Usage:It has been widely used in the fields of petro-chem, pharmacy and elertric power etc. Usage :It has been widely used in the fields of petro-chem, pharmacy and electric power etc.It is used by means of open and close on the pipes of steam,water and oil etc,under the pressure ≤1.0MPa. Usage:It has been widely used in the fields of petro-chem, pharmacy and elertric power etc.It is used by ...