Don't presume when it comes to plant safety

All of the effort expended in designing plant-safety systems is of little value unless accompanied by an adequate 'prooftest' program and regular maintenance. These safety systems - consisting of such components as safety-relief valves, tank vents, critical alarms and protective isolation and shutdown devices - do not operate on a continuous basis. After just a few years of neglect, many protective devices and preventive process loops could become ineffective. Determining the methods and frequencies of testing for critical instrument loops must be tailored to each plant's needs and resources. The following recommendations were developed at the request of Industrial Risk Insurers (Hartford, Conn.) to highlight the elements and practices that are critical for ensuring the lowest practical risk at a given facility. The specific programs discussed in this article were developed for and by the Lake Charles, La. manufacturing complex of PPG Industries, Inc. (Pittsburg, Pa.).