Section 2 Prevention of Fire and Explosion

201. Location and separation of spaces

1. General

(1) Machinery and equipment are to be arranged in accordance with API RP 14J.

(2) Equipment items that could become fuel sources in the event of a fire are to be potential ignition sources by space separation, firewalls or protective walls. The be referred for fuel sources and ignition sources.

separated from following may

(3) For the overall safety of personnel and unit, the followings are to be considered in design:

(A) Separation of non-hazardous areas from those classified as hazardous areas

(B) Minimizing the likelihood of uncontrollable releases of hydrocarbon to the environment

(C) Minimizing the spread of flammable liquids and gases which may result in a hazardous event and facilitating rapid removal of any accumulations

(D) Minimizing the probability of ignition

(E) Minimizing the consequences of fire and explosions

(F) Preventing fire escalation and equipment damage

(G) Providing for adequate arrangements for escape and evacuation

(H) Effective emergency response

(I) Protection of safety systems, critical systems from damage

(J) Equipment arrangements are to provide access for inspection and servicing and safe means

of egress

(4) In case of a occupants to conflagration.

from all machinery spaces.

fire onboard the unit, the means of escape is to permit the safe evacuation of all a safe area, even when the structure they occupy can be considered lost in a

2. Location and separation of production areas

(1) Entrances, air inlets and openings to accommodation spaces are normally not to face production areas.

(2) Control stations are to be located in non-hazardous areas.

(3) Areas which contain production systems, gas flare, cold vent, crude oil storage and crude oil offloading systems are to be arranged in order to provide:

(A) Easy access for operation and maintenance

(B) Easy access for fire fighting

(C) Adequate ventilation

(D) Minimized explosion overpressure in the case of ignited gas release

(4) The outlets of gas disposal systems, e.g. flares, cold vents or pressure relief valves or from large engine exhausts are to be led to areas where radiation, heat or gases will not be a hazard to the unit, personnel or equipment.

(5) Flare and vent systems are to be in accordance with the standards deemed appropriate by the Society. The radiant heat intensities or emissions from flares and vents are not to exceed the following limits:

(A) In areas where emergency action lasting up to 1 minute may be required by personnel with- out shielding, but with appropriate clothing: 6.3 kWĤmË

(B) In areas where emergency action lasting several minutes may be required by personnel with-

out shielding, but with appropriate closing: 4.7 kWĤmË

(C) At any location where personnel are continuously exposed: 1.6 kWĤmË

(D) Temperature rating of electrical and mechanical equipment

(E) At any point on the unit where the gas plumes from vents could be ignited or personnel

could come into contact with such gas: 60% LEL

3. Location and separation of crude oil areas

(1) Separation of crude oil tanks is to taken as follows;

(A) Crude oil tanks are to be isolated from non-hazardous areas by cofferdams, pump rooms, oil bunker tanks or ballast tanks.

(B) Crude oil tanks are to be isolated from machinery spaces by cofferdams, pump-rooms, oil bunker tanks or ballast tanks. The lower portion of the pump-room may be recessed into

machinery spaces of category A to accommodate pumps, provided that the deck head of the recess is in general not more than one third of the moulded depth of the unit above the keel.

(2) Entrances, air inlets and openings to accommodation, service and machinery spaces and control

stations are not to face crude oil areas. They are to be located on end bulkheads not facing crude oil areas and/or on the outboard sides of superstructures or deckhouses at a distance of at

least 4% of the

Length (L) of the unit as specified in Ch 1, 202. of Rules for the

Classification of the Mobile Offshore Drilling Units. but not less than 3m from the end of

superstructures or

deckhouses facing crude oil areas. This distance, however, need not exceed

5m. Furthermore, the following necessary conditions apply to boundaries facing crude oil areas:

(A) Bolted plates for removal of machinery may be fitted in such boundaries. Signboards giving instruction that such plates are to be kept closed unless the unit is gas-free are to be posted

on board.

(B) Windows in navigation bridges may be accepted on the condition that such windows are non-opening types and constructed to "H-60" class standard.

(3) Mooring systems with combustion machinery are to be located outside of hazardous areas unless special precautions to avoid any risks of ignition during normal operations and emergency re-

leases are provided.

(4) Chain lockers and chain pipes are to be arranged in non-hazardous areas.

4. Crude oil tank venting is to comply with the following requirements;

(1) Tanks are to have means for inert gas, gas-freeing and venting in accordance with the appli- cable parts of Pt 8 of Rules for the Classification of Steel Ships.

(2) Hatches, openings for ventilation, ullage plugs or other deck openings for crude oil tanks are not to be arranged in enclosed compartments.

5. Location and Separation of Pump rooms, cofferdams and pipe tunnels

(1) Cofferdams are to be of sufficient size for easy access to parts, and they are to cover the en- tire adjacent tank bulkhead. Minimum distance between bulkheads is to be 600 mm .

(2) In cases where non-hazardous spaces and crude oil tank meet in corner to corner configurations,

diagonal plates may be accepted as cofferdams. Such cofferdams are to be:

(A) Ventilated if accessible

(A) Filled with a suitable compound if not accessible

(3) Pipe tunnels are to have ample space for pipe inspections.

(4) There are to be no connections between pipe tunnels and engine rooms. Access to pipe tunnels

is normally to be made through pump rooms, similar hazardous areas or from open decks. Access openings from crude oil pump rooms are to be provided with watertight closures.

(A) in addition to the bridge operation, the watertight door shall be capable of being manually

closed from outside the pump-room entrance; and

(B) the watertight door shall be kept closed during normal operations of the unit except when access to the pipe tunnel is required.

6. Wellhead areas

(1) Wellhead areas are to be separated or protected from sources of ignition and mechanical damage.

(2) "A-0" firewalls around wellheads are to be used to provide protection from potential uncon-

trolled flow from wellheads with shut-in pressures exceeding 42 kgĤcmË .

7. Fired vessels

(1) Fired vessels(glycol reboilers, etc.) are to be installed away from wellheads and other hydro- carbon processing and storage equipment. If it is not be possible to comply to the above re- quirement, particularly when the space of the process area is limited, causing fired vessels to be located in the unfired process areas, then the fired vessel is to be surrounded on all sides by a minimum of "A-0" class firewall.

(2) For direct fired vessels such as produced fluid heater treater that is considered both as fuel and ignition source, a minimum of "A-0" rated firewall is to be provided as described in (1), re- gardless of where the unit is installed within the production or process areas.