A Review of Crack Detection In-Line Inspection Case Studies

2010 ◽  
Author(s):  
Neil Bates ◽  
David Lee ◽  
Clifford Maier
Keyword(s):  
Crack Growth ◽  
Case Studies ◽  
Crack Detection ◽  
Growth Parameters ◽  
Probability Distributions ◽  
Low Frequency ◽  
Probability Of Failure ◽  
Probability Of Detection ◽  
Inspection Data

This paper describes case studies involving crack detection in-line inspections and fitness for service assessments that were performed based on the inspection data. The assessments were used to evaluate the immediate integrity of the pipeline based on the reported features and the long-term integrity of the pipeline based on excavation data and probabilistic SCC and fatigue crack growth simulations. Two different case studies are analyzed, which illustrate how the data from an ultrasonic crack tool inspection was used to assess threats such as low frequency electrical resistance weld seam defects and stress corrosion cracking. Specific issues, such as probability of detection/identification and the length/depth accuracy of the tool, were evaluated to determine the suitability of the tool to accurately classify and size different types of defects. The long term assessment is based on the Monte Carlo method [1], where the material properties, pipeline details, crack growth parameters, and feature dimensions are randomly selected from certain specified probability distributions to determine the probability of failure versus time for the pipeline segment. The distributions of unreported crack-related features from the excavation program are used to distribute unreported features along the pipeline. Simulated crack growth by fatigue, SCC, or a combination of the two is performed until failure by either leak or rupture is predicted. The probability of failure calculation is performed through a number of crack growth simulations for each of the reported and unreported features and tallying their respective remaining lives. The results of the probabilistic analysis were used to determine the most effective and economical means of remediation by identifying areas or crack mechanisms that contribute most to the probability of failure.

Methodology to Develop Fitness-for-Service Assessments for Crack Detection In-Line Inspection Data

2006 ◽  
Author(s):  
David Shanks ◽  
Rob Leeson ◽  
Corina Blaga ◽  
Rafael G. Mora
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Corrosion Cracking ◽  
Life Extension ◽  
Remaining Life ◽  
Service Monitoring ◽  
Criticality Assessment ◽  
Inspection Data

Implementation of Integrity Management Programs (IMP) for pipelines has motivated the design of Fitness-For-Service methodologies to assess Stress Corrosion Cracking (SCC) and fatigue-dependent features reported by Ultrasonic Crack Detection (UTCD) In-Line Inspections. The philosophical approach defined by the API 579 [1] “Fitness-For-Service” from the petrochemical industry in conjunction with Risk-based standards and regulations (i.e. CSA-Z662-2003 [2] and US DOT 49 Parts 192 [3] and 195 [4]) and in-line inspection validation (i.e. API 1163 [5]) approaches from the pipeline industry have provided the engineering basis for ensuring the safety, reliability and continued service of the in-line inspected pipelines. This paper provides a methodology to develop short and long-term excavation and re-inspection programs through a four (4) phase-process: Pre-Assessment, Integrity Criticality Assessment, Remediation and Repair, Remaining Life Extension and In-Service Monitoring. In the first phase, Pre-assessment, areas susceptible to Stress Corrosion Cracking (SCC) and fatigue-dependent features are correlated to in-line inspection data, soil modeling, pipeline and operating conditions, and associated consequences in order to provide a risk-based prioritization of pipeline segments and technical understanding for performing the assessment. The second phase, Integrity Criticality Assessment, will develop a short-term maintenance program based on the remaining strength of the in-line inspection reported features previously correlated, overlaid and risk-ranked. In addition, sites may be identified in Phase 1 for further investigation. In the third phase, a Remediation and Repair program will undertake the field investigation in order to repair and mitigate the potential threats as well as validating the in-line inspection results and characterization made during the Pre-assessment and Integrity Criticality Assessment (Phases 1 & 2). With the acquired knowledge from the previous three (3) phases, a Remaining Life Extension and In-Service Monitoring program will be developed to outline the long-term excavation and re-inspection program through the use of SCC and Fatigue crack growth probabilistic modeling and cost benefit analysis. The support of multiple Canadian and US pipeline operating companies in the development, validation and implementation of this methodology made this contribution possible.

Analytical Models for the Probability Distributions of Fatigue Parameters and Crack Size of Offshore Structures Based on Bayesian Updating

2002 ◽  
Author(s):  
Ernesto Heredia-Zavoni ◽  
Roberto Montes-Iturrizaga
Keyword(s):  
Crack Detection ◽  
Probability Distributions ◽  
Crack Depth ◽  
Error Variance ◽  
Crack Size ◽  
Offshore Structures ◽  
Probability Of Detection ◽  
Posterior Distributions ◽  
Fatigue Model ◽  
Normally Distributed

In this paper a bayesian framework is used for updating the probability distributions of the parameters of a fatigue model and of crack size in tubular joints using information from inspection reports of fixed offshore structures. For crack detection, the uncertainties are taken into account by means of probability-of-detection (POD) curves. According to the bayesian procedure, if during an inspection no crack is detected, the updated (posterior) distributions depend on the prior ones at time of such inspection and on the POD. On the other hand, if during an inspection a crack is detected and measured, the corresponding predicted crack depth at that time is estimated given values of parameters of a selected fatigue model and of the initial crack depth. Then, a sample value of the model and sizing error associated with the inspection performed, defined as the logarithmic difference between the measured and the predicted crack size, is calculated. Such error is considered to be a normally distributed random variable with known mean and uncertain variance. The distribution of the error variance is taken as a conjugate one for samples of normally distributed variables with known mean and uncertain variance. Based on these assumptions, an analytical expression is obtained for the updated (posterior) distributions of the parameters of the fatigue model and of crack size. It is shown that the updated distributions depend on POD and on the prior and updated parameters of the error variance distribution. Finally, the bayesian method proposed here is illustrated taking as a fatigue model the Paris-Erdogan relation, which estimates crack growth based on linear elastic fracture mechanics. Joint failure is considered to occur when the crack depth reaches the thickness of the element where the crack propagates. The evolution of reliability with time is assessed.

Impact of Prognosis on Asset Life Extension and Readiness

2003 ◽  
Author(s):  
Yevgeny Macheret ◽  
Leo Christodoulou
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Detection ◽  
Crack Size ◽  
Probability Of Detection ◽  
Life Extension ◽  
Growth Data ◽  
Damage State ◽  
The Impact

Fatigue response of structural components is determined by environmental conditions, material microstructure, and loading history. Variation of these factors results in significant scatter in fatigue-crack growth rates and component life. In this paper, the impact of prognosis capability on asset life extension and readiness is evaluated. Fatigue-crack growth data on aluminum samples under controlled spectrum loading are used to describe the statistics of the crack-size distribution. Several sensors with different probability of detection (POD) characteristics are considered for detecting cracks of critical size, and the effect of the POD on the component life extension is evaluated. Although the crack-detection capability leads to the asset life extension, it is not sufficient to maintain required mission readiness. On the other hand, the prognosis capability, which is based on the knowledge of the component’s current damage state, damage evolution laws, and upcoming mission loading, allows required mission readiness to be maintained.

A Tool for Probabilistic Damage Tolerance of Hole Features in Turbine Engine Rotors

2012 ◽  
Author(s):  
Michael P. Enright ◽  
R. Craig McClung ◽  
Wuwei Liang ◽  
Yi-Der Lee ◽  
Jonathan P. Moody ◽  
...  
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Crack Growth ◽  
Crack Detection ◽  
Damage Tolerance ◽  
Federal Aviation Administration ◽  
High Energy ◽  
Probability Of Detection ◽  
Design Assessment ◽  
Turbine Engine

Over the past two decades, the Federal Aviation Administration (FAA) and the aircraft engine industry (organized through the Rotor Integrity Sub-Committee (RISC) of the Aerospace Industries Association) have been developing enhanced life management methods to address the rare but significant threats posed by undetected material or manufacturing anomalies in high-energy rotating components of gas turbine engines. This collaborative effort has led to the release of several FAA advisory circulars providing guidance for the use of probabilistic damage tolerance methods as a supplement to traditional safe-life methods. The most recent such document is Advisory Circular (AC) 33.70-2 on “Damage Tolerance of Hole Features in High-Energy Turbine Rotors.” In parallel with this effort, the FAA has also been funding research and development activities to develop the technology and tools necessary to implement the new methods, including a series of grants led by Southwest Research Institute® (SwRI®). The most significant outcome of these grants is a probabilistic damage tolerance computer code called DARWIN® (Design Assessment of Reliability With INspection). DARWIN integrates finite element models and stress analysis results, fracture mechanics models, material anomaly data, probability of crack detection, and uncertain inspection schedules with a user-friendly graphical user interface (GUI) to determine the probability of fracture of a rotor disk as a function of operating cycles with and without inspection. This paper provides an overview of new DARWIN models and features that directly support implementation of the new AC on hole features. The paper also simultaneously provides an overview of the AC methodology itself. Component geometry and stresses are addressed through an interface with commercial three-dimensional finite element (FE) models, including management of multiple load steps and multiple missions. Calculations of fatigue crack growth (FCG) life employ a unique interface with the FE models, sophisticated new stress intensity factor solutions for typical crack geometries at holes, shakedown modules, a menu of common FCG equations, and algorithms to address the effects of varying temperatures on crack growth rates. The primary random variables are based on the default anomaly distributions and probability-of-detection (POD) curves provided directly in the AC. Fracture risk is computed on a per-feature basis using one of several available computational methods including importance sampling, response surface, and Monte Carlo simulation. The approach is illustrated for risk prediction of a representative gas turbine engine disk. The results can be used to gain a better understanding of the AC and how the problem is solved using the probabilistic damage tolerance framework provided in DARWIN.

Detection of Crack Initiation Based on Repeat In-Line Inspection

2016 ◽  
Author(s):  
Michael Palmer ◽  
Christopher Davies ◽  
Markus Ginten ◽  
Roland Palmer-Jones
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Crack Detection ◽  
Feature Matching ◽  
Data Sets ◽  
Gas Pipelines ◽  
Electromagnetic Acoustic Transducer ◽  
As Stress ◽  
Reliable Solution ◽  
Inspection Data

As Stress Corrosion Cracking (SCC) and other cracking related issues become a more recognised hazard or threat that can be monitored by in-line inspection (ILI), there have been high expectations for the pipeline inspection industry to produce a reliable solution for identifying and sizing cracks. The current leading ILI technologies provided for pipeline crack detection are Ultrasonic (UT) and Electromagnetic Acoustic Transducer (EMAT). The introduction of EMAT In-Line Inspection technologies has provided a proven solution for crack detection that can be used in gas pipelines without having to introduce a liquid couplant into the pipeline. With the development of these technologies worldwide pipeline regulators are putting more pressure on the industry to monitor integrity issues relating to cracking. For example USA pipeline operators are required by the Office of Pipeline Safety to inspect and assess their pipelines that operate within high consequence areas for integrity issues, such as SCC, and repair or replace affected pipe. The inspection options for this include the use of Inline inspection tools — “smart pigs”. These regulations in combination with the majority of pipeline incidents relating to SCC occurring in gas pipelines have led to a significant increase in the use of EMAT ILI technology in recent years. With repeat EMAT ILIs now being conducted on some pipelines there is the option to compare data sets to identify any changes between inspections. Due to the complexities of the EMAT measurement principle and the volumes of data recorded, the process of directly comparing raw signal data from two runs is still in its infancy and cannot currently be used to confirm or discount evidence of crack growth, such as the industry has seen with estimation of corrosion growth based on Magnetic Flux Leakage (MFL) technology signal comparison. However the comparison of EMAT data sets can aid the identification of crack initiation. This technical paper presents a method for identifying the initiation of crack growth (the development of newly detectable cracks) based on repeat EMAT ILI, using feature matching and comparison of raw EMAT inspection data. The implications for integrity management of the identification of newly detectable SCC are discussed, and possible future improvements are outlined. The paper includes a case study that illustrates some of the issues.

Integration of Multiple ILI Technologies for Robust Understanding of Unique Anomalies on a Pipeline

2020 ◽  
Author(s):  
Taylor Shie ◽  
Andrew Lutz ◽  
Paul Taverna
Keyword(s):  
Magnetic Flux ◽  
Crack Detection ◽  
Low Frequency ◽  
Management Program ◽  
Probability Of Detection ◽  
Magnetic Flux Leakage ◽  
Electric Resistance ◽  
Seamless Pipe ◽  
Integrity Management ◽  
Flux Leakage

Abstract Pipeline operators have many choices when selecting inline inspection (ILI) vendors and technologies. No single technology has a one hundred percent probability of detection, identification, and sizing for all anomaly types. Operators must match the threats on their system to the existing capabilities of the ILI technologies to achieve the goals defined by the company’s integrity management program. It is sometimes necessary to run multiple technologies to effectively assess all threats in a pipeline. Multiple technologies may be run during the same timeframe or they may be run at different times during the life of the pipeline to meet program goals. Shell Pipeline Company, LP (SPLC) has a pipeline that is comprised of low frequency electric resistance welded (LFERW) pipe from Youngstown Sheet and Tube, seamless pipe from National Tube, double submerged arc welded (DSAW) pipe from Kaiser, and high frequency electric resistance welded (HF-ERW) pipe. The LF-ERW pipe was installed in 1948 while the HF-ERW was installed during relatively recent replacement projects. The DSAW pipe was installed in 1952 with the seamless pipe being installed in both 1948 and 1952. From 2015 through 2018, SPLC executed an extensive integrity management program. This included: an axial magnetic flux leakage (AMFL) inspection, two circumferential magnetic flux leakage (CMFL) inspections, two deformation inspections, an electro-magnetic acoustic transducer (EMAT) inspection, an ultrasonic crack detection (UTCD) inspection, an ultrasonic wall measurement (UTWM) inspection, and a hydrotest. A dig campaign of nearly 100 excavations was completed as a result of these surveys. One of the focuses of the paper will be the comparison of EMAT to UTCD for Likely Cracks, Possible Cracks and Unlikely Cracks that have been field verified. This paper also shares some of the unique anomalies found through the dig campaign identifying the effectiveness of each technology and their combination for integrity purposes. The paper shows the benefits of combining ILI technologies to properly characterize, assess and mitigate reported anomalies and ensure there are no blind spots in the integrity management program. Case studies including dent with gouge (e.g. AMFL + Deformation), manufacturing, and cracking anomalies as well as the analytics of ILI versus field findings are presented and discussed in the paper. The paper concludes with the knowledge creation resulting from multiple ILI technology integration assisted with subject matter expert experience and analytics to provide a robust understanding of unique anomalies in pipelines.

Comparison of Multiple Crack Detection In-Line Inspection Data to Assess Crack Growth

2010 ◽  
Author(s):  
Mark Slaughter ◽  
Kevin Spencer ◽  
Jane Dawson ◽  
Petra Senf
Keyword(s):  
Crack Growth ◽  
Crack Detection ◽  
Oil And Gas ◽  
Crack Depth ◽  
Field Investigations ◽  
Integrity Management ◽  
Essential Input ◽  
Maximum Crack ◽  
Inspection Data ◽  
Crack Growth Rates

Ultrasonic inline inspection (ILI) tools have been used in the oil and gas pipeline industry for the last 14 years to detect and measure cracks. The detection capabilities of these tools have been verified through many field investigations. ILI ultrasonic crack detection has good correlation with the crack layout on the pipe and estimating the maximum crack depth for the crack or colony. Recent analytical developments have improved the ability to locate individual cracks within a colony and to define the crack depth profile. As with the management of corroding pipelines, the ability to accurately discriminate active from non-active cracks and to determine the rate of crack growth is an essential input into a number of key integrity management decisions. For example, in order to identify the need for and timing of field investigations and/or repairs and to optimize re-inspection intervals crack growth rates are a key input. With increasing numbers of cracks and crack colonies being found in pipelines there is a real need for reliable crack growth information to use in prioritizing remediation activities and planning re-inspection intervals. So as more and more pipelines containing cracks are now being inspected for a second time (or even third time in some cases), the industry is starting to look for quantitative crack growth information from the comparison of repeat ultrasonic crack detection ILI runs. This paper describes the processes used to analyze repeat ultrasonic crack detection ILI data and crack growth information that can be obtained. Discussions on how technical improvements made to crack sizing accuracy and how field verification information can benefit integrity plans are also included.

Bayesian Updating in the Reliability Assessment of Maintained Floating Structures

2002 ◽  
Vol 124 (3) ◽  
pp. 139-145 ◽  
Author(s):  
Y. Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Bayesian Approach ◽  
Crack Detection ◽  
Probability Distributions ◽  
Reliability Assessment ◽  
Bayesian Updating ◽  
Time Dependent ◽  
Fatigue Reliability ◽  
Floating Structures

The present paper adopts a Bayesian approach to update some of the parameters of the probability distributions governing the reliability assessment of maintained floating structures. It is based on a time dependent fatigue reliability formulation presented earlier but the description of the time to crack initiation, crack growth law and probability of crack detection are updated using the information from the inspections. Its performance is demonstrated with a simulated example.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength
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