Tank Cleaning

Back on the Anastasis, we were we were able to "volunteer" for tank cleaning.  Not quite sure this is the same, but it is an interesting read for those of us who are non-medicals and would like to serve!

Often maintenance on the ship has be carried out which is not always that quiet!  At the moment the technical department on in the process of tank cleaning on Deck 1.   That's right - in the bottom of the ship.  But with the ship being made of steel and steel carrying sound extremely well, those up on the upper decks can even hear the noise.

 

 So what is tank cleaning?
Marine regulations and also responsible ship stewardship require the steel tanks to be kept free of corrosion and foreign deposits.  If they aren't cleaned periodically, the ship risks loosing their certification to operate the ship and the life spam of the tanks is shortened.  So they are getting ready for the next inspection in 2014.

The Africa Mercy has a total of 72 tanks.  There is a regular and on-going schedule for cleaning all the tanks to meet specific inspection dates.  Currently it has taken one month to get halfway through the two tanks that are in the worst condition.   

Often this can also be done by shipyards but the cost is very expensive especially when it needs to be done in a short period of time, so doing it with crew saves a lot.

In case you are thinking that it's just a matter of popping in with your sweeping brush and cleaning up a bit, read on.  A ship tank is a confined space, so the most important aspect for the cleaning crew of around 3-5 people is safety.  Following the Mercy Ships Safety Management System, no one is allowed to enter the tank until an empty permit is signed off.  This permit verifies that the air in the tank has been checked and certifies that the air is safe and in sufficient supply.  A spotter is on constant watch outside the tank in case an emergency response is needed.  Fire suits, harnesses and emergency escape breathing devices are kept by the entrance of the tank in case of an emergency evacuation.  The tank is illuminated with floor lights and head lamps.  Special protective clothing is worn, including eye goggles, ear plugs/muffs, steel-toed boots, gloves, breathing masks and coveralls.  Sturdy scaffolding is erected and workers wear safety harnesses for fall protection (yes the tank is that big!).  The cleaning work is done with heavy duty pneumatic needle guns capable of removing scale and leaving a clean steel surface.  The scale is collected, hauled out of the tank and then discarded safely.

Tank Cleaner hoists out a bucket of corrosion and foreign deposits from the tank

To keep air free of scale particle matter and to replenish the tank with fresh air, an extractor and an air supply fan run continually.

So after all that heavy work two important measures are followed to protect them.  First, the newly cleaned steel surface is coated with Intertuf 16, a powerful defence against corrosion.  Second, the zinc anodes, also called sacrificial anodes, are replaced.  Rust prefers zinc to steel, so the anodes are attacked by the rust rather than the steel.

So next time you hear the tanks are being cleaned you know there's more to the job than meets the eye.

Thank you to the fabulous Technical team for all their hard work.