METHOD OF MANUFACTURE OF A COATED VALVING MEMBER

摘要

All areas of the butterfly-type valving member which may be exposed to attack by corrosive substances, are coated with a protective material of the class of tetrafluoroethylene or equivalent substance, by a high-pressure and high-temperature molding process; the process involving withdrawing support from a journal end of the valve member during a critical phase of the molding procedure to ensure adequate coating of said journal end including the customary turning center hole thereof.