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.

A Reconsideration of the Log-Secant Model for Failure Pressure Prediction of Surface-Breaking Axial Cracks in Pipelines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Colin Scott
Keyword(s):  
Surface Crack ◽  
Driving Force ◽  
Crack Extension ◽  
Oil And Gas ◽  
Crack Depth ◽  
Metal Loss ◽  
Regulatory Requirements ◽  
Failure Pressure ◽  
Industry Standards ◽  
Preliminary Validation

Abstract In the late 1960s and early 1970s, the researchers of the NG-18 Committee at the Battelle Institute in Columbus Ohio completed a seminal study on the failure pressures of axial flaws in oil and gas pipelines. Key developments included the “ASME B31G” equations for assessment of blunt metal loss flaws, the log-secant model for sharp through-wall cracks, and the log-secant model for sharp surface-breaking cracks. These equations are well-established and feature in various industry standards, recommended practices, and federal regulatory requirements. This work is a reconsideration of the log-secant model for axial surface-breaking cracks. The original equations were derived based on a through-wall crack, for which the crack length is the driving force for crack extension. However, for a surface crack, the crack depth is the correct driving force for crack extension. This work rederives the log-secant model starting with an infinitely long surface crack, and then empirically corrects for a finite length. The result is a new failure pressure model of similar form to the original log-secant model, but with a few key differences. Preliminary validation work using the original NG-18 data shows promising results.

scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

scholarly journals Determination of the serviceability of bridge upper structures (Case study: Sangsang River bridge at Tohpati-Kusamba highway, Bali)

2019 ◽  
Vol 276 ◽  
pp. 01039
Author(s):  
I Nyoman Sutarja ◽  
Ida Bagus Rai Widiarsa ◽  
I Made Alit Karyawan Salain
Keyword(s):  
Concrete Slab ◽  
Test Method ◽  
Bridge Structure ◽  
Digital Tool ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Non Destructive ◽  
Concrete Girder

The serviceability of upper structures of the Sangsang River Bridge during the designed period has decreased due to several factors such as environmental influences affecting the physical condition of the bridge, as well as the load that exceeds the designed capacity. Sangsang River Bridge needs to be maintained during the serviceability period in order to function optimally, safely and comfortably. The maintenance of the bridge begins with the examination of the existing condition of the bridge by utilizing Non-Destructive Test method using UPV Pundit PLLink 500 Digital tool. The data collected was then analysed to find out the serviceability of bridge structure. The analysed results showed that the value of concrete slab density was 17.8 MPa and of the concrete girder was 18.1 MPa. This values were classified as a deficient criterion and therefore the serviceability needs to be increased. Recommendations for enhancing the bridge serviceability was strengthening using Fibre Reinforced Polymer (FRP). Using 2 Layer SEH-51A or equivalent 2 Layer of E-glass fibre was suggested for concrete slab, meanwhile the use of 2 Layer SCH-41 or equal to 2 Layer Carbon fibre was suggested for concrete girder.

scholarly journals Methodology for Determining the Die-Off Coefficient of Enterococci in the Conditions of Transport through the Karst Aquifer—Case Study: Bokanjac–Poličnik Catchment

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 820 ◽  
Author(s):  
Željko Šreng ◽  
Goran Lončar ◽  
Marin Grubišić
Keyword(s):  
Karst Aquifer ◽  
Field Measurements ◽  
Initial Step ◽  
Seepage Flow ◽  
Mean Value ◽  
Dominant Factor ◽  
Karst Environment ◽  
Karst Catchment

This paper presents the methodology for determining the die-off coefficient of faecal indicator bacteria (enterococci) when transported in a karst environment. The main problem in exploring karst environments, which this methodology strives to cope with, is lack of field measurements, poor data on karst rock formation, fractures and channels within it, and groundwater level dynamics. The analysed karst catchment (Bokanjac–Poličnik) is situated in the hinterland of the city of Zadar (Republic of Croatia) and covers an area of 235.07 km2. In the water supply wells within the analysed catchment, a frequent occurrence of enterococci was observed. The proposed methodology consists of two basic steps. Preliminary analyses as the initial step were used in the accumulation of certain assumptions related to the detection of increased concentrations of enterococci as well as in determination of the potential source of pollution. In the second step, the analytical model was constructed with the aim of resolving processes of sorption and die-off and determining the dominant factor in the process of natural removal of enterococci when transported in karst environment. Within the model, two parts of the pollutant transport are integrated: vertical percolation and horizontal seepage flow and transport. The mean value of the total die-off coefficient by transport through the unsaturated zone in the analysed case is k t o t = 8.25. Within the saturated zone the total die-off coefficient k t o t is within the limits of 0.1 and 0.5.

A More Accurate and Precise Method for Large Metal Loss Corrosion Assessment

2018 ◽  
Author(s):  
Shenwei Zhang ◽  
Jason Yan ◽  
Shahani Kariyawasam ◽  
Terry Huang ◽  
Mohammad Al-Amin
Keyword(s):  
Case Studies ◽  
Pressure Ratio ◽  
Field Measurements ◽  
Assessment Model ◽  
Metal Loss ◽  
Worst Case ◽  
Corrosion Morphology ◽  
Surgical Tool ◽  
Cutting Out

Pipeline integrity decisions are highly sensitive to the assessment model. A less accurate and less precise model can conservatively trigger many unnecessary actions such as excavations without providing additional safety. Therefore, a more accurate and precise model will reduce excavations and provide higher assurance of safety. This is akin to using a more precise surgical tool such as a laser for cutting out a brain tumor where you can cut closer to the edge and be assured of cutting out more of the tumor (safer) and yet cut less of the surrounding brain tissue (less conservative). This paper presents a novel model for assessing large metal-loss corrosion based on in-line inspection (ILI) or field measurement. The model described in this paper utilized an unconventional approach, namely multiple plausible profiles (P2), to idealize the shape of the corrosion, and therefore is referred to as P2 model. In contrast, all existing models use one single profile for characterizing corrosion profile, e.g. RSTRENG utilizes a single worst-case river bottom profile to characterize the shape of corrosion. The P2 model has been initially validated using fourteen (14) full scale specimen-based hydrostatic tests on pipes containing real large corrosion features. Validation results showed that the P2 model is safe, but less conservative and more precise than RSTRENG. The magnitude of reduction in conservatism depends on the corrosion morphology. On average, the P2 model achieves 15% reduction in model bias and 44% reduction in standard deviation of model error. Further validation was provided using the testing data published by PRCI and PETROBRAS. Another set of burst tests are being conducted by TransCanada as part of the continuous validation of P2 model. The effectiveness of the P2 model was demonstrated through two case studies (denoted by Case study 1 and 2). Case Study 1 included 170 external metal-loss corrosion features that were excavated from different pipeline sections, and have field-measurements using laser scan tool. Case Study 2 included 154 ILI-reported external metal-loss corrosion features with RSTRENG calculated rupture-pressure-ratio (RPR) of less than or equal to 1.25 (i.e. RPR ≤ 1.25); hence, these features were classified as immediate features. The Case Studies showed that the use of the P2 model resulted in 80% less number of ILI-reported features requiring immediate action (i.e., RPR ≤ 1.25) and 89% less number of excavated features requiring repair (e.g., sleeve or cut-out) compared to the respective number of features identified by RSTRENG-based assessment. The reduction in the number of features requiring excavation or repair is highly morphology-dependent with the highest reduction achievable for pipeline containing long and wide corrosion clusters (e.g., tape-coated pipeline). However, the P2 model is applicable to all clusters regardless of the number of individual corrosion anomalies associated with the cluster.

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.

The Verification of the Modernization of the Real Estate Cadastre in the Context of the Quality of Cadastral Data – Case Study

2017 ◽  
Author(s):  
Monika Mika
Keyword(s):  
Real Estate ◽  
Field Measurements ◽  
District Office ◽  
The Real ◽  
The Real Estate ◽  
Work Related ◽  
Cadastral Maps ◽  
Direct Measurements

The aim of the modernization is to improve the quality of the collected data. That is necessary especially in those areas where cadastral maps are used in the scale of 1:2880. The most satisfactory results in the process of modernization are obtained on the basis of geodetic field measurements. The aim of the paper is to verify the work related to real estate cadastre modernization in the context of the quality of the cadastral data collected in 1999–2001. This paper presents the results of surveying, which aim was to check whether the data contained in the register of land are a reflection of the facts boundaries and surface parcels. In the analyzes the materials of selected areas from state resources were used. The verification of graphic materials (maps) and descriptive (areas of plots) obtained from the District Office carried out in this paper showed a satisfactory level of data compliance. Factual status on the ground, in most cases, corresponds to the existing in extracts from the land registry, created on the basis of the land and buildings registry modernization in 1999–2001. These data correspond to the areas calculated from the results of the 2016 direct measurements.

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.

Pipeline Integrity Analysis Based on Interdisciplinary Cooperation

2004 ◽  
Author(s):  
Perry Barham ◽  
Bryce Brown ◽  
Martine Fingerhut ◽  
Patrick Porter
Keyword(s):  
High Resolution ◽  
Field Measurements ◽  
Interdisciplinary Cooperation ◽  
Metal Loss ◽  
Reporting Requirements ◽  
Anomaly Classification ◽  
Inspection Data ◽  
Integrity Analysis ◽  
Available Information ◽  
Flux Leakage

For many years, BP Pipelines, North America has used high-resolution Magnetic Flux Leakage (MFL) in-line inspection (ILI) technology to help maintain the integrity of their pipelines. The improvements in this technology that now allow an Operator to make integrity decisions also bring challenges. Reports from ILI can list thousands, or even hundreds of thousands, of individual anomalies or features. When combined with data from NDT field measurements and existing pipe tallies, it can become overwhelming. Methods had to be developed to distill this information for further analysis. BP Pipelines NA encouraged cooperation between all parties involved in the integrity process to adapt reporting requirements and work procedures to provide the best available information for integrity analysis and to ensure continued improvements. This cooperation is a key part of the integrity equation and essential to a successful program. This paper presents an overview of the validation process undertaken on a 51 km (32-mile) section of 457 mm (18-inch) pipeline. This pipe section was inspected in 1999 and again in 2003 by the same inspection company. This provided an opportunity to evaluate improvements in inspection technology, assess repeatability of performance and develop an engineering based approach to review, analyze, and validate high-resolution metal loss MFL data. Field verification and data validation included the use of a several NDE techniques to acquire field measurements to overlay and compare to the ILI inspection data. Anomaly classification and distribution is examined and methods of selecting validation locations for future inspection developed. In addition to the primary goal outlined, the 2003 repair program provided an opportunity to evaluate the performance of the composite sleeve reinforcements applied in 1999, after 4 years of service.

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