COURSE OVERVIEW

The ANSI SP 84 (formerly ISA 84.01) “Application of Safety Instrumented Systems for the Process Industries” standard requires that companies assign a target safety integrity level (SIL) for all safety instrumented systems (SIS) applications. The assignment of the target SIL is a decision requiring the extension of the process hazards analysis (PHA). The assignment is based on the amount of risk reduction that is necessary to mitigate the risk associated with the process to an acceptable level. All of the SIS design, operation, and maintenance choices must then be verified against the target SIL.
This course covers the systematic method for selecting safety integrity levels (SILs) for safety instrumented systems (SIS). Although numerous methods have been proposed and adopted by industry, layer of protection analysis (LOPA) is rapidly becoming the most frequently used method. Its popularity stems from its ease of use and the accuracy of the results it provides. LOPA accounts for most existing layers of protection, more than any other method. With this proper accounting, the SIS is neither overdesigned nor overpriced. The LOPA method ensures that users achieve the maximum return on their risk reduction investments.
The result of using poor methods to select SILs is typically either an overdesigned or an under designed safety instrumented system. The risk analysis that forms the basis for SIL selection, however, can be greatly improved. This will provide the user with more accurate results so formerly inflated requirements can be relaxed, which will in turn lower not only the initial installation costs, but the cost of ongoing maintenance.
Much of the material in this course is based on the application of the safety life cycle as it is described in the international standards ANSI SP 84 (formerly ISA 84.01) “Application of Safety Instrumented Systems for the Process Industries” and EN/IEC 61508/61511. This course expands upon the framework developed in these standards. In addition to describing the tasks that users should perform during the safety life cycle, this course also provides detailed procedures for accomplishing these tasks. These procedures are based on risk analysis and reliability engineering principles from a variety of disciplines.