EE was using a Purox oxygen & accetylene cutting torch to cut an 8"" I-Beam which was at a 45 degree angle & secured with a chain fall on 1 end & welded to another I-Beam on the other. It must have been under pressure because when beam was cut the chain fall slid down & allowed beam to drop Appx 3"" & during this our employee's wrist became squeezed betwen the chain fall & beam.