The "C-type" high-temperature and high-pressure fully open safety valve produced by Shanghai First Ring Road is suitable for working temperatures ≤ 425 ℃; The "Type I" high-temperature and high-pressure fully open safety valve is suitable for medium temperatures ≤ 500 ℃; V-type "≤ 500 ℃ is suitable for steam and other medium equipment or pipelines as an overpressure protection device.