Precast Inc. - November/December 2008 - (Page 62) stressed tendons. Employees involved in stressing operations should be protected by some sort of bed end protection, such as a wall, partition or any other barrier to shield them from broken strands or chucks that may become disengaged. These shields must be fabricated to withstand the forces that could be exerted on them by broken strands or any other flying material due to equipment failure. As an added measure, a secondary wall or barrier could be built at a distance of not less than 10 feet to serve as double protection against a broken strand. It is important to consider that the installation of barriers must be in addition to the other safety precautions, such as keeping unauthorized employees away, signals and monitors in the area. In the event that a chuck must be replaced due to a misplaced or damaged strand, the tension must be released slowly and the tools recommended by the manufacturer must be used. Keep your hands away from any danger zone such as the area between the chuck and the jack. • Never stand behind the strand you are cutting. • Only authorized employees are allowed in the area. Handling and storage OSHA 1926 Subpart Q, “Requirements for Precast Concrete,” and ANSI 10-9 9.3.3 and 3.4 require that all lifting inserts must be capable of supporting four times the intended load and that all lifting hardware must support at least five times the maximum intended load. As in precast concrete, the hazards present during handling include: • Lifting equipment failures • Defective lifting equipment • Lifting insert failures, sometimes due to improperly cured concrete • Overloading • Entrapment between fixed objects and prestressed members Storage hazards for prestressed panels or walls include: • Lack of safe storage procedures • Inadequate ground support for the total weight of the structures • Poorly designed supporting structures for the size of each stored panel • Inadequate supports or locking mechanisms for each individual product in the rack Detensioning operations Detensioning is the process by which the strands are cut after the concrete has cured. This operation is usually done by means of a cutting torch. The following safety rules must be followed: • Follow the order in which strands must be cut. • They should be cut at both ends at the same time. • Relieve pressure by preheating the strand before actually cutting it. Structural precast and panel machinery Innovative Concrete Technologies, Srl Automating for Production Efficiencies BOOTH 1311 THE PRECAST SHOW PANEL WASHING AND FINISHING LONG LINE AUTOMATION CONCRETE DELIVERY AND VIBRATION For more information, contact Phone: 920-497-8725 Email: cti@cti5050.com Website: www.cti5050.com 62 NOVEMBER/DECEMBER 2008 | PRECAST INC. http://www.cti5050.com http://www.cti5050.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.