- Tank cleaning is a common procedure performed on board ships.
- Those associated with the process are very well aware of the hazards involved and fatal accidents that have occurred in the past.
- In spite of all the necessary safety precautions and enclosed space entry procedures, accidents still occur while cleaning tanks on board ships.
An important article published in Marine Insight and written by Dilipan Thomas, brings forth the adherence of safety measures while cleaning a tank.
What happened to the chief officer?
Few months ago, a chief officer died on board a chemical tanker after he entered a cargo tank which contained hydrocarbon vapours and was deficient in oxygen. When the ship sailed at night after the cargo had been discharged, the two tanks that had carried hexene-1 were still inerted with nitrogen gas. As the tanks were to be loaded at the next port within two days, the crew began day/night tank cleaning operations soon after sailing.
What could have been the cause for chief mate’s death?
The chief mate was a non-watch keeper, so was able to direct the tank cleaning crew continuously. Early the next morning, during post-cleaning ventilation, the chief mate, who was preparing to conduct pre-loading inspection of the empty tanks, was informed that a ‘petrol-like’ odour was still coming from 5P tank. He had filled out the enclosed space entry checklists for the tanks he intended to enter that morning, but significantly, no enclosed space entry checklist was filled out for 5P tank.
Later that morning, when the master received an email from the ship’s agent requesting pre-arrival information, he was unable to locate the chief mate. Eventually, his lifeless body was located slumped at the bottom of 5P tank. A rescue team donned BA sets and after carrying out tank entry checks, pulled out the officer and moved him to the upper deck. It was noted that the oxygen content of the atmosphere inside the tank varied between 12 per cent and 16 per cent. Continuous resuscitation efforts were made until the arrival of a helicopter with shore medical personnel, who soon declared that the chief mate was dead. The next day, the vessel arrived at her destination and the chief mate’s body was landed.
Carelessness a cause for this unfortunate accident
Unfortunate accidents like above are still common on ships, mainly due to sheer carelessness of crew members. While it is the responsibility of the master of the vessel or officer in charge to carry out the tank cleaning procedures safely and in accordance with company’s safety procedure manual and other safety guidelines available, it is the duty of every person on board to ensure his and his crew members safety.
Precautions to be taken before making an entry for tank cleaning
- Ventilate the tank using thorough ventilation or forced ventilation method and make the tank suitable for man entry
- Fluid Contents of the tank should be removed as practicable as possible and stripped thoroughly before entering
- Before making a man entry, the atmosphere of the tank should be tested for percentage of oxygen and availability of any toxic gases. This has to be done using remote access if possible, otherwise the person entering the tank for testing atmosphere must wear a breathing apparatus
- Various levels and compartments of tank is tested for the percentage of oxygen and availability of toxic gases. A multi gas analyser is used and a person who is trained and has the knowledge of using such equipment should carry out the inspection.
Once the tank is found suitable for man entry, a detailed plan for carrying out the work is to be laid out, like the duration of work to be carried out, persons entering the tank for cleaning, person in charge etc. This will help in completing the given work safely and without any unwanted delay.
Mentioned below are eleven points that must be followed while carrying out tank cleaning on ships
- Never Enter Without Personal Protective Equipment
- Take All Equipment And Tools Required
- Illuminate the Tank Properly
- Communicate Frequently
- Take break at regular intervals
- Ensure Breathing Air Is Supplied Without Hindrance
- Display Placards On Valves/Pumps
- Handle Chemicals With Extra Care
- Different Tanks Requires Different Cleaning Operations
- Stop Work If It Exceeds Time Limit
- Clear The Area Without Missing Anything
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Source: Marine Insight
