Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Steel or Other Equivalent Material
Definition(s)
Steel or Other Equivalent Material
Steel or other equivalent material means any non-combustible material which, by itself, or due to insulation provided, has structural and integrity properties equivalent to steel at the end of the applicable exposure to the standard fire test (e.g., aluminium alloy with appropriate insulation). Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsSemi-enclosed Space
Definition(s)
Semi-enclosed Space
A semi-enclosed space is considered to be a space which is adjoining an open area, where the natural ventilation conditions within the space are restricted by structures such as decks, bulkheads or windbreaks in such a manner that they are significantly different from those appertaining to the open deck, and where dispersion of gas may be impeded. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsProcess Plant
Definition(s)
Process Plant
Drilling, process plant and industrial machinery and components are the machinery and components which are used in connection with the operation of drilling, production and process systems. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsOpen-air Area
Definition(s)
Open-air Area
An open-air area is one without stagnant regions where vapours are rapidly dispersed by wind and natural convection. Typically, air velocities will rarely be less than 0,5 metres per second and will frequently be above 2 metres per second. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsLighter Than Air
Definition(s)
Lighter Than Air
Gases and vapours are considered lighter than air when their density, on release to atmosphere, is less than approximately 0,75 relative to the ambient air. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsJet-fire Test
Definition(s)
Jet-fire Test
A jet-fire test is used to determine how effective the passive fire protection materials are in withstanding an actual jet fire. The test is not intended to replace the hydrocarbon fire test. Some Administrations require fire protection materials to be assessed by this method and, where requested, LR can advise on the detailed requirements. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global Standards‘H’ Class Divisions (fire divisions)
Definition(s)
‘H’ Class Divisions (fire divisions)
‘H’ Class divisions are those divisions formed by fire walls and decks which comply with the construction and integrity requirements for ‘A’ Class divisions, 2.6.1(a) and (b) and with the following: (a) They are to be so constructed as to be capable of preventing the passage of smoke and flame up to the end of the one hour hydrocarbon fire test. (Note that some administrations may require the ‘H’ Class division integrity to be maintained for 120 minutes). (b) They are to be insulated with approved non-combustible materials such that the average temperature, on the unexposed side, when exposed to a hydrocarbon fire test, will not rise more than 140°C above the original temperature, nor will the temperature at any one point, including any joint, rise more than 180°C above the original temperature within the time listed below: Class ‘H-120’ - 120 minutes Class ‘H-60’ - 60 minutes Class ‘H-0’ - 0 minutes. (c) A test of a prototype fire wall or deck may be required to ensure that it meets the above requirements for integrity and temperature rise. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsFire and Explosion Evaluation (FEE)
Definition(s)
Fire and Explosion Evaluation (FEE)
The FEE is an assessment of the potential fire loadings and blast pressures, based on the specific hazards associated with the general layout of the unit, production and process activities and operational constraints. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsFEE
Definition(s)
FEE
Fire and Explosion Evaluation Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsDrilling Plant
Definition(s)
Drilling Plant
Drilling, process plant and industrial machinery and components are the machinery and components which are used in connection with the operation of drilling, production and process systems. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global StandardsInternal Zones
Definition(s)
Internal Zones
Ballast tanks, liquid storage tanks, and other compartments Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 8, Corrosion Controls, June 2013, Lloyd’s Register, Global StandardsBoot Topping Zone
Definition(s)
Boot Topping Zone
That part of the external structure between the maximum design operating draught and the light design operating draught. For column-stabilised units, see Table 1.1.1. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsEssential Services
Definition(s)
Essential Services
Essential services are those necessary for the propulsion and safety of the unit, such as the following:- Electric propulsion equipment.
- Thruster systems for dynamic positioning.
- Thruster systems for positional mooring.
- Abandonment systems dependent on electric power.
- Ventilation systems for hazardous areas and those maintained at an overpressure to exclude the ingress of dangerous gases.
- Wellhead control and disconnection systems dependent on electric power.
- Electric starting systems for oil engines.
Jack-house
Definition(s)
Jack-house
The structure surrounding the leg chord into which multiple jacking units are installed. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsJacking Gear Unit
Definition(s)
Jacking Gear Unit
The individual reduction gear assembly, comprising drive motor, coupling, enclosed reduction gearing and main pinion normally attached to the jack-house. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsStorm Survival Load
Definition(s)
Storm Survival Load
The maximum static design load in the leg to be supported by the jacking and/or fixation systems. Fixation system. The mechanical locking device, with an engaging mechanism, used to provide positive engagement between the hull support structure and the leg chord. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsUltimate Holding Load
Definition(s)
Ultimate Holding Load
The maximum load capable of being held by the jacking unit, in an emergency situation, without causing slippage of the jacking gear machinery braking device. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsPre-load Holding Load
Definition(s)
Pre-load Holding Load
The maximum design elevated weight of the hull, including pre-load ballast, to be held by the jacking unit during the pre-load operation. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsPre-load Jacking Load
Definition(s)
Pre-load Jacking Load
The maximum design elevated weight of the hull, including pre-load ballast load, to be lowered by the jacking unit in the event of sudden leg penetration during pre-load operation. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsNormal Jacking Load
Definition(s)
Normal Jacking Load
The maximum design elevated weight of the hull, including variable load, to be raised/lowered by the jacking unit, during normal jacking operation. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsRudder Actuator
Definition(s)
Rudder Actuator
Rudder actuator means the components which convert directly hydraulic pressure into mechanical action to move the rudder. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsMaximum Skew Angle
Definition(s)
Maximum Skew Angle
The maximum skew angle of a propeller blade is defined as the angle, in projected view of the blade, between a line drawn through the blade tip and the shaft centreline and a second line through the shaft centreline which acts as a tangent to the locus of the mid-points of the helical blade sections, see Fig. 7.1.1. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global StandardsMass Produced Engines
Definition(s)
Mass Produced Engines
Mass produced engines, for main and auxiliary purposes, are defined as those which are produced under the following criteria:- In quantity under strict quality control of material and parts, according to a quality assurance scheme acceptable to LR.
- By the use of jigs and automatic machine tools designed to machine parts to specified tolerances for interchangeability, and which are verified on a regular inspection basis.
- By assembly with parts taken from stock and requiring little or no fitting.
- With bench tests carried out on individual assembled engines according to a specified programme.
- With appraisal by final examination of engines selected at random after workshop testing.