Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Skid System
Definition(s)
Skid System
Storage, transportation, lifting, and testing frames to facilitate movement of the ROT systems and the modules and components to be replaced or installed. NOTE Skids are used in combination with a skidding system. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsROV Toolskids
Definition(s)
ROV Toolskids
Equipment skids or packages that can be attached onto the external surface of the ROV and are used to perform dedicated tasks. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsROT System
Definition(s)
ROT System
Dedicated, unmanned, subsea tools used for installation and inspection, maintenance, and repair (IMR) tasks that require lift and/or handling capacity beyond that of free-swimming ROV systems. NOTE The ROT system comprises wire-suspended tools with control system and support-handling system for performing dedicated subsea intervention tasks. They are usually deployed on lift wires or a combined lift wire/umbilical. Lateral guidance may be via guidelines, dedicated thrusters, or ROV assistance. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsRemotely Operated Tool System
Definition(s)
Remotely Operated Tool System
Dedicated, unmanned, subsea tools used for installation and inspection, maintenance, and repair (IMR) tasks that require lift and/or handling capacity beyond that of free-swimming ROV systems. NOTE The ROT system comprises wire-suspended tools with control system and support-handling system for performing dedicated subsea intervention tasks. They are usually deployed on lift wires or a combined lift wire/umbilical. Lateral guidance may be via guidelines, dedicated thrusters, or ROV assistance. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsPayload
Definition(s)
Payload <CCU>
The maximum permissible mass or weight of cargo that is authorized for transport by the CCU.
Source: API Standard 2CCU, Offshore Cargo Carrying Units, First Edition, August 2017. Global StandardsPayload
The amount of additional tooling weight carried on the vehicle when it is trimmed neutrally buoyant in seawater. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsOBSROV
Definition(s)
OBSROV
observation class ROV. Source: API Recommended Practice 17H, Remotely Operated Tools and Interfaces on Subsea Production Systems, Second Edition, June 2013 (Addendum 1, October 2014). Global StandardsPSU
Definition(s)
PSU
Practical salinity units. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsWind Spectrum
Definition(s)
Wind Spectrum
Measure of the variance associated with the fluctuating wind speed per unit frequency band. NOTE 1 The wind spectrum is an expression of the dynamic properties of the wind (turbulence). It reflects the fluctuations about and in the same direction as a certain mean wind speed, usually the 1 h sustained wind speed. There is hence no direction variable associated with the wind spectrum within this document. NOTE 2 As the sustained wind speed varies with elevation, the wind spectrum is a function of elevation. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsWave Steepness
Definition(s)
Wave Steepness
Characteristic of individual waves calculated as wave height divided by wave length. NOTE For periodic waves, the concept is straightforward as H/λ. For random waves, the definition is used with the significant wave height (Hs) and the wave length that corresponds with the peak period (Tp) of the wave spectrum in deep water. The significant wave steepness is then defined as Hs/λp = Hs / [(g/2π) Tp2] and is typically in the range of 1/16 to 1/20 for severe sea states. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsWave Spectrum
Definition(s)
Wave Spectrum
measure of the amount of energy associated with the fluctuation of the sea surface elevation per unit frequency band and per unit directional sector. NOTE 1 The wave frequency spectrum (integrated over all directions) is often described by use of some parametric form such as the Pierson-Moskowitz or JONSWAP wave spectrum. NOTE 2 The area under the wave spectrum is the zeroth spectral moment m0, which is a measure of the total energy in the sea state; m0 is used in contemporary definitions of the significant wave height Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsTropical Cyclone
Definition(s)
Tropical Cyclone
Closed atmospheric or oceanic circulation around a zone of low pressure that originates over the tropical oceans NOTE 1 The circulation is counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere. NOTE 2 At maturity, the tropical cyclone can be one of the most intense storms in the world, with wind speeds exceeding 90 m/s and accompanied by torrential rain. NOTE 3 In some areas, local terms for tropical cyclones are used. For example, tropical cyclones are typically referred to as hurricanes in the Gulf of Mexico and North Atlantic, while in the South China Sea and NW Pacific they are called typhoons. In the South Pacific and South Indian Ocean, however, they are commonly referred to as cyclones. NOTE 4 The term cyclone is also used to refer to a tropical storm with sustained wind speeds in excess of 32 m/s (Beaufort Force 12). Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsSwell
Definition(s)
Swell
Sea state in which waves generated by winds remote from the site have travelled to the site, rather than being locally generated. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsStorm Surge
Definition(s)
Storm Surge
Change in sea level (either positive or negative) that is due to meteorological (rather than tidal) forcing. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsStill Water Level
Definition(s)
Still Water Level
Abstract water level typically used for the calculation of wave kinematics for global actions and wave crest elevation for minimum deck elevations NOTE Still water level is an engineering abstract calculated by adding the effects of tides and storm surge to the water depth but excluding variations due to waves (see Figure 1). It can be above or below mean sea level. Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsSquall
Definition(s)
Squall
strong wind event characterized by a sudden onset, a duration of the order of minutes and a rather sudden decrease in speed NOTE 1 A squall is often accompanied by a change in wind direction, a drop in air temperature and by heavy precipitation. NOTE 2 To be classed as a squall the wind speed would typically be greater than about 8 m/s and last for longer than 2 min (thereby distinguishing it from a gust). Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standardsnth spectral moment
Definition(s)
nth spectral moment
Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global StandardsSpectral Moment
Definition(s)
Spectral Moment
Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standards