Validity of the LAPA Method for Assessment of Defects Reported by In-Line Inspection Tools

2004 ◽  
Author(s):  
Richard Fletcher ◽  
Louis Fenyvesi
Keyword(s):  
Alternative Assessment ◽  
Reliable Method ◽  
Burst Pressure ◽  
Independent Validation ◽  
Defect Profile ◽  
Corrosion Defects ◽  
Pipeline Corrosion

Over recent years, RSTRENG has gained acceptance as a reliable method of assessing the effect of pipeline corrosion defects, while reducing the conservatism inherent in some of the alternative assessment models. The Length Adaptive Pressure Assessment (LAPA) algorithm has been developed to apply an adaptation of the RSTRENG methodology directly to the results of a magnetic in-line inspection. Adoption of the LAPA technique offers substantial accuracy and efficiency benefits over the more conventional processes, but the industry requires confirmation of the method’s validity before it can take advantage of these. The paper will describe the LAPA validation work performed by PII, and independent validation undertaken by TransCanada Pipelines and other pipeline operators. The independent validation took the form of a comparison of LAPA-based burst pressure calculations with RSTRENG calculations based on direct infield measurements of the defect profile. TransCanada also performed a series of burst tests to quantify the accuracy of the LAPA calculations.

Assessment Criteria and Burst Pressure Prediction for Pipelines With Long Blunt Defects

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Yield Criterion ◽  
Theoretical Models ◽  
Ultimate Tensile Stress ◽  
Burst Pressure ◽  
Practical Applications ◽  
Average Shear Stress ◽  
Average Shear ◽  
Burst Data ◽  
Corrosion Defects ◽  
Von Mises

Corrosion assessment analysis and burst pressure prediction for an aged pipeline with blunt corrosion defects are essential to its integrity. It has been known that the flow stress based corrosion criteria including ASME B31G and PRCI RSTRENG are often conservative to use, but can be non-conservative in practical applications. The ultimate tensile stress based corrosion criteria such as PCORRC and LPC models largely improved the burst pressure prediction for corrosion defects, but the practice still showed certain non-conservatism of these newer models. This paper reviews and evaluates the commonly-used corrosion criteria. In order to improve the existing criteria for predicting burst pressure for long corrosion defects, three new theoretical models with consideration of strain hardening response for the corroded pipe are developed in terms of Tresca yield criterion, von Mises yield criterion, and a new multi-axial yield criterion, i.e., average shear stress yield criterion proposed recently by the present authors. The existing corrosion criteria and the proposed theoretical models are evaluated using experimental burst data for long machined defects and for long real corrosion defects removed from service. It is found that ASME B31G is over-conservative for long defects, but can be non-conservative for deep defects with intermediate lengths. RSTRENG is conservative for short defects. In contrast, PCORRC (or LPC) and the proposed ZL model predict reasonably conservative results for long corrosion defects.

Burst Pressure Prediction of Pipes With Internal Corrosion Defects

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
M. Fahed ◽  
I. Barsoum ◽  
A. Alfantazi ◽  
M. D. Islam
Keyword(s):  
Parametric Study ◽  
Mechanical Response ◽  
Element Model ◽  
Closed Form Expression ◽  
Burst Pressure ◽  
Form Expression ◽  
Internal Corrosion ◽  
Corrosion Defect ◽  
Internal Lining ◽  
Corrosion Defects

Abstract Corrosion in pipeline walls can lead to severe loss of material to a point which will cause complete loss of pipeline integrity. The contemporary approach of corrosion prevention is to use internal lining system to isolate the corrosive medium from the inner surface of the host pipe. The objective of this study is to assess the burst pressure of pipelines with internal corrosion defects. The mechanical response of carbon steel API X42, X52, and X70 pipe grades are empirically estimated and implemented in a finite element model. The geometry of an internal corrosion defect is defined through its depth, width, and length, and a parametric study is undertaken to investigate the influence of the corrosion defect parameters to the overall burst pressure of the pipe. Based on the results from the parametric study, the Buckingham π-theorem is used to derive an analytical closed-form expression to predict the burst pressure of internally corroded pipes, which is found to agree markedly well with the experimental results.

Determination of Folias Factor for Failure Pressure of Corroded Pipeline

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Mingming Sun ◽  
Xin Li ◽  
Jinkun Liu
Keyword(s):  
Prediction Method ◽  
Fe Analysis ◽  
The Other ◽  
Burst Pressure ◽  
Integrity Assessment ◽  
Failure Pressure ◽  
Failure Assessment ◽  
Corrosion Defects ◽  
Corrosion Assessment

Abstract Corrosion assessment and burst pressure prediction of line pipes with corrosion defects are essential for the integrity assessment of steel transmission pipelines. The failure assessment methods proposed in codes or handbooks may be overly conservative or exhibit significant scatter in their predictions. In this paper, the effects of two key parameters—the flow stress and Folias bulging factor, on predicting the failure pressure of pipelines with defects are studied. The Folias bulging factor is suggested by fitting the results from finite element (FE) analysis. Then, a new prediction method for the failure pressure of pipelines with defects is proposed. The failure pressures predicted by the proposed method are in better agreement with the experimental results than the results by the other methods such as B31G, MB31G, Det Norske Veritas (DNV), and rectangular parabolic area (RPA).

Study on the Distribution of Submarine Pipeline Corrosion Defects Based on Internal Inspection Data and Data Mining Method

2020 ◽  
Author(s):  
Guoxi He ◽  
Sijia Chen ◽  
Kexi Liao ◽  
Shuai Zhao
Keyword(s):  
Least Square ◽  
Support Vector ◽  
Submarine Pipeline ◽  
Distribution Rules ◽  
Pipe Segment ◽  
Integrity Management ◽  
Corrosion Defects ◽  
Inspection Data ◽  
Oil Gas ◽  
Pipeline Corrosion

Abstract Submarine pipelines in the sea are applied for oil, gas, water and mixed transportation. Among them, 91% of the pipes contain CO2. Here, based on the existing pipeline internal inspection data of submarine pipeline, the APRIORI algorithm and least-square-support-vector-machine (LSSVM) are applied to analyze the distribution rules and defect characteristics of internal defects along the pipeline. The corrosion defects are divided into 7 types and the pipeline section is divided into 12 intervals. Also, the pipe segment has been defined as J (general pipe), W (weld) and C (close to weld). The contents include the analysis of the characteristics and types of defects, the distribution of defects along the pipe, the severity of the corrosion defects, the size characteristics of defects, and the comparison of the data detected in multiple rounds. The defect depth of four kinds of pipelines is mostly 10%–20% of the wall thickness, hereby the severity of defects is studied via the percentage distribution of corrosion depth. The data of multi-round inspection shows that the corrosions in the mixed pipeline are active and the defects are increasing. The methods and results in this paper can be employed to predict the most likely defect type, mileage location, clock orientation, and shape size of submarine pipeline corrosion. This is helpful for the integrity management of submarine pipelines.

Finite Element Analysis of Complex Corrosion Defects

2002 ◽  
Author(s):  
Duane S. Cronin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Burst Pressure ◽  
Uniaxial Tensile ◽  
Element Analysis ◽  
Internal Corrosion ◽  
Corrosion Defect ◽  
Elastic Plastic ◽  
Defect Assessment ◽  
Corrosion Defects

Aging gas and oil transmission pipeline infrastructure has led to the need for improved integrity assessment. Presently, external and internal corrosion defects are the leading cause of pipeline failure in Canada, and in many other countries around the world. The currently accepted defect assessment procedures have been shown to be conservative, with the degree of conservatism varying with the defect dimensions. To address this issue, a multi-level corrosion defect assessment procedure has been proposed. The assessment levels are organized in terms of increasing complexity; with three-dimensional elastic-plastic Finite Element Analysis (FEA) proposed as the highest level of assessment. This method requires the true stress-strain curve of the material, as determined from uniaxial tensile tests, and the corrosion defect geometry to assess the burst pressure of corrosion defects. The use of non-linear FEA to predict the failure pressure of real corrosion defects has been investigated using the results from 25 burst tests on pipe sections removed from service due to the presence of corrosion defects. It has been found that elastic-plastic FEA provides an accurate prediction of the burst pressure and failure location of complex-shaped corrosion defects. Although this approach requires detailed information regarding the corrosion geometry, it is appropriate for cases where an accurate burst pressure prediction is necessary.

Evaluation of Corrosion Growth Prediction Methodologies Using Burst Pressure Comparisons From Repeated In-Line Inspections

2018 ◽  
Author(s):  
Chance Wright ◽  
Thomas Dessein ◽  
Yanping Li ◽  
Suzanne Ward
Keyword(s):  
Safety Factor ◽  
Average Rate ◽  
Burst Pressure ◽  
Safe Operation ◽  
Feature Size ◽  
Data Set ◽  
Length Growth ◽  
Integrity Management ◽  
Pipe Joints ◽  
Pipeline Corrosion

At the forefront of the effort to understand and mitigate pipeline corrosion is the prediction of corrosion growth rates. It is important to understand the effect of corrosion growth estimates on integrity management decisions. An overly conservative approach results in unnecessary digs, while removing conservatism increases the potential for a missed feature to grow to a threatening size. While approaches to feature depth growth have been well-established, there has been less investigation into the growth of feature lengths. A literature review was performed on the methodologies applicable to length growth, and their performance was compared to those that only account for depth growth using a sample analysis. For pipelines with multiple in-line inspection (ILI) runs, feature or signal matching can be used to estimate the change in feature size. These rates can be used directly on individual features, averaged across pipe joints, or compiled into a statistical distribution. Alternatively, only one ILI measurement can be used and an assumption made on the age of the defect. These approaches are more commonly applied to depth growth but could be used to predict length growth as well. To compare the growth methodologies, the study used historical ILI measurements of a liquid pipeline to predict feature sizes and estimated burst pressures determined at the time of the latest ILI. The number of defects correctly predicted to have an insufficient burst pressure safety factor for safe operation was compared to the number of defects that were erroneously predicted to not meet this criterion, and those that were predicted to be safe but later found to not meet the safety factor requirement. The number of erroneously flagged defects was found to vary the most between methodologies. For the assessed data set, using the joint average rate based on feature box-matching was non-conservative on average. It was also found that incorporating length growth did not significantly affect the accuracy of the burst pressure predictions.

Study on Pulsed Eddy Current Nondestructive Testing Technology for Pipeline Corrosion Defects Based on Finite Element Method

2011 ◽  
Vol 120 ◽  
pp. 36-41 ◽  
Author(s):  
Han Wu Liu ◽  
Shan Ping Zhan ◽  
Yun Hui Du ◽  
Peng Zhang
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Induced Voltage ◽  
Defect Depth ◽  
Element Analysis ◽  
Pulsed Eddy Current ◽  
The Finite Element Analysis ◽  
Corrosion Defects ◽  
Pipeline Corrosion ◽  
Detection Coil

According to the principle and the type of the oil pipeline corrosion, we use the square wave of wide spectrum, strong signal transmission capability and a certain duty ratio as the excitation source of the pulsed eddy current. The finite element analysis software ANSYS is used to establish a three-dimensional finite element model of the pipeline corrosion defects by applying the boundary conditions of square wave excitation to simulate the distributions of current and induced magnetic field in the pipeline under various defect volumes. It can solve the induced voltage variation with time on detection coil, and can accomplish the finite element analysis and the nondestructive testing about the pipeline internal corrosion defects with the insulation layer and the protection layer. The results of the study show: When there is no corrosion defect in the pipeline, the electric current in the pipeline is basically even distribution. The magnetic field is distributed for the symmetrical vortex shape from head to foot, and it has not obviously gather phenomenon. When there are some corrosion defects in the pipeline, the electric current forms partial symmetrical vortex shape in both sides of the corrosion defect, and it is obviously assembled in the defect place. The simulation results of the different size defects show that the maximum magnetic field strength and the maximum current value increase with the defect depth increasing, while the output voltage decreases with the defect depth increasing. By extracting the induced voltage signals on the detection coil in a certain excitation condition, the quantitative detection of the pipeline corrosion defects can be achieved.

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