Abstract: An adjustable jig assembly for holding a work piece in a desired position, comprising a stand having wall members defining a pair of opposed substantially vertically extending slide channels, mounting means slidable in the slide channels for fixedly mounting therebetween an axially rotatable retaining means in desired vertical and axial orientation, and a work piece engaging member adapted to be fixedly retained by the retaining means in desired orientation about an axis normal to that of the axially rotatable retaining means. The adjustable jig assembly is particularly useful in manufacturing replacement flanged pipes due to the criticality of reproducing the exact spatial orientation of the flange members. Present practice requires that individual jigs be custom made for each flange and that the individual jigs be identifiably coded so that they can be reused during a stress relieving treatment subsequent to welding and machining operations.