Mean Static Offset

Mean Static Offset

Definition(s)


Mean Static Offset (of vessel)

Mean static offset includes static offset due to steady forces from current, wind and wave, offset due to low-frequency motions and active positioning of the vessel. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Mean Temperature

Mean Temperature

Definition(s)


Mean Temperature

Average temperature in a flowing line or vessel. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Mean Time Between Failures

Mean Time Between Failures

Definition(s)


Mean Time Between Failures

Expectation of the time between failures. NOTE The MTBF of an item can be longer or shorter than the design life of the system. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global Standards  

Mean Time Between Failures

MTBF expected time between successive failures of a repairable item Note 1 to entry: In the cases illustrated in Figure 4, the MTBF is linked with MTTF and MTTRes by the following relationship: MTBF = MTTF+MTTRes. More generally It is also linked to the MUT and MDT by MTBF = MUT+MDT. Note 2 to entry: The acronym MTBF is sometimes defined as the mean operating time between failures (e.g. in IEV191[14]). This is not at all the same and, in this case, the formula described in Note 1 to entry is no longer valid. This is very confusing, therefore the traditional definition of the MTBF is retained in this Technical Report. FIG.4 Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards
Mean Time to Demand

Mean Time to Demand

Definition(s)


Mean Time to Demand

expected time before the demand on the safety system occurs. Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards
Mean Time to Failure

Mean Time to Failure

Definition(s)


Mean Time to Failure

Expectation of the time to failure [2]. NOTE The MTTF of an item can be longer or shorter than the design life of the system. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global Standards  

Mean Time to Failure

expectation of the down time mean time to failure   FIG.3 Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standardss  
Mean Time to Repair

Mean Time to Repair

Definition(s)


Mean Time to Repair

Expectation of the time to restoration. Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global Standards  

Mean Time to Repair

expected time to achieve the repair of a failed item Note 1 to entry: This term MTTR is used in ISO 14224[15] and ISO 20815[16] where the fault detection time is not really considered: ISO 14224[15] deals with detected faults (in fact, the actual time spent to detect the fault is never known and cannot be collected); ISO 20815[16] deals mainly with immediately revealed failure where t he t ime spent to detect the faults is close to 0 (i.e. negligible). As the fault detection time is very important for the purpose of this Technical Report there is a need to clearly distinguish between the two following times (cf. Figure 5): 1) the time elapsing from the actual occurrence of the failure of an item to its detection (cf. 3.1.35, MFDT); 2) the time elapsing from the detection of the failure of an item to the restoration of its function (cf. 3.1.33, MRT). Note 2 to entry: The acronym MTTR is defined as the mean time to restore in the IEC 60500–191[14] or in the IEC 61508[2]. This is not the same as in ISO 14224[15] or ISO 20815[16]. Therefore, in order to avoid any mixed-up, the acronym MTTRes is used in this Technical Report instead of MTTR (cf. 3.1.32). FIG.5 Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards
Mean Time to Restoration

Mean Time to Restoration

Definition(s)


Mean Time to Restoration

MTTRes expected time to achieve the following actions: (see Figure 5, Figure 6 and Figure 7): • the time to detect the failure a; and, • the time spent before starting the repair b; and, • the effective time to repair c; and, • the time before the component is made available to be put back into operation d   Note 1 to entry: Figure 5 illustrates how the times a, b, c and d defined in the IEC 61508[2] standard are linked to the delays defined in the IEC 60050–191[14] standard. Time b starts at the end of a; time c starts at the end of b; time d starts at the end of c. Note 2 to entry: Figure 5, Figure 6 and Figure 7 can be used to understand the differences between the definitions of MTTRes, MRT and MART used in this Technical Report. Note 3 to entry: The MTTRes is linked to the MRT and the MFDT by the following formula: MTTRes = MFDT + MRT.   FIG.5     FIG.6     FIG.7 Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards    
Mean Time to Safe State

Mean Time to Safe State

Definition(s)


Mean Time to Safe State

MTTS expected time needed for the protected installation to reach a safe state after a dangerous failure of a safety system has been detected EXAMPLE When a dangerous fault is revealed for a safety system operating in demand mode, it may be decided to reach a safe state rather to undertake the repair of the fault and this may take some time: a MTTS of 8 h means, for example, that, on average, 8 h are needed to shut down the process. After the shut down, a safe state is reached, the fault is no longer dangerous and it is not necessary to take into account the remaining time spent to complete the repair. This is illustrated in Figure 6, Figure 7 and Figure B.1. Note 1 to entry: When the MTTS is defined as a maintenance procedure it is necessary to take it into consideration for the probabilistic calculations of hazardous events. In this case the MTTS replaces the MRT (see 3.1.33) with regard to the probabilistic calculations. Reciprocally it is necessary to verify that this MTTS is respected during the actual repair actions in order to keep the probabilistic calculations valid. Note 2 to entry: The role of the MTTS is close to the role of the MPRT. The difference is that the MPRT is a maximum duration allowed to reach a safe state when the MTTS is the average of the random duration of the TTS needed to reach the safe state when a dangerous fault is revealed (see Figure 6 and Figure 7). The methods developed in this Technical Report have been focused on average random values (MTTRes, MRT, MTTS) rather than on deterministic values (MPRT), but the MPRT can be easily handled by using Petri nets and Monte Carlo simulations.   FIG.6   FIG.7   FIGUREB.1 Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards
Mean Up Time

Mean Up Time

Definition(s)


Mean Up Time

expectation of the up time Note 1 to entry: See Figure 3 and also ISO 14224[15] or IEC 60050–191[14] for definitions of up time and down time. [SOURCE: IEC 60050 −191] Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards
Mean Wind Speed

Mean Wind Speed

Definition(s)


Mean Wind Speed

time-averaged wind speed, averaged over a specified time interval NOTE The mean wind speed varies with elevation above mean sea level and the averaging time interval; a standard reference elevation is 10 m and a standard time interval is 1 h. See also sustained wind speed (3.37) and gust wind speed (3.8). Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standards
Mean Zero-Upcrossing Period

Mean Zero-Upcrossing Period

Definition(s)


Mean Zero-Upcrossing Period

average period of the (up or down) zero-crossing waves in a sea state NOTE In practice the mean zero-crossing period is often estimated from the zeroth and second moments of the wave spectrum as. formula Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standards  

Mean Zero-Upcrossing Period

average intrinsic period of the zero-upcrossing waves in a sea state. NOTE 1 In practice, the mean zero-crossing period is often estimated from the zeroth and second moments of the wave spectrum as given by Equation (3.41-1): formula where f        is the frequency in cycles per second (hertz); m0     is the zeroth spectral moment and is equivalent to σ2, the variance of the corresponding time series; m2     is the second spectral moment; T2 and Tz     are the average zero-crossing period of the water surface elevation, defined by the zeroth and second order spectral moments, (T2 = Tz); ω     is the wave frequency in radians per second. NOTE 2 Adapted from ISO 19901-1:2005, definition 3.17. Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards  
Means of Connection

Means of Connection

Definition(s)


Means of Connection

mechanical parts (e.g. hooks, links, rings, etc.) intended for connection of the life saving equipment to the launching and recovery appliances NOTE: The term „means of connection“ covers both those parts which are integral to the life saving equipment and those parts which are integral to the lifting appliance. Source: Rules for Classification and Construction, IV Industrial Services, 6 Offshore Technology, 9 Guideline for Personnel Transfers by Means of Lifting Appliances, Edition 2011, Germanischer Lloyd SE, Global Standards
Measure

Measure

Definition(s)


Measure

Determining of dimensional value and recording of it on a worksheet. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards  

Measure

Variable to which a value is assigned as the result of measurement. [SOURCE: ISO/IEC 15939:2007]
  • Note 1 to entry: The term “measures” is used to refer collectively to base measures, derived measures, and indicators.
Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global Standards  

Measure

Measures includes both plant and equipment (ie hardware) and also management systems (ie software). Source: Prevention of Fire and Explosion, and Emergency Response on Offshore Installations, Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995, Approved Code of Practice and guidance (UK HSE L65), Second Edition, 1997. Regulatory Guidance  

Measure

Measures has the same meaning as in paragraph 35. In the context of this regulation measures for control purposes include plant, equipment and workplace procedures. Examples are listed in the box below: ESD systems, ballast control system, vents and drains, emergency response procedures, ie sending key personnel to determine the appropriate actions, automatic isolation valves, blowdown and flare systems, portable fire-fighting equipment. Source: Prevention of Fire and Explosion, and Emergency Response on Offshore Installations, Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995, Approved Code of Practice and guidance (UK HSE L65), Second Edition, 1997. Regulatory Guidance  
Measurement

Measurement

Definition(s)


Measurement

Process to determine a value.
  • Note 1 to entry: In the context of information security the process of determining a value requires information about the effectiveness of an information security management system and its associated controls using a measurement method, a measurement function, an analytical model, and decision criteria.
Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global Standards
Measurement Function

Measurement Function

Definition(s)


Measurement Function

Algorithm or calculation performed to combine two or more base measures. [SOURCE: ISO/IEC 15939:2007]. Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global Standards
Measurement Method

Measurement Method

Definition(s)


Measurement Method

Logical sequence of operations, described generically, used in quantifying an attribute with respect to a specified scale. [SOURCE: ISO/IEC 15939:2007]
  • Note 1 to entry: The type of measurement method depends on the nature of the operations used to quantify an attribute. Two types can be distinguished:
    • subjective: quantification involving human judgment;
    • objective: quantification based on numerical rules.
Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global Standards
Measurement Results

Measurement Results

Definition(s)


Measurement Results

One or more indicators and their associated interpretations that address an information need. Source: ISO/IEC 27000:2014, Information technology — Security techniques — Information security management systems — Overview and vocabulary, Third Edition, January 2014. Global Standards
Measurement While Drilling (MWD)

Measurement While Drilling (MWD)

Definition(s)


Measurement While Drilling (MWD)

The measurement of physical properties while drilling, such as pressure, temperature and borehole trajectory, by tools installed in the BHA. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global Standards 
Mechanical Barrier

Mechanical Barrier

Definition(s)


Mechanical Barrier

A subset of physical barriers that features mechanical equipment; not set cement or a hydrostatic fluid column. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global Standards  

Mechanical barrier

Subset of physical barriers that features engineered, manufactured equipment. NOTE Does not include set cement or a hydrostatic fluid column. EXAMPLES Permanent or retrievable bridge plugs, downhole packers, wellhead hanger seals, and liner hanger seals. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards
Mechanical Completion

Mechanical Completion

Definition(s)


Mechanical Completion

Verification that the components, equipment and the systems are constructed, installed and tested in accordance with applicable drawings and specifications and are ready for testing and commissioning in a safe manner. Source: Rules for Classification – Offshore units, DNVGL-OU-0101, Offshore drilling and support units, DNV GL, July 2015. Global Standards
Mechanical Damage

Mechanical Damage

Definition(s)


Mechanical Damage

A defect type that includes dents, bows, gouges, holes, and separated or severed members. Source: API RP 2SIM, Structural Integrity Management of Fixed Offshore Structures, First Edition, November 2014. Global Standards
Mechanical Efficiency

Mechanical Efficiency

Definition(s)


Mechanical Efficiency

Efficiency of the mechanical linkage between an engine and the pump or compressor it is driving. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Mechanical Energy

Mechanical Energy

Definition(s)


Mechanical Energy

Ability to apply a force to an object causing it to move.. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Mechanical Integrity

Mechanical Integrity

Definition(s)


Mechanical Integrity

Defined by EPA as "no significant leak in the casing, tubing, and packer and no significant fluid movement into a USDW through vertical channels adjacent to the injection wellbore." Source: API BULLETIN E3, Environmental Guidance Document: Well Abandonment and Inactive Well Practices for U.S. Exploration and Production Operations, First Edition, January 1993 (Reaffirmed June 2000). Global Standards  
Mechanical Joint

Mechanical Joint

Definition(s)


Mechanical Joint

Joint between GRP piping components which can resist thrust from internal pressure and is not made by bonding. 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 Standards
Mechanical Losses

Mechanical Losses

Definition(s)


Mechanical Losses

Friction losses in bearings and stuffing boxes and other rotational contact points. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Mechanical Protection

Mechanical Protection

Definition(s)


Mechanical protection

Layer of material that encloses a prescribed length of flexible pipe in order to protect it against abrasion and impact loads or to provide clearance between the flexible pipe and other subsea lines. Source: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards
Mechanical Vapor Plug

Mechanical Vapor Plug

Definition(s)


Mechanical Vapor Plug

Used to provide a gas vapor seal when required during pipe replacement and repair. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Mechanical Work

Mechanical Work

Definition(s)


Mechanical Work

Force acting on an object through a distance. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Medical Treatment Case

Medical Treatment Case

Definition(s)


Medical Treatment Case (MTC)

A recordable incident involving injury or illness that has required management and care of the patient above and beyond first aid, but not severe enough to be a reportable fatality or lost work day case or restricted work day case. Source: OGP Report No. 456, Process Safety – Recommended Practice on Key Performance Indicators, International Association of Oil & Gas Producers, November 2011. Global Standards