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- Navy and Coast Guard
John Jackson MIDN USN Navy and Coast Guard vessels are both subject - - PowerPoint PPT Presentation
John Jackson MIDN USN Navy and Coast Guard vessels are both subject - - PowerPoint PPT Presentation
John Jackson MIDN USN 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
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- 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
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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
- n 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
- f 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
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Before Trials After week four of experiment
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Before Trials After week four of experiment
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Before Trials After week four of experiment
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Before Trials After week four of experiment
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Before Trials After week four of experiment
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Before Trials After week four of experiment
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Slope (g/day) stdev Zn ‐0.00036 0.00085 Zn ZnCl2 0.003663 0.001151 Zn ZnCH3COO 0.001396 0.00288 NaHCO3 ‐0.00715 0.003966 Buffer 0.00558 0.000727 Control ‐0.06298 0.004625
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Zinc Strips Zinc Strips and ZnCl2 Zinc Strips and Zn(CH2COO)2 Control
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NaHCO3 Phosphate Buffer Control
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slope stdev Zn ‐0.88455 0.26879 Zn ZnCl2 ‐0.04465 0.004641 Zn ZnCH3COO ‐0.12391 0.019039
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Zinc Strips Zinc Strips and ZnCl2 Zinc Strips and Zn(CH2COO)2
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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
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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
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- Dr. Swithenbank, Dr. Gray, and LT Maisano
- f the U.S. Coast Guard Academy advised
this project and spent hours in lab with me
- LCDR Wolfe of USCGA shared his wealth of