ILI to ILI Comparisons: Quantifying the Impact of Multiple Inspections

2016 ◽  
Author(s):  
Pamela J. Moreno ◽  
Matthew A. Ellinger ◽  
Thomas A. Bubenik
Keyword(s):  
Wall Thickness ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Data Sets ◽  
General Corrosion ◽  
Pipeline Segment ◽  
One To One ◽  
Pipe Geometry ◽  
The Impact ◽  
Flux Leakage

Det Norske Veritas (U.S.A.), Inc. (DNV GL) prepared this paper in order to study the repeatability of inspection results between subsequent in-line inspections. DNV GL has access to a significant amount of data that spans many different pipeline operators, ILI vendors, inspection years, and inspection technologies. DNV GL is well suited to complete this study as a result of our access to these various data sets. Over 55,000 one-to-one metal loss defect comparisons were assembled from ILI-to-ILI analyses. Reported metal loss defect depths, lengths, and widths spanning from 2003 through 2015 from 13 pipeline operators and 36 pipeline segments were compiled to meet the objectives of this paper. Inspection technologies include axial magnetic flux leakage (MFL), ultrasonic wall thickness (UTWT), spiral MFL, and circumferential MFL ILI. From analyses of these data, the following conclusions were generated: • Effect of ILI vendor: ILI repeatability is generally improved when the same ILI vendor is used (when compared to using two different ILI vendors in subsequent inspections), but this is not always true. • Reported metal loss depths: ILI repeatability decreases with increasing metal loss depth. • Pipe geometry and type: ILI repeatability is better in larger diameter pipelines and with increasing wall thickness. • POF classification: ILI repeatability is better for pitting, general corrosion, and axial grooving defects as compared to the other POF classifications. Based on these insights, the authors make the following recommendations: • Pipeline operators should consider using the same ILI vendor and tool if the goal is to identify change and/or corrosion growth in the pipeline segment. A raw signal review is encouraged in order to verify the presence, or lack thereof, changes in metal loss morphologies. The raw data review is especially important when comparing inspections from two different ILI vendors. • If the goal is to identify corrosion growth, and a pipeline operator uses different ILI vendors, it is recommended that a statistical review of one-to-one matched metal loss features take place to identify candidate locations that are more likely to be growing. The candidate locations should have a raw signal review in order to verify whether or not growth is taking place.

Oblique Field Magnetic Flux Leakage Inline Survey Tool: Implementation and Results

2010 ◽  
Author(s):  
James Simek ◽  
Jed Ludlow ◽  
Phil Tisovec
Keyword(s):  
Experimental Data ◽  
Magnetic Flux ◽  
Full Range ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Data Sets ◽  
Data Set ◽  
Survey Tool ◽  
Oblique Field ◽  
Flux Leakage

InLine Inspection (ILI) tools using the magnetic flux leakage (MFL) technique are the most common type used for performing metal loss surveys worldwide. Based upon the very robust and proven magnetic flux leakage technique, these tools have been shown to operate reliably in the extremely harsh environments of transmission pipelines. In addition to metal loss, MFL tools are capable of identifying a broad range of pipeline features. Most MFL surveys to date have used tools employing axially oriented magnetizers, capable of detecting and quantifying many categories of volumetric metal loss features. For certain classes of axially oriented features, MFL tools using axially oriented fields have encountered difficulty in detection and subsequent quantification. To address features in these categories, tools employing circumferential or transversely oriented fields have been designed and placed into service, enabling enhanced detection and sizing for axially oriented features. In most cases, multiple surveys are required, as current tools do not incorporate the ability to collect both data sets concurrently. Applying the magnetic field in an oblique direction will enable detection of axially oriented features and may be used simultaneously with an axially oriented tool. Referencing previous research in adapting circumferential or transverse designs for inline service, the concept of an oblique field magnetizer will be presented. Models developed demonstrating the technique are discussed, shown with experimental data supporting the concept. Efforts involved in the implementation of an oblique magnetizer, including magnetic models for field profiles used to determine magnetizer configurations and sensor locations are presented. Experimental results are provided detailing the response of the system to a full range of metal loss features, supplementing modeling in an effort to determine the effects of variables introduced by magnetic property and velocity induced differences. Included in the experimental data results are extremely narrow axially oriented features, many of which are not detected or identified within the axial data set. Experimental and field verification results for detection accuracies will be described in comparison to an axial field tool.

ILI-to-Field Data Comparisons: What Accuracy Can You Expect?

2016 ◽  
Author(s):  
Matthew A. Ellinger ◽  
Thomas A. Bubenik ◽  
Pamela J. Moreno
Keyword(s):  
Wall Thickness ◽  
Signal Analysis ◽  
Metal Loss ◽  
Data Sets ◽  
Line Segments ◽  
Failure Pressure ◽  
General Field ◽  
Inspection Systems ◽  
Data Signal ◽  
Flux Leakage

Det Norske Veritas (U.S.A.), Inc. (DNV GL) prepared this paper in order to study the expected accuracy of in-line inspections (ILI) as a function of year, depth (both reported and field measured), and length, amongst other factors. DNV GL has access to a significant amount of data that span many different pipeline operators, ILI vendors, inspection years, and inspection technologies. DNV GL is well suited to complete this study as a result of our access to these various data sets. Over 3,000 individual comparisons of ILI and field depths and lengths spanning from 2010 through 2015 from 11 operators and 68 line segments were compiled to meet the objectives of this paper. Inspection technologies include axial magnetic flux leakage (MFL), ultrasonic wall thickness (UTWT), spiral MFL, and circumferential MFL. Based on the analyses conducted in this paper, the following conclusions were generated. • Axial MFL and UTWT inspections show significant improvements over the last several years. • Axial MFL inspection systems are capable of meeting a depth accuracy of +/−10% of the wall thickness with 80% certainty, but this has not always been the case. UTWT inspection systems are capable of meeting a higher depth accuracy. • Axial MFL inspection systems report more pits and circumferential grooves than UTWT systems. This could suggest UTWT systems are less sensitive to pits and circumferential grooves than axial MFL systems. • Both axial MFL and UTWT inspection systems routinely under call defects with field measured depths greater than 50 to 80% of the wall thickness. This is contrary to a widely held notion that ILI is conservative for deep defects. • ILI reported defect lengths do not correlate well to field measured defect lengths. In general, field measured defect lengths are greater than ILI reported defect lengths. • Depth accuracy tends to decrease slightly for very short defects (less than 1-inch) and for very long defects (greater than 40-inches). Based on these conclusions, the authors make the following recommendations: • Pipeline operators should dig more than the deepest reported defects to better understand the accuracy of the inspection tools being used and to determine whether deeper anomalies are being under called. • Pipeline operators should consider methods for evaluating change in corrosion depth from ILI survey to ILI survey to lessen the dependence on the accuracy of the ILI tools. This should include a raw data signal analysis in order to determine whether the general morphology (metal loss length and width) are changing between ILI surveys. • ILI reported defect lengths should be used in conjunction with field measured defect depths (if available) when performing failure pressure calculations. • Additional accuracy, especially for deeper defects, may only come with new tool developments. Industry support of such developments will be required to bring them to fruition.

Development of Pinhole Corrosion Management Using MFL

2018 ◽  
Author(s):  
Guy Desjardins ◽  
Joel Falk ◽  
Vitaly Vorontsov
Keyword(s):  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Physical Measurement ◽  
Reporting Accuracy ◽  
Magnetic Modeling ◽  
Number Of Factors ◽  
Modeling Software ◽  
Measurement Methodology ◽  
Integrity Management ◽  
Flux Leakage

While In-line Inspection Magnetic Flux Leakage (MFL) tools have been used for many years to successfully manage corrosion related threats, small pinhole-sized metal-loss anomalies remain a significant concern to pipeline operators. These anomalies can grow undetected to develop leaks and cause significant consequences. The physical dimensions of these anomalies, their proximity to and/or interaction with other nearby anomalies can challenge MFL’s detection and sizing capabilities. Other factors such as tool speed, cleanliness of the line and incorrect assumptions have an impact as well. For pipeline operators to develop effective and efficient mitigation programs and to estimate risks to an asset, the underlying uncertainties in detection and sizing of pinholes need to be well understood. By using magnetic modeling software, the MFL response of metal-loss anomalies can be determined, and the effect of a number of factors such as radial position, wall thickness, depth profile, pipe cleanliness and tool speed on MFL response and reporting accuracy can be determined. This paper investigates these factors to determine the leading causes of uncertainties involved in the detection and sizing of pinhole corrosion. The understanding of these uncertainties should lead to improvements in integrity management of pinhole for pipeline operators. This paper first investigates the physical measurement methodology of MFL tools to understand the limitations of MFL technology. Then, comparisons of actual MFL data with field excavation results were studied, to understand the limitations of specific MFL technologies. Finally, recommendations are made on how to better use and assess MFL results.

Remaining Local Buckling Resistance of Corroded Pipelines

2010 ◽  
Author(s):  
Qishi Chen ◽  
Heng Aik Khoo ◽  
Roger Cheng ◽  
Joe Zhou
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Phase 1 ◽  
Compressive Strain ◽  
Research Work ◽  
Local Buckling ◽  
Model Verification ◽  
Metal Loss ◽  
General Corrosion ◽  
Buckling Resistance

This paper describes a multi-year PRCI research program that investigated the local buckling (or wrinkling) of onshore pipelines with metal-loss corrosion. The dependence of local buckling resistance on wall thickness suggests that metal-loss defects will considerably reduce such resistance. Due to the lack of experimental data, overly conservative assumptions such as a uniform wall thickness reduction over the entire pipe circumference based on the defect depth have been used in practice. The objective of this research work was to develop local buckling criteria for pipelines with corrosion defects. The work related to local buckling was carried out in three phases by C-FER and the University of Alberta. The first phase included a comprehensive finite element analysis to evaluate the influence of various corrosion defect features and to rank key parameters. Based on the outcome of Phase 1 work, a test matrix was developed and ten full-scale tests were carried out in Phase 2 to collect data for model verification. In Phase 3, over 150 parametric cases were analyzed using finite element models to develop assessment criteria for maximum moment and compressive strain limit. Each criterion includes a set of partial safety factors that were calibrated to meet target reliabilities selected based on recent research related to pipeline code development. The proposed criteria were applied to in-service pipeline examples with general corrosion features to estimate the remaining load-carrying capacity and to assess the conservatism of current practice.

Geometric Magnetic and Discriminator Sensor for Smart Pigs

2004 ◽  
Author(s):  
Vinicius de C. Lima ◽  
Jose´ A. P. da Silva ◽  
Jean Pierre von der Weid ◽  
Claudio Soligo Camerini ◽  
Carlos H. F. de Oliveira
Keyword(s):  
High Resolution ◽  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Research Partnership ◽  
Technical Aspects ◽  
Pipeline Inspection ◽  
Catholic University ◽  
Laboratory Results ◽  
Flux Leakage

A result of a research partnership between Catholic University of Rio de Janeiro – PUC-Rio, PETROBRAS and PIPEWAY is presented: The development of an innovative sensor head for high resolution MFL Pigs, the GMD sensor, Geometric Magnetic and Discriminator. This head makes high resolution magnetic pipeline readings using the MFL - Magnetic Flux Leakage technique, with the addition of geometric readings and the outside/inside defects discriminations. This technique makes possible, with only one crown of GMD sensors, the caliper, metal loss and outside/inside discrimination pipeline inspection. Technical aspects of the development, e.g.: the construction details of the sensor, evaluation tests and laboratory results are also presented.

The Design of a Mechanical Damage Inspection Tool Using Dual Field Magnetic Flux Leakage Technology

2005 ◽  
Vol 127 (3) ◽  
pp. 274-283 ◽  
Author(s):  
J. Bruce Nestleroth ◽  
Richard J. Davis
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
High Magnetic Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Unexpected Result ◽  
Lower Field ◽  
Study Results ◽  
Flux Leakage

This paper describes the design of a new magnetic flux leakage (MFL) inspection tool that performs an inline inspection to detect and characterize both metal loss and mechanical damage defects. An inspection tool that couples mechanical damage assessment as part of a routine corrosion inspection is expected to have considerably better prospects for application in the pipeline industry than a tool that complicates existing procedures. The design is based on study results that show it is feasible to detect and assess mechanical damage by applying a low magnetic field level in addition to the high magnetic field employed by most inspection tools. Nearly all commercially available MFL tools use high magnetic fields to detect and size metal loss such as corrosion. A lower field than is commonly applied for detecting metal loss is appropriate for detecting mechanical damage, such as the metallurgical changes caused by impacts from excavation equipment. The lower field is needed to counter the saturation effect of the high magnetic field, which masks and diminishes important components of the signal associated with mechanical damage. Finite element modeling was used in the design effort and the results have shown that a single magnetizer with three poles is the most effective design. Furthermore, it was found that for the three-pole system the high magnetization pole must be in the center, which was an unexpected result. The three-pole design has mechanical advantages, including a magnetic null in the backing bar, which enables installation of a pivot point for articulation of the tool through bends and restrictions. This design was prototyped and tested at Battelle’s Pipeline Simulation Facility (West Jefferson, OH). The signals were nearly identical to results acquired with a single magnetizer reconfigured between tests to attain the appropriate high and low field levels.

Characterization of Mechanical Damage Through Use of the Tri-Axial Magnetic Flux Leakage Technology

2006 ◽  
Author(s):  
Vanessa Co ◽  
Scott Ironside ◽  
Chuck Ellis ◽  
Garrett Wilkie
Keyword(s):  
Magnetic Flux ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Field Investigations ◽  
Non Destructive ◽  
Flux Leakage

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.

scholarly journals Improved methods for sizing metal loss in dents for ECA

2020 ◽  
Vol 4 (2) ◽  
pp. 126-136
Author(s):  
Rhett Dotson ◽  
◽  
Fernando Curiel ◽  
Luis Sacramento ◽  
Zach Locks ◽  
...  
Keyword(s):  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Significant Challenge ◽  
Advanced Analysis ◽  
Lift Off ◽  
Improved Methods ◽  
Flux Leakage

Dents interacting with metal loss remain as a significant challenge to operators. Existing regulations require that dents with metal loss within high consequence areas be treated as immediate repairs or 60-day conditions, resulting in costly excavations for many operators. At the time when these regulations were written, it was not clear whether inline inspection technologies could discriminate the nature of the metal loss (i.e. corrosion or mechanical damage) or provide accurate sizing. Furthermore, advanced analysis techniques such as finite element analysis were limited, and fitness- forservice evaluations were not common. While the technological hurdles involved with evaluating interacting dent and metal loss features have been overcome, sensor lift-off remains a challenging issue for magnetic flux leakage (MFL) inspection tools, as sizing accuracy degrades at larger lift-off distances. Until recently, the sensor lift-off issue limited the ability to perform fitness- for- service evaluations because the metal loss in dent features could not be confidently sized. This study demonstrates how integrated lift-off sensors can be used to quantify the lift-off as the MFL sensors pass over a dent. This technology integration has allowed the confident application of sizing specifications for many dents with metal loss, thereby permitting robust fitness- for- service evaluations. Several case studies are examined in this paper, demonstrating how the integrated MFL and lift-off technology can serve to reduce excavations while still ensuring safe pipeline operations.

Sign in / Sign up

Export Citation Format

Share Document