Shear-Wave Ultrasonic Crack Inspection Tool Performance for Cracks Associated With Metal Loss

2016 ◽  
Author(s):  
Paola Scholte Mendoza ◽  
Steven Bott ◽  
Yvan Hubert
Keyword(s):  
Incomplete Information ◽  
Shear Wave ◽  
Continuous Improvement ◽  
Pipe Wall ◽  
Ultrasonic Inspection ◽  
Ultrasonic Pulse ◽  
Metal Loss ◽  
Comprehensive Review ◽  
Tool Performance

Shear-wave ultrasonic in-line tools are used for crack management in liquids pipelines. An ultrasonic pulse is generated, travels in the pipe wall and reflects on axially oriented artifacts that could be geometric or crack-like in nature. If several geometrical artifacts are present, detection and sizing efficiency of these ultrasonic inspection tools could be reduced. Cracking located within corrosion is one possible interacting set of geometrical artifacts that could affect in-line inspection (ILI) performance. As part of continuous improvement, a comprehensive review of two thousand three hundred and thirty eight in-the-ditch measurements of cracking in corrosion were compared to crack ILI reported features in order to determine the tool performance in cases where cracks were associated with metal loss. Relationships of depth and predicted burst pressures were reviewed and compared to cracks not associated with metal loss. Additionally, field NDE results that had incomplete information in the ILI-NDE correlation files with indications of being potential defects were reviewed to examine the possibility of undocumented coincident cracking in metal loss that could represent an integrity threat. This paper summarizes the results and potential implications for management of cracking in corrosion using shear-wave ultrasonic crack ILI.

scholarly journals A Pipeline Dent Assessment Model Considering Localised Effects

2000 ◽  
Author(s):  
A. Dinovitzer ◽  
A. Bhatia ◽  
R. Walker ◽  
R. Lazor
Keyword(s):  
Service Life ◽  
Pipe Wall ◽  
Element Model ◽  
Assessment Model ◽  
Metal Loss ◽  
Concentration Effects ◽  
Pipe Segment ◽  
Weld Toe ◽  
Pipeline Design ◽  
Weld Seams

The Canadian Pipeline Design Standard (CSA Z662) [1] requires the repair of smooth dents with depths exceeding 6% of the pipeline’s outside diameter. This limit on dent depth is reduced in the presence of additional localised effects such as pipe wall gouges, corrosion or planar flaws. Furthermore, it has been observed that pipe wall metal loss, planar flaws and weld seam interaction with dents can significantly reduce the service life of a dented pipe segment. A previously developed pipeline dent assessment model, based on the actual dent profile and in-service pressure history applied to non-linear pipe finite element model with a fracture mechanics crack growth algorithm, has been used to explore the consequences of these localised effects. The effects of corrosion (uniform or local pitting), weld seams (including their weld toe stress concentration effects and residual stress fields), planar flaws (cracks) and gouges on the service life of a dent are reviewed in this investigation. The performance of the model is demonstrated based on its agreement with field observations. The dent assessment model application and validation processes has indicated that the model presented here can be reliably used to predict the service life of dented pipelines in the presence of various localised effects.

Using MFL Corrosion Signals to Determine Biaxial Stress in Operating Pipelines

2000 ◽  
Author(s):  
Alfred E. Crouch
Keyword(s):  
Magnetic Flux ◽  
Internal Pressure ◽  
Pipe Wall ◽  
Axial Stress ◽  
Wall Stress ◽  
Biaxial Stress ◽  
Metal Loss ◽  
Pipe Surface ◽  
The Difference ◽  
Hoop Stresses

Previous work has shown that a corrosion assessment more accurate than B31.G or RSTRENG can be made if pipeline stresses are considered. A shell analysis can be carried out if both the corrosion profile and local pipe wall stresses are known. The corrosion profile can be approximated from analysis of magnetic flux leakage (MFL) signals acquired by an inline inspection tool (smart pig), but a measure of pipe wall stress has not been available. Approximations have been made based on pipe curvature, but a more direct measurement is desirable. Recent work has produced data that show a correlation between multi-level MFL signals from metal-loss defects and the stress in the pipe wall at the defect location. This paper presents the results of MFL scans of simulated corrosion defects in pipe specimens subjected to simultaneous internal pressure and four-point bending. MFL data were acquired at two different magnetic excitations using an internal scanner. The scanner’s sensor array measured axial, radial and circumferential magnetic flux components on the inner pipe surface adjacent to the defect. Comparison of the signals at high and low magnetization yields an estimate of the difference between axial and hoop stresses. If internal pressure is known, the hoop component can be determined, leaving data proportional to axial stress.

Uncertainty Quantification of Wall Thickness of Onshore Gas Transmission Pipelines

2020 ◽  
Author(s):  
Wenxing W. Zhou ◽  
Ji Bao
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Metal Loss ◽  
Pipeline System ◽  
Pipe Wall Thickness ◽  
Reliability Based Design ◽  
Wide Range ◽  
Pipe Joints ◽  
Welded Pipe ◽  
Transmission Pipelines

The present study quantifies probabilistic characteristics of the wall thickness of welded pipe joints in onshore gas transmission pipelines based on about 5900 field-measured wall thicknesses collected from a pipeline system in Canada. The collected data cover a wide range of the pipe nominal wall thickness, from 3.18 to 16.67 mm. By considering the measurement error involved in the collected wall thickness data, statistical analyses indicate that the actual-over-nominal wall thickness ratio (AONR) follows a normal distribution with a mean of 1.01 and a coefficient of variation (COV) ranging from 1.6 to 2.2% depending on the nominal pipe wall thickness. The implications of the developed AONR statistics for the reliability analysis of corroded pipe joints are investigated. This study provides key input to the reliability-based design and assessment of pipelines with respect to various threats such as metal-loss corrosion and stress corrosion cracking.

THE FEATURES OF NON-DESTRUCTIVE INSPECTION OF CARBON FIBER REINFORCED PLASTIC SOLID LAMINATE SAMPLES DURING LOW-CYCLIC FATIGUE TESTING

2020 ◽  
pp. 108-115
Author(s):  
A.S. Boychuk ◽  
◽  
I.A. Dikov ◽  
A.S. Generalov ◽  
S.I. Yakovleva ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
Ultrasonic Inspection ◽  
Cyclic Fatigue ◽  
Ultrasonic Pulse ◽  
Back Wall ◽  
Testing Specimen ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Pulse Echo ◽  
Non Destructive

The results of CFRP samples ultrasonic inspection during low-cyclic fatigue testing are given in this article. It is established that for ultrasonic pulse-echo inspection during cycling mechanical testing and after the special correction of flaw detector’s gain and inspection’s sensitivity concerning back-wall echo decreasing in compare with testing specimen is necessary.

Assessment of In-Line Inspection Performance and Interpretation of Field Measurements for Characterization of Complex Dents

2016 ◽  
Author(s):  
Luis A. Torres ◽  
Matthew J. Fowler ◽  
Jordan G. Stenerson
Keyword(s):  
Management Strategies ◽  
Mechanical Damage ◽  
Field Measurements ◽  
Management Program ◽  
Metal Loss ◽  
Tool Performance ◽  
Integrity Management ◽  
Technical Specifications ◽  
Shape Complexity

Integrity management of dents on pipelines is currently performed through the interpretation of In-Line Inspection (ILI) data; this includes Caliper, Magnetic Flux Leakage (MFL), and Ultrasonic Testing (UT) tools. Based on the available ILI data, dent features that are recognized as threats from a mechanical damage perspective are excavated and remediated. Federal codes and regulations provide rules and allow inference on what types of dent features may be a result of mechanical damage; nonetheless, there are challenges associated with identifying dents resulting from mechanical damage. One of the difficulties when managing the mechanical damage threat is the lack of information on how MFL and UT ILI tool performance is affected by dented areas in the pipe. ILI vendors do not offer any technical specifications for characterizing and sizing metal loss features in dents. It is generally expected that metal loss tool performance will be affected in dented areas of the pipe, but it is not known to what degree. It is likely that degradation will vary based on feature shape, sensor design, and sensor placement. Because metal loss tool performance is unknown within the limits of the dented pipe, other methods for recognizing mechanical damage have been incorporated into the management strategies of mechanical damage. Some of these methods include strain based assessments and characterization of shape complexity. In order to build a more effective integrity management program for mechanical damage, it is of critical importance to understand how tool technology performance is affected by dented areas in the pipe and what steps can be taken to use ILI information more effectively. In this paper, the effectiveness of MFL and UT wall measurement tools in characterizing and sizing metal loss features within dents is studied by evaluating against field results from non-destructive examinations of mechanical damage indications. In addition, the effectiveness of using shape complexity indicators to identify mechanical damage is evaluated, introducing concepts such as dents in close proximity and multi-apex dents. Finally, the effectiveness of ILI tools in predicting dent association with girth welds is also explored by comparing ILI and field results.

Enhanced Use of ILI Data to Improve Integrity Decisions

2012 ◽  
Author(s):  
Collin Taylor ◽  
Renkang Rain Zhu
Keyword(s):  
Metal Loss ◽  
Pipeline System ◽  
Precision Data ◽  
Data Alignment ◽  
Joint Characteristics ◽  
Tool Performance ◽  
Integrity Management ◽  
Data Improvement ◽  
Longitudinal Seam ◽  
Flux Leakage

With the current generation of in-line inspection (ILI) tools capable of recording terabytes of data per inspection and obtaining millimeter resolution on features, integrity sciences are becoming awash in a sea of data. However, without proper alignment and relationships, all this data can be at best noise and at worst lead to erroneous assumptions regarding the integrity of a pipeline system. This paper will explore the benefits of a statistical alignment method utilizing joint characteristics, such as length, long seam orientation (LSO), wall thickness (WT) and girth weld (GW) counts to ensure precision data alignment between ILI inspections. By leveraging the “fingerprint” like morphology of a pipeline system many improvements to data and records systems become possible including but not limited to: • Random ILI Tool performance errors can be detected and compensated for. • Repair history and other records become rapidly searchable. • New statistically accurate descriptions are created by leveraging the sensitivities of various ILI technologies. One area of material data improvement focused on within this paper relates to long seam type detection through ILI tools. Due to the differing threat susceptibility of various weld types, it is accordingly important to identify the long seam weld types for integrity management purposes. Construction records of older vintage lines do not always contain information down to the joint level; therefore, ILI tools may be leveraged to increase the accuracy of construction records down to this level. In this paper, the possibility of ILI tools, such as magnet flux leakage tools, ultrasonic crack tools, and ultrasonic metal loss tools, to distinguish different types of longitudinal seam welds is also discussed.

Coke Drum Weld Inspection

2007 ◽  
Author(s):  
John McMillan
Keyword(s):  
Shear Wave ◽  
Phased Array ◽  
Ultrasonic Inspection ◽  
Time Of Flight ◽  
Single Pass ◽  
Weld Region ◽  
Time Of Flight Diffraction ◽  
Grey Scale ◽  
Areas Of Concern ◽  
Pulse Echo

Conventional Ultrasonic Inspection of Coke Drums may require the use of Automated Pulse Echo or Time of Flight Diffraction Techniques (TOFD). The more recent application of Phased Array ultrasonic technology enables a faster and more accurate location and depth discrimination of the cracks detected in the welds. Pulse Echo ultrasonic inspection requires the use of three transducers from each side of the weld. A zero degree compression transducer and two angle transducers, most likely 60° or 70°. The advantage of this techniques is that it provides positional information as to the location of the crack in the weld and accurate length measurement. The problem is that additional techniques have to be used to determine the depth of any cracks detected. An alternative to Pulse Echo inspection is the Time of Flight Diffraction technique. The TOFD technique uses multimode transducers to insonify the weld region with Lateral, Compression and Shear Wave ultrasound. The technique accurately detects and determines the length and depth of reflectors in the weld region. The technique was initially developed for the Nuclear Industry as a sizing technique. More recently it has become used for detection and sizing of flaws. The TOFD technique does not place the flaw in the cross section of the weld in order to achieve this another technique such as Pulse Echo Ultrasound is required. The TOFD technique is not sensitive to small flaws which are open to either surface. In order to detect small flaws such as “Toe Cracks” a supplementary technique such as ACFM or Eddy Current inspection may be required. The illustration shows the format of the sound generated from a TOFD transducer arrangement. The advantage for welds < 1.50" in thickness is that careful selection of the transducers and appropriate spacing may allow the weld to be inspected in a single pass. The illustration below shows two displays, an unrectified “RF” display which corresponds to which ever cursor is active and a grey scale display adjacent. The Grey Scale Display is a stacked “RF” display where each vertical line correspond to a single location along the line of the weld non-conforming perturbations in the display indicate areas of concern which can be identified by length and depth as shown in the boxes at the lower left of the illustration. The first significant amplitude group on the grey scale display corresponds to the Lateral Wave, the second the Compression and the third the Shear Wave. Flaws detected between the Lateral and the Compression Wave are often repeated between the Compression and the Shear Waves. Phased Array technology has been available for some time, however only recently has the software been able to display the data in a format which provides clear data which can be used to locate and size of the flaws in a variety of weld configurations. Coke Drums have several significant areas of concern, Weld Seams which may be Shell to Shell, Shell to Head or Shell to Skirt format. We will consider the Circumferential Shell weld and the Skirt weld at this time. The photographs show a shell seam which reduces in section for this example the weld was inspected from one side only. The signals were corrected for Beam Path Length and the amplitudes of the signals were equalized for angle. The following data were collected: Two Notches were machined in the plate one either side of the weld on the underside. The plate was then scanned from one, the thicker, side using the Phased Array probe. The reflectors which were the same depth are depicted with a similar amplitude at their correct relative positions, one on the near and the other on the far side of the weld root. With the signals equalized all the reflector were detected from a single scan location and with similar amplitudes. The Skirt to Shell weld was simulated in a solid piece of carbon steel. EDM notch reflectors were machined in the samples at critical locations. The critical angles were calculated which would produce reflections from each of the potential crack areas and the Phased Array inspection was performed to verify the calculations. A single plot is shown as an example, containing the reflector on the Shell side near the crotch on the inside of the weld. The illustration shows the sound path of the Phased Array which detects a reflector close to the crotch on the inside between the Skirt and the Shell. Discriminating this flaw with conventional ultrasonic inspection would be extremely difficult. It is the ability of the Phased Array Sector Scan to use multiple angles on a single pass which enables flaws at multiple locations and angles to be detected by a line scan and imaged at their relative location.

Cracks in Dents: How Can I Use an ILI Robot to Detect Them?

2020 ◽  
Author(s):  
Rogelio Guajardo ◽  
Thomas Hennig ◽  
Carlota Mendez ◽  
Beatriz Tarramera
Keyword(s):  
Pipe Wall ◽  
Mechanical Design ◽  
Incidence Angle ◽  
Ultrasonic Pulse ◽  
Optimal Position ◽  
Performance Specification ◽  
Detection And Identification ◽  
Pump Test ◽  
Point Detection ◽  
Interacting Features

Abstract Cracks in dents or linear anomalies interacting with dents are a major pipeline threat. These combined anomalies represent challenges to the Mechanical Engineers that design ILI tools as they need to keep the sensor in an optimal position towards the inner pipe wall. Ultrasonic Crack (UC) tools consist in a sensor plate with a fixed incidence angle that depends on the coupling medium. This plate is then attached to the skids; these are in constant contact with the internal pipe wall. When the tool interacts with a dent, the incidence angle is not optimal; therefore, detection of any interacting feature is compromised. By not having the optimum angles in the pipe wall, the amplitudes from the reflections caused by cracks will be attenuated. Depending on the magnitude of the attenuation, these might be below analysis thresholds meaning that an algorithm and/or analyst will not consider them as relevant signals. Up to this point, detection of interacting features sounds like a “guess “ or “luck”. So, how can we use UC inspection to detect the interacting features? How can operators manage their assets knowing that they have dents but there is an uncertainty if there are interacting features? To answer these questions, a systematic approach had to be used. It consisted of multiple phases where 1.- The mechanical design of the tool was understood, 2.- Simulation campaigns to understand the ultrasonic pulse while interacting with the dent, 3.- Pump tests with artificial features, and 4.- Pump test with real features. All of the data gathered through the different phases allowed the authors to understand the attributes from the features and conditions that influence detection and identification of cracks in dents. This derived in a performance specification stating the truth capabilities to detect interacting features in a dent. These learnings were applied to commercial inspections where the feedback loop is closed with the field verifications.

Fast UT: A New Ultrasonic Inspection Technique

2000 ◽  
Author(s):  
Steve L. Sikorski ◽  
Rick Pfannenstiel
Keyword(s):  
Shear Wave ◽  
Mode Conversion ◽  
Ultrasonic Inspection ◽  
Direct Shear ◽  
Wave Reflections ◽  
Longitudinal Waves

The method discussed in this paper uses a simple and concise procedure, which is effective and reliable for locating tip-diffracted signals. The technique utilizes refracted longitudinal waves to both detect and size planar flaws. Confusing signals which are traditionally associated with angled L-wave techniques, due to mode conversion and direct shear wave reflections, are significantly reduced, while enhancing the ability to detect tip signals by using the FAST™ technique. This technique increases the speed of detection and simplifies sizing compared to traditional shear wave examinations and/or other advanced techniques. FAST™ is an acronym for Flaw Analysis and Sizing Technique.

Integration of Data From Multiple In-Line Inspection Systems to Improve Crack Detection and Characterization

2018 ◽  
Author(s):  
Mark Piazza ◽  
Justin Harkrader ◽  
Rogelio Guajardo ◽  
Thomas Henning ◽  
Miguel Urrea ◽  
...  
Keyword(s):  
Data Integration ◽  
Crack Detection ◽  
Detailed Examination ◽  
Metal Loss ◽  
Recent Experience ◽  
Destructive Testing ◽  
Tool Performance ◽  
Inspection Systems ◽  
Integrity Management

In-line inspection (ILI) systems continue to improve in the detection and characterization of cracks in pipelines, and are relied on substantially by pipeline operators to support Integrity Management Programs for continual assessment of conditions on operating pipelines that are susceptible to cracking as an integrity threat. Recent experience for some forms of cracking have shown that integration of data from multiple ILI systems can improve detection and characterization (depth sizing, crack orientation, and crack feature profile) performance. This paper will describe the approach taken by a liquids pipeline operator to integrate data from multiple ILI systems, namely Ultrasonic axial (UC) and circumferential (UCc) crack detection and Magnetic Flux Leakage (MFL) technologies, to improve detection and characterization of cracks and crack fields on a 42 miles long, 12-inch OD liquid pipeline with a 38-year operating history. ILI data has indicated a large number of crack features, including 4000+ crack features reported by UC, 1000+ crack features by UCc, and 2500+ metal loss features reported by MFL. Initial excavations demonstrated a unique pattern of blended circumferential-, oblique- and axial-orientated cracks along the entire extent of the 42-mile pipeline, requiring advanced methods of data integration and analysis. Applying individual technologies and their analysis approaches showed limitations in performance for identification and characterization of these blended features. The outcome of the study was the development of a feature classification approach to classify the cracks with respect to their orientation, and rank them based on the depth sizing by using multiple datasets. Several sections of the 42-mile pipeline were cut-out and subjected to detailed examination using multiple non-destructive examination (NDE) methods and destructive testing to confirm the crack depths and profiles. These data were used as the basis for confirming the ILI tool performance and providing confirmation on the improvements made to crack detection and sizing through the data integration process.

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