Safety

Only Safety aspects which are specific for Tank Cleaning are described in this section. All other regulations for the safe operation of tankers have to be followed even if not mentioned below.
Tank cleaning is essential on a chemical tanker, but it must be recognised as a potentially hazardous operation, which involves special Hazards such as Fire, Explosion, Asphyxiation etc. It is therefore of utmost importance that the greatest possible care is exercised in connection with all tank cleaning operations to avoid accidents and incidents.

All personnel on board should be notified that a tank cleaning operation is about to begin.
If crafts are alongside their personnel should be notified and their compliance with all appropriate safety measures should be checked.
As a general rule tank cleaning and gas freeing should not take place concurrently with cargo handling. If for any reason this is necessary, there should be close consultation with, and agreement by, both the terminal representative and the port authority
All hoses should be tested for electrical conductivity in a dry condition prior to use and in no case should the resistance exceed 6 ohms per meter length
During the Planning of a cleaning operation the Physical Properties and Product Characteristics of the involved products and cleaning agents should be checked carefully for Flammability, Toxicity and Corrosiveness.
The cleaning operation must be planned in a way that risks are minimized. If for example a product with a low flash point must be cleaned, the product must be carefully drained in order to reduce the amount of fuel. In addition the first cleaning step should be executed in a way that electrostatic charges cannot be accumulated. The pre-cleaning temperature should be as low as possible (ambient). This way the risk of Fire & Explosion is minimized
Tank entries may only be done with a valid entry permit which is issued by an authorized person. This involves verification that tank atmosphere does not contain any toxic vapours (Dräger tube for the product which has been cleaned), tank atmosphere has 21% Oxygen and no explosive mixture. Further it has to be verified that the tank is disconnected from other spaces that could contain hazardous products. This way the risk of Overexposure and Asphyxiation is minimized.
Emission of cargo to the air and into the water should be minimized and MARPOL regulation must be strictly adhered to.

Risk is the likelihood of a specified undesired event multiplied by the severity of the consequences if it does happen.
Risk = Probability * Severity
Proper risk analysis of each cleaning step regarding involved risks should be discussed and considered as in the following examples. Risk analysis starts with the identification of the hazards involved in the operation followed by consideration how likely it is that these hazards will result in an accident.
Risk Management is done by reducing Probability or Severity or both so that the product of the equation becomes negligible, meaning low or acceptable risk. This requires a sound understanding of the potential hazards as well as basic physics and chemistry to derive actions which will reduce the probability that an accident can occur.
It is recommended to apply a structured procedure, preferably by application of a risk assessment tool.