Current Search: Pipelines--Cathodic protection (x)
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(1 - 5 of 5)
- Title
- Cathodic protection modeling of marine pipelines.
- Creator
- Lysogorski, Diane K., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A governing equation for potential attenuation along a pipeline cathodically protected by identical, evenly-spaced, spherical anodes is developed. The numerical solution, obtained using a coordinate based mapping (CoMB) finite difference method (FDM), can be used to predict the potential profile of a pipeline. In addition, a modified version of Ohm's Law is developed to provide an improved approach to design of pipeline CP systems. Both approaches address anode-electrolyte, coating...
Show moreA governing equation for potential attenuation along a pipeline cathodically protected by identical, evenly-spaced, spherical anodes is developed. The numerical solution, obtained using a coordinate based mapping (CoMB) finite difference method (FDM), can be used to predict the potential profile of a pipeline. In addition, a modified version of Ohm's Law is developed to provide an improved approach to design of pipeline CP systems. Both approaches address anode-electrolyte, coating-polarization, and metallic path resistance, but the latter neglects to address the potential gradient associated with the one-dimensional nature of pipelines. These two approaches were compared to results from existing potential prediction methods and Boundary Element Methods (BEM). Furthermore, a procedure was developed to calculate the resistance of rectangular conductor arrays. This procedure was utilized to calculate the resistance of an anode sled. Combination of the first principles based equation and the rectangular array resistance procedure allows one to predict the potential profile for a pipeline protected by identical, evenly-spaced, anode sleds.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12850
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection
- Format
- Document (PDF)
- Title
- Potential attenuation and anode current output determination alternatives for galvanic anode cathodic protection upon offshore pipelines.
- Creator
- Bethune, Keith P., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
A recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing...
Show moreA recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing method for attenuation prediction, namely the Boundary Element Method (BEM). As both the FDM and BEM solutions are mathematically complex and time consuming, it is then demonstrated that a modified form of Ohm's Law that quantitatively interrelates (1) design life, (2) anode size, weight, and properties, (3) pipe size, current demand, and coating quality, (4) sea water resistivity, (5) magnitude of polarization, and (6) anode spacing is sufficient for design purposes where metallic resistance of the pipeline itself is negligible. This new method can be easily adapted in a spreadsheet type analysis as no numerical subroutine is necessary. One size pipeline of varying lengths is analyzed using these methods for comparisons and validation and the effect of metallic resistance on attenuation profiles is examined. It is concluded that for small diameter pipelines with anode spacing up to 800 m metallic resistance is negligible, and thus all three methods can be used with reasonable confidence for spacings below 800 m. An analysis to illustrate the effect of a stratified electrolyte in the vicinity of the pipeline has been initiated and preliminary results are also presented.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12672
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection
- Format
- Document (PDF)
- Title
- Galvanic anode cathodic protection (CP) retrofit upon offshore pipelines: An analytical model for CP potential profiles.
- Creator
- Pierson, Patrick Robert., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
An analytical model for cathodic protection (CP) attenuation along a one-dimensional structure such as a pipeline is developed in terms of non-dimensional polarization and, alternately, cathode potential. The derivation is based upon the fundamental principle that (1) potential is, in fact, the potential difference across the metal/electrolyte interface, (2) an assumption of a linear potential and current density relationship, and (3) the treatment of Galvanic anodes as spherical current...
Show moreAn analytical model for cathodic protection (CP) attenuation along a one-dimensional structure such as a pipeline is developed in terms of non-dimensional polarization and, alternately, cathode potential. The derivation is based upon the fundamental principle that (1) potential is, in fact, the potential difference across the metal/electrolyte interface, (2) an assumption of a linear potential and current density relationship, and (3) the treatment of Galvanic anodes as spherical current sources. The resulting expression characterizes the distribution of protection in terms of physical design variables and electrochemical properties of the cathode. Polarization is presented graphically in terms of two parameters which are comprised of the aforementioned variables and make for a novel method of analysis. Two sample pipeline CP systems are analyzed by this method, one of which is an existing design and the other a hypothetical design used to illustrate the effect of the varying parameters. Some sample anode life calculations based upon the analytical model are performed, and a method for correcting the model for the existence of a non-spherical bracelet anode is proposed. It is concluded that electrolyte resistance (or alternately anode resistance) is of greater importance in all practical Galvanic CP attenuation calculations than is the metallic (Ohmic) resistance.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15581
- Subject Headings
- Petroleum pipelines--Cathodic protection, Natural gas pipelines--Cathodic protection
- Format
- Document (PDF)
- Title
- Design approaches for asymmetrical marine pipeline cathodic protection systems.
- Creator
- Qian, Haijun., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Marine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A...
Show moreMarine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A series of equations based on the Slope Parameter Method (SPM) has been modified for more extensive applicability. Several design examples have been analyzed and the results verified by BEM. Cathode potential and current demands projected by the new method are consistent with those of BEM. The inclusive equation for even anode spacing CP has been modified to include the cable parameters by combining cable resistance and the anode resistance. Current demand for existing pipelines can be determined by either of two methods. The first utilizes the inclusive equation and involves solving this for current demand based upon a known potential profile. The other is based on SPM.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/13098
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection, Boundary element methods
- Format
- Document (PDF)
- Title
- Modeling of bracelet anodes and anode arrays for pipeline CP systems.
- Creator
- Zhang, Xiaolin., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Two models for pipeline bracelet anodes depletion with time were analyzed: one with uniform corrosion and the other with localized corrosion. The potential of the pipeline was determined to become more positive with time due to corrosion of the anode. The pipeline protected by the anode with localized corrosion had more a positive potential than the one protected by the anode with uniform corrosion. A method based upon the equations of Sunde was developed for determining resistance of linear...
Show moreTwo models for pipeline bracelet anodes depletion with time were analyzed: one with uniform corrosion and the other with localized corrosion. The potential of the pipeline was determined to become more positive with time due to corrosion of the anode. The pipeline protected by the anode with localized corrosion had more a positive potential than the one protected by the anode with uniform corrosion. A method based upon the equations of Sunde was developed for determining resistance of linear and rectangular anode arrays. Accuracy of this approach was evaluated using Boundary Element Modeling (BEM). The difference between the two methods was defined as Error. A corrected function of Sunde's equation was developed in order to get a more accurate resistance of a 1 x N anode array. The influence on resistance of a M x N (M < N) anode array of anode size, separation distance and array number was analyzed. Error increased with increasing anode size and decreased with increasing number of anodes and separation distance. The application and limitations of commonly used anode resistance formulas are discussed.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/13087
- Subject Headings
- Pipelines--Cathodic protection, Corrosion and anti-corrosives, Underwater pipelines, Anodes
- Format
- Document (PDF)
