Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Equipment Class
Definition(s)
Equipment Class
Class of similar type of equipment units (e.g. all pumps). NOTE Annex A describes a variety of equipment classes. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsDown Time
Definition(s)
Down Time
Time interval during which an item is in a down state. NOTE The down time includes all the delays between the item failure and the restoration of its service. Down time can be either planned or unplanned. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsDowntime
Time interval during which an item is in a non-working state. NOTE The downtime includes all the delays between the item failure and the restoration of its service. Downtime can be either planned or unplanned. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global StandardsDown State
Definition(s)
Down State
Internal disabled state of an item characterized either by a fault or by a possible inability to perform a required function during preventive maintenance. NOTE This state is related to availability performance (see 3.1). Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsDown State
Internal disabled state of an item characterized either by a fault or by a possible inability to perform a required function during preventive maintenance. NOTE This state is related to availability performance. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global StandardsDemand
Definition(s)
Demand
Activation of the function (includes functional, operational and test activation). NOTE For a more detailed description, see C.2.2. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsDegraded Failure
Definition(s)
Degraded Failure
Failure that does not cease the fundamental function(s), but compromises one or several functions. NOTE The failure can be gradual, partial or both. The function can be compromised by any combination of reduced, increased or erratic outputs. An immediate repair can normally be delayed but, in time, such failures can develop into a critical failure if corrective actions are not taken. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsCritical Failure
Definition(s)
Critical Failure
Failure of an equipment unit that causes an immediate cessation of the ability to perform a required function. NOTE Includes failures requiring immediate action towards cessation of performing the function, even though actual operation can continue for a short period of time. A critical failure results in an unscheduled repair. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsCorrective Maintenance
Definition(s)
Corrective Maintenancee
Maintenance carried out after fault recognition and intended to put an item into a state in which it can perform a required function. NOTE For more specific information, see IEC 60050-191:1990, Figure 191-10. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsCorrective Maintenance
Maintenance that is carried out after a fault recognition and intended to put an item into a state in which it can perform a required function. See IEC 60050-191:1990, Figure 191-10 [2], for more specific information. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global StandardsCorrective Maintenance
maintenance carried out after fault detection to effect restoration Note 1 to entry: Corrective maintenance of software invariably involves some modification. Note 2 to entry: Sometimes the corrective maintenance is also called curative maintenance. [SOURCE: IEC 60050‑191-46-06] Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global StandardsCommon-Cause Failure
Definition(s)
Common-Cause Failure
Failures of different items resulting from the same direct cause, occurring within a relatively short time, where these failures are not consequences of another. NOTE Components that fail due to a shared cause normally fail in the same functional mode. The term common mode is, therefore, sometimes used. It is, however, not considered to be a precise term for communicating the characteristics that describe a common-cause failure. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsCommon Cause Failure
Failures of different items resulting from the same direct cause, occurring within a relatively short time, where these failures are not consequences of each other. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global StandardsCommon Cause Failure
failures of different items, resulting from a single event, where these failures are not consequences of each other Note 1 to entry: It is generally accepted that the failures occur simultaneously or within a short time of each other. Note 2 to entry: Common cause failures can lead to common mode failures. Note 3 to entry: Common cause failures reduce the effect of system redundancy. Note 4 to entry: Explicit and implicit CCF are defined in 5.4.2. Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global StandardsBoundary
Definition(s)
Boundary
Interface between an item and its surroundings. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsBoundary
Software, hardware, or other physical barrier that limits access to a system or part of a system [9]. Source: ANSI/ISA–99.00.01–2007, Security for Industrial Automation and Control Systems, Part 1: Terminology, Concepts, and Models, 29 October 2007. National StandardActive Maintenance Time
Definition(s)
Active Maintenance Time
That part of the maintenance time during which a maintenance action is performed on an item, either automatically or manually, excluding logistic delays. NOTE 1 A maintenance action can be carried out while the item is performing a required function. NOTE 2 For a more detailed description and interpretation of maintenance times, see Figure 4 and Annex C. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsAvailability
Definition(s)
Availability
Ability of an item to be in a state to perform a required function under given conditions at a given instant or over a given time interval, assuming that the required external resources are provided.Source: DNVGL-RP-G108, Cyber security in the oil and gas industry based on IEC 62443, DNV GL, September 2017. Global Standards
Availability
Extent to which the system/structure/equipment is capable of retaining its functional integrity. Source: ISO 16530-1:2017, Petroleum and natural gas industries - Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global StandardsAvailability
The property of being accessible and usable upon demand. Extended Definition: In cybersecurity, applies to assets such as information or information systems. Adapted from: CNSSI 4009, NIST SP 800-53 Rev 4, 44 U.S.C., Sec 3542 Source: NICCS™ Portal Cybersecurity Lexicon, National Initiative for Cybersecurity Careers and Studies (https://niccs.us-cert.gov/glossary) as of 11 November 2015, Global StandardsAvailability
Fraction of time that a system (e.g. safety instrumented system, atmospheric-relief system, or flare-relief system) is able to perform the designated function if required for use.
Source:API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsAvailability
Property of being accessible and usable upon demand by an authorized entity. Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global StandardsAvailability
Probability that a system will operate on demand. 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 GuidelinesAvailability
Ability of an item to be in a state to perform a required function under given conditions at a given instant of time or over a given time interval, assuming that the required external resources are provided. NOTE: For a more detailed description and interpretation of availability, see Annex C. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsAvailability
The ability, measured in terms of uptime percentage, of a system to perform its required function. Source: OGP Report No. 415, Asset integrity – the key to managing major incident risks, International Association of Oil & Gas Producers, December 2008. Global StandardsAvailability
Ability of an item to be in a state to perform a required function under given conditions at a given instant of time, or in average over a given time interval, assuming that the required external resources are provided. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global StandardsAvailability
Probability that an asset, under the combined influence of its reliability, maintainability, and security, will be able to fulfill its required function over a stated period of time, or at a given point in time.
Source: ANSI/ISA–99.00.01–2007, Security for Industrial Automation and Control Systems, Part 1: Terminology, Concepts, and Models, 29 October 2007. National StandardAvailability
Note that the definition of availability given in IEC 60050-191:1990, 3.1.1, can be misleading because it can lead one to think that “availability” and “reliability” are the same concepts. This is not true because the meaning of “over a given time interval” is not at all the same for the concepts of “availability” and “reliability”. Even if the definitions of “availability” and “reliability” seem very close, these concepts are completely different, specifically: availability: item working at a given instant (no matter what has happened before); reliability: item working continuously over a whole period of time. “Availability” characterizes a function that can be interrupted without any problem and “reliability,” a function that cannot be interrupted over a whole period of time. Source: API STD 689, Collection and Exchange of Reliability and Maintenance Data for Equipment, First Edition, July 2007. Global StandardsWetted Area
Definition(s)
Wetted Area
Surface area of a tank exposed to liquid on the interior and heat from a fire on the exterior. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsThermal Out-Breathing
Definition(s)
Thermal Out-Breathing
Movement of vapours out of a tank when vapours in the tank expand and liquid in the tank vapourizes as a result of weather changes (e.g. an increase in atmospheric temperature). Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsThermal Inbreathing
Definition(s)
Thermal Inbreathing
Movement of air or blanketing gas into a tank when vapours in the tank contract or condense as a result of weather changes (e.g. a decrease in atmospheric temperature). Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsSet Pressure
Definition(s)
Set Pressure
Inlet gauge pressure at which a pressure-relief device is set to open under service conditions.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsSet Pressure
Gauge pressure at the device inlet at which the relief device is set to start opening under service conditions. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. GlobalStandardsStandard Cubic Feet Per Hour (SCFH)
Definition(s)
Standard Cubic Feet Per Hour (SCFH)
USC unit for volumetric flow rate of air or gas (same as free air or free gas) at a temperature of 15,6 °C (60 °F) and an absolute pressure of 101,3 kPa (14,7 psi), expressed in cubic feet per hour. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsRollover
Definition(s)
Rollover
Uncontrolled mass movement of stored liquid, correcting an unstable state of stratified liquids of different densities and resulting in a significant evolution of product vapour. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsRequired Flow Capacity
Definition(s)
Required Flow Capacity
Flow through a relief device required to prevent excessive pressure or vacuum in a tank under the most severe operating or emergency conditions. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsRelieving Pressure
Definition(s)
Relieving Pressure
Pressure at the inlet of a relief device when the fluid is flowing at the required relieving capacity. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsRelief Device
Definition(s)
Relief Device
Device used to relieve excess pressure and/or vacuum that has developed in a tank. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsRefrigerated Tank
Definition(s)
Refrigerated Tank
Container that stores liquid at a temperature below atmospheric temperature with or without the aid of refrigeration, either by evaporation of the tank contents or by a circulating refrigeration system. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsPV Valve
Definition(s)
PV Valve
Weight-loaded, pilot-operated, or spring-loaded valve, used to relieve excess pressure and/or vacuum that has developed in a tank. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsPetroleum Products
Definition(s)
Petroleum Products
Hydrocarbon materials or other products derived from crude oil. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsPetroleum Products
“Petroleum products” has the same meaning as in the Energy Act 1976 (Note: 1976 c. 76). Source: UK Offshore Safety Act 1992, 1992 c. 15 (February 2013). LegislationPetroleum Products
"Petroleum product" means any commodity made from petroleum or natural gas and includes refined crude oil, processed crude petroleum, residuum from crude petroleum cracking stock, uncracked fuel oil, fuel oil, treated crude oil residuum, casing head gasoline, natural gas gasoline, naphtha, distillate gasoline, kerosene, bitumen, asphalt and tar, waste oil, blended gasoline, lubricating oil, blends or mixture of oil with one or more liquid products or by products derived from oil or gas and blends or mixtures of two or more liquid products or by-products derived from oil condensate and gas or petroleum hydrocarbons not specified hereinbefore. Source: The Oil Industry (Development) Act, 1974, Act No. 47 of 1974, India, as amended as of May 2013. LegislationPetroleum Product
“Petroleum product” means any commodity made from petroleum or natural gas and shall include refined crude oil, processed crude petroleum, residum from crude petroleum, cracking stock, uncracked fuel oil, fuel oil, treated crude oil residum, casing head gasoline, natural gas gasoline, naptha, distillate gasoline, kerosene, waste oil, blended gasoline, lubricating oil, blends or mixture of oil with one or more liquid products or by-products derived from oil or gas, and blends or mixtures of two or more liquid products or by-products derived from oil condensate; gas or petroleum hydrocarbons; whether herein enumerated or not. Source: The Petroleum and Natural Gas Rules, 1959 (As amended from time to time), India, as amended as of May 2013. RegulationsPetroleum
Definition(s)
Petroleum
Crude oil. Source: API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks, Sixth Edition, November 2009. Global StandardsPetroleum
“Petroleum” means oil or gas; hydrocarbures. Source: Canada-Nova Scotia Offshore Petroleum Resources Accord Implementation Act, S.C. 1988, c. 28, Canada, current to May 26, 2013. Legislation Source: Canada Petroleum Resources Act, R.S.C. 1985, c. 36 (2nd Supp.), current to April 29, 2013. LegislationPetroleum
"Petroleum" means any liquid hydro-carbon or mixture of hydro- -carbons and any inflammable mixture (liquid, viscous or solid) containing any liquid hydro-carbon. Source: The Petroleum Act, 1934 (Act No. 30 of 1934), India, 1934. LegislationPetroleum
“Petroleum” has the same meaning as in the Petroleum Act, 1934 and includes natural gas and refinery gas. Source: The Petroleum Mineral Pipelines (Acquisition of Right of User in Land) Act, 1962, Act No. 50 of 1962, India, as amended as of May 2013. LegislationPetroleum
Petroleum means:- any naturally occurring hydrocarbon, whether in a gaseous, liquid or solid state; or
- any naturally occurring mixture of hydrocarbons, whether in a gaseous, liquid or solid state; or
- any naturally occurring mixture of:
- one or more hydrocarbons, whether in a gaseous, liquid or solid state; and
- one or more of the following, that is to say, hydrogen sulphide, nitrogen, helium and carbon dioxide; and:
- includes any petroleum as defined by paragraph (a), (b) or (c) that has been returned to a natural reservoir; and
- for the purposes of the pipeline provisions, also includes any petroleum as defined by paragraph (a), (b), (c) or (d), where:
- one or more things have been added; or
- one or more things have been wholly or partly removed; or both; and
- for the purposes of the pipeline provisions, also includes any mixture that:
- has been recovered from a well; and
- includes petroleum as defined by paragraph (a), (b), (c) or (d); whether or not:
- one or more things have been added; or
- one or more things have been wholly or partly removed; or both.
Petroleum
Disregard the definition of petroleum in section 7 of this Act in determining the meaning that the expression petroleum has or had in the Petroleum (Submerged Lands) Act 1967. Source: Offshore Petroleum and Greenhouse Gas Storage Act 2006, Australia, amended 2012. LegislationPetroleum
“Petroleum” means petroleum under the law on petroleum. Source: Law of Information Energy, Act on Offences Relating to Offshore Petroleum Production Places B.E. 2530 (1987), Thailand, as of June 2013. LegislationPetroleum
“Petroleum” means crude oil, natural gas, natural gas liquid, by-products and other naturally occurring hydrocarbons in a free state, whether solid, semi-solid, liquid or gaseous, and it shall include all heavy hydrocarbons which can be recovered in situ by thermal or chemical processes, but shall not include coal, oil shale or other kinds of rocks from which oil can be extracted by application of heat or chemical process. Source: Law of Information Energy, Petroleum Act B.E. 2514 (1971), Thailand, as of June 2013. LegislationPetroleum
“Petroleum” has the same meaning as in Part I of the Petroleum Act 1998 (Note: 1998 c. 17). Source: UK Offshore Safety Act 1992, 1992 c. 15 (February 2013). LegislationPetroleum
In paragraph (1) “petroleum” means any mineral oil or relative hydrocarbon and natural gas existing in its natural condition in strata, but does not include coal or bituminous shales or other stratified deposits from which oil can be extracted by destructive distillation. Source: The Borehole Sites and Operations Regulations 1995, UK S.I. 1995/2038, 1995. RegulationsPetroleum
“Petroleum”—- includes any mineral oil or relative hydrocarbon and natural gas, whether or not existing in its natural condition in strata; and
- does not include coal or bituminous shales or other stratified deposits from which oil can be extracted by destructive distillation.
Petroleum
For S.I. 1995/738, in regulation 2(1) (interpretation) before the definition of “pipeline”, insert ““petroleum”—- includes any mineral oil or relative hydrocarbon and natural gas, whether or not existing in its natural condition in strata; and
- does not include coal or bituminous shales or other stratified deposits from which oil can be extracted by destructive distillation.
Petroleum
For S.I. 1995/743, in regulation 2(1) (interpretation) after the definition of “personal protective equipment”, insert ““petroleum”—- includes any mineral oil or relative hydrocarbon and natural gas, whether or not existing in its natural condition in strata; and
- does not include coal or bituminous shales or other stratified deposits from which oil can be extracted by destructive distillation”.