Pressure-relief valve system for high-pressure fuel gas long-distance pipeline

The invention discloses a pressure-relief valve system for a high-pressure fuel gas long-distance pipeline. The pressure-relief valve system comprises a tubular shell, a piston and a mechanical control structure, wherein the piston is arranged in the shell and the mechanical control structure is located between the shell and the piston and is used for controlling the switch-on/off of a pressure-relief gas outlet. According to the pressure-relief valve system, the pressure, which is reasonably arranged, of a third spring is utilized to control the pressure in the pipe within a certain scope; a pure mechanical valve on-off control structure is adopted, so that the response is quick; a sealing ring is tightly pressed under an interaction force between a roller wheel and a sealing baffle, so that a larger pressing force is formed on the sealing ring and an excellent sealing effect is achieved; during a repeated on-off process, the structure stability is high and is free from failure; a cylindrical structure is adopted for the piston, a sliding plate and a sliding ring are arranged at front and rear ends and are used for supporting and sliding, and the structure is relatively symmetrical, so that the structure is relatively stable.