EE PEROFRMING MAINTENANCE WORK IN PLANT. WAS SECURING ()HOLDING) LADDER WHIL ANOTHER EE WAS HANDLING A PIPE COUPLER. COUPLER WAS DROPPED & FELL APPROX 6', STRIKING VICTIM IN HEAD, CAUSING LACE RATIONS & BRUISES. LACERATION REQUIRED STITCHES. EE WAS NOT WEARING HARD HAT AT TIME OF ACCIDENT.