Burst Tests on Pipeline Containing Long Real Corrosion Defects

Author(s):  
Ricardo Dias de Souza ◽  
Adilson Carvalho Benjamin ◽  
Jose Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz

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.

Author(s):  
Adilson C. Benjamin ◽  
Aldo R. Franzoi ◽  
Jose´ Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz

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.


Author(s):  
Adilson C. Benjamin ◽  
Ronaldo D. Vieira ◽  
Jose Luiz F. Freire ◽  
Jaime T. P. de Castro

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipeline with long corrosion defects. In the first phase of this project, burst tests of 9 tubular specimens containing a single external simulated corrosion defect were carried out. These specimens were cut from longitudinal welded tubes made of API 5L X60 steel with an outside diameter of 323.9 mm and a wall thickness of 9.53 mm. All corrosion defects were smooth rectangular defects fabricated using spark erosion. Tensile specimens were tested to determine material properties. Each corroded specimen was instrumented with 10 post-yield strain gages rosettes, one displacement transducer and three pressure transducers. This paper describes the tubular specimens tested and the instrumentation used. The measured burst pressures are compared with those predicted by the ASME B31G, the RSTRENG 085dL, the RSTRENG Effective Area and the DNV RP-F101 (Part B) methods.


Author(s):  
Adilson C. Benjamin ◽  
Jose Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz ◽  
Edmundo Q. de Andrade

In this paper the burst tests of seven 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). The specimen IDTS 1 is a defect-free pipe. The specimen IDTS 2 contains only one defect, herein called base defect. The base defect is an external flat bottomed defect with uniform width (circumferential dimension). The other five specimens contain groups of interacting defects constituted by the combination of two or more base defects. All the defects were machined using spark erosion. Measurements were carried out in order to determine the actual dimensions of each tubular specimen and its respective groups of defects. 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 interacting defects.


2020 ◽  
Vol 23 (14) ◽  
pp. 3128-3139
Author(s):  
Selene Capula Colindres ◽  
Gerardo Terán Méndez ◽  
Julio Cesar Velázquez ◽  
Roman Cabrera-Sierra ◽  
Daniel Angeles-Herrera

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.


Author(s):  
Adilson C. Benjamin ◽  
Jose Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Edmundo Q. de Andrade

In this paper the burst tests of five tubular specimens are presented. In these tests the tubular specimens were loaded with internal pressure only. The specimens were cut from a longitudinal welded tube 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). The specimen IDTS 8 contains only one defect, herein called base defect. The base defect is an external flat bottomed defect with uniform width (circumferential dimension). The other four specimens contain groups of interacting defects constituted by the combination of three or more base defects. All the defects were machined using spark erosion. Measurements were carried out in order to determine the actual dimensions of each tubular specimen and its respective groups of defects. 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 five assessments methods, namely: the ASME B31G method, the RSTRENG 085dL method, the DNV RP-F101 method for single defects, the RPA method and the RSTRENG Effective Area method.


Author(s):  
Adilson C. Benjamin ◽  
Jose Lui´z F. Freire ◽  
Ronaldo D. Vieira ◽  
Jaime T. P. de Castro

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipeline with long nonuniform 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. The specimens were cut from longitudinal welded tubes made of API 5L X60 steel with an outside diameter of 323.9 mm and a nominal wall thickness of 9.53 mm. Each of the two tubular specimens was instrumented with 17 post-yield strain gages rosettes, one displacement transducer and two pressure transducers. This paper describes the tubular specimens tested and the instrumentation used. The measured burst pressures are compared with those predicted by the ASME B31G and the RSTRENG Effective Area methods. The material properties used were determined by tests of tensile specimens. Photographs of the fractured defects are presented along with comments about their differences in shape. Some values of strain measured during the tests are also presented and commented.


Author(s):  
Adilson C. Benjamin ◽  
Jose´ Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz

Circumferential defects are the ones in which the width w is greater than the length L (w > L). In this paper the burst tests of three 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 three specimens had one external circumferential 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 burst tests are compared with those predicted by five assessments methods, namely: the ASME B31G method, the RSTRENG 085dL method, the DNV RP-F101 method for single defects (Part B), the RPA method and the Kastner equation.


Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 954 ◽  
Author(s):  
Yuyao Cheng ◽  
Chenyang Zhao ◽  
Jian Zhang ◽  
Zhishen Wu

Corrosion of main steel reinforcement is one of the most significant causes of structuraldeterioration and durability reduction. This research proposes a two-level detection strategy tolocate and quantify corrosion damage via a new kind of long-gauge fiber Bragg grating (FBG) sensor.Compared with the traditional point strain gauges, this new sensor has been developed for bothlocal and global structural monitoring by measuring the averaged strain within a long gauge length.Based on the dynamic macrostrain responses of FBG sensors, the strain flexibility of structures areidentified for corrosion locating (Level 1), and then the corrosion is quantified (Level 2) in terms ofreduction of sectional stiffness of reinforcement through the sensitivity analysis of strain flexibility.The two-level strategy has the merit of reducing the number of unknown structural parametersthrough corrosion damage location (Level 1), which guarantees that the corrosion quantification(Level 2) can be performed efficiently in a reduced domain. Both numerical and experimentalexamples have been studied to reveal the ability of distributed long-gauge FBG sensors for corrosionlocalization and quantification.


Author(s):  
Edmundo Q. de Andrade ◽  
Adilson C. Benjamin ◽  
Paulo R. S. Machado ◽  
Leonardo C. Pereira ◽  
Breno P. Jacob ◽  
...  

This paper describes the application of solid finite element models in the analysis of five tubular specimens containing interacting corrosion defects. Each of these specimens has been submitted to hydrotest up to failure as part of a previous research project. 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). The analyses accounted for large strains and displacements, stress-stiffening and material nonlinearity. The failure pressures predicted by the solid finite element models are compared with the failure pressures of these specimens measured in the laboratory burst tests carried out previously. Also the failure behavior of each specimen is described and illustrated by contour plots of stresses.


2011 ◽  
Vol 70 ◽  
pp. 422-427 ◽  
Author(s):  
José L. F. Freire ◽  
Adilson C. Benjamin ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz

The elastic and plastic strain data of tubular specimens undergoing rupture under internal pressure tests are presented and analyzed. Six tubular specimens were tested. The specimens were cut from longitudinally welded tubes made of API 5L X80 steel with a nominal outside diameter of 457.2mm (18in) and a nominal wall thickness of 7.93mm (0.312in). Each of the six specimens had one external longitudinal or circumferential corrosion defect that had been machined using spark erosion. Tensile specimens and impact test specimens were tested to determine material properties. Post-yielding electrical resistance strain gages were used to measure the elastic and plastic strains. The failure pressures measured in the laboratory tests were compared with those predicted by the DNV RP-F101 method for single defects and by the Kastner equation. The paper also discusses the strength of the pipe segments used in the tests under the assumptions of following the Tresca rupture criterion.


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