Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Natural Ventilation
Definition(s)
Natural Ventilation
Movement of air and its replacement with fresh air due to the effects of wind and/or temperature gradients. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsExtent of Zone
Definition(s)
Extent of Zone
Distance in any direction from the source of release to the point where the gas/air mixture has been diluted by air to a value below the lower explosive limit. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsIgnition Temperature
Definition(s)
Ignition Temperature
Lowest temperature of a heated surface at which, under specified conditions, the ignition of a flammable substance in the form of a gas or vapour mixture with air will occur. [IEV 426-02-01, modified] NOTE IEC 60079-4 and IEC 60079-4A standardize a method for the determination of this temperature. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsVapour Pressure
Definition(s)
Vapour Pressure
Pressure exerted when a solid or liquid is in equilibrium with its own vapour. It is a function of the substance and of the temperature. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsVapour Pressure
Vapour pressure is the equilibrium pressure of the saturated vapour above a liquid expressed in Pascals (Pa) at a specified temperature. Source: Resolution MEPC.119(52), 2004 amendments to the International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk (IBC Code), 15 October 2004, International Maritime Organization. Regulatory GuidanceBoiling Point
Definition(s)
Boiling Point
Temperature of a liquid boiling at an ambient pressure of 101,3 kPa (1 013 mbar) NOTE The initial boiling point that should be used for liquid mixtures is to indicate the lowest value of the boiling point for the range of liquids present, as determined in a standard laboratory distillation without fractionation. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsFlammable Material
Definition(s)
Flammable Material (Flammable Substance)
Material which is flammable of itself, or is capable of producing a flammable gas, vapour or mist. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsOffshore Installation
Definition(s)
Offshore Installation
Regulation 3 defines an ‘offshore installation’ for the purpose of these Regulations. This definition replaces that formerly contained in section 1 of MWA12 as the definition of an offshore installation for the purposes of health and safety law. Existing Regulations which refer to installations (for example SCR4) are amended by these Regulations to use the new definition. Regulations, such as PFEER,10 refer to the definition given in MAR. Any variation from it will be explained in the guidance on those Regulations. Source: A Guide to the Offshore Installations and Pipelines Works (Management and Administration) Regulations 1995, Guidance on Regulations (UK HSE L70), Second Edition, 2002. RegulatoryOffshore Installation
“Offshore installation” means an installation that is located at an offshore production site or offshore drill site, and includes an accommodation installation and a diving installation (installation au large des côtes). Source: Canada Oil and Gas Installations Regulations, SOR/96-111, Canada, current to May 1, 2014. Regulations Source: Canada Oil and Gas Installations Regulations, SOR/96-118, February 2013. RegulationsOffshore Installation
The Offshore Installations and Pipeline Works (Management and Administration) Regulations (MAR) 1995 (the 1995 Regulations) introduced a new definition of an ‘offshore installation’ and modified the definition of ‘person in control’. Further details are set out in the guidance to MAR, regulation 3. Source: Health Care and First Aid on Offshore Installations and Pipeline Works, Offshore Installations and Pipeline Works (First-Aid) Regulations 1989, Approved Code of Practice and Guidance (UK HSE L123), Second Edition, 2000. Regulatory GuidanceOffshore Installation
A general term for mobile and fixed structures, including facilities, which are intended for exploration, drilling, production, processing or storage of hydrocarbons or other related activities or fluids. The term includes installations intended for accommodation of personnel engaged in these activities. Offshore installation covers subsea installations and pipelines. The term does not cover traditional shuttle tankers, supply boats and other support vessels which are not directly engaged in the activities described above. Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global StandardsOffshore Installation
“Offshore installation” has the meaning given in article 4(2) and (3) of this Order. Source: The Health and Safety at Work etc. Act 1974 (Application outside Great Britain) Order 2001, UK S.I. 2013/214, 2013. RegulationsOffshore Installation
In this Order “offshore installation” means subject to paragraph (3) of this article, a structure which is, is to be, or has been, used while standing or stationed in water, or on the foreshore or other land intermittently covered with water—- for the exploitation, or exploration with a view to exploitation, of mineral resources by means of a well;
- for undertaking activities falling within article 8(2);
- for the conveyance of things by means of a pipe;
- for undertaking activities that involve mechanically entering the pressure containment boundary of a well; or
- primarily for the provision of accommodation for persons who work on or from a structure falling within any of sub-paragraphs (a) to (d), together with any supplementary unit which is ordinarily connected to it and all the connections.
- a structure which is connected with dry land by a permanent structure providing access at all times and for all purposes;
- a well;
- a mobile structure which has been taken out of use and is not yet being moved with a view to its being used for any of the purposes specified in paragraph (2) of this article;
- any part of a pipeline; and
- a structure falling within article 10(c).
Offshore Installation
“Offshore installation” includes any part of an offshore installation whether or not capable of being manned by one or more persons. Source: The Offshore Installations (Inspectors and Casualties) Regulations 1973, UK S.I. 1973/1842, 1973. RegulationsOffshore Installation
“Offshore installation” means an offshore installation within the meaning of the 1971 Act which is within- tidal waters and parts of the sea in or adjacent to Great Britain up to the seaward limit of territorial waters;
- waters in any area designated under section 1(7) of the Continental Shelf Act 1964. Note: 1964 c. 29;
- inland waters within Great Britain.
Offshore Installation
“Offshore installation” shall be construed in accordance with regulation 3. Source: The Offshore Installations and Pipeline Works (Management and Administration) Regulations 1995, UK S.I. 1995/738, 1995. RegulationsOffshore Installation
offshore installation Subject to the provisions of this regulation, in these Regulations the expression “offshore installation” means a structure which is, or is to be, or has been used, while standing or stationed in relevant waters, or on the foreshore or other land intermittently covered with water— (a) for the exploitation, or exploration with a view to exploitation, of mineral resources by means of a well; (b) for the storage of gas in or under the shore or bed of relevant waters or the recovery of gas so stored; (c) for the conveyance of things by means of a pipe; or (d) mainly for the provision of accommodation for persons who work on or from a structure falling within any of the provisions of this paragraph, and which is not an excepted structure. (2) For the purposes of paragraph (1), the excepted structures are— (a) a structure which is connected with dry land by a permanent structure providing access at all times and for all purposes; (b) a well; (c) a structure or device which does not project above the sea at any state of the tide; (d) a structure which has ceased to be used for any of the purposes specified in paragraph (1), and has since been used for a purpose not so specified; (e) a mobile structure which has been taken out of use and is not for the time being intended to be used for any of the purposes specified in paragraph (1); and (f) any part of a pipeline. (3) For the purposes of these Regulations there shall be deemed to be part of an offshore installation— (a) any well for the time being connected to it by pipe or cable; (b) such part of any pipeline connected to it as is within 500 metres of any part of its main structure; (c) any apparatus or works which are situated—- on or affixed to its main structure; or
- wholly or partly within 500 metres of any part of its main structure and associated with a pipe or system of pipes connected to any part of that installation.
Offshore Installation
In regulation 2 (interpretation) of the Offshore Installations (Emergency Pipe-line Valve) Regulations 1989 (Note: S.I. 1989/1029.) for the definition of “offshore installation” there shall be substituted the following definition: ““offshore installation” means an installation within the meaning of regulation 3 of the 1995 Regulations other than an installation which is—- used exclusively for flaring, or
- used exclusively for the loading of substances into vessels or for their reception and storage prior to such loading and which normally has no persons on board”.
Offshore Installation
In regulation 2 (interpretation) of the Offshore Installations and Pipeline Works (First-Aid) Regulations 1989 (Note: S.I. 1989/1671.) for the definition of “offshore installation” there shall be substituted the following definition: ““offshore installation” has the same meaning as in regulation 3 of the 1995 Regulations”. Source: The Offshore Installations and Pipeline Works (Management and Administration) Regulations 1995, UK S.I. 1995/738, 1995. RegulationsOffshore Installation
In this section— “offshore installation” means any installation which is an offshore installation within the meaning of the Mineral Workings (Offshore Installations) Act 1971, or is to be taken to be an installation for the purposes of sections 21 to 23 of the Petroleum Act 1987. Source: UK Offshore Safety Act 1992, 1992 c. 15 (February 2013). LegislationOffshore Installation
Offshore installation includes process platform, unmanned wellhead platform, drilling rig, modular rig, FPSO, FSU, SBM etc. Source: Guidance Notes on Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, Oil Industry Safety Directorate (India), 2012. Regulatory GuidanceOffshore Installation
“Offshore installation” means a mobile or fixed installation including any pipeline attached thereto, which is or is to be, or has been used, while standing or stationed in relevant waters with a view to explore or exploit petroleum and natural gas. Source: Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, India, 18th June 2008. RegulationsOffshore Installation
A buoyant or non-buoyant construction engaged in offshore operations including drilling, production, storage or support functions, and which is designed and intended for use at a location for an extended period. Source: Rules for Classification – Offshore units, DNVGL-OU-0101, Offshore drilling and support units, DNV GL, July 2015. Global StandardsRelative Density of a Gas (or vapour)
Definition(s)
Relative Density of a Gas (or Vapour)
Density of a gas or a vapour relative to the density of air at the same pressure and at the same temperature (air is equal to 1,0). Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsUpper Explosive Limit
Definition(s)
Upper Explosive Limit
Concentration of flammable gas or vapour in air, above which the gas atmosphere is not explosive. [IEV 426-02-10, modified]. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsLower Explosive Limit
Definition(s)
Lower Explosive Limit
Concentration of flammable gas or vapour in air, below which the gas atmosphere is not explosive. [IEV 426-02-09, modified]. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsLower Explosive Limit
“Lower explosive limit” means the lower limit of flammability of a chemical agent or a combination of chemical agents at ambient temperature and pressure, expressed- for a gas or vapour, as a percentage per volume of air, and
- for dust, as the weight of dust per volume of air.
Air Lock
Definition(s)
Air Lock
Compartment connecting two different environments, usually at different pressures, that enables personnel to transfer from one environment to the other. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsNormal Operation
Definition(s)
Normal Operation
Operating the system to perform the intended basic functionality. Source: API SPEC 17F, Specification for Subsea Production Control Systems, Second Edition, December 2006 (Reaffirmed April 2011). Global StandardsNormal Operation
Situation when the equipment is operating within its design parameters NOTE 1 Minor releases of flammable material may be part of normal operation. For example, releases from seals which rely on wetting by the fluid which is being pumped are considered to be minor releases. NOTE 2 Failures (such as the breakdown of pump seals, flange gaskets or spillages caused by accidents) which involve urgent repair or shutdown are not considered to be part of normal operation nor are they considered to be catastrophic. NOTE 3 Normal operation includes start-up and shutdown conditions. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsRelease Rate
Definition(s)
Release Rate
Quantity of flammable gas or vapour emitted per unit time from the source of release. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsSecondary Grade of Release
Definition(s)
Secondary Grade of Release
Release which is not expected to occur in normal operation and, if it does occur, is likely to do so only infrequently and for short periods. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsPrimary Grade of Release
Definition(s)
Primary Grade of Release
Release which can be expected to occur periodically or occasionally during normal operation. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsContinuous Grade of Release
Definition(s)
Continuous Grade of Release
Release which is continuous or is expected to occur frequently or for long periods. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsGrades of Release
Definition(s)
Grades of Release
There are three basic grades of release, as listed below in order of decreasing frequency and likelihood of the explosive gas atmosphere being present: a) continuous grade; b) primary grade; c) secondary grade. A source of release may give rise to any one of these grades of release, or to a combination of more than one. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsNon-Hazardous Area
Definition(s)
Non-Hazardous Area
Area in which an explosive atmosphere is not expected to be present in quantities such as to require special precautions for the construction, installation and use of equipment. Source: IEC 60079-14:2013, Explosive atmospheres – Part 14: Electrical installations design, selection and erection, Edition 5.0, November 2013. Global Standards Source: IEC 60079-17:2013, Explosive atmospheres – Part 17: Electrical installations inspection and maintenance, Edition 5.0, November 2013. Global StandardsNon-Hazardous Area
Area in which an explosive gas atmosphere is not expected to be present in quantities such as to require special precautions for the construction, installation and use of apparatus. [IEV 426-03-02, modified] Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsNon-Hazardous Area
Any area not classified as Zone 0, 1 or 2 and deemed to be non-hazardous with respect to the absence of any possibility of occurrence of a flammable atmosphere. Source: International Association of Drilling Contractors, Appendix 2 to Health, Safety and Environment Case Guidelines for Offshore Drilling Contractors, Issue 3.3.2, February 2010. IADC GuidelinesNon-Hazardous Area
Non-hazardous areas are those which are not classified as hazardous according to the above definitions. 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 StandardsExplosive Atmosphere
Definition(s)
Explosive Atmosphere
Mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour, mist or dust, in which, after ignition, combustion spreads throughout the unconsumed mixture. [IEV 426-02-02, modified] Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsArea Classification
Definition(s)
Area Classification
Division of an installation into hazardous areas and non-hazardous areas and the sub-division of hazardous areas into zones Note 1 to entry: This classification is based on the materials which can be present and the probability of a flammable atmosphere developing. Area classification is primarily used in the selection of electrical equipment to minimize the likelihood of ignition if a release occurs. Source: ISO 13702:2015, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore production installations — Requirements and guidelines, Second Edition, August 2015. Global StandardsArea Classification
Assessed division of a facility into hazardous and non-hazardous areas, and the subdivision of the hazardous areas into zones. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsHazardous Area
Definition(s)
Hazardous Area
Three-dimensional space in which a combustible or explolsive atmosphere can be expected to be present frequently enough to require special precautions for the control of potential ignition sources- Note: 1 to entry: Hazardous areas are typically defined by local, national or international standards (e.g. the National Electric Code (NEC) in the United States).
Hazardous Area
Three-dimensional space in which a flammable atmosphere can be expected to be present at such frequencies as to require special precautions for the control of potential ignition sources. Source: ISO 13702:2015, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore production installations — Requirements and guidelines, Second Edition, August 2015. Global StandardsHazardous Area
“Hazardous area” means an area classified as hazardous in the Recommended Practice referred to in subsection (2) (zone dangereuse). Source: Canada Oil and Gas Installations Regulations, SOR/96-111, Canada, current to May 1, 2014. Regulations Source: Canada Oil and Gas Installations Regulations, SOR/96-118, February 2013. Regulations Source: Nova Scotia Offshore Petroleum Installations Regulations, SOR/95-191, Canada, current to May 31, 2012. RegulationsHazardous Area
Area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment. Source: IEC 60079-14:2013, Explosive atmospheres – Part 14: Electrical installations design, selection and erection, Edition 5.0, November 2013. Global StandardsHazardous Area
Area in which an explosive gas atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of apparatus.[IEV 426-03-01, modified] Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsHazardous Area
Area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment- Note: 1 to entry: For the purposes of this standard, an area is a three-dimensional region or space.