Pressure relief system. Summary.

Pressure relief system. Relief systems are of vital importance in plants that handle flammable gases, as they guarantee the safe disposal of gases that cannot be handled at some point in the process and can cause overpressure in the equipment.
The relief system is usually made up of relief valves, collection heads, liquid separation and water seal drums, and as a final element the flare.
One of the first steps when designing the pressure relief system is to identify and analyze emergency situations or scenarios that may pose a danger condition due to overpressure of equipment or process lines.
When evaluating a piece of equipment or line, all the causes of an emergency are considered, leaving only the final cause of the emergency situation to study. These can be classified into two types: general and specific contingencies.
Once the possible causes have been established, their feasibility for each specific system will be evaluated. If they are credible causes, the flow of relief and the area required for each contingency will be quantified, selecting the most unfavorable for the design of the system. Another aspect to consider is that there will be gases that can be discharged into the atmosphere, and those that will not be sent to a controlled burning system such as the torch, according to their dangerousness. These vary according to the environmental regulations of each country.
Among the international standards applicable to pressure relief systems are: API STD 521 (ISO 23251), API STD520 part I, API RP 520 part II, API STD 526, API STD 537, API STD 2000, ASME B31.3, ASME SEC VIII DIV1, ISO 4126.