The invention comprises a device for expanding tubular members to a controlled diameter and its method of fabrication. The device includes an expandable bladder held in a convoluted form. After the device is inserted into a cylindrical tube to be evenly expanded, the bladder is expanded by hydraulic pressure to a controlled maximum diameter. It is then deflated so the device can then be moved to another location and reused. The bladder is formed from a flexible impervious material having integral reinforcing fibers. It is initially formed in a fully expanded configuration over a convoluted mandrel and a removable cylindrical shell. When the shell is removed vacuum or external pressure draws the bladder against the mandrel. The bladder is overmolded with a resilient cover to hold it in reduced form until pressurized. The bladder cover prevents the bladder from kinking during the expansion.