In order to meet the production requirements of high grade steels, the No.4 vacuum treatment facility of CSC No.2 Steelmaking Shop was revamped and enhanced. This is the first revamping project in the world in that the twin-vessel-design vacuum treatment facility was divided into two independent and yet, simultaneously treatable RH stations. The production rate and the quality of the produced steels in No.2 Steelmaking Shop should be increased after the revamping project and thus, the competitive edge of CSC.