John Jackson MIDN USN
John Jackson MIDN USN
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Navy and Coast Guard vessels are both subject to bilge corrosion and the consequences that arise from it
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Several factors affect corrosion • • • •
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Moisture Molarity of saltwater Length of exposure Wet and dry cycles
Three ships have been sent into emergency drydock Currently, no inhibitors or sacrificial anodes are used in the bilges of vessels
In general chemistry, inhibitors have been used to slow or accelerate the rates of reactions such as corrosion Sacrificial anodes (Zn) have been used successfully on the hulls of steel vessels for decades. However, none are known to be used on the interior of hulls Buffers are chemical solutions that have been created to hold the pH of a solution constant which could either increase or decrease the rate of corrosion
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6 pieces of steel were placed equally spaced in each of the 6 containers 3 containers included small zinc strips included with the steel Pieces were stood up, allowing for a wet and dry region Each container contained a 0.5M NaCl solution to replicate bilge water
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Zn Zn ZnCl2 Zn ZnCH3COO NaHCO3 Buffer Control
Slope (g/day) stdev ‐0.00036 0.00085 0.003663 0.001151 0.001396 ‐0.00715 0.00558 ‐0.06298
0.00288 0.003966 0.000727 0.004625
Zinc Strips
Zinc Strips and Zn(CH2COO)2
Zinc Strips and ZnCl2
Control
NaHCO3
Control
Phosphate Buffer
Zn Zn ZnCl2
slope stdev ‐0.88455 0.26879 ‐0.04465 0.004641
Zn ZnCH3COO ‐0.12391 0.019039
Zinc Strips
Zinc Strips and Zn(CH2COO)2
Zinc Strips and ZnCl2
Zinc sacrificial anodes are a proven way to decrease the corrosion to a hull The zinc maintains its mass when zinc ions are put into the solution, and the steel maintains its mass as well Sodium bicarbonate will slow the rate of corrosion Phosphate buffer drastically slows the corrosion process
Phosphate is a chemical that ignites algae blooms Experiment with more buffers Experiments need to be conducted for longer‐duration Investigate how sacrificial anodes in bilges of vessels will be effective with the different pools of water and electrical connections Analyze benefits to adding inhibitors to a bilge on a cost basis
Dr. Swithenbank, Dr. Gray, and LT Maisano of the U.S. Coast Guard Academy advised this project and spent hours in lab with me • LCDR Wolfe of USCGA shared his wealth of knowledge about cutters and his experiences as a EO •
•
Navy and Coast Guard vessels are both subject to bilge corrosion and the consequences that arise from it
•
Several factors affect corrosion • • • •
•
•
Moisture Molarity of saltwater Length of exposure Wet and dry cycles
Three ships have been sent into emergency drydock Currently, no inhibitors or sacrificial anodes are used in the bilges of vessels
In general chemistry, inhibitors have been used to slow or accelerate the rates of reactions such as corrosion Sacrificial anodes (Zn) have been used successfully on the hulls of steel vessels for decades. However, none are known to be used on the interior of hulls Buffers are chemical solutions that have been created to hold the pH of a solution constant which could either increase or decrease the rate of corrosion
•
•
•
•
6 pieces of steel were placed equally spaced in each of the 6 containers 3 containers included small zinc strips included with the steel Pieces were stood up, allowing for a wet and dry region Each container contained a 0.5M NaCl solution to replicate bilge water
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Before Trials
After week four of experiment
Zn Zn ZnCl2 Zn ZnCH3COO NaHCO3 Buffer Control
Slope (g/day) stdev ‐0.00036 0.00085 0.003663 0.001151 0.001396 ‐0.00715 0.00558 ‐0.06298
0.00288 0.003966 0.000727 0.004625
Zinc Strips
Zinc Strips and Zn(CH2COO)2
Zinc Strips and ZnCl2
Control
NaHCO3
Control
Phosphate Buffer
Zn Zn ZnCl2
slope stdev ‐0.88455 0.26879 ‐0.04465 0.004641
Zn ZnCH3COO ‐0.12391 0.019039
Zinc Strips
Zinc Strips and Zn(CH2COO)2
Zinc Strips and ZnCl2
Zinc sacrificial anodes are a proven way to decrease the corrosion to a hull The zinc maintains its mass when zinc ions are put into the solution, and the steel maintains its mass as well Sodium bicarbonate will slow the rate of corrosion Phosphate buffer drastically slows the corrosion process
Phosphate is a chemical that ignites algae blooms Experiment with more buffers Experiments need to be conducted for longer‐duration Investigate how sacrificial anodes in bilges of vessels will be effective with the different pools of water and electrical connections Analyze benefits to adding inhibitors to a bilge on a cost basis
Dr. Swithenbank, Dr. Gray, and LT Maisano of the U.S. Coast Guard Academy advised this project and spent hours in lab with me • LCDR Wolfe of USCGA shared his wealth of knowledge about cutters and his experiences as a EO •
