Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Pressure Deployment
Definition(s)
Pressure Deployment
Process of deploying or recovering drill string or coiled tubing components from a live or pressurized well. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure Design Thickness
Definition(s)
Pressure Design Thickness
Minimum allowed pipe wall thickness needed to hold the design pressure at the design temperature.- NOTE: 1 Pressure design thickness is determined using the rating code formula, including needed reinforcement thickness.
- NOTE: 2 Pressure design thickness does not include thickness for structural loads, corrosion allowance, or mill tolerances and therefore should not be used as the sole determinant of structural integrity for typical process piping (e.g. 7.3).
Pressure End Load
Definition(s)
Pressure End Load
Axial load resulting from internal pressure applied to the area defined by the maximum seal diameter. Source: API Specification 16A, Specification for Drill-through Equipment, Fourth Edition, April 2017. Global Standards Source: API SPEC 16A, Specification for Drill-through Equipment, Third Edition, June 2004 (Errata/Supplement November 2004). Global StandardsPressure End Load
The axial load resulting from internal pressure applied to the area defined by the maximum seal diameter. Source: API SPEC 16RCD, Specification for Drill Through Equipment—Rotating Control Devices, Upstream Segment, First Edition, February 2005. Global StandardsPressure Equalization Valve (Dump Valve)
Definition(s)
Pressure Equalization Valve (Dump Valve)
A device used to control bottom-riser annulus pressure by establishing direct communication with the sea. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global StandardsPressure Gradient
Definition(s)
Pressure Gradient, Normal
The normal pressure divided by true vertical depth. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global StandardsPressure Control
Change of pressure with depth, usually expressed as pounds per square inch per foot. A scale of pressure differences in which there is a uniform difference in pressure from point to point. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure Integrity
Definition(s)
Pressure Integrity
Structural and leak-resistant capability of a product to contain applied pressure. Source: API RP 17A Addendum 1, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, December 2010. Global StandardsPressure Integrity
The structural and leak resistant capability of a product to contain applied pressure. Source: API SPEC 16C, Specification for Choke and Kill Systems, First Edition, January 1993 (Reaffirmed 2001). Global StandardsPressure Loss
Definition(s)
Pressure Loss
Rate of decrease in pressure along the flowing line or vessel (P f) due to friction of the fluid against the pipe wall. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure Operations
Definition(s)
Pressure operations
Well operations where any of the following conditions exist: the wellbore hydraulic fluid column is not expected to contain formation pressure, if well kill operations are anticipated or if surface pressure control equipment is required during a well operation. Source: OGP Report No. 476, Recommendations for enhancements to well control training, examination and certification, International Association of Oil & Gas Producers, October 2012. Global StandardsPressure Rating
Definition(s)
Pressure Rating
Rating for a component, relating to its long-term resistance to failure when subjected to either static or standardized cyclic internal pressure loading. Source: ISO 14692-1:2017, Petroleum and natural gas industries — Glass-reinforced plastics (GRP) piping — Part 1: Vocabulary, symbols, applications and materials, Second Edition, August 2017. Global StandardsPressure Regulator
Definition(s)
Pressure Regulator
A control system component that permits attenuation of control system supply pressure to a satisfactory pressure level to operate components downstream. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global StandardsPressure Relief Device
Definition(s)
Pressure-relief device
Device actuated by inlet static pressure and designed to open during emergency or abnormal conditions to prevent a rise of internal fluid pressure in excess of a specified design value.- NOTE: The device may be a pressure-relief valve, a rupture disk device, or a buckling pin device.
Pressure Relief Device (PRD)
A device designed to open and relieve excess pressure (e.g. safety valve, thermal relief, rupture disk, rupture pin, deflagration vent, pressure/vacuum vents). Source: OGP Report No. 456, Process Safety – Recommended Practice on Key Performance Indicators, International Association of Oil & Gas Producers, November 2011. Global StandardsPressure Relief Device
A device for relieving pressure, such as a direct spring-loaded safety valve, rupture disk, or shear-pin set safety valve. Source: Petroleum Safety Orders--Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. RegulationsPressure Retaining
Definition(s)
Pressure Retaining
Device or part that is stressed due to the effects of a differential pressure acting on its boundary.
Source:API SPECIFICATION 19TT, Specification for Downhole Well Test Tools and Related Equipment, First Edition, October 2016. Global StandardsPressure Reversal
Definition(s)
Pressure Reversal
Change from predominant pressure in the annulus to predominant pressure in the work string bore or vice versa.
Source:API SPECIFICATION 19TT, Specification for Downhole Well Test Tools and Related Equipment, First Edition, October 2016. Global StandardsPressure Reversal
Change in the direction of the pressure differential across the packing element from above to below or vice versa. Source: API SPEC 11D1, Packers and Bridge Plugs, Upstream Segment, Second Edition, July 2009. Global StandardsPressure System
Definition(s)
Pressure System
System of vessels, pipes, and other equipment operating with an internal pressure exceeding atmospheric.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsPressure System
“Pressure system” means a boiler, pressure vessel, pump, compressor and the piping system connected thereto that contains or is intended to contain a gas, vapour or at a pressure greater than atmospheric pressure. Source: Nova Scotia Offshore Petroleum Occupational Health & Safety Requirements, Canada-Nova Scotia Offshore Petroleum Board, Canada, December 2000. RegulationsPressure Tank
Definition(s)
Pressure Tank
Pressure tank means a tank having a design pressure greater than 0.07 MPa gauge. A pressure tank shall be an independent tank and shall be of a configuration permitting the application of pressure-vessel design criteria according to recognized standards. 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. Regulatory guidance, International Maritime OrganizationPressure Tank or Process Vessel
Definition(s)
Pressure Tank or Process Vessel
Tank or vessel used for an integrated operation in petrochemical facilities, refineries, gas plants, oil and gas production facilities, and other facilities. cf. storage tank (3.74). NOTE A process tank or vessel used for an integrated operation can involve, but is not limited to, preparation, separation, reaction, surge control, blending, purification, change in state, energy content, or composition of a material. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsPressure Test
Definition(s)
Pressure Test
A test performed on pressure vessels that have been in service and that have undergone an alteration or repair to the pressure boundary(s) to indicate that the integrity of the pressure components are still compliant with the original construction code. The pressure test can be hydrostatic, pneumatic, or a combination thereof. Pressure tests at less than those specified by the construction code to determine if there may be leaks in the system are generally referred to as tightness tests.
Source: API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration, Tenth Edition, May 2014, with Addendum May 2017. Global StandardsPressure Test
Application of pressure to a piece of equipment or a system to verify the pressure containment capability for the equipment or system. Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global StandardsPressure Test
The periodic application of pressure to a piece of equipment or a system to verify the pressure containment capability for the equipment or system. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global StandardsPressure Transient
Definition(s)
Pressure Transient
Pressure waves, traveling through the pipes at the wave speed of the fluid and caused by changes in the operation of the system. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure Transmitters
Definition(s)
Pressure Transmitters
Instruments to measure and report pressure. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure Vessel
Definition(s)
Pressure Vessel
A container designed to withstand internal or external pressure. This pressure may be imposed by an external source, by the application of heat from a direct or indirect source, or by any combination thereof. This definition includes heat exchangers, air coolers, columns, towers, unfired steam generators (boilers), and other vapor generating vessels that use heat from the operation of a processing system or other indirect heat source. (Specific limits and exemptions of equipment covered by this inspection code are provided in Section 1 and Annex A.). Source: API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration, Tenth Edition, May 2014, with Addendum May 2017. Global StandardsPressure Vessel
Tank or vessel used for an integrated operation in petrochemical facilities, refineries, gas plants, oil and gas production facilities, and other facilities.- NOTE: 1 See storage tank (3.1.79).
- NOTE: 2 A process tank or vessel used for an integrated operation can involve, but is not limited to, preparation, separation, reaction, surge control, blending, purification, change in state, energy content, or composition of a material.
Pressure Vessel
A container designed to withstand internal or external pressure. This pressure may be imposed by an external source, by the application of heat from a direct or indirect source, or by any combination thereof. This definition includes heat exchangers, air-coolers, unfired steam generators and other vapor generating vessels which use heat from the operation of a processing system or other indirect heat source. (Specific limits and exemptions of equipment covered by this inspection code are given in Section 1 and Appendix A.) Source: API 510, Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration Downstream Segment, Ninth Edition, June 2006. Global StandardsPressure Vessel
Vessel in a consistometer into which the slurry container is placed for the thickening-time test. Source: API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005 (Reaffirmed: July 2010). Global StandardsPressure Vessel
For BOP control systems, a pressure vessel is a container for the containment of internal fluid pressure. 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 StandardsPressure Vessel
“Pressure vessel” means a closed container capable of withstanding internal or external pressures, or both, greater than one atmosphere (appareil sous pression). Source: Canada Oil and Gas Diving Regulations, SOR/88-600, February 2013. Regulations Source: Nova Scotia Offshore Area Petroleum Diving Regulations, SOR/95-189, Canada, current to May 31, 2012. RegulationsPressure Vessel
“Pressure vessel” means a closed container capable of withstanding internal or external pressures, or both, greater than one atmosphere (appareil sous pression). Source: Canada Oil and Gas Diving Regulations, SOR/88-600, February 2013. Regulations Source: Nova Scotia Offshore Area Petroleum Diving Regulations, SOR/95-189, Canada, current to May 31, 2012. RegulationsPressure Vessel
A container, including cylinders, used for the storage or accumulation of any gas or liquid under pressure and as defined in the Unfired Pressure Vessel Safety Orders with the following exceptions:- Those exceptions defined in Section 451 of the Unfired Pressure Vessel Safety Orders.
- Pressure vessels constructed entirely of pipe and fittings conforming to and in service as prescribed in the applicable ANSI code.
- High and low pressure gas holder covered by General Order No. 94-B of the Public Utility Commission of the State of California with revised Section 4a, effective November 12, 1970.
Pressure Vessel
A tank with design gas or vapour pressure exceeding 0.7 bar. Source: Rules for Classification – Offshore units, DNVGL-OU-0101, Offshore drilling and support units, DNV GL, July 2015. Global StandardsPressure Vessel
"Pressure-vessel" means a storage tank or vessel which has been designed to operate at pressures above 15 psi. Source: State of Wyoming Occupational Safety and Health Rules and Regulations for Oil and Gas Well Drilling, Revised January 8, 2013. RegulationsPressure Vessel Engineer
Definition(s)
Pressure vessel engineer
A person acceptable to the owner/user who is knowledgeable and experienced in the engineering disciplines associated with evaluating mechanical and material characteristics that affect the integrity and reliability of pressure vessels. The pressure vessel engineer, by consulting with appropriate specialists, should be regarded as a composite of all entities needed to properly assess the technical requirements. Wherever the term “engineer” is used in this code, it refers to a pressure vessel engineer.
Source: API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration, Tenth Edition, May 2014, with Addendum May 2017. Global StandardsPressure vessel engineer
A person acceptable to the owner/user who is knowledgeable and experienced in the engineering disciplines associated with evaluating mechanical and material characteristics which affect the integrity and reliability of pressure vessels. The pressure vessel engineer, by consulting with appropriate specialists, should be regarded as a composite of all entities needed to properly assess the technical requirements. Wherever the term "engineer" is used in this code, it refers to a pressure vessel engineer. Source: API 510, Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration Downstream Segment, Ninth Edition, June 2006. Global StandardsPressure Vessel Quality
Definition(s)
Pressure Vessel Quality
Structural and leak-resistant capability of a product to contain applied pressure. Source: API SPEC 16C, Specification for Choke and Kill Systems, First Edition, January 1993 (Reaffirmed 2001). Global StandardsPressure Vessel Quality
Metallic material the integrity of which is such that it can be used to safely contain pressure without risk of leakage or rupture. Source: API SPEC 16RCD, Specification for Drill Through Equipment—Rotating Control Devices, Upstream Segment, First Edition, February 2005. Global StandardsPressure Vessel –Phase Separation
Definition(s)
Pressure Vessel –Phase Separation
First Option. Single four – phase separation vessel using velocity drop in the first compartment to create gas and solids phase separation. Liquids cascade to the back compartments where with sufficient residence time the interface forms. Requires sufficient time for the interface between liquids to take place which means the vessel has to be correspondingly large to accomplish the process. Second Option. A series of vessels designed to separate the phases sequentially. Order of phase separation may vary from system to system. Different systems available are: Gas to be separated first as it is compressible and of lower density than solids or liquids. Remove solids first as they will erode pipe work and components in the system. Separation of gas, solids, and liquids occurs in individual hydro-cyclones connected in series, parallel, or a combination of both. In all separators, the design should make it impossible for gas to travel down the liquid leg and liquid to travel down the gas leg. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPressure While Drilling (PWD)
Definition(s)
Pressure While Drilling (PWD)
The measurement of downhole pressure while drilling by a tool installed in the BHA. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsPressure-Boundary Penetration
Definition(s)
Pressure-Boundary Penetration
Device that penetrates directly into or communicates with the well-bore and is not defined elsewhere in this International Standard. EXAMPLES Grease or sealant injection fitting; check valve; control, test or gauge port plug and fitting, needle valve on test, gauge or injection port; electric and control line penetration. Source: API RP 17A Addendum 1, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, December 2010. Global StandardsPressure-containing
Definition(s)
Pressure-containing
Product or part whose failure to function as intended results in a release of retained fluid to the atmosphere.
Source: API STANDARD 18LCM, Product Life Cycle Management System Requirements for the Petroleum and Natural Gas Industries, First Edition, April 2017. Global StandardsPressure-containing
Part whose failure to function as intended results in a release of wellbore fluid to the environment (API 6A). Source: API TR 1PER15K-1, Protocol for Verification and Validation of High-pressure High-temperature Equipment, First Edition, March 2013. Global StandardsPressure-Containing Equipment
Definition(s)
Pressure-Containing Equipment
Equipment (parts or members) whose failure to function as intended can result in a release of fluids to the environment.
Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global StandardsPressure-Containing Equipment
Equipment [part(s) or member(s)] exposed to wellbore fluids whose failure to function as intended can result in a release of wellbore fluid to the environment. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global StandardsPressure-Containing Part
Definition(s)
Pressure-Containing Part
Part exposed to wellbore fluids whose failure to function as intended would result in a release of wellbore fluid to the environment.- NOTE: 1 Examples include bodies and bonnets.
- NOTE: 2 Examples of items that are not included are operating cylinders and cylinder heads.