Machine translation from English source
Oxygen deficiency
If a void or other enclosed space has been closed for some time, the oxygen content may have decreased as a result of the corrosion process. Oxygen deficiency can occur in boilers and pressure vessels where oxygen-scavenging chemicals have been used to prevent rusting.
Oxygen depletion can occur in cargo spaces from oxygen-absorbing cargoes such as cakes, steel products, shavings, etc. Oxygen deficiency can also occur in cargo holds, e.g. when transporting ore concentrates, even if the hatch covers are removed and cargo unloading has begun (crewell vacancies).
If CO2 vapor or other fire extinguishing chemical was released into a space, the oxygen content in that space will be depleted.
TOXIC HAZARD
There is always the possibility of dangerous vapor from poorly stacked chemical drums.
Disturbance by rust, scale or sediment from animal, vegetable or mineral cargoes or water that may cover such substances may result in the release of toxic or flammable gases.
PREPARING THE SPACE FOR ENTRANCE
When opening an entrance to a hazardous space, care should be taken to avoid the effects of possible release of pressure or vapors from the space.
The space must be isolated and protected from the entry of hazardous substances by sealing pipes or other openings or closing valves. The valves must then be tied or other means used to prevent accidental operation.
If necessary, the area should be cleaned or flushed to remove, as far as practicable, any silt or other sediment likely to produce hazardous fumes. This type of work may require special precautions for the reasons already stated.
The space should be thoroughly ventilated by natural or mechanical means to ensure that all harmful gases are removed. Compressed oxygen should never be used to ventilate a room.
Officials should be briefed on the bridge, cargo control room and engine room and warning signs posted to warn of accidental use of equipment, valves or stopping of ventilation, etc. If necessary, pumping operations should be suspended if the space becomes dangerous to enter .
