EE was in the surface fabrication shop. EE was holding a ¾"" pipe as a punch, to push a keeper pin into place. Another EE used a pipe, as a hammer, to hit the pipe EE was holding. When the pipes made contact, the pipe being swung ricocheted and struck the small finger of the EE's left hand. This caused a laceration that required stitches, and a fracture to the finger.