a process and apparatus for making a metal annular member of precise tolerances . the workpiece is formed by welding sheet metal into a tube . the workpiece is presized by expanding it and plastically stretching it into a precise predetermined annular configuration adapted to closely fit a post element having a pair of spaced annular liquid seals mounted thereon . the post element and workpiece are positioned within an annular lower outer die . a cup - shaped upper outer die is placed over the lower die and is used to compress the post element to squeeze the liquid seals to expand them . forming of the workpiece is accomplished by pumping liquid into the post element between the liquid seals forcing the workpiece to expand against the outer dies and the sheet metal at the end portions of the workpiece to feed into the part being formed from between the outer dies and the post element .