Section 2 Extent of Hazardous Area

201. Application

For the purpose of machinery and electrical installations, hazardous areas are classified as in 202. to 204. Hazardous areas not covered (such as, but not limited to, well test equipment areas, heli- copter fuel storage areas, acetylene cylinder storage areas, battery rooms, paint lockers, flammable gas or vapour vents and diverter line outlets) in this section should be classified in accordance with 102.

202. Hazardous areas Zone 0 Hazardous areas Zone 0 include ;

(1) The internal spaces of closed tanks and pipes of the mud-circulating system between the well and the final degassing discharge.

(2) The internal spaces of closed tanks and piping for containing oil that has a closed-cup

flash-point below 60°C.

(3) The internal spaces of closed tanks and pipes for oil and gas products including escape gas out- let pipes.

(4) The spaces in which an oil-gas-air mixture is continuously present or present for long periods.

203. Hazardous areas Zone 1 Hazardous areas Zone 1 include ;

(1) Enclosed spaces containing any part of the mud-circulating system that has an opening into the spaces and is between the well and the final degassing discharge.

(2) In outdoor or semi-enclosed locations except as provide for in Subparagraph (4), the area within

1.5 m of the boundaries of any openings to equipment which is part of

specified in Subparagraph (1), any ventilation outlets of Zone 1 spaces, or 1 spaces.

(3) Pits, ducts or similar structures in locations which otherwise would be Zone ranged so that the dispersion of gas may not occur.

the mud system as any access to Zone

2 but which are ar-

(4) Enclosed spaces or semi-enclosed locations that are below the drill floor and contain a possible source of release such as the top of a drilling nipple.

(5) Enclosed spaces that are on the drill floor and which are not separated by a solid floor from

the spaces in Subparagraph (4).

(6) Outdoor locations below the drill floor and within a radius of 1.5 m from a possible source of release such as the top of a drilling nipple.

204. Hazardous areas Zone 2 Hazardous areas Zone 2 include;

(1) Enclosed spaces which contain open sections of the mud circulating system from the final de- gassing discharge to the mud pump suction connection at the mud pit.

(2) Outdoor locations within the boundaries of the drilling derrick up to a height of 3 m above the drill floor.

(3) Semi-enclosed derricks to the extent of their enclosures above the drill floor or to a height of 3

m above the drill floor, whichever is the greater.

(4) Semi-enclosed locations below and contiguous with the drill floor and to the boundaries of the derrick or to the extent of any enclosure which is liable to trap gases.

(5) Outdoor locations below the drill floor and within a radius of 1.5 m from the area specified in

203. (6).

(6) The areas 1.5 m beyond the Zone 1 areas specified in 203. (2) and beyond the semi-enclosed locations specified in 203. (4).

(7) Outdoor spaces within 1.5 m of the boundaries of any ventilation outlet from or

Zone 2 space.

(8) Air locks between a Zone 1 and a non-hazardous area.

access to a

205. Openings, access and ventilation conditions affecting the extent of zones

1. Except for operational reasons access doors or other openings are not to be provided following spaces.

(1) A non-hazardous space and a hazardous zone

(2) A Zone 2 space and a Zone 1 space

hazardous between the

2. Where such access doors or other openings referred to under Par 1 are provided, any enclosed space not referred to under 203. or 204. and having a direct access to any Zone 1 location or Zone 2 location becomes the same zone as the location except that ;

(1) An enclosed space with direct access to any Zone 1 location can be considered as Zone 2 :

(A) The access is fitted with a gas-tight door opening into the Zone 2 space, and

(B) Ventilation is such that the air flow with the door open is from the Zone 2 space into the Zone 1 location, and

(C) Loss of ventilation is alarmed at a manned station.

(2) An enclosed space with direct access to any Zone 1 location is not considered hazardous if ;

(A) The access is fitted with a self-closing gas-tight door forming an air lock, and

(B) The space has ventilation overpressure in relation to the hazardous space, and

(C) Loss of ventilation overpressure is alarmed at a manned station.

(3) An enclosed space with direct access to any Zone 2 location is not considered hazardous if ;

(A) The access is fitted with a self-closing gas-tight door that opens into the non-hazardous lo- cation, and

(B) Ventilation is such that the air flow with the door open is from the non-hazardous space into the Zone 2 locations, and

(C) Loss of ventilation is alarmed at a manned station.

3. Where ventilation arrangements of the intended safe space are considered sufficient by the Society to prevent any ingress of gas from the Zone 1 location, the two self-closing doors forming an air lock may be replaced by a single self-closing gas-tight door which opens into the non-hazardous location and has no hold-back device.

4. Piping systems should be designed to preclude direct communication between hazardous areas of

different classifications and between hazardous

5. Hold-back devices should not be used on boundaries.

and nonhazardous areas.

self-closing gastight doors forming hazardous area