Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
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 StandardsMechanical 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 StandardsMechanical 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 StandardsMechanical 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 StandardsMean Temperature
Definition(s)
Mean Temperature
Average temperature in a flowing line or vessel. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsMean Pressure
Definition(s)
Mean Pressure
Average pressure in a flowing line or vessel. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsMean Effective Pressure
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 StandardsMAWP
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 StandardsMAWP
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 StandardsMAWP
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 StandardsMaximum 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.