EMPLOYEE WAS HELPING CUT AND FASTEN 3 SECTIONS OF 2 PLY BELTING TO A 72' LONG PIECE OF ANGLE IRON. THE TWO EMPLOYEES CARRIED THE BELTING AND ANGLE IRON UP THE PLANT. FIRST EMPLOYEE PROCEEDED INJURED UP THE STAIRS. INJURED THEN WENT TO THE PLANT OFFICE AND STATED THAT HE HAD HURT HIS BACK.