Maximum Allowable Working Pressure (MAWP)

The Maximum Allowable Working Pressure (MAWP) is an ASME classification and one of the most critical parameters in the oil and gas industry and determines the safety and efficiency of pressure systems in reactors, heat exchangers, pipelines, and storage tanks.

This value indicates the highest pressure that the component can safely withstand, enabling the establishment of safety protocols and the prevention of explosions by ensuring that the system never exceeds the safe working pressure.

ASME Boiler and Pressure Vessel Code (BPVC)

What is ASME - the American Society of Mechanical Engineers?

The Maximum Allowable Working Pressure (MAWP) is an ASME designation that establishes the pressure rating of pressure relief components in pressure vessels. MAWP refers to the highest pressure that the weakest component of a device, system, or pressure vessel can withstand during normal operation at a given temperature.

Several factors determine the MAWP, including the material and thickness of the vessel, the design pressure, and the operating temperature. It is critical that pressure vessels operate within safe limits, as exceeding the MAWP can cause catastrophic failures, resulting in significant safety risks, property damage, and environmental harm.

Keys To Calculating MAWP

MAWP is found using the following equation (when the equipment is a cylindrical vessel)

Sumitomo Chemical Co., Ltd.
Process and Production Technology Center
Takuyo KAIDA

This very informative PDF file contains detailed information about the formula established by ASME for calculating the design pressure of a pressure vessel in relation to the MAWP.
Credit: Fitness-For-Service Assessment for Pressure Equipment in Chemical Plants, sumitomo-chem.co.jp.

Summary

MAWP is a calculated pressure limit specified in the ASME standard and is determined for a specific component, a specific temperature, and specific loading conditions. This value can vary between components and compartments within a vessel and is typically determined by the degree of corrosion. MAWP is established based on a component-level evaluation, taking into account the simultaneous pressure, static head, and external loads. When MAWP is established in accordance with the requirements of ASME Section VIII, this value constitutes the pressure limit used for design, testing, and operation.