Soft seals and hard seals have their own characteristics. Soft seals use a combination of metal and non-metal, good sealing but not high temperature resistance, easy to wear; hard seals are made of metal, high temperature resistance, abrasion resistance, but sealing is slightly inferior. Soft seals are suitable for room temperature and low pressure environment, while hard seals are adapted to a wider range of temperature and pressure conditions. Both have their own advantages in structure and application, complementing each other.