Cathodic protection of ships in brackish water

Inventions, 2021

Studies overviewed in the paper have yielded a number of new scientific results including the following: suggested is a technique for conducting experimental investigations of electrochemical characteristics of hull structures of ships and floating facilities on the juvenile surface under cathodic polarization in a test seawater solution with the use of the test facility developed for investigating electrochemical characteristics of hull structures of ships and floating facilities on the juvenile surface under cathodic polarization; obtained are the results of laboratory experiments on various shipbuilding steels without surface oxide films in test seawater solutions with a widely ranging salinity spectrum; developed is a neural network-based technique for predicting the protection potential of ships and floating facilities from local corrosion mechanical damages; developed is an algorithm for obtaining the protective potential for hull structures of ships and floating facilities; s...

Brodogradnja

Corrosion is the gradual deterioration of a material or its properties through a chemical reaction with its environment. There are several methods of preventing a material from corroding. Cathodic protection (CP) and coatings are very popular methods for corrosion protection. Each individual method has its own benefits and drawbacks, whereas experience has shown that the most effective method of corrosion prevention is a combination of both CP and coatings. This combination can provide very good protection over a long period of time. This paper focuses on the combined use of both CP and coatings for ships. Calculation of a CP design is explained briefly and the factors affecting the choice of the type of CP system are demonstrated. Then, a sample anode plan of a ship is shown. Finally, the calculation of a cathodic protection system of a ship is presented using data provided by coating manufacturers and shipyards.

WIT transactions on engineering sciences, 2007

This paper presents a 3D software tool for the design and optimization of cathodic protection systems for submerged structures. It provides the corrosion engineer with a powerful tool for managing operational costs, significantly reducing expensive commissioning surveys and costly repairs, adding major value to the cathodic protection business. The software is entirely CAD integrated such that it can deal with 3D CP-configurations of arbitrary complexity with parameterisation of all geometrical dimensions. The CP model is based on the potential model describing the ohmic drop in the electrolyte (soil, water) with non-linear boundary conditions that model the electrochemical reactions at anodes and cathodes. In this paper, it is explained why the Finite Element Method is used to solve the problem. As an example the protection level of a hypothetical marine vessel using impressed current cathodic protection (ICCP) systems will be investigated. In addition, the underwater electric potential (UEP) of the vessel will be calculated.

Ships and Offshore Structures, 2011

The extent of corrosion between a miniature steel ship model at different relative velocities of sea water fitted with commercial sacrificial anodes of aluminium (Al) in sea water and magnesium (Mg) in fresh water is studied. The experimental results show that the degree of cathodic protection represented by the cathode potential at a given distance from different types of sacrificial anodes decreases slightly with an increase in the relative velocity. The results also show that the amount of Al or Mg required to protect the ship cathodically increases as the relative velocity increases.

2014

This paper studies the efficiency of sacrificial anodes in nautical engineering, marine and maritime. The anode design, quality manufacturing process and proper installation are critical processes for maximum protection of equipment and vessels. The damage, which causes corrosion, can be reduced; can even be avoided by protection methods economically profitable. The predictable future savings will come by the correct use of the current state of knowledge. This acquired knowledge is not always used rationally despite the great progress and current knowledge we have about the physical-chemical corrosion phenomena. Aspects relating to the assembly, distribution and support must be optimized for optimum performance and facilities are properly protected. Determine guidelines to consider in the design of the equipment (compatibility and incompatibility of the materials), the manufacturing quality of the elements to prevent galvanic corrosion, as in the embodiment of different patterns of ...

2016

Corrosion is a material deterioration process due to chemical interactions with surrounding environment. Metallic components of amphibious vehicles are exposed to aggressive species such as chlorine in marine environment. These components must be coated or well protected to inhibit corrosion. Peeling and cracked paint on the surfaces of the vehicle hulls may result in undesired chemical interactions on damaged areas. Cathodic protection application with sacrificial anodes is an effective solution to corrosion of steel components in direct contact with seawater. The scope of this study covers investigation of corrosion kinetics for selected steel types and determination of appropriate cathodic protection system for steel components of amphibious vehicles. Steel samples were subjected to accelerated corrosion tests in artificial seawater. Electrochemical data were obtained by potentiostatic test techniques. The data were then introduced to COMSOL Multiphysics modeling software as inpu...

Journal of Marine Science and Engineering, 2020

In the present work, an impressed current cathodic protection (ICCP) system for the protection against corrosion of a 399-m-length container ship throughout its service life is designed. The study is carried out with the aid of a boundary element method code, accelerated by an adaptive cross approximation scheme, utilizing a detailed large-scale model. The exact geometry of the ship, the progressive damage of the coating system, and the dynamic state during the cruise of the ship are the main parameters taken into consideration in modelling. The main objective of the design process is to minimize the electric power, delivered by the ICCP system, determining the optimal number and location of the installed inert anodes to accomplish the absolute minimum protection potential on the immersed steel surfaces of the ship and, simultaneously, avoid overprotection. Performing an extensive parametric study, a six-zone ICCP system is proposed, consisting of 10 anodes at the hull and four iden...

CORROSION, 2002

Experiments were performed where steel specimens were cathodically polarized in natural seawater by galvanic coupling through an external resistor to an aluminum anode. Temperature was either ambient or 5°C, and pressure was atmospheric or 8.96 ± 0.14 MPa (1,300 ± 20 psi), which is equivalent to a water depth of 899 m (2,950 ft). For some experiments, dissolved oxygen concentration was controlled at 5.5 ± 0.2 mg/L and pH was 7.8. These corresponded to values that were measured at the indicated depth for a specific Gulf of Mexico site. The apparent steady-state potential (φ c) and current density (i c) for the different experiments were compared with previously reported ambient temperature and pressure data. Calcareous deposits that formed on specimens from each of the test categories were viewed and analyzed. The long-term φ c-i c trend for the different tests was the same at the two pressures and for 5.5 mg/L compared to 9 mg/L O 2. Also, i c was independent of φ c over the potential range investigated (~-0.80 V vs saturated calomel electrode [SCE] to-1.10 V SCE), despite differences in the calcareous deposit structure and composition. The results are discussed in terms of, first, design criteria for deepwater cathodic protection (CP) and, second, experimental testing to develop such criteria.

JOURNAL ASRO, 2020

In carrying out these basic tasks the Navy relies heavily on the readiness of the Indonesian Warship (KRI),including the readiness of underwater construction in KRI from corrosion attack on sea water. Nowadays, KRIuses Sacrificial Anode Cathodic Protection (SACP) from corrosion attack. Whereas, SACP system has someweakness, such as the lifetime protection is short. The aim of this paper is to the analysis of Impressed CurrentCathodic Protection (ICCP) design of the underwater structure of KRI using computative theory calculation andspecimen test. The results of ICCP design showed that the specimens I required 0.081 Ampere (A) forprotection current, specimen 2 required 0.010 A for protection current, specimens 3 required 0.00251 A. Withpotential protection between -800 mV up to -1100 mV, it described that the ICCP system is reasonable. Theresult of cathodic protection design towards an underwater structure of KRI (TR-40 Type) showed that 1.75 forAmpere (A) and 3.35 volt DC for voltag...