MAWHP

MAWHP

Definition(s)

Maximum allowable working pressure (MAWP)

The maximum gauge pressure pennitted at the top of a pressure vessel in its operating position for a designated temperature. This pressure is based on calculations using the minimum (or average pitted) thickness for all critical vessel elements, (exclusive of thickness designated for corrosion) and adjusted for applicable static head pressure and non-pressure loads, e.g. wind, earthquake, etc. Source: API 510, Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration Downstream Segment, Ninth Edition, June 2006. Global Standards  

MAWHP

Maximum anticipated wellhead pressure. Source: API  Bulletin 97, Well Construction Interface Document Guidelines, First Edition, December 2013. Global Standards Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards  

MAWHP

Maximum anticipated wellhead pressure (for subsea wells). Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
MASP

MASP

Definition(s)

MASP

Maximum anticipated surface pressure. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards Source: API  Bulletin 97, Well Construction Interface Document Guidelines, First Edition, December 2013. Global Standards Source: OGP Report No. 476, Recommendations for enhancements to well control training, examination and certification, International Association of Oil & Gas Producers, October 2012. Global Standards  
Lower Kelly Valve

Lower Kelly Valve

Definition(s)

Lower Kelly Valve

A full-opening valve installed immediately below the kelly, with outside diameter equal to the drill pipe tool joint outside diameter. NOTE 1: This valve can be closed under pressure to remove the kelly and can be stripped into the hole if a closed IBOP valve is installed above it. NOTE 2: Some lower kelly valve models are not designed to withstand external pressure encountered in stripping operations. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Lower Kelly Valve

An essentially full-opening valve installed immediately below the kelly, with outside diameter equal to the tool joint outside diameter. Valve can be closed to remove the kelly under pressure and can be stripped in the hole for snubbing operations. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global Standards  

Lower Kelly Valve (Kelly Cock)

Essentially full-opening valve installed immediately below the kelly, with outside diameter equal to the tool joint outside diameter. NOTE The valve can be closed to remove the kelly under pressure and can be stripped in the hole for snubbing operations. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards  
Lost Returns

Lost Returns

Definition(s)

Lost Returns

Loss of drilling fluid into the formation resulting in a decrease in pit volume. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Lost Returns

See Lost Circulation. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Kick

Kick

Definition(s)

Kick

Influx of reservoir fluid into the wellbore during drilling or workover that results in shutting in the well and increased pressure below the shut-in device (usually a BOP). Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Kick

Influx of formation liquids or gas into the wellbore. NOTE: Without corrective measure, this condition can result in a blowout. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Kick

Intrusion of formation fluids into the well bore. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Kick

Unplanned, unexpected influx of liquid or gas from the formation into the wellbore, where the pressure of fluid in the wellbore is insufficient to control the inflow. If not corrected can result in a blowout. Source: IADC UBO / MPD Glossary, December 2011. Global Standards  

Kick

"Kick" means the intrusion of formation liquids or gas that results in an increase in circulation pit volume. Without corrective measures, this condition can result in a blowout. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. Regulations
IOM

IOM

Definition(s)

IOM

Installation, operation, and maintenance. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Interlock Sequencing

Interlock Sequencing

Definition(s)

Interlock Sequencing

An arrangement of control system functions designed to require the actuation of one function as a prerequisite to actuate another function. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Inside Blowout Preventer (IBOP)

Inside Blowout Preventer (IBOP)

Definition(s)

Inside Blowout Preventer (IBOP)

A device that can be installed in the drill string that acts as a check valve allowing drilling fluid to be circulated down the string but prevents back flow. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Inside BOP

A device that can be installed in the drill string that acts as a check valve allowing drilling fluid to be circulated down the string but prevents back flow. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
IBOP

IBOP

Definition(s)

IBOP

Inside blowout preventer. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Hydrostatic Head

Hydrostatic Head

Definition(s)

Hydrostatic Head

The pressure that is exerted at any point in the wellbore, due to the weight of the column of fluid above that point. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Hydrostatic Head

The true vertical length of fluid column, normally in feet. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Hydrostatic Head

The true vertical length of fluid column, normally in ft. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  
Hydrogen Sulfide Equipment Service

Hydrogen Sulfide Equipment Service

Definition(s)

Hydrogen Sulfide Equipment Service

Equipment designed to resist the effects caused by exposure to hydrogen sulfide (H2S). Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Hydraulic Chamber Test

Hydraulic Chamber Test

Definition(s)

Hydraulic Chamber Test

The application of a pressure test to any hydraulic operating chamber. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
High-pressure, High-temperature Well

High-pressure, High-temperature Well

Definition(s)

High-Pressure, High-Temperature Well

Wells with a potential pressure greater than 15,000 psi (103.42MPa) at the wellhead or with a potential flowing temperature of greater than 350 °F (177 °C) at the wellhead. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Hang-off

Hang-off

Definition(s)

Hang-Off

An action whereby the weight of that portion of the drill string below a ram BOP is supported by a tool joint resting on the closed pipe ram or through the use of a special hang-off tool that lands in the wellhead. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Hang-Off

Riser when disconnected from seabed. NOTE Hang-off is usually differentiated from disconnected. Disconnected is normally the condition directly after disconnecting the riser. Hang-off is normally associated with the riser suspended from the rotary table. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Gate Valve

Gate Valve

Definition(s)

Gate Valve

A valve that employs a sliding gate to open or close the flow passage. NOTE: The valve may or may not be full opening. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Gate Valve

A valve that employs a sliding gate to open or close the flow passage. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  

Gate Valve

Valve assembly with a gate operating within the body, 90° to the conduit, to effect a closure. Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global Standards  

Gate Valve

Valve that closes by lowering a flat plate or gate to block the flow through the valve. Source: IADC UBO / MPD Glossary, December 2011. Global Standard
Function Test

Function Test

Definition(s)

Function Test

Closing and opening (cycling) equipment to verify operability. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards

Function Test

The operation of a piece of equipment or system to verify its intended operation. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Function Test

"Function-test" means to actuate a component to demonstrate its proper functioning without subjecting it to pressure. Source: Alaska Oil and Gas Conservation Commission, Definitions, Alaska Admin. Code tit. 20, § 25.990, December 7, 2012. Regulations    
Full-Bore Valve

Full-Bore Valve

Definition(s)

Full-Bore Valve

A valve with unobstructed flow area dimensionally equal to or greater than the nominal connection size. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Full-Bore Valve

Valve whose closure mechanism has a bore dimension the same as or larger than the valve body. Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global Standards  
Flex/Ball Joint

Flex/Ball Joint

Definition(s)

Flex/Ball Joint

Device(s) installed between the bottom of the diverter and LMRP joint, to permit relative angular movement of the riser, to reduce stresses due to vessel motion and environmental forces. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Flex/Ball Joint

A device installed directly above the subsea BOP stack and at the top of the telescopic riser joint to permit relative angular movement of the riser to reduce stresses due to vessel motions and environmental forces. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  
Fill-up Line

Fill-up Line

Definition(s)

Fill-up Line

Line usually connected to the diverter housing, or bell nipple, above the BOPs to facilitate adding drilling fluid to the riser main tube, at atmospheric pressure.

Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards

Fill-up Line

A line usually connected into the diverter housing, or bell nipple, above the BOPs to facilitate adding drilling fluid to the hole, at atmospheric pressure. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Fill-up Line

The line through which fluid is added to the riser annulus. Source: API RP 16Q, Recommended Practice for Design, Selection, Operation and Maintenance of Marine Drilling Riser Systems, First Edition, November 1993 (Reaffirmed August 2001). Global Standards Source: ISO 13624-1:2009, Petroleum and natural gas industries – Drilling and production equipment – Part 1:Design and operation of marine drilling riser equipment. Global Standards  

Fill-up Line

A line usually connected into the bell nipple above the BOP to allow adding drilling fluid to the hole while pulling out of the hole to compensate for the metal volume displacement of the drill string being pulled. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards
Equipment User

Equipment User

Definition(s)

Equipment User

The company that owns the well, wellhead, or wellhead assemblies on which the equipment is to be installed. NOTE: This entity may also be the equipment owner in cases where the equipment is rented from a third party supplier, in part or wholly, depending on the level of equipment supplied. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  
Equipment Owner

Equipment Owner

Definition(s)

Equipment Owner

The purchaser or renter of the equipment to be installed on the wellhead. NOTE: In most cases this is the drilling contractor. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Equipment Owner

Owner of the equipment repaired or remanufactured in conformance with this document.

Source: API STANDARD 16AR, Standard for Repair and Remanufacture of Drill-through Equipment, First Edition, April 2017. Global Standards
EDS

EDS

Definition(s)

EDS

Emergency disconnect sequence. Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards Source: Deepwater Well Control Guidelines. IADC Guidelines Source: Oil & Gas UK, Guidelines on subsea BOP systems, Issue 1, July 2012, Global Standards  

EDS

Emergency Disconnect System. Source: OGP Report No. 476, Recommendations for enhancements to well control training, examination and certification, International Association of Oil & Gas Producers, October 2012. Global Standards  

EDS

Emergency disconnect sequenced systems. Source: NORSOK D-001, Drilling facilities, Rev. 3, December 2012. Global Standards  
Drill String Float

Drill String Float

Definition(s)

Drill String Float

A check valve in the drill string that will allow fluid to be pumped in to the well but will prevent wellbore fluids from entering the drill pipe. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Drill String Float

A check valve in the drill string that will allow fluid to be pumped into the well but will prevent flow from the well through the drill pipe. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Drilling Spool

Drilling Spool

Definition(s)

Drilling Spool

Pressure-containing piece of equipment having end connections with or without side outlet connections, used below or between drill-through equipment.

Source: API STANDARD 16AR, Standard for Repair and Remanufacture of Drill-through Equipment, First Edition, April 2017. Global Standards

Drilling Spool

Pressure-containing piece of equipment having end connections and outlets, used below or between drill-through equipment. Source: API Specification 16A, Specification for Drill-through Equipment, Fourth Edition, April 2017. Global Standards Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Drilling Spool

A flanged joint placed between the BOP and casing-head or between BOPs that serve as a spacer or crossover. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Drilling Spool

A flanged joint placed between the BOP and casing-head that serves as a spacer or crossover. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  

Drilling Spool

Pressure-containing piece of equipment having end connections, used below or between drill-through equipment. NOTE When outlet connections are provided, they shall be manufactured in accordance with this American National Standard. Source: API SPEC 16A, Specification for Drill-through Equipment, Third Edition, June 2004 (Errata/Supplement November 2004). Global Standards  

Drilling Spool

BOP stack connection, with flanged ends, used as a spacer between bop equipment, may or may not have side outlets for connection to auxiliary lines. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Drill Pipe Safety Valve

Drill Pipe Safety Valve

Definition(s)

Drill Pipe Safety Valve

An essentially full-opening valve located on the rig floor with threads to match the drill pipe connections or other tubulars in use. NOTE: This valve is used to close off the drill pipe to prevent flow and may be crossed over to fit other connections and sizes of tubulars being installed in the well. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Drill Pipe Safety Valve

An essentially full-opening valve located on the rig floor with threads to match the drill pipe in use. This valve is used to close off the drill pipe to prevent flow. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Drill Pipe Safety Valve

An essentially full-opening valve located on the rig floor with threads to match the drill pipe in use. This valve is used to close off the drill pipe to prevent flow. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards    
CSR

CSR

Definition(s)

CSR

Casing shear ram. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards Source: Oil & Gas UK, Guidelines on subsea BOP systems, Issue 1, July 2012, Global Standards  

CSR

Offshore Installations (Construction and Survey) Regulations 1974. Source: Prevention of Fire and Explosion, and Emergency Response on Offshore Installations, Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995, Approved Code of Practice and guidance (UK HSE L65), Second Edition, 1997. Regulatory Guidance
Control Manifold

Control Manifold

Definition(s)

Control Manifold

The system of valves and piping to control the flow of hydraulic fluid to operate the various components of the BOP stack. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Control Manifold

The assemblage of valves, regulators, gauges and piping used to regulate pressures and control the flow of hydraulic power fluid to operate system functions. Source: API SPEC 16D, Specification for Control Systems for Drilling Well Control Equipment and Control Systems for Diverter Equipment, Upstream Segment, Second Edition, July 2004. Global Standards  
Competent Person

Competent Person

Definition(s)

Competent Person

A person with characteristics or abilities gained through training, experience, or both, as measured against the manufacturers’ or equipment owner’s established requirements. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Competent Person

A person identified by the employer as being capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to personnel, and who has authorization to take prompt corrective measures to eliminate them (OSHA 1926.32). The concept of “competent person” is performance-based relative to the context of the work to be done. 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 Standards  

Competent Person

A competent person [defined in Rule-2(g)] is a person, with appropriate knowledge (theoretical and practical) and experience of operations (including equipment and process). He can carry out thorough examination of operations, which will enable him to detect defects & weaknesses and assess their importance to safety and operations. Source: Guidance Notes on Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, Oil Industry Safety Directorate (India), 2012. Regulatory Guidance  

Competent Person

Competent person means a person with sufficient theoretical knowledge and practical experience to make an informed assessment of the likelihood of a dangerous atmosphere being present or subsequently arising in the space. .Source: IMO resolution A.1050(27), Revised recommendations for entering enclosed spaces aboard ships, 21 December 2011, International Maritime Organization. Regulatory Guidance   

Competent Person

"Competent Person" means one who is capable of identifying existing and predictable hazards in the surrounding or working conditions which are unsanitary, hazardous, or dangerous to employees and who has authorization to take prompt corrective measures to eliminate them or who can recommend directly to persons in authority that such corrective measures be taken. Source: State of Wyoming Occupational Safety and Health Rules and Regulations for Oil and Gas Well Drilling, Revised January 8, 2013. Regulations  

Competent Person

As defined in the EC Directives for Supply of Machinery. Source: NORSOK D-001, Drilling facilities, Rev. 3, December 2012. Global Standards  

Competent Person

A person possessing adequate qualifications such as suitable training and sufficient knowledge, experience and skill for the safe performance of the specific work to a specific standard. Source: NORSOK D-001, Drilling facilities, Rev. 3, December 2012. Global Standards  

Competent Person

Competent person means a person who has the knowledge, experience, skill, and qualifications to carry out a task required by these regulations. Source: Health and Safety in Employment (Petroleum Exploration and Extraction) Regulations 2013, SR 2013/208, New Zealand, as of May 2013. Regulations  

Competent Person

Competent person means any person who has— (a) the relevant knowledge, experience, and skill to carry out a task required or permitted by these regulations to be carried out by a competent person; and (b) either— (i) a relevant qualification evidencing the person’s possession of that knowledge, experience, and skill; or (ii) if the person is an employee, a certificate issued by the person’s employer evidencing the person’s possession of that knowledge, experience, and skill. Source: Health and Safety in Employment (Mining—Underground) Regulations 1999, SR 1999/331, New Zealand, as of 8 October 1999. Regulations  

Competent Person

“Competent person” means a person recognized by the Chief Controller to be a competent person, or a person who holds a certificate of competency for the job in respect of which competency is required from an institution recognized by the Chief Controller in this behalf. Source: The Petroleum Rules, 1976, India, 1976. Regulations Source: The Petroleum Rules, 2002, India, 13th March 2002. Regulations  

Competent Person

“Competent person” means a person who is capable of identifying existing and predictable hazards associated with his area of activities and who has authorization to take prompt corrective measures to eliminate them. Source: Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, India, 18th June 2008. Regulations  

Competent Person

Person, organisation or unit who has sufficient theoretical knowledge and practical experience to examine and judge the technical safety of lifting appliances, in order to issue reports and certificates. Guidance note: The term Competent Person corresponds to the term Enterprice of Competence (EOC) used by The Offshore Mechanical Handling Committee (OMHEC). In some countries the Authorities require that the Competent person shall be certified, authorised or accredited. Source: Verification of Lifting Appliances for the Oil and Gas Industry, DNV-OSS-308, October 2010, Det Norske Veritas AS, Global Standards
Closing Ratio

Closing Ratio

Definition(s)

Closing Ratio

Area of the operator piston exposed to the close operating pressure, divided by the cross-sectional area of the piston shaft exposed to wellbore pressure. Source: API Specification 16A, Specification for Drill-through Equipment, Fourth Edition, April 2017. Global Standards

Closing Ratio (CR)

The area of the operating piston exposed to the close operating pressure, divided by the cross sectional area of the piston shaft exposed to well bore pressure. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards
Clamp Connection

Clamp Connection

Definition(s)

Clamp Connection

A pressure-sealing device used to join two items without using conventional bolted flange joints. NOTE The two items to be sealed are prepared with clamp hubs. These hubs are held together by a clamp containing four bolts. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards