Modeling Pipeline Metal Loss Defects at Tool Speed

2018 ◽  
Author(s):  
Matthew Romney ◽  
Adrian Belanger
Keyword(s):  
Computer Simulation ◽  
Simulation Modeling ◽  
Pipeline Steel ◽  
Model Development ◽  
Metal Loss ◽  
General Corrosion ◽  
Element Analysis ◽  
Physical Test ◽  
Field Response ◽  
Flux Leakage

Accurate defect sizing is crucial for maintaining effective pipeline safety and operation. Under growing pressure from local, national and world organizations, pipeline operators demand improved magnetic flux leakage (MFL) metal-loss sizing accuracy and classification from in-line inspection (ILI) tools. The axial MFL field response in pipeline steel near a metal-loss defect is a very complex phenomenon. Although critical for proper sizing model development, the effects of tool speed due to product flow is very difficult to model during finite element analysis (FEA) and therefore is often overlooked. However, understanding the dynamic MFL response is crucial for proper ILI tool design and the development of accurate defect sizing algorithms. T.D. Williamson (TDW) utilizes dynamic computer simulation modeling, paired with laboratory testing, to develop the complex parametric relationships between metal loss geometry, pipeline material and ILI tool speed. The blend of simulation and physical test results allow for TDW to iterate more quickly across multiple physics variables with simulation models, while maintaining a firm footing in reality with physical test validation. Accurately simulating magnetic field responses of metal loss under dynamic conditions produces the data necessary to identify optimal magnetizer design, including optimizing sensor spacing and placement for metal-loss defect sizing and characterization. This paper will provide an overview of advances in the use of computer simulation modeling for predicting dynamic flux leakage field response. Besides increasing accuracy, results from this work will extend specifications beyond optimal speed ranges and provide the basis for general corrosion profilometry predictions from decomposition of the full MFL signal.

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.

A Parametric Study of Variable Crack Initiation Criterion in XFEM on Pipeline Steel

2020 ◽  
Author(s):  
Meng Lin ◽  
Yong Li ◽  
Mohammad Salem ◽  
J. J. Roger Cheng ◽  
Samer Adeeb ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Initiation ◽  
Parametric Study ◽  
Pipeline Steel ◽  
Stress Triaxiality ◽  
Element Analysis ◽  
Physical Test ◽  
Crack Initiation Criterion ◽  
Element Method

Abstract The integrity decisions for cracked pipelines can be made based on the conventional Finite Element Method (FEM). However, it is extremely time-consuming due to the requirement of remeshing to continuously conform to the geometric discontinuities as the crack propagates. The more recently developed Extended Finite Element Method (XFEM) provides a more robust approach in which a crack can propagate through the finite element analysis mesh and thus alleviates the requirement for remeshing. However, the current criteria for crack initiation and propagation in XFEM framework have not been calibrated to pipeline steels. The current built-in criterion in Abaqus assumes a fixed value as the damage strain. Crack initiation occurs after this strain is exceeded. However, the accuracy of numerical crack propagating path is questionable, especially in a side-grooved single edge notched tension (SENT) model. Faster crack initiation at specimen side over the center conflicts with the actual crack propagating path obtained from a physical test. This paper develops a new crack initiation criterion which defines a variable damage strain as a function of the stress configuration at the crack tip. The criterion is modified from the Mohr-Coulomb fracture criterion as a function of stress triaxiality and Lode angle parameters. The damage strain exponentially decreases as the stress triaxiality increases. This paper presents a parametric study on the effects of material parameters considered in the criterion on the development of damage strain locus. The new crack initiation criterion is applied to a side-grooved SENT model, in which the corresponding failure mechanism is defined by the user’s subroutine UDMGINI in Abaqus.

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.

New Procedures for the Residual Strength Assessment of Corroded Pipe Subjected to Combined Loads

1996 ◽  
Author(s):  
Marina Q. Smith ◽  
Stephen C. Grigory
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Failure Modes ◽  
Model Development ◽  
Metal Loss ◽  
General Corrosion ◽  
Moment Capacity ◽  
Strength Assessment ◽  
Global Buckling ◽  
Buckling Failure

Motivated by the inability to accurately address non-pressure related stresses within the framework of current assessment guidelines, a three phase study aimed at the progressive development of a reliable and readily-useable procedure suitable for the analysis of internally pressurized degraded pipes which sustain large settlement and/or axial loads was performed. To ensure accuracy of the resulting procedure, full-scale experiments and finite element numerical simulations of artificially corroded 48-inch (122-cm) diameter X65 pipes subjected to combined loadings were designed to produce upper and lower bound rupture and global buckling failure envelopes for a given set of representative corrosion dimensions. The evaluation model accommodates combined stresses arising from internal pressure, axial bending, and axially compressive loadings to predict operational margins of safety for a pipe containing discrete or multiple metal loss regions guided by failure criteria which considers two critical failure modes: 1) a von Mises type failure criterion for rupture moment capacity determination, and 2) a global buckling failure criterion for identification of the critical moment capacity approximating collapse of the pipe mid-section due to a reduction in bending stiffness attributed in part to ovalization of the cross-section. The new methodology has been incorporated in the personal computer based program SAFE (Shell Analysis Failure Envelope), developed by Southwest Research Institute (SwRI) for the Alyeska Pipeline Service Company. The user-friendly program allows for definition of combined applied stresses and geometry of the degraded region through implementation of field-obtainable pre-or post-excavation measurements, and employs unique features which provide for the examination of pipe sections exhibiting distinct areas of general corrosion, or “patches,” separated both longitudinally and circumferentially, in a single analysis run. This paper outlines the model development and validation with supporting experiments and numerical analyses, and extension of the new procedure through sophisticated numerical techniques embodied in SAFE to actual corrosion profiles and service loadings. Detailed information included in the review are the finite element and SAFE program failure predictions for pipes analyzed with a given set of corrosion dimensions and load magnitudes, and a thorough discussion of the practical application of the SAFE program.

Laboratory study and computer model development related to gross solids' movement in combined sewers

1996 ◽  
Vol 33 (9) ◽  
pp. 39-47 ◽  
Author(s):  
John W. Davies ◽  
Yanli Xu ◽  
David Butler
Keyword(s):  
Computer Simulation ◽  
Pipe Flow ◽  
Model Development ◽  
Simulation Models ◽  
Laboratory Studies ◽  
Pilot Model ◽  
Sewer Systems ◽  
Flow Quality ◽  
Computer Simulation Models ◽  
Theoretical Considerations

Significant problems in sewer systems are caused by gross solids, and there is a strong case for their inclusion in computer simulation models of sewer flow quality. The paper describes a project which considered methods of modelling the movement of gross solids in combined sewers. Laboratory studies provided information on advection and deposition of typical gross solids in part-full pipe flow. Theoretical considerations identified aspects of models for gross solids that should differ from those for dissolved and fine suspended pollutants. The proposed methods for gross solids were incorporated in a pilot model, and their effects on simple simulations were considered.

Investigating the Effectiveness of Techniques Used in Assessing the Integrity of Non-Piggable Pipelines

2004 ◽  
Author(s):  
Giorgio G. J. Achterbosch ◽  
Gerard A. J. Stallenberg
Keyword(s):  
Detection Threshold ◽  
Metal Loss ◽  
Substantial Part ◽  
Valuable Insight ◽  
Specific Situation ◽  
General Corrosion ◽  
Survey Techniques ◽  
Detection Probabilities ◽  
The Sixties ◽  
Coating Defect

A substantial part of the high pressure gastransport network of Gastransport Services as part of N.V. Nederlandse Gasunie in the Netherlands is not piggable. It is therefore foreseen that an ECDA approach including coating survey techniques, CP measurements and bell hole excavations, will be implemented to establish the integrity of these non-piggable lines. In order to get a better understanding of the performance of some techniques for our specific situation, a test program was carried out on a pipeline of 33 kilometres with a diameter of 8” and bitumenous coating, constructed in the sixties. DCVG, Pearson and a combination of CIPS and Pearson (CIPP) were tested in combination with 3 MFL intelligent pigruns, current attenuation measurements by the Stray Current Mapper (SCM) and bell hole excavations. Initial results for the three coating survey techniques showed that the detection probabilities for a coating defect ranged from 18% to 68% under the assumption that no false calls were generated. Using results from repeat measurements and taking into account the possibility of false calls, the detection probabilities increased to potential maximum values of 48% to 94%. Better estimations of the values could be obtained after verification of some indications from CIPP, leading to maximum values in the range of 70% to 84% for the best two techniques. Additional measurements at pre-selected locations by means of pipe-to-soil-potentials and pin-current measurements did not indicate active corrosion. Verification excavations at 14 locations indicated that in all situations a coating defect existed and that mild general corrosion was present in eight situations due to the very aggressive soil (soil resistances of several Ωm’s were measured). Current attenuation measurements by the SCM suggested a uniform distribution of coating quality. The results from the three intelligent pigruns were of relatively little use because of the detection threshold of 15% wall thickness and the fact that the suppliers often did not agree on the interpretation of metal loss. Therefore the results could not be considered to be an absolute true reference for relating the coating defects to. Although the results of the program gave very valuable insight into the characteristics of the different techniques it is recognized that not all results can be translated to other circumstances/pipelines. Therefore additional tests and surveys will be carried out in the coming year(s) to further work out the ECDA procedure for the specific situation of the non-piggable pipelines of Gastransport Services.

Corrosion Metal Loss Interaction From In-Line Inspection and How it Can Affect the Calculated Failure Pressure

2012 ◽  
Author(s):  
Lucinda Smart ◽  
Richard McNealy ◽  
Harvey Haines
Keyword(s):  
Field Measurements ◽  
Metal Loss ◽  
Data Correlation ◽  
Failure Pressure ◽  
Industry Standards ◽  
Direct Measurements ◽  
Non Destructive ◽  
Flux Leakage

In-Line Inspection (ILI) is used to prioritize metal loss conditions based on predicted failure pressure in accordance with methods prescribed in industry standards such as ASME B31G-2009. Corrosion may occur in multiple areas of metal loss that interact and may result in a lower failure pressure than if flaws were analyzed separately. The B31G standard recommends a flaw interaction criterion for ILI metal loss predictions within a longitudinal and circumferential spacing of 3 times wall thickness, but cautions that methods employed for clustering of ILI anomalies should be validated with results from direct measurements in the ditch. Recent advances in non-destructive examination (NDE) and data correlation software have enabled reliable comparisons of ILI burst pressure predictions with the results from in-ditch examination. Data correlation using pattern matching algorithms allows the consideration of detection and reporting thresholds for both ILI and field measurements, and determination of error in the calculated failure pressure prediction attributable to the flaw interaction criterion. This paper presents a case study of magnetic flux leakage ILI failure pressure predictions compared with field results obtained during excavations. The effect of interaction criterion on calculated failure pressure and the probability of an ILI measurement underestimating failure pressure have been studied. We concluded a reason failure pressure specifications do not exist for ILI measurements is because of the variety of possible interaction criteria and data thresholds that can be employed, and demonstrate herein a method for their validation.

Reelability Assessment of Adhesively Bonded Mechanically Lined Pipe

2021 ◽  
Author(s):  
Grégory Alexandre Toguyeni ◽  
Jens Fernandez-Vega ◽  
Richard Jones ◽  
Martin Gallegillo ◽  
Joachim Banse
Keyword(s):  
Finite Element ◽  
Adhesive Layer ◽  
Element Model ◽  
Curing Temperature ◽  
Sensitivity Analyses ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Physical Test ◽  
Weld Overlay ◽  
Outer Pipe

Abstract A solution to prevent liner wrinkling in Mechanically Lined Pipes (MLP) with a standard 3.0mm thick liner during reeling, without the use of pressurisation, has been developed in the form of the GluBi® lined pipe. The liner being adhesively bonded to the outer pipe, its integrity is maintained despite the global plastic strain applied by the installation method. This new linepipe product has been qualified for offshore use through testing accompanied by a detailed Finite Element Analysis programme to fully capture the pipe and adhesive behaviours under and range of temperatures and loading conditions. The objective of this analysis program was to investigate the reelability of the GluBi® pipe. The instalability was defined as the capability of the pipe to tolerate cyclic plastic deformation representative of a typical pipeline installation by reeling without the formation of wrinkling of the CRA liner, and to maintain the integrity of the adhesive layer, particularly near the weld overlay at the pipe ends. Important areas of the GluBi® pipe design are the pipe extremities, particularly the transition between the liner and the weld overlay length. A detailed Finite Element model of the pipe was created. It captured all stages of the pipe manufacturing: pipe lining, hydrostatic expansion, adhesive curing, overlay weld deposition and reeling simulation. The pipe modelled was 312.1mm OD × 19.7mm WT SMLS 450 with a nominal 3.0mm thick Alloy 625 liner. An important validation work was performed to obtain a precise material response of the adhesive layer between liner and outer pipe. The adhesive mechanical properties were thus assessed in shearing and peeling over a range of temperatures covering all possible manufacturing and installation conditions. The model's elements and adhesive property modelling were validated against physical test results. Sensitivity analyses were done on the adhesive curing temperature, the geometry of the adhesive transition between the liner and the overlay weld at the pipe ends and on the liner thickness. The model was subjected to reeling simulation corresponding to Subsea 7's reel-lay vessels. The liner's integrity post reeling was assessed according to a range of acceptance criteria. These studies made it possible to establish parameter ranges for the safe installation of the linepipe.

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