Kishawy, H.A. Gabbar / International Journal of Pressure Vessels and Piping 87 (2010) 373e380378
� Leak detection by using a variety of measures including: 1)mass-balance method, also referred to as the materials balancemethod, uses the continuity equation of one-dimensional flowbetween an upstream point and a downstream point tocalculate the amount of flow due to leakage or rupture, 2)pressure-drop method, measured by pressure transducers, isuseful especially when the spacing between transducers issmall, 3) computational modeling of pipeline systems, whichsets up a system of equations on the computer based on fluidmechanics and input data pertaining to the pipeline system, topredict the velocity, discharge, pressure, and temperature, 4)visual and photographic observations, 5) round-penetratingradar, 6) pigs used to examine pipes for dents, corrosion (loss ofmetals), and possible cracks and 7) dogs that can detect thescent at concentrations as low as 10e18 molar.
� Visual inspection of pipe exterior for any exposed pipe orexposed portion of a pipeline.
� Underwater inspection of pipe exterior for submarine pipes byusing divers or special submarines carrying photographicequipment.
PipelineStructure Degradation
Deterioration
PipelineOperation
MaterialsOperatingProcedures(Recipe)
ControlSystems
PipelineBehavior
Fig. 6. Knowledge structure of pip
� Remote sensing by satellites for early detection of encroach-ment by heavy vehicles traveling on or across a pipeline right-of-way, or detection of other conditions that may threaten thepipeline’s integrity, such as a flood, a landslide, or groundsubsidence.
� Line patrols flying over pipeline right-of-way to detect prob-lems or potential problems.
� Daily checking of pumps and other rotating machines used inrunning the pipeline.
� Checking of pressure regulators and pressure-relief valves.� Checking of control valves.� Checking the calibration of flow meters, pressure transducers,and other sensors.
Considering the laboriousness and inefficiency of the mostconventional methods listed above, more andmore attentions havebeen paid to the development of intelligent integrity monitoringsystems. For instance, some industries [15] developed and appliedfiber optic sensing technologies in pipeline integrity monitoring. Inthis monitoring system, the light is launched into the fiber core and
EnvironmentImpacts
MaintenanceStrategy
InspectionTasks
ConditionMonitoringTasks
RepairTasks
Scheduling
Risk &ReliabilityAnalysis
eline integrity management.
Pipe FailurePressure (Q)
Cross-Sectional Area of MetalLost in Corroded Region (inLongitudinal Axis of Pipe)
Original Cross-Sectional Area ofCorroded Region
Folias Factor for Pipe BulgingBefore Failure
Flow Stress & Yield Stress
Pipe Diameter & Wall Thickness
Average Defect Depth& Longitudinal Length
Pipe Wall Thickness &Defect Longitudinal
Length
Corrosion Rate forDefect Depth & Length
Probability ofFailure
Probability ofDetection
MeasurementError
PipelineInspection
RepairCriteria
MaximumAllowablePressure
ConditionAssessment
OverallDefect
Population
DetectedDefect
Population
Defect Size
Fig. 7. Knowledge structure of pipeline inspection, repair, and maintenance.
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propagates along the length of the fiber attached to the pipeline.Specialized sensing instrumentation was configured such that anyexternal disturbance of the fiber, which alters some of the charac-teristics of the guided light (i.e., amplitude, phase, wavelength,polarization, modal distribution and time-of flight), can be moni-tored and related to the magnitude of the disturbing influence.Awawdeh et al. [16] investigated the application of an AdHocwireless network coupled with accelerometer sensors for non-invasive continuous monitoring of flow rate and other flowpatterns in large pipeline networks. The sensors rely on trackingflow-induced vibrations to directly estimate the change in the flowrate, and thus provide a means for detection and early warning ofintegrity loss in pipeline infrastructure. More recently, Bonny et al.[17] utilized vibration and acoustic emission sensor with shortwavelengths to recognize the change in the flow characteristics ofa liquid medium as it passed through a section of damaged pipelineand associated the change in sound emission profile with the
Table 1Detailed knowledge structure to support pipeline integrity management.
Pipeline structure Segment id, geometry, portsPipeline behavior Phenomena, state equations, transitionsPipeline operation Procedure, unit procedure, operation, and phase, steps,
formula, preepost conditionsMaterials Material properties, materials involved in each
operation/behaviorDegradation/
deteriorationFailure class, symptoms, causes, consequences,behavioral equations of failure
simulated failure modes. The result was found that piezoelectricvibration sound emission sensor is capable of detecting changes inthe flow characteristics and has potential to form the basis of anintegrated wireless sensor device.
6. Design of pipeline integrity management system
6.1. Activity models
Pipeline goes through life cycle starting from design, construc-tion, commissioning, operation, maintenance, and decommission-ing or replacement. Pipeline integrity management should beconsidered throughout the life cycle. In order to understand theproposed pipeline integrity management process models and toformulate best practices of pipeline integrity management, IDEF0[18] is used to develop activity models, as shown in Fig. 4.
6.2. Pipeline design process models
In the above activity models pipeline design is the cornerstonestage where all operational and maintenance activities are definedand validated, which is denoted as activity A1 in Fig. 4. In order tounderstand the detailed activities involved in pipeline design,detailed process models are developed as shown in Fig. 5. Pipelinedesign includes defining process models, fluid dynamic models,operation models, control models, risk and reliability analysis,failure analysis, monitoring and maintenance requirements,construction specifications, and demolishing specifications [19].Standards such as API (API 1160) [20], ASME B31.8 [21], ISA, ISO, andIEC are employed to support the design stage, and to confirm thefitness for service and integrity measures.
6.3. Knowledge structure
Integrity management can be viewed as risk-informed deci-sions to ensure fitness for service throughout the life time of
H.A. Kishawy, H.A. Gabbar / International Journal of Pressure Vessels and Piping 87 (2010) 373e380380
pipeline. This requires constructing knowledge structure tosupport pipeline life cycle. A typical knowledge structure isproposed as shown in Fig. 6 which is further described as inTable 1.
Fig. 7 shows the detailed knowledge structure of pipelineinspection, repair and maintenance. It includes repair criteria andmaximum allowable pressure, which is linked with pipe failurepressure, probability of failure, inspection, probability of detection(i.e. detectability), measurement error, defect size and defect pop-ulation. It shows the relationships between pipe failure, stress,corrosion factor, and geometry.
7. Conclusion
As a “sub-industry,” pipeline integrity appears to havea bright future. Pipeline integrity practices and technologies mustcontinue to evolve. As the world’s energy needs continue to risewith growing international industrialization, the world’s pipelineinfrastructure will have to meet the increasing pressures ofdemand. In order to maintain their own fiscal health as well asthe safety and well-being of the environment and the commu-nities they serve, pipeline companies will continue to rely onadvances in pipeline integrity practices and management forcontinuing benefit.
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