17. CLOSED AND CONFINED SPACES
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).
86