Effects of depth in external and internal corrosion defects on failure pressure predictions of oil and gas pipelines using finite element models

2020 ◽  
Vol 23 (14) ◽  
pp. 3128-3139
Author(s):  
Selene Capula Colindres ◽  
Gerardo Terán Méndez ◽  
Julio Cesar Velázquez ◽  
Roman Cabrera-Sierra ◽  
Daniel Angeles-Herrera
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Effective Area ◽  
The Finite Element Method ◽  
Internal Corrosion ◽  
Failure Pressure ◽  
Corrosion Defect ◽  
Corrosion Defects ◽  
Pipeline Failure ◽  
First Time

This study presents, for the first time, the mechanical behavior of API 5L pipeline steels X42, X52, X60, X70, X80, and X100 with external and internal corrosion defects as well as a combination of both defects that has been named external–internal corrosion defects. The conventional methods to predict failure pressure in corroded pipes, such as B31G, RSTRENG-1, SHELL, DNV-99, PCORRC, and FITNET FFS, have also been discussed in this article. In addition, pipeline failure pressure has been estimated using the finite element method, considering that it is the best approach to calculate actual failure pressure. The external and internal corrosion defect investigated in this research manifests as a rectangular shape with spherical ends at the edges. When the external–internal corrosion defect appears, failure pressure data decrease dramatically because of severe damage. This is due to the decrease in the ligament (effective area) caused by the corrosion defect. To have a good estimation of the pipeline failure pressure with an external–internal corrosion defect, DNV-99 method can be used with acceptable certainty.

On the Influence of the Corrosion Defect Size in the Welding Bead, Heat-Affected Zone, and Base Metal in Pipeline Failure Pressure Estimation: A Finite Element Analysis Study

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
G. Terán ◽  
S. Capula-Colindres ◽  
J. C. Velázquez ◽  
D. Angeles-Herrera ◽  
E. Torres-Santillán
Keyword(s):  
Finite Element ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Defect Size ◽  
Localized Corrosion ◽  
Defect Depth ◽  
Element Analysis ◽  
Failure Pressure ◽  
Corrosion Defect ◽  
Pipeline Failure

In this study, failure pressure prediction was conducted in a pipeline with localized corrosion in base metal (BM), heat-affected zone (HAZ), and welding bead (WB) by finite element (FE) analysis. In the gas pipeline industry, there are methods (B31G, RESTRENGH, Shell, DNV, PCORR, and Fitnet FFS) and authors' approaches (Choi and Cronin) to determine the failure pressure. However, one disadvantage of these methods is that their equations do not consider damage corrosion at the HAZ or WB. They consider corrosion only in the BM. The corrosion shape is rectangular with a radius at the edges. In this study, the corrosion defect depth (d) was varied. The corrosion defect length (L) and the corrosion defect width (W) were equal. A type of rectangular corrosion defect with a radius at the edges in the longitudinal and circumferential directions was proposed. True stress–strain curves for BM, HAZ, and WB of an API 5 L X52 were introduced in the FE program. The results show that the pressure decreases as d, L, and W increase. This is because the damage corrosion is more severe as it grows, which causes the failure pressure to decrease.

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.

Burst Tests on Pipeline Containing Long Real Corrosion Defects

2004 ◽  
Author(s):  
Ricardo Dias de Souza ◽  
Adilson Carvalho Benjamin ◽  
Jose Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz
Keyword(s):  
Oil And Gas ◽  
Corrosion Damage ◽  
Effective Area ◽  
Assessment Methods ◽  
Corrosion Defect ◽  
Corrosion Defects ◽  
Level 1 ◽  
Tubular Specimens ◽  
Level 2 ◽  
Outside Diameter

Long defects are one of the various corrosion-damage geometries that may occur in oil and gas pipelines. Long internal defects appear in general at the bottom of the pipe, around 6 o’clock position, due to the presence of water at this place. Long external defects are caused in general by faults in the protective coating. The words “long defect” are being used herein to mean a corrosion defect longer than 20Det. In this paper the burst tests of five end-capped tubular specimens containing a single internal real corrosion defect are presented. In these tests the tubular specimens were loaded with internal pressure only. The specimens were cut from five longitudinal welded tubes made of API 5L X46 steel with an outside diameter of 457.2 mm and a wall thickness of 6.35 mm. The tubes are corroded pipe segments that were removed from service as part of a rehabilitation campaign. Each one of the five tubes contains a long and complex shaped internal defect. Measurements were carried out in order to determine the actual dimensions of each tubular specimen and its respective defect. Tensile specimens were tested to determine material properties. The failure pressures measured in the laboratory tests are compared with those predicted by two Level-2 assessment methods: the RSTRENG Effective Area method and the DNV RP-F101 method for complex shaped defects. Comparisons between the measured failure pressures and the failure pressures predicted by three Level-1 assessment methods (the ASME B31G method, the RSTRENG 085dL method and the DNV RP-F101 method for single defects) are also presented.

Failure Pressure Prediction of Cracks in Corrosion Defects Using XFEM

2020 ◽  
Author(s):  
Xinfang Zhang ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
Samer Adeeb
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Crack Depth ◽  
Average Error ◽  
Extended Finite Element ◽  
Defect Depth ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Coating and cathodic protection degradation can result in the generation of several types of flaws in pipelines. With the increasing number of aging pipelines, such defects can constitute serious concerns for pipeline integrity. When flaws are detected in pipelines, it is extremely important to have an accurate assessment of the associated failure pressure, which would inform the appropriate remediation decision of repairing or replacing the defected pipelines in a timely manner. Cracks-in-corrosion (CIC) represent a class of defect, for which there are no agreed upon method of assessment, with no existing analytical or numerical models to predict their failure pressures. This paper aims to create a set of validated numerical finite element analysis models that are suitable for accurately predicting the failure pressure of 3D cracks-in-corrosion defects using the eXtended Finite Element Method (XFEM) technique. The XFEM for this study was performed using the commercially available software package, ABAQUS Version 6.19. Five burst tests of API 5L X60 specimens with different defect depths (varying from 52% to 66%) that are available in the literature were used to calibrate the XFEM damage parameters (the maximum principal strain and the fracture energy). These parameters were varied until a reasonable match between the numerical results and the experimental measurements was achieved. Symmetry was used to reduce the computation time. A longitudinally oriented CIC defect was placed at the exterior of the pipe. The profile of the corroded area was assumed to be semi-elliptical. The pressure was monotonically increased in the XFEM model until the crack or damage reached the inner surface of the pipe. The results showed that the extended finite element predictions were in good agreement with the experimental data, with an average error of 5.87%, which was less conservative than the reported finite element method predictions with an average error of 17.4%. Six more CIC models with the same pipe dimension but different crack depths were constructed, in order to investigate the relationship between crack depth and the failure pressure. It was found that the failure pressure decreased with increasing crack depth; when the crack depth exceeded 75% of the total defect depth, the CIC defect could be treated as crack-only defects, since the failure pressure for the CIC model approaches that for the crack-only model for ratios of the crack depth to the total defect depth of 0.75 and 1. The versatility of several existing analytical methods (RSTRENG, LPC and CorLAS) in predicting the failure pressure was also discussed. For the corrosion-only defects, the LPC method predicted the closest failure pressure to that obtained using XFEM (3.5% difference). CorLAS method provided accurate results for crack-only defects with 7% difference. The extended finite element method (XFEM) was found to be very effective in predicting the failure pressure. In addition, compared to the traditional Finite Element Method (FEM) which requires extremely fine meshes and is impractical in modelling a moving crack, the XFEM is computationally efficient while providing accurate predictions.

Numerical Analysis of API 5L X42 and X52 Vintage Pipes with Cracks in Corrosion Defects Using Extended Finite Element Method

2021 ◽  
Author(s):  
Xinfang Zhang ◽  
Meng Lin ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Pipe Wall ◽  
Crack Depth ◽  
Initial Crack ◽  
Extended Finite Element ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Cracks and corrosion in pipelines can occur simultaneously, representing a hybrid defect known as cracks in corrosion (CIC), which is often difficult to model using the available assessment codes or methods. As a result, detailed modeling of CIC has not been studied extensively. In this study, the extended finite element method (XFEM) has been applied to predict the failure pressures of CIC defects in API 5L Grade X42 and X52 pipes. The pipes were only subjected to internal pressure and the XFEM models were validated using full-scale burst tests available in the literature. Several CIC models with constant total defect depths (55%, and 60% of wall thickness) were constructed to investigate the effect of the initial crack depth on the failure pressure. The failure criterion was defined when wall penetration occurred due to crack growth, i.e., the instance the crack reached the innermost element of the pipe wall mesh. It was observed that for shorter cracks, the failure pressure decreased with the increase of the initial crack depth. The results indicated that the CIC defect could be treated as crack-only defects when the initial crack depth exceeded 50% of the total defect depth. However, for longer cracks, the initial crack depth was found to have a negligible effect on the failure pressure, implying that the CIC defect could be treated as either a crack or a corrosion utilizing the available assessment methods.

The Evaluation of Failure Pressure for Corrosion Defects Within Girth or Seam Weld in Transmission Pipelines

2004 ◽  
Author(s):  
Young-pyo Kim ◽  
Woo-sik Kim ◽  
Young-kwang Lee ◽  
Kyu-hwan Oh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Limit Load ◽  
The Body ◽  
Element Analysis ◽  
Burst Test ◽  
Corrosion Defect ◽  
Seam Weld ◽  
Failure Assessment ◽  
Corrosion Defects

The failure assessment for corroded pipeline has been considered with the burst test and the finite element analysis. The burst tests were conducted on 762mm diameter, 17.5mm wall thickness and API 5L X65 pipe that contained specially manufactured rectangular corrosion defect. The failure pressures for corroded pipeline have been measured by burst testing and classified with respect to corrosion sizes and corroded regions — the body, the girth weld and the seam weld of pipe. Finite element analysis was carried out to derive failure criteria of corrosion defect within the body, the girth weld and the seam weld of the pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.

Failure Analysis of a Composite Frangible Cover Based on Transient Dynamics

2013 ◽  
Vol 395-396 ◽  
pp. 55-59 ◽  
Author(s):  
Wei Zeng ◽  
Yi Jiang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Failure Analysis ◽  
Failure Process ◽  
Transient Dynamics ◽  
Bonding Layer ◽  
The Finite Element Method ◽  
Failure Pressure ◽  
Element Method

The failure analysis of a fly through frangible canister cover is studied based on transient dynamics via the finite element method. The cover, which is fabricated with five plan-liked parts, is cohesively bonded together forming several weak paths. Five test specimens are designed according to the length of bonded fiber cloth. The cover is subjected to an impulsive blast and the failure process is obtained and analyzed. The failure pressure and time are determined at different cloth length. The result shows that the failure pressure and the corresponding time rise as the length of bonding layer increases.

Predicting the Failure Pressure of Pipelines Containing Nonuniform Depth Corrosion Defects Using the Finite Element Method

2003 ◽  
Author(s):  
Adilson Carvalho Benjamin ◽  
Edmundo Queiroz de Andrade
Keyword(s):  
Finite Element ◽  
Shell Model ◽  
Failure Behavior ◽  
Solid Model ◽  
Second Phase ◽  
The Finite Element Method ◽  
Spark Erosion ◽  
Corrosion Defects ◽  
Tubular Specimens ◽  
Deep Defects

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipelines containing long nonuniform depth corrosion defects. In the first phase of this project, burst tests of two tubular specimens were carried out. Each of the two specimens had one external nonuniform depth corrosion defect, machined using spark erosion. This defect consists of two short and deep defects within a long and shallow corrosion patch, longitudinally oriented. The second phase of the project aims at appraising the performance of two different finite element models: a shell model and a solid model. This paper describes the application of these models in the analysis of the two tubular specimens containing a long nonuniform depth defect that were tested in the first phase of this project. The failure pressures predicted by the two types of FE models are compared with the burst pressures measured in the laboratory tests. Also a comparison between the results obtained by these models is presented. It is concluded that the solid model is more accurate than the shell model, but both models proved to be capable of simulating the failure behavior of defects constituted by a long and shallow corrosion patch with deep defects over it.

Burst Tests on Pipeline Containing Irregular Shaped Corrosion Defects

2008 ◽  
Author(s):  
Adilson C. Benjamin ◽  
Aldo R. Franzoi ◽  
Jose´ Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz
Keyword(s):  
Depth Profile ◽  
Effective Area ◽  
Metal Loss ◽  
Defect Depth ◽  
Corrosion Defect ◽  
Spark Erosion ◽  
X80 Steel ◽  
Corrosion Defects ◽  
Tubular Specimens ◽  
Outside Diameter

A corrosion defect can be considered as being of a regular shape if its defect depth profile is relatively smooth and the longitudinal area of metal loss is approximately rectangular. A corrosion defect can be considered as being of an irregular shape if its defect depth profile presents one or more major peaks in depth. In this paper the burst tests of four tubular specimens are presented. In these tests the tubular specimens were loaded with internal pressure only. The specimens were cut from longitudinal welded tubes made of API 5L X80 steel with a nominal outside diameter of 457.2 mm (18 in) and a nominal wall thickness of 7.93 mm (0.312 in). Each of the four specimens had one external irregular shaped corrosion defect, machined using spark erosion. Measurements were carried out in order to determine the actual dimensions of each tubular specimen and its respective defect. Tensile specimens and impact test specimens were tested to determine material properties. The failure pressures measured in the laboratory tests are compared with those predicted by six assessments methods, namely: the ASME B31G method, the RSTRENG 085dL method, the DNV RP-F101 method for single defects, the RPA method, the RSTRENG Effective Area method and the DNV RP-F101 method for complex shaped defects.

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