Thinking about this a bit more, not only was your employer negligent in using this type of Chemical, but also in the design of the injection system, i.e. it is inherently unsafe to inject the chemical into the air vent cock line, which exposed you to the concentrated chemical, it should have had its own injection point, to design out the danger that you were exposed to. You were of course guilty of contributory negligence in not wearing PPE, but that is the final safety barrier, routine watch keeping should be MADE sufficiently safe for you not to have to wear body armour and full Nuclear Chemical and Biological Warfare kit.
Another question, why were you having to vent air from the SW line, was the main air vent from the Sea Chest to the Deck blocked? Or was there some other problem.
It appears to me that the owners/operators were negligent:-
1) For selecting a system that exposed the crew to a Toxic Chemical when safer alternatives were available.
2)Failing to ensure that the system was installed in a safe manner (rather than into the vent cock line)
3)Failure to maintain the proper air vent line, forcing you to manually vent air.
4)Failing to take remedial action after they learnt of the results of your first exposure.
On another point, most of these systems are designed to maintain sufficient concentrations of chemical in Sea Water to make molluscs let go of the pipe for one hour and then be switched off for 1 or 2 days in order to save Chemicals and the environment, most ships I go on they are running 24/7 but the dosage rate has been reduced in order to reduce chemical consumption, to the point where it is useless.
In order to set the system up correctly, you have to find the pumping rates of the Sea Water pumps on the system and calculate the normal flow rate of the Sea Water through the system per hour.
The chemical maker will tell you the concentration that you have to have in Sea water, from that tons of Sea water pumped per hour, you calculate how much chemical you have to inject in one hour.
You then set up the chemical dosing pump to deliver that quantity of chemical over a period of one hour.
You then set up a timer to operate the pump for one hour a day or every two days.
As RJH says, the chemical is supposed to put a "Non Stick" film on the inside of the pipe to stop shellfish adhering to the pipe, in the first place. I believe the newer formulae are muscle relaxants that cause the baby shellfish to lose their grip and be pumped through the system with the Water flow, rather than poisons to kill them. Pin head shell fish are no problem inside the pipes, it is only when they grow to a large size that they become a problem, so shifting them all every couple of days is perfectly adequate, to prevent a reduction in coolant flow.
I hope people are now looking at the systems on their ships to see if they are as safe as practical and being operated correctly.
Safe Sailing everyone.
Last edited by Big Pete
on Tue Sep 15, 2015 11:54 pm, edited 2 times in total.
It is always better to ask a stupid question than to do a stupid thing.