Section 1 General

101. Application

1. The hazardous areas defined in this Chapter are those which normally apply to offshore drilling units for oil and gas exploration. The hazardous areas as specified may be extended or reduced de- pending on the actual arrangements in each case, by use of windshields, special ventilation arrange- ments, structural arrangements, etc.

2. For the purpose of this Chapter :

(1) An enclosed space is considered to be a space bounded by bulkheads and decks which may have doors, windows, of other similar openings.

(2) A semi-enclosed location is considered to be a location where natural conditions of ventilation are notably different from those on open decks due to the presence of structure such as roofs,

windbreaks and bulkheads and which are so arranged that the dispersion of gas may not occur.

102. Definition of hazardous area

1. Hazardous areas are all those areas where, due to the possible presence of a flammable atmosphere arising from the drilling operations, the use without proper consideration of machinery or electrical equipment may lead to fire hazard or explosion.

2. Hazardous areas are divided into zones as follows;

Zone 0 : an area in which an explosive gas-air mixture is continuously present or present for long periods.

Zone Zone

1 : an area in which an explosive gas-air mixture is likely to occur in normal operating conditions.

2 : an area in which an explosive gas-air mixture is not likely to occur, and if it occurs, it will only exist for a short time.