Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Stoichiometric Air
Definition(s)
Stoichiometric Air
Chemically correct ratio of fuel to air capable of perfect combustion with no unused fuel or air. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsStaged Flare
Definition(s)
Staged Flare
Group of two or more flares or burners that are controlled so that the number of flares or burners in operation is proportional to the relief gas flow. 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 StandardsShear Pin Device
Definition(s)
Shear Pin Device
Non-reclosing pressure-relief device actuated by static differential or static inlet pressure and designed to function by the shearing of a load-carrying member that supports a pressure-containing member. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsSafety Relief Valve
Definition(s)
Safety Relief Valve
Spring-loaded pressure-relief valve that can be used as either a safety valve or a relief valve depending on the application. 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 StandardsSafety-Integrity Level (SIL)
Definition(s)
Safety Integrity Level
Discrete integrity level of a safety instrumented function in a safety instrumented system.- NOTE: SILs are categorized in terms of probability of failure; see Annex E.
Safety-Integrity Level (SIL)
Discrete integrity level of a safety instrumented function in a safety instrumented system. NOTE SILs are categorized in terms of probability of failure; see Annex E. Source: API STD 521, Pressure-relieving and Depressuring Systems, Fifth Edition, January 2007 (Addendum May 2008). Global StandardsSafety-Integrity Level (SIL)
discrete level (one out of four) for specifying the safety integrity requirements of the safety instrumented functions to be allocated to the safety instrumented systems Note 1 to entry: Safety integrity level 4 is related to the highest level of safety integrity; safety integrity level 1 has the lowest. Note 2 to entry: The safety integrity level is a requirement about a safety instrumented function. The higher the safety integrity level, the higher the probability that the required safety instrumented function (SIF) will be carried out upon a real demand. Note 3 to entry: This term differs from the definition in IEC 61508–4[2] t o r eflect d ifferences i n p rocess sector terminology. Source: ISO/TR 12489:2013(E), Global StandardsYoke Magnetization
Definition(s)
Yoke Magnetization
Magnetic field induced in OCTG, or in an area of a OCTG, by means of an external electromagnet shaped like a yoke. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRupture-Disk Device
Definition(s)
Rupture-Disk Device
Nonreclosing pressure-relief device actuated by static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a rupture disk.- NOTE: A rupture disk device includes a rupture disk and a rupture disk holder.
Rupture-Disk Device
Non-reclosing pressure-relief device actuated by static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a rupture disk.- NOTE:1 A rupture disk device includes a rupture disk and a rupture disk holder.
- NOTE: 2 In ISO 4126-2, this is termed a bursting-disc safety device.
Wrench Tight
Definition(s)
Wrench Tight
When thread protector is tightened by hand using strap wrench, pipe wrench or thread protector wrench. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsVoltage
Definition(s)
Voltage (V)
Unit potential causing the flow of current. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTorn Threads
Definition(s)
Torn Threads (Tears)
Thread crests which have portions that are chipped, rough, or ragged. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsTool Marks
Definition(s)
Tool Marks
Surface roughness on thread, chamfer, or counterbore surfaces caused by the machining action and condition of the cutting edge of single-point, die, or chaser tools; also can occur in the form of a longitudinal ridge across thread crests due to an improperly shaped or adjusted chaser. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsSubsurface Discontinuity
Definition(s)
Subsurface Discontinuity (or Imperfection)
Any discontinuity that does not open to the surface (either ID or OD). Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsStress
Definition(s)
Stress
Load per unit area. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsSkip
Definition(s)
Skip
Path of the ultrasonic beam in the OCTG from the point of entry on the surface to the back surface and reflecting to the front surface again. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsSkip
“Skip” means a stage, cage, basket or wet bell in which a diver may be lowered to or raised from an underwater work site (skip). 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. RegulationsSkelp
Definition(s)
Skelp
Coil or strip of metal produced to a certain thickness, width, and edge configuration from which welded pipe is made. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsSkelp
Hot-rolled steel strip used for manufacturing EW pipe. Source: API SPEC 5CT, Specification for Casing and Tubing, Upstream Segment, Ninth Edition, July 2011 (Errata September 2012). Global StandardsZero
Definition(s)
Zero
Act of setting a dial indicating depth gauge for "zero depth". Past tense is "zeroed". Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsShoe
Definition(s)
Shoe
See Detector Shoe. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsResidual Field
Definition(s)
Residual Field
Remaining magnetic field retained by ferromagnetic materials after they have been exposed to a magnetic force. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRecommended Practice
Definition(s)
Recommended Practice (RP)
Standard to facilitate the broad availability of proven sound engineering and operating. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRecommended Practice (RP)
The recommended practice publications cover proven technology and solutions which have been found by DNV to represent good practice, and which represent one alternative for satisfy the requirements stipulated in the DNV offshore standards or other codes and standards cited by DNV. Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global StandardsReadout
Definition(s)
Readout
Device that visually indicates a condition, voltage, or current. Typical devices used in inspection requirements are galvanometers and CRTs. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRadioisotope
Definition(s)
Radioisotope
Unstable isotope of an element that disintegrates spontaneously, emitting radiation. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsPulse Duration
Definition(s)
Pulse Duration
Time from initial current flow until the magnetization current has decayed to one-half the peak magnitude. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRelieving Conditions
Definition(s)
Relieving Conditions
Inlet pressure and temperature on a pressure-relief device during an overpressure condition.- NOTE: The relieving pressure is equal to the valve set pressure (or rupture disk burst pressure) plus the overpressure. The temperature of the flowing fluid at relieving conditions can be higher or lower than the operating temperature.
Process Capability
Definition(s)
Process Capability
Ability of a process or NDT method to repeatedly detect a defect under normal conditions of variability. Sometimes related to confidence level. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsProbe
Definition(s)
Probe
Transducer or search unit. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsNonrelevant Indication
Definition(s)
Nonrelevant Indication
Magnetic particle indications that can occur singly or in patterns as a result of leakage fields created by conditions that require no evaluation such as changes in section (like keyways and drilled holes), inherent material properties (like the edge of a bimetallic weld), magnetic writing, etc. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsMill Grind
Definition(s)
Mill Grind
Area of the OCTG surface removed by grinding during the manufacturing process. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsRelief Valve
Definition(s)
Relief Valve
A device that is built into a hydraulic or pneumatic system to relieve (dump) any excess 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 StandardsRelief Valve
Spring-loaded pressure-relief valve actuated by the static pressure upstream of the valve, which normally opens in proportion to the pressure increase over the set pressure.NOTE A relief valve is normally used with incompressible fluids.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global StandardsRelief Valve
Spring-loaded pressure-relief valve actuated by the static pressure upstream of the valve, due to which the valve normally opens in proportion to the pressure increase over the opening pressure.- NOTE: A relief valve is normally used with incompressible fluids.