... steel Special heat treatment High Strength and toughness The characteristic valve seatJinzhou Shenghua Petroleum Geology Machinery Factory have been in the ... output of 100000 tons to 150000 tons.Items: Elbow,Tee,Cross,Socket,Union,Bushing,Backnut, Nipple,Crossover, Caps,Plug etc.We ... home and abroad contact with us and promote business relations. valve seat