depressurize

Usually for this service it is a good practice to install a pressure control valve betwen your system and flare header.

Hope this help

First of all, you have to define the purpose of the depressuring.

Emergency Depressuring intended to evacuate system inventory (flammable, toxic, explosive, hazardous, etc) to disposal system as fast as possible during process and non process contingency in order to minimize possible catastrophic events.

Manual depressuring is intended to evacuate system inventory in proper manner so that the system can be properly purged and inert-ed for system maintenance or other purpose.

The depressuring strategy is subject to the purpose of depressuring and limitation of system. Thus, control or non-control depressuring may be adopted. Read more in Controlled and Non-controlled Type Depressuring.