Papers by Keyword: ICCP

Abstract: Corrosion at the bilge due to direct contact with the seawater is an issue which is necessary to be taken into account. The problem can be solved by giving combined protection such as coating and cathodic protection impressed current cathodic protection (ICCP). For broader range, there is occasionally a possibility of over-protection at certain area especially that is close to anodes. It can trigger cathodic disbondment to occur. Cathodic disbondment is a situation when the coating loses its adhesion to the steel due to the voltage originated from cathodic protection. This trial was conducted by using several samples of LR Grade A plate coated by primer coat epoxy and top coat polyurethane. The plate was then given artificial defect with the size of R2, R3 and R4 accoring to ISO 4628-3 or is equal to 0,5% ; 1% and 8% of the plate surface width. Futhermore, impressed current cathodic protection was conducted with the steel anode, Ag/AgCl reference electrode and over-protection voltage were-1,5 ; -2,0 ; -2,5 ; -3,0 ; -3,5 and-4,0 volt. Electrolyte media employed was seawater. Furthermore, the disbondment taken place was measured after 6 hours and analyzed the corrosion product produced. In the research, it could be seen that the broader the defect was, the smaller the disbondment area was. The width of disbondment area was depending on current density. The smaller the voltage (volt) was, the broader the disbondment in accordance with the increase of disbondment width taking place on the plate surface. The corrosion product produced was Fe₃O₄ (Magnetite).

Abstract: Impressed current cathodic protection is an international generally accepted and effective protection method of concrete is adopted in seawater cooling intake & outfall structures in Zawal port, Kingdom of Saudi Arabia. Total protected concrete area is about 27000m2, including diaphragm walls, edge beams, all walls (main wall and cross wall), floor slab, top slab and wing walls. This project is extensive, changed-constructed and the operating environment is severe. The successful implementation of this project has certain significance in relative projects in the industry.

Abstract: This experiment represents the effect of impressed current cathodic protection with a variable resistor on concrete specimens. The effect of cathodic protection (CP) system on concrete structures can be changed at different condition. Especially, in marine concrete structures, it is difficult in applying impressed current CP by means of one rectifier in both high resistivity area (dry area) and low resistivity one (wet area). Thus, in this study, the variable resistor was utilized to fulfill similar CP effect on both high resistivity zone and low resistivity one in order to manage the problem. Specimens were concrete slab type with a base of 400mm × 400mm and a height of 70mm. Test factors were CP potential, CP current, and 4-hour depolarization potential. Test results showed that the variable resistor could have positive influences on an improvement in CP effects. In addition, environmental conditions had to be considered to reach enough CP potential and current in this system.

Abstract: Marine gravity aided INS navigation, in which Gravity anomaly and gravity gradient of earth gravity field from sensors sensitive to gravity have been supplementary information aided to correct positioning error accumulated with time to achieve precise navigation and graphic trace, has been a fervent and frontier issue in underwater passive navigation technology in application to Autonomous Underwater Vehicle (AUV). Core theoretical technology of gravity aided INS navigation was matching algorithm, in which Terrain Contour Matching (TERCOM), Sandia Inertial Terrain Aided Navigation (SITAN) and Iterative Closest Contour Point (ICCP) were three typical representatives based on gravity reference map. However, these algorithms more or less had some limitations in certain conditions such as a relatively larger INS positioning error. Aiming at the application limitation that positioning error from INS were commonly large when after a long voyage AUVs entered into the region in which gravity could be used to matching, above three algorithms were integrated to use on base of expounding their algorithm models, computation progress and advantages and disadvantages analysis, then integration theory, algorithm design and model foundation were presented to meet practice application demand better.

Abstract: Cathodic protection is a system of preventing corrosion by forcing all surfaces of a hull to be cathode by providing external anodes. A metal can be made cathodic by electrically connecting it to a more anodic metal within the electrolyte. Anodes of these metals corrodepreferentially, the corrosion current of the anode achieving cathodic protection of the underwater hull to which they are connected. This paper presents a new current control algorithm for ICCP (Impressed Current Cathodic Protection) system. The anode of ICCP system is controlled by an external DC source with converter. The function of anode is to conduct the protective current into seawater. The DC source is generally obtained from main power system that contains a transformer, converter and etc. The proposed algorithm can operate AC-DC converter with current link. This algorithm includes the harmonic suppression control strategy and the optimum protection strategy and has tried to test the requirement current density for protection, the influence of voltage, the protection potential. Also, the properties of ICCP protected hull of ship in seawater are evaluated.