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 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

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

Zinc Strips Zinc Strips and ZnCl2 Zinc Strips and Zn(CH2COO)2 Control

NaHCO3 Phosphate Buffer Control

slope stdev Zn ‐ 0.88455 0.26879 Zn ZnCl2 ‐ 0.04465 0.004641 Zn ZnCH3COO ‐ 0.12391 0.019039

Zinc Strips Zinc Strips and ZnCl2 Zinc Strips and Zn(CH2COO)2

� 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