An expandable pipe plug assembly comprising: an electrical discharge machining plug adapted for plugging a hole drilled by electrical discharge machining, the EDM plug having a first end and a second end, a ratchet nut on the first end of the EDM plug, a pipe plug on the second end of the EDM plug, the pipe plug being connected to the ratchet nut via a plug bolt having threads that mate with threads provided on the ratchet nut, the ratchet nut configurable to tighten hold of the plug bolt to draw the plug bolt and the pipe plug toward the EDM plug, and an expandable bushing assembly between the EDM plug and the pipe plug, the expandable bushing assembly configured to expand as the pipe plug is drawn toward the EDM plug, the expandable bushing assembly comprising a plurality of bushing sections with longitudinal gaps between the bushing sections, each bushing section having a longitudinal wall that forms a longitudinal wall section of the expandable bushing assembly and a flat bushing section base existing at approximately a normal angle from the longitudinal wall of the bushing section that forms a flat base section of the expandable bushing assembly, and characterized by a circular retaining ring configured to hold the bushing sections together, the retaining ring including a gap (16b1) that mates with a boss (16d1) located on the base of one of the bushing sections, the boss being configured to ensure that the retaining ring does not rotate while the retaining ring holds the bushing sections together; and a retaining ring groove located between the longitudinal wall and the flat base section of each bushing section, the retaining ring groove being configured to hold the retaining ring in position near the base of the bushing assembly. an electrical discharge machining plug adapted for plugging a hole drilled by electrical discharge machining, the EDM plug having a first end and a second end, a ratchet nut on the first end of the EDM plug, a pipe plug on the second end of the EDM plug, the pipe plug being connected to the ratchet nut via a plug bolt having threads that mate with threads provided on the ratchet nut, the ratchet nut configurable to tighten hold of the plug bolt to draw the plug bolt and the pipe plug toward the EDM plug, and an expandable bushing assembly between the EDM plug and the pipe plug, the expandable bushing assembly configured to expand as the pipe plug is drawn toward the EDM plug, the expandable bushing assembly comprising a plurality of bushing sections with longitudinal gaps between the bushing sections, each bushing section having a longitudinal wall that forms a longitudinal wall section of the expandable bushing assembly and a flat bushing section base existing at approximately a normal angle from the longitudinal wall of the bushing section that forms a flat base section of the expandable bushing assembly, and characterized by a circular retaining ring configured to hold the bushing sections together, the retaining ring including a gap (16b1) that mates with a boss (16d1) located on the base of one of the bushing sections, the boss being configured to ensure that the retaining ring does not rotate while the retaining ring holds the bushing sections together; and a retaining ring groove located between the longitudinal wall and the flat base section of each bushing section, the retaining ring groove being configured to hold the retaining ring in position near the base of the bushing assembly. a plurality of bushing sections with longitudinal gaps between the bushing sections, each bushing section having a longitudinal wall that forms a longitudinal wall section of the expandable bushing assembly and a flat bushing section base existing at approximately a normal angle from the longitudinal wall of the bushing section that forms a flat base section of the expandable bushing assembly, and characterized by a circular retaining ring configured to hold the bushing sections together, the retaining ring including a gap (16b1) that mates with a boss (16d1) located on the base of one of the bushing sections, the boss being configured to ensure that the retaining ring does not rotate while the retaining ring holds the bushing sections together; and a retaining ring groove located between the longitudinal wall and the flat base section of each bushing section, the retaining ring groove being configured to hold the retaining ring in position near the base of the bushing assembly.