EMPLOYEE REPORTED A 4"" PVC PLASTIC DISCHARGE LINE HUNG ALONG SIDE A CONVEYER BELT HAD GOT INTO A BOTTOM ROLLER AND WAS PARTIALLY CUT INTO, WHEN HE WAS EXAMINING THE DAMAGE TO THE WATER LINE, THE WATER LINE BROKE IN TWO, ONE END FLEW UP STRIKING VICTIM'S FOREHEAD, RESULTING IN A MILD CONCUSSION.