Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Tanks, Sealed
Definition(s)
Tanks, Sealed
Tanks that are sealed against gas and vapor leakage and are without provisions for inspection or maintenance from within the location. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsTanks, Open
Definition(s)
Tanks, Open
Tanks that allow the continuous free communication of the tank’s internal atmosphere into the surrounding location or space. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsTanks, Closed Top
Definition(s)
Tanks, Closed Top
Tanks with limited number of small openings or penetrations, such as shafts, through which gas may occasionally leak within the location. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsTanks, Accessible
Definition(s)
Tanks, Accessible
Tanks that under normal operating conditions are sealed against gas and vapor leakage, but the interior of which may be readily accessed for inspection and maintenance from within the location. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsSpaces, Enclosed
Definition(s)
Spaces, Enclosed
Spaces delineated by floors, bulkheads and decks, which may have doors or windows. (IMO—MODU Code 1.3.33. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsLocations Semi-enclosed
Definition(s)
Locations Semi-enclosed
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. (IMO—MODU Code 1.3.34. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsLocations, Open (Outdoor)
Definition(s)
Locations, Open (Outdoor)
Locations substantially free of structures (or other obstructions) where natural ventilation is not impeded and causes the rapid dispersion (dilution) of gases and vapors, and stagnant areas are not present. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsType 3 Open Drains
Definition(s)
Type 3 Open Drains
Type 3 Open Drains are open drains that can allow releases (through drain openings) of lighter-than-air flammable gases or vapors at atmospheric pressure. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsType 2 Open Drains
Definition(s)
Type 2 Open Drains
Type 2 Open Drains are open drains that do not allow an accumulation of flammables above grade; flammables may accumulate below grade, however, due to flammable liquids or heavier-than-air flammable vapors settling into low spot(s) created by the drain or drain piping. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsType 1 Open Drains
Definition(s)
Type 1 Open Drains
Type 1 Open Drains are open drains designed to be operated in such a manner to prevent flammables from entering or exiting the drain system. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsDrain Entry
Definition(s)
Drain Entry
A drain entry is defined as an open fluid collection system, such as a trough or gutter, that routes the drained fluid to the drain opening. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsDrain Opening
Definition(s)
Drain Opening
A drain opening is defined as an opening in the drain system where the drained fluid actually enters the drain piping from the atmosphere. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsOpen Containment System
Definition(s)
Open Containment System
An open containment system is defined as a system open to the atmosphere. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsOpen Drain
Definition(s)
Open Drain
An open drain is defined as a drain that is open to the atmosphere [at its entrance (drain opening) or elsewhere] before (or where) its discharge enters a sump, pit, or other containment device. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUsage Areas
Definition(s)
Usage Areas
Also included as “usage areas” are areas where cleaning rags containing solvents or open containers of paint products are present. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUsed
Definition(s)
Used
“Used” is defined as operations such as cleaning paint brushes with flammable solvents and mixing paint with solvents where volatile gases or vapors will be given off to the atmosphere. Also included as “usage areas” are areas where cleaning rags containing solvents or open containers of paint products are present. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUsed
“Used” is defined as laboratory operations or analysis where samples are mixed with flammable solvents where volatile gases or vapors will be given off to the atmosphere. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsInadequately Ventilated Areas
Definition(s)
Inadequately Ventilated Areas
Inadequately ventilated areas are defined as rooms, buildings, or spaces that do not have a natural or a mechanical ventilation system providing for adequate ventilation as defined in 6.3.2. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsAdequate Ventilation
Definition(s)
Adequate Ventilation
Adequate ventilation is defined as ventilation (natural or artificial) that is sufficient to prevent the accumulation of significant quantities of vapor-air or gas-air mixtures in concentration above 25 % of their lower flammable (explosive) limit, LFL (LEL). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUEL
Definition(s)
UEL
upper explosive limit (UFL preferred) API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUEL
upper explosive limit. API RP 2201, Safe Hot Tapping Practices in the Petroleum & Petrochemical Industries, Fifth Edition, July 2003 (Reaffirmed October 2010), Global StandardsNPL
Definition(s)
NPL
neutral pressure level API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Sta/ndardsWireline Work Areas
Definition(s)
Wireline Work Areas
Those areas in which wireline work is being performed on a well through a lubricator. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVolatile Flammable Liquid
Definition(s)
Volatile Flammable Liquid
A flammable liquid whose temperature is above its flash point, or a Class II combustible liquid having a vapor pressure not exceeding 276 kPa (40 psia) at 37.8 °C (100 °F) whose temperature is above its flash point. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Inadequate
Definition(s)
Ventilation, Inadequate
Ventilation that is less than adequate. See 6.3.3 of API 500 or 6.6.3 of API 505, as applicable.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global StandardsVentilation, Inadequate
Ventilation that is less than adequate. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Inadequate
The degree of ventilation (i.e. the movement and transfer of air) achieved when, under normal operating conditions, the ventilation provided does not meet the locations required criteria (e.g. less than a specified minimum number of air changes per hour). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Adequate
Definition(s)
Ventilation, Adequate
Ventilation (natural or artificial) that is sufficient to prevent the accumulation of significant quantities of vapor-air mixtures in concentrations above 25 % of their lower flammable (explosive) limit, LFL (LEL). See 6.3.2 of API 500 or 6.6.2 of API 505, as applicable.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standards