The purpose of the Code for the Construction and Equipment of Mobile Offshore Drilling Units, hereinafter referred to as the Code, is to recommend design criteria, construction standards and other safety measures for mobile offshore drilling units so as to minimize the risk to such units, to the personnel on board and to the environment.
1.2.1 The Code applies to mobile offshore drilling units as defined in 1.3.1 to 1.3.4.
1.2.2 The coastal State may impose additional requirements regarding the operational aspects of industrial systems not dealt with by the Code.
For the purpose of this Code, unless expressly provided otherwise, the terms used therein have the meanings defined in the following paragraphs.
“Mobile offshore drilling unit” or “unit” is a vessel capable of engaging in drilling operations for the exploration for or exploitation of resources beneath the sea-bed such as liquid or gaseous hydrocarbons, sulphur or salt.
“Surface unit” is a unit with a ship or barge-type displacement hull of single or multiple hull construction intended for operation in the floating condition.
“Self-elevating unit” is a unit with moveable legs capable of raising its hull above the surface of the sea.
“Column stabilized unit” is a unit with the main deck connected to the underwater hull or footings by columns or caissons.
“Administration” means the Government of the State whose flag the unit is entitled to fly.
“Coastal State” means the Government of the State exercising administrative control over the drilling operations of the unit.
“Organization” means the Inter-Governmental Maritime Consultative Organization (IMCO).
“Certificate” means Mobile Offshore Drilling Unit Safety Certificate.
“1974 SOLAS Convention” means the International Convention for the Safety of Life at Sea, 1974.
“1966 Load Line Convention” means the International Convention on Load Lines, 1966.
“Mode of operation” means a condition or manner in which a unit may operate or function while on location or in transit. The modes of operation of a unit include the following:
Operating conditions – conditions wherein a unit is on location for the purpose of conducting drilling operations, and combined environmental and operational loadings are within the appropriate design limits established for such operations. The unit may be either afloat or supported on the sea-bed, as applicable.
Severe storm conditions – conditions wherein a unit may be subjected to the most severe environmental loadings for which the unit is designed. Drilling operations are assumed to have been discontinued due to the severity of the environmental loadings. The unit may be either afloat or supported on the sea-bed, as applicable.
Transit conditions – conditions wherein a unit is moving from one geographical location to another.
“Freeboard” is the distance measured vertically downwards amidships from the upper edge of the deck line to the upper edge of the related load line.
“Length” (L) means 96% of the total length on a waterline at 85% of the least moulded depth measured from the top of the keel, or the length from the foreside of the stem to the axis of the rudder stock on that waterline, if that be greater. In units designed with a rake of keel the waterline on which this length is measured should be parallel to the designed waterline.
“Weather tight” means that in any sea conditions water will not penetrate into the unit.
“Normal operational and habitable conditions” means:
1. conditions under which the unit as a whole, its machinery, services, means and aids ensuring safe navigation when underway, safety when in the industrial mode, fire and flooding safety, internal and external communications and signals, means of escape and winches for rescue boats, as well as the minimum comfortable conditions of habitability are in working order and functioning normally; and
2. drilling operations.
“Gas-tight door” is a solid, close-fitting door designed to resist the passage of gas under normal atmospheric conditions.
“Main source of electrical power” is a source intended to supply electrical power for all services necessary for maintaining the unit in normal operational and habitable conditions.
“Dead ship condition” is the condition under which the main propulsion plant, boilers and auxiliaries are not in operation due to the absence of power.
“Main switchboard” is a switchboard directly supplied by the main source of electrical power and intended to distribute electrical energy to the unit’s services.
“Emergency switchboard” is a switchboard which in the event of failure of the main system of electrical power supply is directly supplied by the emergency source of electrical power and/or the transitional source of emergency power and intended to distribute electrical energy to the emergency services.
“Emergency source of electrical power” is a source of electrical power intended to supply the necessary services in the event of failure of the main source of electrical power.
“Main steering gear” is the machinery, the steering gear power units, if any, and ancillary equipment and the means of applying torque to the rudder stock, e.g. tiller or quadrant, necessary for effecting movement of the rudder for the purpose of steering the unit under normal service conditions.
“Auxiliary steering gear” is that equipment which is provided for effecting movement of the rudder for the purpose of steering the unit in the event of failure of the main steering gear.
“Steering gear power unit” means, in the case of:
1. electric steering gear, an electric motor and its associated electrical equipment;
2. electrohydraulic steering gear, an electric motor and its associated electrical equipment and connected pump;
3. other hydraulic gear, a driving engine and connected pump.
“Maximum ahead service speed” is the greatest speed which the unit is designed to maintain in service at sea at its deepest seagoing draught.
“Maximum astern speed” is the speed which it is estimated the unit can attain at the assumed maximum astern power at its deepest seagoing draught.
“Machinery spaces of category A” are all spaces which contain internal combustion type machinery used either:
1. for main propulsion; or
2. for other purposes where such machinery has in the aggregate a total power of not less than 375 kilowatts, or which contain any oil fired boiler or oil fuel unit; and trunks to such spaces.
“Machinery spaces” are all machinery spaces of Category A and all other spaces containing propelling machinery, boilers and other fired processes, oil fuel units, steam and internal combustion engines, generators and major electrical machinery, oil filling stations, refrigerating, stabilizing, ventilation and air-conditioning machinery and similar spaces; and trunks to such spaces.
“Control stations” are those spaces in which the unit’s radio or main navigating equipment or the emergency source of power is located or where the fire recording or fire control equipment or the dynamical positioning control system is centralized. However, in the application of Chapter 9 the space where the emergency source of power is located is not considered as being a control station.
“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.
“Enclosed spaces” are spaces delineated by floors bulkheads and/or decks which may have doors and/or windows.
“Semi-enclosed locations” are locations where natural conditions of ventilation are notably different from those on open decks due to the presence of structures such as roofs, windbreaks and bulkheads and which are so arranged that dispersion of gas may not occur.
“Industrial machinery and components” are the machinery and components which are used in connection with the drilling operation.
“Non-combustible material” means a material which neither burns nor gives off flammable vapours in sufficient quantity for self- ignition when heated to approximately 750°C, this being determined to the satisfaction of the Administration by an established test procedure. Any other material is a combustible material.
“A Standard Fire Test” is a test as defined in Regulation 3(b) of Chapter II-2 of the 1974 SOLAS Convention.
“”A” Class Divisions” are those divisions as defined in Regulation 3(b) of Chapter II-2 of the 1974 SOLAS Convention.
“”B” Class Divisions” are those divisions as defined in Regulation 3(b) of Chapter II-2 of the 1974 SOLAS Convention.
“”C” Class Divisions” are those divisions constructed of non-combustible materials approved by the Administration. They need meet no requirements relative to the passage of smoke and flame or to the limiting of temperature rise.
“Steel or other equivalent material” means steel or any material which, by itself or due to insulation provided, has structural and integrity properties equivalent to steel at the end of the applicable fire exposure to the standard fire test (e.g. aluminium alloy with appropriate insulation).
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