17. CLOSED AND CONFINED SPACES 86 17. Closed and confined spaces Closed and confined space refers to an area that is large enough that the employee is able to go in there and do the work assigned, has limited access and it is not designed for continuous employee working. Examples of confined spaces include various tanks, silos, pressure vessels, double bottoms. There is a history of serious accidents in the shipbuilding industry that have taken place in different confined spaces. Typically in these accidents the risk factors had not been recognized or were ignored. Therefore, it is important that you make these important preparations before entering a confined space and that you accomplish the work strictly according to the work plan. Types of accidents that occur in confined spaces are: explosions caused by flammable gas leaks suffocation in a space that has been closed for a long time suffocation caused by shield gas leaks poisoning (e.g. carbon monoxide poisoning, nitrogen oxide) electric shock from contact with an electrically charged surface injuries where the structure of the space and/or the type of accident have made the rescue operations very difficult The corrosion of metal and drying of paint consume oxygen and it is possible that the oxygen content in confined spaces is dangerously low. There can also be poisonous, flammable and explosive gases and gases hazardous for health in tanks. Only authorized adequately trained persons can work in closed and confined spaces. Also, persons who issue work permits in closed and confined spaces, as well as backup persons, must have adequate training. The work permit issuer, the person entering the confined space, as well as the back-up person must go through their obligations and responsibilities. Also site- specific instructions and practices must be taken under account. Before starting work in a closed and confined space, the safety of air quality must be verified by measurement. Normal conditions are: Oxygen 20.9% Carbon monoxide 0 ppm Explosive gases formed during hot work 0% LEL (otherwise 10% LEL) Find out your company’s procedure regarding confined space entry permits, as well as the instructions relating to working in confined spaces. Depending on the circumstances there might be different requirements e.g. use of electrical equipment with protective extra low voltage (PELV), ventilation and estinguishers (when performing hot work).
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