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.

SCC Management and Integrity Planning in a Gas Pipeline

2006 ◽  
Author(s):  
David Katz ◽  
Sergio Limon ◽  
Ming Gao ◽  
Rick McNealy ◽  
Ravi Krishnamurthy ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Detection ◽  
Management Strategies ◽  
Field Measurements ◽  
Gas Pipeline ◽  
Oil Pipeline ◽  
Integrity Management ◽  
Crack Growth Rates

Stress Corrosion Cracking (SCC) is a major integrity management concern for many gas and oil pipeline operators. Predictive models for Stress Corrosion Crack growth were developed using laboratory test data from the mid 1970’s, and limited inspection data and excavation measurements from the early 1990’s. Extensive efforts continue to be made to develop strategies for a better management of the SCC problem. In this paper, a study of crack growth rates was conducted on the Williams 16-inch gas pipeline using data from two consecutive in-line crack detection tool runs and direct field measurements. Findings from this study provide a direct measurement of crack growth rates for ILI crack features with depths ranging from 12.5%wt to 40%wt. Future integrity of the pipeline was assessed. The integrity management strategies could be further refined using the calculated crack growth rate, field excavation data and fracture mechanics based API 579 FAD approach.

Applying Advanced Ultrasonic In-Line Inspection Technologies to Effectively Manage Hook Cracks

2020 ◽  
Author(s):  
Cory Wargacki ◽  
Wade Forshner ◽  
Rogelio Guajardo ◽  
Thomas Hennig
Keyword(s):  
Crack Detection ◽  
Crack Depth ◽  
Welding Process ◽  
Pipeline System ◽  
Data Set ◽  
Wide Range ◽  
Pipeline Segment ◽  
Integrity Management ◽  
Inspection Data ◽  
Pulse Echo

Abstract Axial cracking inspections have become common place on a global level within pipeline operator’s integrity management programs. As technology continues to improve, operators are presented with more accurate assessments of the assets that are in current operation. However as more information is collected more threats are being identified and need to be assessed in a manner that is more applicable to their specific morphology. It is well known that vintage ERW manufacturing techniques can suffer from a wide range of potential threats such as lack of fusion or inclusions within the steel forming hook cracks during the rolling and welding process. Current In-line inspection technologies that are designed to detect, Identify and size cracklike flaws in pipelines are very proficient at doing so. However, due to the physical principals of the Ultrasonic pulse echo technology, deep features approaching, or above pulse echo saturation amplitudes pose challenges in determining accurate depth sizing. In 2015 a Canadian pipeline operator determined the need to inspect one of their 16” assets for axial crack-like indications. During the analysis of this inspection data set, a number of saturated crack-like indications were reported. Saturated cracklike signals present a challenge to operators as they have to be considered in a conservative manner as 4mm or deeper which in turn leads to difficulties in the prioritization of resources associated with the excavation program. The operator approached NDT Global in 2017, after the release of NDT Global’s Enhanced sizing depth algorithm to reevaluate the features that were present in the previous crack inspection data set. Working together with the operator, NDT Global applied the Enhanced sizing methodology to all features of significance in the pipeline segment and compared the results to lab measurements and in field NDE measurements. The outcome of the reanalysis using the most up to date software algorithms utilizing enhanced sizing showed great benefits by increasing the accuracy of the crack depth sizing as NDT Global was now able to report full through wall depth sizing, however there were still some limitations on the ability to accurately size crack-like features as the primary threat is believed to be a result of hook cracks. As a final step in this program NDT Global was provided sample spools that were cut out of the pipeline segment to perform a pull testing campaign utilizing the newest crack detection technology that was specifically targeted towards accurately sizing tilted and skewed crack like features. The authors will briefly discuss the pipeline system and inspection campaign and in detail will discuss the benefits of using technology that has been developed to help pipeline operators better understand the threats in their integrity management program.

Pipeline SCC in Near-Neutral pH Environment: Recent Progress

1996 ◽  
Author(s):  
W. Zheng ◽  
R. W. Revie ◽  
F. A. MacLeod ◽  
W. R. Tyson ◽  
G. Shen
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Pressure Fluctuation ◽  
Oil And Gas ◽  
Crack Depth ◽  
Pressure Level ◽  
Depth Measurement ◽  
Growth Crack ◽  
Crack Depth Measurement ◽  
Crack Growth Rates

Transgranular stress corrosion cracking in oil and gas linepipe was studied by testing full-scale pipes in soil environments. Three pipes made of Grade 359 (X-52) and Grade 414 (X-60) steels were used. Sixteen cracks were prepared on the external surface of each pipe, and crack growth was monitored and studied as a function of the pressure level and pressure fluctuation, the latter being described by the minimum to maximum stress ratio (R) and the loading rate. The overall results suggest strong mechanical effects on crack growth. Crack growth rates were found to be affected by both the pressure level and the level and rate of pressure fluctuation. For the Grade 414 pipe, reducing pressure fluctuation by increasing R from 0.6 to greater than 0.97 reduced the crack growth rates to below 5*10−9 mm/s, the detection limit of the crack depth measurement system used. Similar effects of pressure fluctuation were also seen for the Grade 359 pipes.

Integrity Planning and SCC Management in a Liquid Pipeline

2004 ◽  
Author(s):  
Bill Gu ◽  
Wayne Feil ◽  
Richard Kania ◽  
Ming Gao ◽  
Ravi Krishnamurthy
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Detection ◽  
Management Strategies ◽  
Field Measurements ◽  
Oil Pipeline ◽  
Integrity Management ◽  
First Time ◽  
Crack Growth Rates

Stress corrosion cracking (SCC) is a major concern for many gas and oil pipeline operators. Extensive efforts continue to be made to develop strategies for a better management of the problem. Predictive models for stress corrosion crack growth were developed using lab testing data, limited inspection and excavation measurements since mid 70s and early 90s, respectively. In this paper, a systematic study of crack growth rates was conducted on the Imperial Oil Rainbow 24 NPS pipeline based on the two consecutive UltraScan Crack Detection (USCD) tool runs and field measurements. Findings of this study provide, perhaps, for the first time since the phenomenon was discovered, a direct measurement of crack growth rates for shallow cracks (in the category of <12.5%wt). Future integrity of the pipeline was assessed and the integrity management strategies were refined using the determined crack growth rate and fracture mechanics based approach. In addition, the susceptibility of SCC was studied in detail using a decision tree approach for data mining. Some important correlations between SCC susceptibility and environmental and mechanical variables were identified and presented. Findings on SCC susceptibility are discussed in terms of environmental and loading parameters such as soil, drainage, topography, pressure, and CP along the pipeline.

The Stress Corrosion Cracking of Copper:Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
F. King ◽  
C. D. Litke ◽  
B. M. Ikeda
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Crack Depth ◽  
Corrosion Cracking ◽  
Bulk Solution ◽  
Buffer Material ◽  
Maximum Crack ◽  
Current Densities ◽  
Crack Growth Rates

AbstractThe extent of stress corrosion cracking (SCC) of copper nuclear waste containers is being predicted on the basis of a “limited propagation” argument. In this argument, it is accepted that crack initiation may occur, but it is argued that the environmental conditions and material properties required for a through-wall crack to propagate will not be present.In this paper, the effect of one environmental parameter, the supply of oxidant (Jox), on the crack growth rate is examined. Experiments have been conducted on two grades of Cu in NaNO2 environments using two loading techniques. The supply of oxidant has been varied either electrochemically in bulk solution using different applied current densities or by embedding the loaded test specimens in compacted buffer material containing O2 as the oxidant. Measured and theoretical crack growth rates as a function of Jox are compared with the predicted oxidant flux to the containers in a disposal vault and an estimate of the maximum crack depth on a container obtained.

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.

Integrity inspection planning updated with cost of risk

2017 ◽  
Vol 57 (2) ◽  
pp. 647
Author(s):  
Yury Sokolov
Keyword(s):  
Oil And Gas ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Individual Risk ◽  
Plant Management ◽  
Inspection Planning ◽  
Worst Case ◽  
Integrity Management ◽  
Inspection Data ◽  
New Generation

The industry expenditure savings motive requires a cost/benefit analysis to optimise Integrity Management budgets. The challenge of estimating precise risk costs requires that numeric Probabilities of Failure (PoF) be known at the highest possible level of confidence, as equipment items specific PoFs govern the actual probability of financial losses and safety implications. The first-hand information on the equipment actual integrity condition is contained in numeric results of integrity inspections. In practice, these results are seldom analysed statistically, being collapsed into single ‘worst case’ values. This simplification prevents assessing of equipment specific actual PoFs and from quantifying failure risks when using traditional methods. We developed a new-generation inspection planning and assessment strategy applied to oil and gas pressure equipment. Evaluating equipment PoFs enables assessing risk costs and optimising the budgets, as well as setting justified internal inspection coverage and frequency objectives. This is achieved by a statistical analysis of numeric inspection data. Existing inspection data (such as ultrasonic testing spot-checks) can be used for a first-pass analysis. Statistical plotting of such data automatically visualises the data quality, and the relevant recommendations for improving inspection coverage or tools are drawn where necessary. We found that two criteria drive integrity decision making: failure total costs and annual fatality expectancies. These criteria are mutually complementary. Both need to be considered for a safe and profitable plant operation. Equipment individual risk control strategy is then developed from safety compliance and budget savings maximising standpoints, thereby also enabling confident design and procurement decisions. This is a new-generation strategy suitable for bringing together all branches of plant management and for improving confidence of the parties. We see it as an evolutionary update to Risk Based Inspection and Maintenance practice, which is now in high demand due to cost pressures.

Continuous Depth Sizing of ILI Ultrasonic Crack Detection

2016 ◽  
Author(s):  
Abdullahi Atto ◽  
Marius Grigat ◽  
Jens Voss
Keyword(s):  
Crack Detection ◽  
Performance Test ◽  
Crack Depth ◽  
Integrity Assessment ◽  
Depth Profiles ◽  
Field Verification ◽  
Large Populations ◽  
Continuous Crack ◽  
General Improvement ◽  
Inspection Data

Since the market launch of Ultrasonic crack detection tools, the conventional crack depth sizing is based on four depth classes or buckets. A more differentiated, continuous depth sizing is becoming increasingly relevant for the pipeline operators and especially for pipelines with large populations of planar anomalies (SCC colonies, lack-of-fusion in ERW seam-welds, etc.). The ILI industry is introducing a continuous crack depth sizing. Next to the better differentiation and the linearity of the depth reporting, the main advantage of the continuous depth sizing is the direct comparability to the results of the field verifications. The continuous depth sizing improves the ability to assess the performance validation of the depth sizing and thus, contributes to a general improvement of the crack depth sizing. This paper describes the development and implementation of a continuous crack depth sizing approach and shows its advantages in comparison to the conventional depth classes. A sizing model is introduced, making use of an empirically derived function, that relates the amplitude measurement to the defect depth. The continuous depth sizing applies to crack-like defects with depths ranging from 1mm to 4mm. The parameters of the model are derived from performance tests based on artificial flaws. In addition, the model is validated by means of field verification results. The depth sizing accuracy and confidence levels are obtained from the performance test data in accordance to API 1163 [1] and POF 2009 [2]. In addition, the paper discusses the extraction of the crack depth profiles from inspection data, making use of the newly developed continuous depth sizing model. In comparison to standard reporting of maximum depth and length, crack depth profiles deliver more accurate and more valuable input to the integrity assessment for pipeline operators. Examples of a direct comparison of these crack depth profiles to field verification data are included.

SCC Detection and Mitigation Based on In-Line Inspection Tools

2004 ◽  
Author(s):  
Walter Kresic ◽  
Scott Ironside
Keyword(s):  
High Resolution ◽  
Management System ◽  
Crack Detection ◽  
Fitness For Purpose ◽  
Preventative Maintenance ◽  
Precise Method ◽  
Field Inspection ◽  
Integrity Management ◽  
Inspection Data ◽  
Ongoing Monitoring

The focus of the Enbridge Integrity Management System is to prevent leaks or ruptures caused by all duty-related pipe deterioration including SCC. As with all pipe defect types, ongoing monitoring programs are employed to determine whether SCC has occurred. Where it has, preventative maintenance programs are employed to mitigate the SCC. Where required, Enbridge employs high-resolution crack in-line inspection (ILI) as the most precise method for managing SCC. As a member of the Canadian Energy Pipeline Association (CEPA), Enbridge participated in the development of a basic framework for SCC management programs and has adopted this framework as the basis for the Enbridge program. Ultrasonic crack detection ILI, capable of detecting SCC, has been employed on over 3000 km of Enbridge pipe and several hundred investigative excavations have been conducted in relation to the ILI data. The results gathered from these investigations have been trended to define the effectiveness of crack detection ILI to detect, size, and discriminate SCC defects. This paper and presentation describes Enbridge’s experience utilizing ultrasonic crack detection ILI for SCC management. The Enbridge trends have shown that ILI can be reliably utilized to detect SCC but, additional innovation is required for defect sizing. While ILI sizing is limited, trends developed from field inspection data have provided the ability to categorize ILI signals into general classifications that ensure all relevant SCC features are highlighted. The categorization is accurate but added precision would reduce the number of investigative excavations, which currently, are also conducted on many sub-relevant features. Coincident with SCC activities driven by ILI data, trends were also developed for peripheral aspects such as field NDT technology, fitness-for-purpose equations, and SCC initiation and growth causes. Observations and trends related to these activities are also described herein.

Measurement of Fatigue Crack Growth Rates for Steels in Hydrogen Storage

2009 ◽  
Author(s):  
Yoru Wada ◽  
Kouichi Takasawa ◽  
Ryoji Ishigaki ◽  
Yasuhiko Tanaka ◽  
Tadao Iwadate
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Depth ◽  
Load Ratio ◽  
Gaseous Hydrogen ◽  
Test Machine ◽  
Critical Crack ◽  
Crack Growth Rates

Fatigue crack growth rates (da/dN) in up to 90MPa high-pressure gaseous hydrogen environments of quenched and tempered low alloy Cr-Mo steel: JIS-SCM435 with ultimate tensile strength level of 950MPa were measured utilizing a cycle, ranging from 0.3sec from 1000sec long with a road ratio R = 0.1. The longer cycle time tests (15sec to 1000sec per cycle) were conducted utilizing internal pressure test apparatus by utilizing cylinder (= CY) specimens, while shorter cycle (0.3sec to 25sec per cycle) tests were performed utilizing fatigue test machine using compact tension (= C(T)) specimens. Crack depth of CY specimens were measured by Time Of Flight Diffraction (TOFD) technique and the crack length of C(T) specimens were measured by compliance technique. Both C(T) and CY specimen showed accelerated sub-critical crack growth in gaseous hydrogen compared that in air or inert gas atmosphere. The effect of load ratio was also evaluated.

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