Rupture tests were performed on pressure vessels to determine the effectiveness of repairs made using a carbon/epoxy composite material system. The carbon/epoxy system is intended to repair externally damaged or corroded steel pipe. Rupture vessels were constructed from six inch nominal diameter, Schedule 40, A-106, Grade B steel pipes cut into 5 ft. (1.52 m) lengths with welded end-caps. To simulate external corrosion, defects were machined into the outer surface of each pressure vessel to determine limitations of the carbon/epoxy repair system. The test specimen geometries include: a six inch wide circumferential flaw, a patch removal of an area measuring 6 inches by 6 inches (15.2 cm by 15.2 cm), and no surface defect. For the defect geometries, vessels were prepared at wall losses of 50 and 80 percent. Results indicate the vessels repaired with the carbon/epoxy repair system performed significantly better than those vessels without the applied repair systems, approaching but not exceeding the virgin pipe strength with no defect.