Global Standards

Definition(s)

---

Meter Prover

Device to test (“prove”) meter accuracy and determine the meter factor. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Meter Multiplier

Used when actual voltages or currents are too large for the meter and would be out of range. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Meter Banks

Single meters arranged in parallel configurations. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Membrane Nitrogen

Reduced Oxygen content air produced by passing compressed air over a membrane to reduce the oxygen content to 2-5% on average. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Mechanical Work

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

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

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

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

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

Definition(s)

---

Mean Temperature

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

Definition(s)

---

Mean Pressure

Average pressure in a flowing line or vessel. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Mean Effective Pressure

Theoretical constant pressure applied during each power stroke to produce the brake horsepower of an engine. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

MAWP

The maximum gauge pressure permitted at the top of a pressure vessel in its operating position for a designated temperature. This pressure is based on calculations using the minimum (or average pitted) thickness for all critical vessel elements, (exclusive of thickness designated for corrosion) and adjusted for applicable static head pressure and nonpressure loads (e.g. wind, earthquake, etc.). The MAWP may refer to either the original design or a rerated MAWP obtained through a FFS assessment. Source: API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration, Tenth Edition, May 2014, with Addendum May 2017. Global Standards  

MAWP

The maximum internal pressure permitted in the piping system for continued operation at the most severe condition of coincident internal or external pressure and temperature (minimum or maximum) expected during service. It is the same as the design pressure, as defined in ASME B31.3 and other code sections, and is subject to the same rules relating to allowances for variations of pressure or temperature or both. If the piping system is being rerated, the new MAWP shall be the rerated MAWP.

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 Standards

MAWP

Maximum allowable working pressure. Source: API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration, Tenth Edition, May 2014, with Addendum May 2017. Global Standards 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 Standards

Maximum allowable working pressure

Maximum gauge pressure permissible at the top of a completed vessel in its normal operating position at the designated coincident temperature specified for that pressure.

• NOTE: 1 See design pressure (3.1.24).
• NOTE: 2 The MAWP is the least of the values for maximum allowed working pressure for any of the essential parts of the vessel.

Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global Standards  

MAWP

Maximum Allowable Working Pressure. See MAOP. Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global Standards  

MAWP

Maximum Allowable Working Pressure. See MAOP. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Maximum Operating Pressure (MOP)

Maximum pressure permitted for normal line or vessel operation; MOP is related to pipe strength and the pipe's ability to withstand internal pressure. MOP results from the lowest of three factors: design pressure, hydrostatic test pressure, or flange rating. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Man Machine Interface (MMI)

Interface between an operator and a computer. Source: IADC UBO / MPD Glossary, December 2011. Global Standards

Definition(s)

---

Master Choke Line Valve

The valve on a choke and flow line that is nearest to the preventer assembly, used to stop flow through flow line and choke. Source: IADC UBO / MPD Glossary, December 2011. Global Standards