Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Primary Explosive
Definition(s)
Primary Explosive
A very sensitive explosive compound used as the first material in an explosive train that is initiated by the appropriate application of flame, friction, heat, impact, or spark. Also referred to as primary high explosive. Source: API RP 67, Recommended Practice for Oilfield Explosives Safety, Upstream Segment, Second Edition, May 2007. Global StandardsPrimary Grade of Release
Definition(s)
Primary Grade of Release
Release which can be expected to occur periodically or occasionally during normal operation. Source: IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas. Global StandardsPrimary Load
Definition(s)
Primary Load
Axial load to which the equipment is subjected in operation. Source: API RP 8B, Recommended Practice for Procedures for Inspections, Maintenance, Repair and Remanufacture of Hoisting Equipment, Seventh Edition, March 2002 (Reaffirmed: August 2012). Global StandardsPrimary Load
Load which is independent of structural deformation in the riser and induces an internal force that is necessary to satisfy the laws of static equilibrium. NOTE The internal force acts as long as the load is applied, and does not diminish when yielding occurs. EXAMPLE Internal pressure, external hydrostatic pressure, self-weight, contents and buoyancy of the riser. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global StandardsPrimary Load
Load that arises within the equipment when the equipment is performing its primary design function. Source: API SPEC 7K, Drilling and Well Servicing Equipment Upstream Segment, Fifth Edition, June 2010 (August 2010). Global Standards Source:API SPECIFICATION 7K, Drilling and Well Servicing Equipment, Sixth Edition, December 2015. Global StandardsPrimary Load
Axial load that equipment is subjected to in operations. Source: API SPEC 8C, Drilling and Production Hoisting Equipment (PSL 1 and PSL 2), Fifth Edition, April 2012. Global StandardsPrimary Load Path Parts
Definition(s)
Primary Load Path Parts
Primary load path parts are those intended to control or regulate the movement of pressurized fluids (pressure controlling) and/or those whose failure to function as intended would result in the release of retained fluid to the atmosphere (pressure containing). Source: API SPEC 7K, Drilling and Well Servicing Equipment Upstream Segment, Fifth Edition, June 2010 (August 2010). Global Standards Source:API SPECIFICATION 7K, Drilling and Well Servicing Equipment, Sixth Edition, December 2015. Global StandardsPrimary Load-bearing Components
Definition(s)
Primary Load-bearing Components
The primary load-bearing components for a mud pump shall be defined as those containing the discharge pressure, with the exception of expendable items and closure components such as liners, pistons, piston rods, packing, packing glands, valves and seats, covers, heads, clamps, bushings, plugs, and fasteners.
Source:API SPECIFICATION 7K, Drilling and Well Servicing Equipment, Sixth Edition, December 2015. Global StandardsPrimary Load-carrying Equipment
Definition(s)
Primary Load-carrying Equipment
Equipment (parts or members) whose failure can compromise the integrity of the entire riser string.
Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global StandardsPrimary Location Instruments
Definition(s)
Primary Location Instruments
Location where the instruments normally used to monitor flow conditions are located. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPrimary Marking
Definition(s)
Primary marking
Primary marking is defined as marking of major structural members and systems that need to be identified for operational, installation, and retrieval purpose. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsPrimary marking
Primary marking is defined as the marking of major structural members and systems that need to be identified for operational, installation and retrieval purposes. Recommended character height for marking of symbols is 170 mm (6,693 in) to 500 mm (19,685 in). Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsPrimary Means of Escape
Definition(s)
Primary Means of Escape
Fixed stairways or fixed ladders of non-combustible construction. 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 StandardsPrimary Method
Definition(s)
Primary Method, of Evacuation
Preferred method of leaving the installation in an emergency which can be carried out in a fully controlled manner under the direction of the person in charge. Source: ISO 15544:2000, Petroleum and natural gas industries – Offshore production installations – Requirements and guidelines for emergency. Global StandardsPrimary Process Piping
Definition(s)
Primary Process Piping
Process piping in normal, active service that cannot be valved-off or, if it were valved off, would significantly affect unit operability. Primary process piping typically does not include small bore or auxiliary process piping (see also secondary process piping). Source: API 570, Piping Inspection Code: In-service Inspection, Rating, Repair, and Alteration of Piping Systems, Fourth Edition, February 2016, with Addendum May 2017. Global StandardsPrimary Stakeholders
Definition(s)
Primary Stakeholders
Those individuals or groups who are directly impacted (positively or negatively) by the project, including beneficiaries of the project. Primary stakeholders typically have a heightened interest in the project and have the ability to strongly influence its progress (positively or negatively). Source: Identifying and assessing water sources: Guidance document for the onshore oil and gas industry, International Petroleum Industry Environmental Conservation Association (IPIECA), 2014. Global StandardsPrimary Stress
Definition(s)
Primary Stress
Stress that satisfies the laws of equilibrium of pressure, external force and moment (i.e. load effects). NOTE 1 Regarding the mechanical behaviour of a structure, the basic characteristic of this type of stress is that in case of (non-admissible) increment of external load, the deformations upon full plasticification of the section considerably increases without being self-limiting. NOTE 2 Regarding primary stress, distinction is made between membrane stress and bending stress with respect to their distribution across the cross-section governing the load-carrying behaviour. Primary membrane stress is defined as the average value of the respective stress components distributed over the section governing the load-carrying behaviour. Primary bending stress is defined as primary stress distributed linearly across the considered section and proportional to the distance from the neutral axis. NOTE 3 Regarding the distribution of membrane stress along the wall, distinction is made between general primary membrane stress and local primary membrane stress. Membrane stress due to gross structural discontinuities (e.g. integral attachments) is considered as local. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global StandardsPrimary Stress
A primary stress is one that is induced by the external loads or preload and is necessary to satisfy the laws of static equilibrium. Examples of primary stress are the membrane stress in a rod loaded by an axial force and the bending stress in a simple beam. Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global StandardsPrimary Stress
Normal or shear stress developed by the imposed loading which is necessary to satisfy the laws of equilibrium of external and internal forces and moments (ASME BPVC, Section VIII, Division 2, Paragraph 5.12). NOTE The basic characteristic of a primary stress is that it is not self-limiting. Primary stresses that considerably exceed the yield strength will result in failure or at least in gross distortion. A general primary membrane stress is one that is distributed in the structure such that no redistribution of load occurs as a result of yielding. Source: API TR 1PER15K-1, Protocol for Verification and Validation of High-pressure High-temperature Equipment, First Edition, March 2013. Global StandardsPrimary Structural Damage
Definition(s)
Primary Structural Damage
Damage which can result from lightning strike to units which do not provide a path of low resistance to earth for the passage of lightning currents, for example units of non-metallic construction or those having substantial non-metallic members. Source: IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation, Third Edition, December 2013. Global Standards Source: IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation. Global StandardsPrimary Structure
Definition(s)
Primary Structure
Load-carrying and supporting frames and load-carrying panels.- NOTE: Primary structure includes, but is not limited to, the following structural components:
— internal securing points
Source: API Standard 2CCU, Offshore Cargo Carrying Units, First Edition, August 2017. Global StandardsPrimary Well Barrier
Definition(s)
Primary Well Barrier
First set of well barrier elements that prevent flow from a source of inflow. Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global StandardsPrimary Well Barrier
First set of barrier elements that prevents flow from a source. Source: API RP 90, Annular Casing Pressure Management for Offshore Wells, Upstream Segment. First Edition, August 2006. Global StandardsPrimary Well Control
Definition(s)
Primary Well Control
Prevention of formation fluid flow by maintaining a hydrostatic pressure equal to or greater than formation pressure. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global StandardsPrimary-Load-Carrying Component
Definition(s)
Primary-Load-Carrying Component
Component of the equipment through which the primary load is carried. Source: API RP 8B, Recommended Practice for Procedures for Inspections, Maintenance, Repair and Remanufacture of Hoisting Equipment, Seventh Edition, March 2002 (Reaffirmed: August 2012). Global Standards Source: API SPEC 7K, Drilling and Well Servicing Equipment Upstream Segment, Fifth Edition, June 2010 (August 2010). Global Standards Source:API SPECIFICATION 7K, Drilling and Well Servicing Equipment, Sixth Edition, December 2015. Global Standards Source: API SPEC 8C, Drilling and Production Hoisting Equipment (PSL 1 and PSL 2), Fifth Edition, April 2012. Global StandardsPrime Pipe
Definition(s)
Prime Pipe
Pipe meeting all of the specified inspection and testing requirements. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsPrincipal Stress
Definition(s)
Principal Stress
Stress on a principal plane for which the shear stress is zero. NOTE For any general state of stress at any point, there exist three mutually perpendicular planes at that point on which shearing stresses are zero. The remaining normal stress components on these three planes are principal stresses. The largest of these three stresses is called the maximum principal stress. Source: API TR 5C3, Technical Report on Equations and Calculations for Casing, Tubing, and Line Pipe Used as Casing or Tubing; and Performance Properties Tables for Casing and Tubing, Upstream Segment, First Edition, December 2008. Global StandardsPrior Exposure
Definition(s)
Prior Exposure
The historical exposure of a platform to the design metocean, seismic, or ice loading. Source: API RP 2SIM, Structural Integrity Management of Fixed Offshore Structures, First Edition, November 2014. Global StandardsPrivacy
Definition(s)
Privacy
The assurance that the confidentiality of, and access to, certain information about an entity is protected. Extended Definition: The ability of individuals to understand and exercise control over how information about themselves may be used by others. From: NIST SP 800-130; Adapted from: DHS personnel. Source: NICCS™ Portal Cybersecurity Lexicon, National Initiative for Cybersecurity Careers and Studies (https://niccs.us-cert.gov/glossary) as of 11 November 2015, Global StandardsPrivate Key
Definition(s)
Private Key
A cryptographic key that must be kept confidential and is used to enable the operation of an asymmetric (public key) cryptographic algorithm. Extended Definition: The secret part of an asymmetric key pair that is uniquely associated with an entity. Adapted from: CNSSI 4009, NIST SP 800-63 Rev 1, FIPS 201-2, FIPS 140-2, Federal Bridge Certificate Authority Certification Policy 2.25. Source: NICCS™ Portal Cybersecurity Lexicon, National Initiative for Cybersecurity Careers and Studies (https://niccs.us-cert.gov/glossary) as of 11 November 2015, Global StandardsProactive MPD
Definition(s)
Proactive MPD
Using MPD methods and/or equipment to actively control the pressure profile throughout the exposed wellbore. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsProbabilistic Method
Definition(s)
Probabilistic Method
Approach which uses distributions of geometric and material property values to calculate a distribution of performance property values. Source: API TR 5C3, Technical Report on Equations and Calculations for Casing, Tubing, and Line Pipe Used as Casing or Tubing; and Performance Properties Tables for Casing and Tubing, Upstream Segment, First Edition, December 2008. Global StandardsProbabilistic Seismic Hazard Analysis
Definition(s)
Probabilistic Seismic Hazard Analysis
Framework permitting the identification, quantification, and rational combination of uncertainties in earthquakes' intensity, location, rate of recurrence, and variations in ground motion characteristics. Source:API RP 2EQ, Seismic Design Procedures and Criteria for Offshore Structures, First Edition, November 2014. Global StandardsProbability
Definition(s)
Probability
Numerical value between zero and one assigned to a random event (which is a subset of the sample space) in such a way that the assigned number obeys three axioms: 1) the probability of the random event "A" must be equal to, or lie between, zero and one; 2) the probability that the outcome is within the sample space must equal one; and3) the probability that the random event "A" or "B" occurs must equal the probability of the random event "A" plus the probability of the random event "B" for any two mutually exclusive events.
Source:API STANDARD 780, Security Risk Assessment Methodology for the Petroleum and Petrochemical Industries, First Edition, May 2013. Global StandardsProbability
Numerical value between zero and one assigned to a random event (which is a subset of the sample space) in such a way that the assigned number obeys three axioms: (1) the probability of the random event ―A‖ must be equal to, or lie between, zero and one; (2) the probability that the outcome is within the sample space must equal one; and (3) the probability that the random event ―A‖ or ―B‖ occurs must equal the probability of the random event ―A‖ plus the probability of the random event ―B‖ for any two mutually exclusive events. Sample Usage: The probability of a coin landing on "heads" is 1/2. Annotation:- 1.Probability can be roughly interpreted as the percent chance that something will occur. For example, a weather forecaster’s estimate of a 30 percent chance of rain in the Washington, DC area is equivalent to a probability of 0.3 that rain will occur somewhere in Washington, DC.
- 2.A probability of 0 indicates the occurrence is impossible; 1 indicates that the occurrence will definitely happen.
- 3.Probability is used colloquially as a synonym for likelihood, but in statistical usage there is a clear distinction.
- 4.The probability that event A occurs is written as P(A).
- 5.Event A and event B are mutually exclusive if they cannot occur at the same time. For example, a coin toss can result in either heads or tails, but both outcomes cannot happen simultaneously.
- 6.Event A and event B are statistically independent if the occurrence of one event has no impact on the probability of the other. Examples of two events that are independent are the systems designed to prevent an attack as described the Fault Tree example and Event Tree example. The probability that the Personnel Action to Stop Attack is successful is not affected by whether the Security Equipment to Stop Attack is successful and vice versa. Two events that may not be independent are the collapse of a bridge and the occurrence of a major earthquake in the area. Clearly the probability of a bridge collapse can be affected by the occurrence of a major earthquake. However, the two events may also be independent: a bridge can survive an earthquake and a bridge can collapse in the absence of any earthquake.
- 7.Conditional probability is the probability of some event A, given the occurrence of some other event B, written as P(A|B). An example is the conditional probability of a person dying (event A), given that they contract the pandemic flu (event B).
- 8.Joint probability is the probability of two events occurring in conjunction -that is, the probability that event A and event B both occur, written as ) or P(AB) and pronounced A intersect B. The probability of someone dying from the pandemic flu is equal to the joint probability of someone contracting the flu (event A) and the flu killing them (event B). Joint probabilities are regularly used in Probabilistic Risk Assessments and Event Trees.
- 9.Conditional and joint probabilities are related by the following formula: