Maximum allowable operating pressure
Encyclopedia
Maximum allowable operating pressure or MAOP refers to the wall strength of a pressurized cylinder
such as a pipeline
or storage tank
and how much pressure the walls may safely hold in normal operation.
The MAOP is less than the MAWP (maximum allowable working pressure). MAWP being the maximum pressure based on the design code
s that the weakest component of a pressure vessel
can handle. Commonly standard wall thickness components are used in fabricating pressurised equipment, and hence are able to withstand pressures above their design pressure.
Design pressure is the maximum pressure a pressurised item can be exposed to. Due to the availability of standard wall thickness materials many components will have a MAWP higher than the required design pressure.
Relief valve
s are set at the design pressure of the pressurised item and sized to prevent the pressurised item being overpressured. Depending on the design code that the pressurised item is designed, an overpressure
allowance can be used when sizing the relief valve. This is +10% for PD 5500, and ASME Section VIII div 1 & 2 (with an additional +10% allowance in ASME Section VIII for a fire relief case). ASME have different criteria for steam boilers.
Pneumatic cylinder
Pneumatic cylinders are mechanical devices which utilize the power of compressed gas to produce a force in a reciprocating linear motion....
such as a pipeline
Pipeline transport
Pipeline transport is the transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used....
or storage tank
Storage tank
A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs , and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, American English and moderately common in British...
and how much pressure the walls may safely hold in normal operation.
The MAOP is less than the MAWP (maximum allowable working pressure). MAWP being the maximum pressure based on the design code
Design code
A design code is a document that sets rules for the design of a new development. It is a tool that can be used in the design and planning process, but goes further and is more regulatory than other forms of guidance commonly used in the English planning system over recent decades...
s that the weakest component of a pressure vessel
Pressure vessel
A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.The pressure differential is dangerous and many fatal accidents have occurred in the history of their development and operation. Consequently, their design,...
can handle. Commonly standard wall thickness components are used in fabricating pressurised equipment, and hence are able to withstand pressures above their design pressure.
Design pressure is the maximum pressure a pressurised item can be exposed to. Due to the availability of standard wall thickness materials many components will have a MAWP higher than the required design pressure.
Relief valve
Relief valve
The relief valve is a type of valve used to control or limit the pressure in a system or vessel which can build up by a process upset, instrument or equipment failure, or fire....
s are set at the design pressure of the pressurised item and sized to prevent the pressurised item being overpressured. Depending on the design code that the pressurised item is designed, an overpressure
Overpressure
The term Overpressure is applied to a pressure difference, relative to a "normal" or "ambient" pressure, in various circumstances:* In engineering: the pressure difference over the wall thickness of a pressure vessel...
allowance can be used when sizing the relief valve. This is +10% for PD 5500, and ASME Section VIII div 1 & 2 (with an additional +10% allowance in ASME Section VIII for a fire relief case). ASME have different criteria for steam boilers.