Spring-loaded pressure relief valve, particularly for containers of pressurized fluids

A spring-loaded pressure relief valve, particularly for containers of pressurized fluids, comprising a valve body that is associable with a container and forms a discharge port that is controlled by a main piston, an auxiliary valve being further provided which controls a venting port and drives the intervention of said main piston, said main piston is accommodated in a cavity that is formed in said valve body and is open in an axial direction on the opposite side with respect to said venting port, wherein said auxiliary valve is provided with an auxiliary body and is removably engaged with a valve seat of said valve body, said venting port being closed by means of an auxiliary gasket supported by an auxiliary piston which is pushed by an auxiliary spring acting at its other end against a setting ring and suitable to be adjusted according to a settled operated pressure and suitable to retain its setting even if said auxiliary valve is removed for replacement.