Maximum Allowable Working Pressure (MAWP) - maximum gauge pressure permissible at the top of the equipment in its operating position for a designated temperature (e.g. maximum pressure that the weakest component of the system can handle). Note: the maximum allowable working pressure is the basis for the pressure setting of the pressure relief devices that protect the equipment.

Maximum Allowable Pressure (MAP) or Maximum Allowable Operating Pressure (MAOP) - maximum pressure at which the equipment may be operated under; in another word, it is the maximum pressure in the new and cold condition of the equipment.

Maximum Operating Pressure (MOP) - maximum operating pressure is the maximum pressure that equipment can be operated at below its high pressure alarm or shutdown, or 95% of MAWP, whichever is lower.

Burst Pressure - Burst pressure is the maximum internal pressure that a pressurized component such as piping or joint or tube can withstand before rupture or “burst”. When maximum internal pressure exceeds the burst pressure, the pipe will crack, leak, explode.

Design Pressure - the maximum pressure that the system that can be exposed to and sets the system relief valve at the same pressure. This should be below MAWP and based on company standards can vary from 10% to 25% above the maximum operating pressure of the system. Maximum operating pressure is usually the high trip pressure of the system.

Hydrotest Pressure - hydrostest pressure is the required pressure that pressurized systems such as vessels, pipelines, plumbing, gas cylinders, boilers, tanks can be tested for strength and leak. Hydrotest pressure is 1.5 * (design pressure) as a rule of thumb. ASME code gives detail guidance with formulas for calculating hydrotest pressure based on stress ratio.

Proof Pressure (overpressure) - the maximum pressure that can be applied to a pressurized component without changing quality from its original specification. After the internal pressure is released, the pressurized component will return to the original state if the pressure is under the proof pressure limit.

Relief Pressure (typically in pressure relief valve, PRV, PSV) - A preset pressure to protect or control a pressurized system/component during an overpressure event from instrument or equipment failure, or fire.

Surge Pressure (pressure surge or fluid hammer) - happens when fluid velocity in a piping system changes suddenly by a valve is opened or closed to rapidly. This will result in sudden change in pressure that creates a shock wave in the piping walls and fittings and can cause severe vibration, and piping rupture.

Target Pressure - target pressure for any particular pressurized equipment should be set to the project's operating pressure which is usually 10-25% lower than the design pressure. See working pressure vs. design pressure.

Working Pressure (safe working pressure) - the internal pressure of the pressurized component in the working conditions range, normally called pressure range.