Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Cellar
Definition(s)
Cellar
Excavation around the wellhead to provide space for items of equipment at the top of the wellbore. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global Standards Source: API RP 74, Recommended Practice for Occupational Safety for Onshore Oil and Gas Production Operation, First Edition, October 2001 (March 2007). Global StandardsCellar
A pit beneath the rig floor to provide additional height between the rig floor and the wellhead and to allow the installation of the bops / rotating head / rotating diverter, rat hole mouse hole etc. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsCellar
“Cellar” means an excavation around the wellhead to provide space for items of equipment at the top of the wellbore. Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. RegulationsCellar
An excavation around the well head to provide space for equipment at the top of the well bore. Source: Petroleum Safety Orders--Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. RegulationsCatwalk
Definition(s)
Catwalk
Elongated platform adjacent to the rig floor where pipe is laid out and lifted into the derrick. The catwalk is connected to the rig floor by a pipe ramp. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsCatwalk
“Catwalk” means a elongated platform to the side of a rig where pipe is laid out and lifted into the derrick. Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. RegulationsCathead
Definition(s)
Catline, Cathead
Catline is a line powered by the cathead, which is a concave, rotating, pulley-type device mounted on the end of the cat shaft of the drawworks. Catlines are used to lift or pull equipment around a rig. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsCathead
“Cathead” means a rotating device mounted on the end of a shaft of the draw works. Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. RegulationsCathead
Unless referred to as “automatic” cathead, means a spool shaped metal mechanical device mounted on the end of a shaft on which a rope is wrapped. The rotating cathead imparts a pulling power to the rope that is wrapped on it. Source: Petroleum Safety Orders--Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. RegulationsCatline
Definition(s)
Catline, cathead
Catline is a line powered by the cathead, which is a concave, rotating, pulley-type device mounted on the end of the cat shaft of the drawworks. Catlines are used to lift or pull equipment around a rig. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsCatline
A rope, usually reeved on a crown block sheave in a derrick or mast, for the primary purpose of lifting and transferring materials from one place to another about the derrick or mast floor. A rotating cathead imparts the pulling power to the catline that is wrapped on it. Source: Petroleum Safety Orders--Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. RegulationsBlowout Preventer Remote Control
Definition(s)
Blowout preventer remote control
A set of control tools that can be used to actuate the blowout preventer from a position some distance away from the blowout preventer, usually the rig floor or accumulator. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsBypass
Definition(s)
Bypass
Usually refers to a pipe connection around a valve or other control mechanism. A bypass is installed in such cases to permit passage of fluid through the bypass line while adjustments or repairs are made on the control that is bypassed. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsBreaking Out Pipe
Definition(s)
Breaking out pipe
Operation of unscrewing a pipe section. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsBlocks, Crown, and Traveling
Definition(s)
Blocks, Crown, and Traveling
The fixed upper and movable lower blocks, respectively, of the block and tackle assembly on a rig that raises and lowers the drill string or tubing. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsBlocks, Crown, and Traveling
“Blocks, crown, and traveling” means the fixed upper and movable lower blocks, respectively, of the block and tackle assembly on a rig that raises and lowers the drill string or tubing. Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. RegulationsBack Up
Definition(s)
Back up
Refers to the act of “backing up” or preventing rotation of one section of pipe or rods while another is screwed out of or into it. Also applied to screwing nuts on or off bolts. A backup wrench refers to any wrench being used to hold the pipe, rods, or bolt. Backup tongs refers to the pipe tongs suspended in the derrick and used to hold a section of pipe while another section is screwed out of or into it by use of other tongs. The backup man is the crew member who operates the backup tongs. The backup position refers to the workstation of the backup man. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsAnnular Space
Definition(s)
Annular space
Space surrounding pipe in the wellbore. The outer wall of the annular space may be open hole or pipe. Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global StandardsTWA
Definition(s)
TWA
Time weighted average. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global Standards Source: API RP 98, Personal Protective Equipment Selection for Oil Spill Responders, First Edition, August 2013. Global StandardsTWA
Average airborne exposure in any 8-hour work shift of a 40-hour workweek that shall not be exceeded (see 29 CFR 1910.1000, Table Z2). Source: API RP 98, Personal Protective Equipment Selection for Oil Spill Responders, First Edition, August 2013. Global StandardsTPQ
Definition(s)
TPQ
Threshold planning quantity. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsTLV
Definition(s)
TLV® s
Threshold limit values. API RP 2201, Safe Hot Tapping Practices in the Petroleum & Petrochemical Industries, Fifth Edition, July 2003 (Reaffirmed October 2010), Global StandardsThreshold limit value (TLVs®)
Recommended exposure limits published annually by the American Conference of Governmental Industrial Hygienists in Threshold Limit Values and Biological Exposure Indices. (TLV® is a registered trademark of the American Conference of Governmental Industrial Hygienists.) API RP 2201, Safe Hot Tapping Practices in the Petroleum & Petrochemical Industries, Fifth Edition, July 2003 (Reaffirmed October 2010), Global Standards API RP 2009, Safe Welding, Cutting, and Hot Work Practices in the Petroleum and Petrochemical Industries, Seventh Edition, February 2002 (Reaffirmed, March 2012), Global StandardsThreshold limit value (TLV)
Airborne concentrations of substances representing conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effects. These value may be expressed as 8-hour time weighted average (TWA), Ceiling Limits, or 15-minute Short-Term Exposure Levels (STEL). Refer to American Conference of Governmental Industrial Hygienists (ACGIH), Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. “TLV” is a trademarked term of ACGIH. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsThreshold Limit Value
Definition(s)
Threshold limit value
Exposure limits published annually by the American Conference of Governmental Industrial Hygienists in Threshold Limit Values and Biological Exposure Indices. (TLV® is a registered trademark of the American Conference of Governmental Industrial Hygienists). API RP 2201, Safe Hot Tapping Practices in the Petroleum & Petrochemical Industries, Fifth Edition, July 2003 (Reaffirmed October 2010), Global Standards Source:API RP 2009 (2002) Safe welding, cutting and hot work practices in the petroleum and petrochemical industries. Global StandardThreshold limit value (TLV)
Airborne concentrations of substances representing conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effects. These value may be expressed as 8-hour time weighted average (TWA), Ceiling Limits, or 15-minute Short-Term Exposure Levels (STEL). Refer to American Conference of Governmental Industrial Hygienists (ACGIH), Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. “TLV” is a trademarked term of ACGIH. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsTemporary Safe Haven
Definition(s)
Temporary safe haven
Refer to “shelter-in-place.” Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSulfur Dioxide
Definition(s)
Sulfur dioxide
Chemical formula is SO2. A toxic product of combustion of hydrogen sulfide, normally heavier than air. CAUTION: Inhalation at certain concentrations can lead to injury or death. Refer to Appendix B. Source API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSpecial Operations
Definition(s)
Special operations
Any service performed on or in a well other than the normal drilling or service operations that are accomplished in their entirety by a drilling or servicing rig. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSO2
Definition(s)
SO2
Sulfur dioxide. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global Standards Source: Resolution MEPC.184(59), 2009 Guidelines for exhaust gas cleaning systems, 17 July 2009, International Maritime Organization. Regulatory GuidanceShould
Definition(s)
Should
For the purposes of this publication, the term should denotes a RP a) where a safe comparable alternative practice is available; b) that may be impractical under certain circumstances; or c) that may be unnecessary under certain circumstances or applications. This word indicates that the rule is a recommendation, the advisability of which depends on the facts in each situation. Sources: API RP 2D, Operation and Maintenance of Offshore Cranes, Sixth Edition, May 2007. Global StandardsShould
As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification. Sources: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards Sources: API RP 13C, Recommended Practice on Drilling Fluids Processing Systems Evaluation, Upstream Segment, Fourth Edition, December 2010. Global StandardsShould
“Should” is used to state that a provision is not mandatory, but is recommended as good practice. Sources: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global StandardsShould
Denotes a “recommended practice(s)”- Where a safe comparable alternative practice(s) is available;
- That may be impractical under certain circumstances; or
- That may be unnecessary under certain circumstances.
Should
Denotes a recommended practice:- Where a safe comparable alternative practice is available;
- That may be impractical under certain circumstances: or
- That may be unnecessary for personnel safety under certain circumstances.
Should
Denotes a recommended practice(s) a) where a safe comparable alternative practice(s) is available; b) that may be impractical under certain circumstances; or c) that may be unnecessary under certain circumstances or applications. Sources: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global StandardsShould
As used in a standards, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification. Sources: API RP 67, Recommended Practice for Oilfield Explosives Safety, Upstream Segment, Second Edition, May 2007. Global StandardsShould
For the purpose of this document, should denotes a recommended practice(s)- Where a safe comparable alternative practice(s) is available;
- That may be impractical under certain circumstances; or
- That may be unnecessary for personnel safety under certain circumstances.
Should
The term “should” denotes a recommendation or that which is advised but not required in order to conform to the recommended practice. Sources: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsShould
SHOULD is used to indicate that a provision is not mandatory, but RECOMMENDED as good practice. Sources: API SPEC 5CRA, Specification for Corrosion Resistant Alloy Seamless Tubes for Use as Casing, Tubing and Coupling Stock, Upstream Segment, First Edition, February 2010 (Errata August 2011). Global Standards Sources: API SPEC 5DP, Specification for Drill Pipe, First Edition, August 2009. Global StandardsShould
As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification. Sources: API SPEC 5CRA, Specification for Corrosion Resistant Alloy Seamless Tubes for Use as Casing, Tubing and Coupling Stock, Upstream Segment, First Edition, February 2010 (Errata August 2011). Global Standards Sources: API SPEC 5CT, Specification for Casing and Tubing, Upstream Segment, Ninth Edition, July 2011 (Errata September 2012). Global Standards Sources: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global StandardsShould
Should: As used in a standard, "should" denotes a recommendation or that which is advised but not required in order to conform to the specification. Sources: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global Standards Sources: API SPEC 10A, Specification for Cements and Materials for Well Cementing, Twenty-fourth Edition, December 2010. Global Standards Sources: API SPEC 11D1, Packers and Bridge Plugs, Upstream Segment, Second Edition, July 2009. Global Standards Sources: API SPEC 13A, Specification for Drilling Fluids Materials, Eighteenth Edition, February 2010. Global Standards Sources: API SPEC 17E, Specification for Subsea Umbilicals, Upstream Segment, Fourth Edition, October 2010. Global StandardsShould
Refers to a recommended method which provides an example of how an operator can meet an expectation, but does not prevent an operator from selecting alternative best practices. Source: Incident Reporting and Investigation Guidelines, The Canada-Nova Scotia Offshore Petroleum Board and Canada-Newfoundland and Labrador Offshore Petroleum Board, Canada, November 30, 2012. Regulatory GuidanceShould
Indicates a recommendation that a certain course of action is preferred or particularly suitable. Alternative courses of action are allowable under the standard where agreed between contracting parties but shall be justified and documented. Sources: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global StandardsShould
"Should" means recommended. Sources: State of Wyoming Occupational Safety and Health Rules and Regulations for Oil and Gas Well Drilling, Revised January 8, 2013. RegulationsShould
“Should”, means the authorities' recommended way of fulfilling the functional requirement. Alternative solutions with documented corresponding functionality and quality can be used without having to present this to the authorities. Source: Guidelines Regarding the Framework Regulations, Norway, updated December 2012. Regulatory GuidanceShould
Verbal form used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred, but not necessarily required. Source: NORSOK D-002, Well intervention equipment, Rev. 2, June 2013. Global StandardsShould
Should is a recommendation. Alternative solutions having the same functionality and quality are acceptable. Source: NORSOK D-007, Well Testing Systems, Rev. 1, January 1996. Global StandardsShould
Indicates a preferred course of action or recommended practice to be adopted. Source: Approved Code of Practice for Managing Hazards to Prevent Major Industrial Accidents, Health and Safety in Employment Act 1992, Department of Labour, New Zealand, July 1994. Regulatory GuidanceShould
verbal form used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required . Source: Rules for Classification and Construction, IV Industrial Services, 6 Offshore Technology, 9 Guideline for Personnel Transfers by Means of Lifting Appliances, Edition 2011, Germanischer Lloyd SE, Global StandardsShould
Indicates that among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required. Other possibilities may be applied subject to agreement. Source: Verification of Lifting Appliances for the Oil and Gas Industry, DNV-OSS-308, October 2010, Det Norske Veritas AS, Global StandardsSTEL
Definition(s)
Short term exposure limit (STEL)
A 15-minute TWA exposure that should not be exceeded at any time during a workday. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSTEL
short-term exposure limit. Source: API RP 98, Personal Protective Equipment Selection for Oil Spill Responders, First Edition, August 2013. Global StandardsSTEL
Fifteen-minute TWA exposure limit that shall not be exceeded at any time during a workday unless another time limit is established. Source: API RP 98, Personal Protective Equipment Selection for Oil Spill Responders, First Edition, August 2013. Global StandardsShort Term Exposure Limit
Definition(s)
Short term exposure limit (STEL)
A 15-minute TWA exposure that should not be exceeded at any time during a workday. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsShelter-in-place
Definition(s)
Shelter-in-place
The concept of providing the public protection from exposure to toxic gas or vapor releases to the environment by having residents stay indoors until emergency evacuators arrive or the emergency is over. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSERC
Definition(s)
SERC
State Emergency Response Commission. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSCF
Definition(s)
SCF
"Scf" means standard cubic feet. Source: Alaska Oil and Gas Conservation Commission, Definitions, Alaska Admin. Code tit. 20, § 25.990, December 7, 2012. RegulationsSCF
Stress concentration factor. Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global Standards Source: Rules for Classification – Offshore units, DNVGL-OU-0101, Offshore drilling and support units, DNV GL, July 2015. Global Standards Source: Verification of Lifting Appliances for the Oil and Gas Industry, DNV-OSS-308, October 2010, Det Norske Veritas AS, Global StandardsSCF
Equal to the local peak stress in a component (including welds) divided by the nominal stress in the component cross-section at the location of the local peak stress
Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global StandardsSCF
Standard cubic feet. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsSCF
Local peak alternating stress in a component (including welds) divided by the nominal alternating stress in the pipe wall at the location of the component.- NOTE: This factor is used to account for the increase in the stresses caused by geometric stress amplifiers that occur in the riser component.
SCF
Factor relating a nominal stress to the local stress at a detail. NOTE Adapted from ISO 19902:2007, definition 3.50. Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global StandardsSARA
Definition(s)
SARA
Superfund Amendments and Reauthorization Act. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsRQ
Definition(s)
RQ
Reportable quantity. Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global StandardsRP
Definition(s)
RP
Recommended Practice. Source: DNVGL-RP-G108, Cyber security in the oil and gas industry based on IEC 62443, DNV GL, September 2017. Global StandardsSource: API RP 781 Security Plan Methodology for the Oil and Natural Gas Industries.1st Ed. September 2016. Global Standards Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global StandardsRP
Recommended Practice(s). Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global Standards Source: API RP 14G, Recommended Practice for Fire Prevention and Control on Fixed Open-type Offshore Production Platforms: Upstream Segment, Fourth Edition, April 2007. Global Standards Source: 117 OLF, Norwegian Oil and Gas Association recommended guidelines for Well Integrity, No. 117, Revision No. 4, June 2011. Global Standards Source: OGP Report No. 456, Process Safety – Recommended Practice on Key Performance Indicators, International Association of Oil & Gas Producers, November 2011. Global Standards Source: Verification of Lifting Appliances for the Oil and Gas Industry, DNV-OSS-308, October 2010, Det Norske Veritas AS, Global StandardsRP
Person, business, or entity that has been identified as owning the vessel or facility that caused the spill.- NOTE: The term does not imply criminal negligence.