Determination of Cathodic Protection Potential Criteria for Thermally Insulated Pipeline in Synthetic Groundwater

CORROSION ◽  
2009 ◽  
Vol 65 (2) ◽  
pp. 88-95 ◽  
Author(s):  
Y-S. Choi ◽  
J-G. Kim
Keyword(s):  
Cathodic Protection ◽  
Synthetic Groundwater ◽  
Protection Potential

scholarly journals Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Numerical Model ◽  
Current Density ◽  
Cathodic Protection ◽  
Electric Potential ◽  
Protection System ◽  
Nonlinear Polarization ◽  
Electrode Surfaces ◽  
Polarization Characteristics ◽  
Cathodic Protection System

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

Fatigue-Corrosion of High Strength Steels in Synthetic Seawater under Cathodic Protection

2020 ◽  
Vol 841 ◽  
pp. 294-299
Author(s):  
Sergio Lorenzi ◽  
Cristian Testa ◽  
Marina Cabrini ◽  
Francesco Carugo ◽  
Luigi Coppola ◽  
...  
Keyword(s):  
Cathodic Protection ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Loading Frequency ◽  
Offshore Pipelines ◽  
Synthetic Seawater ◽  
Steel Grades ◽  
Protection Potential ◽  
Fatigue Corrosion

The paper is aimed to the study of the corrosion-fatigue behavior of high strength steels for offshore pipelines. Tests have been performed in order to study fatigue crack growth in synthetic seawater under cathodic protection. The tests have been carried out on three different steel grades from 65 to 85 ksi with tempered martensite and ferrite-bainite microstructures. The effect of stress intensity factor, cathodic protection potential and cyclic loading frequency is shown.

Cathodic protection criteria of low alloy steel in simulated deep water environment

2020 ◽  
Vol 67 (4) ◽  
pp. 427-434
Author(s):  
Haijing Sun ◽  
Weihai Xue ◽  
Jiaxin Xu ◽  
Guoliang Chen ◽  
Jie Sun
Keyword(s):  
Shallow Water ◽  
Alloy Steel ◽  
Deep Water ◽  
Cathodic Protection ◽  
Water Environment ◽  
Deep Ocean ◽  
Low Alloy Steel ◽  
Content Type ◽  
Offshore Industry ◽  
Protection Potential

Purpose The purpose of this work is to provide theoretical guidance and experimental analysis for optimized cathodic protection (CP) design of low alloy steel in deep water environments. Design/methodology/approach In the present study, the CP criteria of 10Ni5CrMoV low alloy steel were investigated in a simulated deep water environment (350 m) regarding the theoretical protection potential and measured protection potential. The influences of hydrostatic pressure (HP) and temperature were also discussed in detail. The theoretical protection potential was analyzed with the Nernst equation, and the measured minimum protection potential was derived by extrapolating the Tafel portion of anodic polarization curves. Findings The results indicate that the minimum protection potential of low alloy steel shifts to a positive value in a deep-ocean environment. This can be attributed to the combined effects of HP and the temperature. Moreover, the temperature has a stronger influence compared with HP. The results suggest that the CP potential criteria used in shallow water are still applicable in the deep ocean, which is further confirmed through the SEM and x-ray diffraction analysis of the corrosion products resulted from the potentiostatic cathodic polarization experiments at −0.85 VCSE. Originality/value In recent decades, successful applications of CP for long-term corrosion protection of the steel components applied at a subsea level have enabled the offshore industry to develop reliable and optimized CP systems for shallow water. However, differences in the seawater environment at greater depths have raised concerns regarding the applicability of the existing CP design for deeper water environments. Hence, this research focuses on the CP criteria of low alloy steel in simulated deep water environment concerning the theoretical protection potential and measured protection potential. The influences of HP and temperature were also discussed.

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