Effect of Model Error on Reliability Analysis of Surface Cracks

2018 ◽  
Author(s):  
Mahmoud Ibrahim ◽  
Karmun Doucette ◽  
Sherif Hassanien ◽  
Doug Langer
Keyword(s):  
Reliability Analysis ◽  
Structural Integrity ◽  
Service Failure ◽  
Epistemic Uncertainty ◽  
Model Error ◽  
Management Program ◽  
Quantitative Risk Assessment ◽  
Normal Operation ◽  
Pipeline System ◽  
Failure Data

The application of reliability-based structural integrity enables the process of quantitative risk assessment as part of pipelines’ integrity management program (IMP). This paper explores two topics that present challenges in terms of the practical adoption of a reliability-based IMP. The first challenge is the balance between perceived and true risk when implementing a quantitative reliability-based integrity model. This is a cornerstone for building stakeholder confidence in the calculated probability of failure (PoF) which is applied to safety and economically driven integrity decisions. The second challenge is the assurance that all relevant sources of uncertainty have been incorporated, which is essential for ensuring an accurate representation of the risk of failure of the pipeline. The level of conservatism (i.e. sufficient margin of error to maintain safety) incorporated when addressing these challenges may create a situation where calculated PoFs become inflated; becoming disproportionate to the failure history and contradictory to the current safe operation of pipelines being modeled. Two different PoF calibration approaches are proposed as practical options to address these challenges. The first method calibrates model error using an operator’s in-service failure history (i.e. failures that occurred under normal operation). The second method uses a set of failure data (including hydrostatic test failures and in-service failures) as selected by the operator considering key factors to ensure adequate representation of their specific pipeline system. These options will be demonstrated by assessing the integrity reliability of a hypothetical pipeline system. This work is expected to help evaluate the feasibility of challenging current practices regarding practical inclusion of epistemic uncertainty in integrity reliability analysis of pipelines.

Testing of Acoustic Emission Technology to Detect Cracks and Corrosion in the Marine Environment

2010 ◽  
Vol 26 (02) ◽  
pp. 106-110
Author(s):  
Ge Wang ◽  
Michael Lee ◽  
Chris Serratella ◽  
Stanley Botten ◽  
Sam Ternowchek ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Structural Integrity ◽  
Pilot Project ◽  
Development Project ◽  
Management Program ◽  
Pipeline System ◽  
Inspection Planning ◽  
Structural Degradation ◽  
Integrity Management ◽  
Acoustic Emission Technology

Real-time monitoring and detection of structural degradation helps in capturing the structural conditions of ships. The latest nondestructive testing (NDT) and sensor technologies will potentially be integrated into future generations of the structural integrity management program. This paper reports on a joint development project between Alaska Tanker Company, American Bureau of Shipping (ABS), and MISTRAS. The pilot project examined the viability of acoustic emission technology as a screening tool for surveys and inspection planning. Specifically, testing took place on a 32-year-old double-hull Trans Alaska Pipeline System (TAPS) trade tanker. The test demonstrated the possibility of adapting this technology in the identification of critical spots on a tanker in order to target inspections. This targeting will focus surveys and inspections on suspected areas, thus increasing efficiency of detecting structural degradation. The test has the potential to introduce new inspection procedures as the project undertakes the first commercial testing of the latest acoustic emission technology during a tanker's voyage.

STRUCTURAL RELIABILITY ANALYSIS BASED ON P-BOXES

2020 ◽  
Vol 92 (6) ◽  
pp. 51-58
Author(s):  
S.A. SOLOVYEV ◽  
Keyword(s):  
Probability Distribution ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Epistemic Uncertainty ◽  
Random Variable ◽  
Strength Criterion ◽  
Structural Elements ◽  
Structural Element ◽  
Limit States ◽  
Distribution Shape

The article describes a method for reliability (probability of non-failure) analysis of structural elements based on p-boxes. An algorithm for constructing two p-blocks is shown. First p-box is used in the absence of information about the probability distribution shape of a random variable. Second p-box is used for a certain probability distribution function but with inaccurate (interval) function parameters. The algorithm for reliability analysis is presented on a numerical example of the reliability analysis for a flexural wooden beam by wood strength criterion. The result of the reliability analysis is an interval of the non-failure probability boundaries. Recommendations are given for narrowing the reliability boundaries which can reduce epistemic uncertainty. On the basis of the proposed approach, particular methods for reliability analysis for any structural elements can be developed. Design equations are given for a comprehensive assessment of the structural element reliability as a system taking into account all the criteria of limit states.

Using ECA in Structural Integrity of Submarine Pipelines for Optimalization of Intervention Work

2010 ◽  
Author(s):  
Ragnar T. Igland ◽  
Trond Lamvik
Keyword(s):  
Structural Integrity ◽  
Bending Moment ◽  
Pipeline System ◽  
Unstable Fracture ◽  
Axial Capacity ◽  
Detail Design ◽  
Management Scheme ◽  
Residual Capacity ◽  
Girth Welds ◽  
Intervention Costs

The paper deals with the design methodology to define the design loads and determine the maximum allowable size of girth weld defects. The motivation for this work is reduced intervention costs obtained by opening all free spans as these are governing for rock infill volumes. 20–30% reduction of the intervention work is obtained. Structural integrity of the pipeline related to the interference with fishing gear is an important design scenario. Trawling in free span, pull-over loads with clump weight as an ALS condition is the main issue. REINERTSEN observed during detail design a lack of acceptance criteria for ALS conditions in the DNV OS-F101 design code, Ref. [1] for interference between trawl gear and subsea pipelines with low D/t ratio. Curvature in the trawl pull-over point as a function of time is found approximately constant while trawl load is increasing. The membrane forces carry most of the trawl load a few seconds after the trawl impact while bending moment decreases. This is in accordance to the philosophy that the strain and the curvature will be nearly constant for increased loading. The global load bearing mechanism is membrane and less bending. This means that we have control on the strain and that the pipeline system maintains its stiffness against loading for this high axial capacity of the flowline. These observations leads to a deformation controlled trawl load approach where an ECA of the flowline can be used to document structural integrity. Engineering Criticality Assessment (ECA) analysis is applied to evaluate the integrity of the flowlines with respect to risk for unstable fracture in girth welds due to impact from trawl equipment. The fatigue load effects from installation, temporary and operational phases are included in the ECA analysis. Geometric effects and external/internal pressure are included using the tailormade softwares LINKpipe, Ref. [7] and Crackwise4, Ref. [8]. The residual capacity of the flowlines is calculated with emphasis on fatigue during operation after the trawl pull-over. The fatigue life should be within the inspection interval, reflecting the Integrity Management Scheme.

Overcoming Technical Limitations in Identifying and Characterizing Critical Complex Corrosion

2012 ◽  
Author(s):  
Shahani Kariyawasam ◽  
Patrick Yeung ◽  
Stuart Clouston ◽  
Geoffrey Hurd
Keyword(s):  
Management Program ◽  
Pipeline System ◽  
Root Cause ◽  
Signal Characteristics ◽  
Key Characteristics ◽  
Critical Defect ◽  
External Corrosion ◽  
Failure Location ◽  
Microbiologically Induced Corrosion ◽  
Technology Processes

In 2009 a pipeline within the TransCanada pipeline system experienced a rupture. As this pipeline was already under a rigorous In Line Inspection (ILI) based corrosion management program this failure led to an extensive root cause analysis. Even though the hazard causing the failure was microbiologically induced corrosion (MIC) under tape coating, the more troubling question was “Why had the severity of this anomaly not been determined by the ILI based corrosion management program?” This led to an investigation of what key characteristics of the ILI signals resulting from areas of “complex corrosion” are more difficult to correctly interpret and size and furthermore where the line condition is such that manual verification is needed. By better understanding the limitations of the technology, processes used, and the critical defect signal characteristics, criteria were developed to ensure that “areas of concern” are consistently identified, manually verified and therefore the sizing is validated at these potentially higher risk locations. These new criteria were applied on ILI data and then validated against in-the-ditch measurements and a hydrotest. This process in conjunction with optimization of ILI sizing algorithms enabled the operator to overcome some of the known challenges in sizing areas of complex corrosion and update its corrosion management process to improve the detection and remediation of critical defects. This paper describes this investigation of the failure location, development of the complex corrosion criteria, and the validation of effectiveness of the criteria. The criteria are focused on external corrosion and have been currently validated on pipelines of concern. Application to other lines should be similarly validated.

Probability of Exceedance (POE) Methodology for Developing Integrity Programs Based on Pipeline Operator-Specific Technical and Economic Factors

2002 ◽  
Author(s):  
Rafael G. Mora ◽  
Curtis Parker ◽  
Patrick H. Vieth ◽  
Burke Delanty
Keyword(s):  
Decision Making ◽  
Probabilistic Models ◽  
Cost Benefit Analysis ◽  
Management Program ◽  
Metal Loss ◽  
Decision Making Process ◽  
Pipeline System ◽  
Probability Of Exceedance ◽  
Integrity Verification ◽  
Inspection Data

With the availability of in-line inspection data, pipeline operators have additional information to develop the technical and economic justification for integrity verification programs (i.e. Fitness-for-Purpose) across an entire pipeline system. The Probability of Exceedance (POE) methodology described herein provides a defensible decision making process for addressing immediate corrosion threats identified through metal loss in-line inspection (ILI) and the use of sub-critical in-line inspection data to develop a long term integrity management program. In addition, this paper describes the process used to develop a Corrosion In-line Inspection POE-based Assessment for one of the systems operated by TransGas Limited (Saskatchewan, Canada). In 2001, TransGas Limited and CC Technologies undertook an integrity verification program of the Loomis to Herbert gas pipeline system to develop an appropriate scope and schedule maintenance activities along this pipeline system. This methodology customizes Probability of Exceedance (POE) results with a deterministic corrosion growth model to determine pipeline specific excavation/repair and re-inspection interval alternatives. Consequently, feature repairs can be scheduled based on severity, operational and financial conditions while maintaining safety as first priority. The merging of deterministic and probabilistic models identified the Loomis to Herbert pipeline system’s worst predicted metal loss depth and the lowest safety factor per each repair/reinspection interval alternative, which when combined with the cost/benefit analysis provided a simplified and safe decision-making process.

Learnings From Data Management and Integration Efforts on the Enbridge Pipeline System

2004 ◽  
Author(s):  
Garry L. Sommer ◽  
Brad S. Smith
Keyword(s):  
Data Management ◽  
Management Program ◽  
Pipeline System ◽  
Data Set ◽  
Data Alignment ◽  
Commercial Market ◽  
History Of ◽  
Integrity Management ◽  
Management Effort ◽  
Analysis System

Enbridge Pipelines Inc. operates one of the longest and most complex pipeline systems in the world. A key aspect of the Enbridge Integrity Management Program (IMP) is the trending, analysis, and management of data collected from over 50 years of pipeline operations. This paper/presentation describes Enbridge’s challenges, learnings, processes, and innovations for meeting today’s increased data management/integration demands. While much has been written around the premise of data management/integration, and many software solutions are available in the commercial market, the greatest data management challenge for mature pipeline operators arises from the variability of data (variety of technologies, data capture methods, and data accuracy levels) collected over the operating history of the system. Ability to bring this variable data set together is substantially the most difficult aspect of a coordinated data management effort and is critical to the success of any such project. Failure to do this will result in lack of user confidence and inability to gain “buy-in” to new data management processes. In 2001 Enbridge began a series of initiatives to enhance data management and analysis. Central to this was the commitment to accurate geospatial alignment of integrity data. This paper/presentation describes Enbridge’s experience with development of custom software (Integrated Spatial Analysis System – ISAS) including critical learnings around a.) Data alignment efforts and b.) Significant efforts involved in development of an accurate pipe centreline. The paper/presentation will also describe co-incident data management programs that link to ISAS. This includes enhanced database functionality for excavation data and development of software to enable electronic transfer of data to this database. These tools were built to enable rapid transfer of field data and “real time” tool validation through automated unity plots of tool defect data vs. that measured in the field.

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