Ball Model: Q42F structural features of valve and valve seat seal according to different conditions, respectively soft seal, high temperature nickel-based alloys (hardness greater than HRC60), supersonic Tu tungsten-cobalt alloy (hardness greater than HRC70) and special hardened materials more kind of advanced technology, for a variety of harsh conditions, soft seal suitable conditions below 200 ℃, hard seal steel does not exceed 425 ℃, stainless steel does not exceed ℃