Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
DC-Block
Definition(s)
DC-Block
Distance calibration block. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsCPLG
Definition(s)
CPLG
Unattached couplings. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsBC
Definition(s)
BC
Buttress thread casing. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsBC
API Spec 5B buttress thread casing connection. Source: API SPEC 5CT, Specification for Casing and Tubing, Upstream Segment, Ninth Edition, July 2011 (Errata September 2012). Global StandardsMarked Burst Pressure or Rated Burst Pressure (Rupture Disk)
Definition(s)
Marked Burst Pressure or Rated Burst Pressure (Rupture Disk)
Burst pressure, established by tests for the specified temperature and marked on the disk tag by the manufacturer. NOTE The marked burst pressure can be any pressure within the manufacturing design range unless otherwise specified by the customer. The marked burst pressure is applied to all of the rupture disks of the same lot. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsALTFLD
Definition(s)
ALTFLD
Full-length alternate drifted. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsYoke
Definition(s)
Yoke
U-shaped piece of soft magnetic material, either solid or laminated, around which a coil is wound to carry a magnetizing current. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsWetting Agent
Definition(s)
Wetting Agent
Substance which lowers the surface tension of a liquid. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsVernier Calliper
Definition(s)
Vernier Calliper (or Dial Calliper)
Measuring device, usually with two legs or jaws, that can be adjusted to measure the thickness, diameter, and distance between surfaces. NOTE Vernier callipers have a vernier scale readout whereas dial callipers have a dial readout. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsVanish Point
Definition(s)
Vanish Point
Location where the external thread runs out or terminates on the OCTG outside surface. NOTE The vanish point is the point where the lead of the chaser tool makes its final cut. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsUpset
Definition(s)
Upset (Noun)
Forged metal end of OCTG with increased wall thickness and diameter, later to be threaded or welded. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsUpset
A pipe end with increased wall thickness. The outside diameter may be increased, or the inside diameter may be reduced, or both. Upsets are usually formed by hot forging the pipe end. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsUpset
Forged end of a drill pipe tube used to increase wall thickness. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsUltrasonic Velocity
Definition(s)
Ultrasonic Velocity
Speed at which ultrasonic sound waves travel through a medium. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsUltrasonic
Definition(s)
Ultrasonic
Having a frequency above the audible range, i.e. above 20 kHz. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsUltrasonic Test
Definition(s)
Ultrasonic Test
NDT method using high-frequency sound waves. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTransverse
Definition(s)
Transverse
Across, usually circumferential or substantially circumferential in direction. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTransducer
Definition(s)
Transducer
Device which converts one form of energy to another. EXAMPLES Ultrasonic probes, search coils, eddy-current probes and most other detectors. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTransducer
See sensor. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsTolerance
Definition(s)
Tolerance
Permissible deviation from the specified value. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTolerance
The amount of variation permitted. 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 Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsTolerance
Amount of variation permitted. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsTolerance
The amount of skim hydrocarbons that may be recovered before the produced water disposal system operator must allocate to the producing property. Source: Oil and Gas Division, Texas Administrative Code, Title 16, Chapter 3, February 2013. RegulationsThreshold
Definition(s)
Threshold
Investigation level established during EMI or UT inspection, above which indications are further investigated. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsThread Protector
Definition(s)
Thread Protector
Protection device placed on the end of OCTG to protect threads and seals from damage. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsThread Protector
Cap or insert used to protect threads and seals during handling, transportation and storage. Source: API SPEC 5CT, Specification for Casing and Tubing, Upstream Segment, Ninth Edition, July 2011 (Errata September 2012). Global Standards Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global StandardsThread Form
Definition(s)
Thread Form
Profile of a thread in an axial (longitudinal) plane for a length of one pitch. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsThread Form
The form of thread is the thread profile in an axial plane for a length of one pitch. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsThread Form
Thread profile in an axial plane for a length of one pitch. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsTest Block
Definition(s)
Test Block
Special precision blocks, used as standards to verify calibration of an inspection instrument. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsMach Number
Definition(s)
Mach Number
Actual fluid velocity divided by the velocity at which sound waves propagate through the fluid at the associated temperature.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsMach Number
Ratio of a fluid’s velocity, measured relative to some obstacle or geometric figure, divided by the speed at which sound waves propagate through the fluid. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsLiquid Seal or Water Seal
Definition(s)
Liquid Seal or Water Seal
Device that directs the flow of relief gases through a liquid (normally water) on the path to the flare burner, used to protect the flare header from air infiltration or flashback, to divert flow, or to create back pressure for the flare header. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsLift
Definition(s)
Lift
Actual travel of the disc from the closed position when a valve is relieving. Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global Standards Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsLateral
Definition(s)
Lateral
Section of pipe connecting the outlet(s) of single-source relief device(s) to a header where other sources are tied in.- NOTE: The relief flow in a lateral is always from a single source, whereas the relief flow in a header can be from either single or multiple sources simultaneously.
Lateral
Section of pipe from outlet flange(s) of single-source relief device(s) downstream of a header connection where relief devices from other sources are tied in.- NOTE: The relief flow in a lateral is always from a single source, whereas the relief flow in a header can be from either single or multiple sources simultaneously.
Lateral
“Lateral” means a portion of a directional well past the point where the well bore has been intentionally departed from the vertical. Source: Oil and Gas, New Mexico Administrative Code Title 19, Chapter 15, January 2013. RegulationsKnockout Drum
Definition(s)
Knockout Drum
Vessel in the effluent handling system designed to remove and store liquids. Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global Standards Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsJet Fire
Definition(s)
Jet Fire
Turbulent diffusion flame resulting from the combustion of a fuel continuously released with significant momentum in a particular direction. 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 StandardsJet Fire (JF)
Turbulent diffusion flame resulting from the combustion of a fuel continuously released with momentum in a particular direction. Source: ISO 13702:2015, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore production installations — Requirements and guidelines, Second Edition, August 2015. Global StandardsJet Fire
Fire created when a leak from a pressurized system ignites and forms a burning jet.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsJet Fire
Fire created when a leak from a pressurized system ignites and forms a burning jet.- NOTE: A jet fire can impinge on other equipment, causing damage.