Design and Evaluation of Safety Instrumented Systems: A Simplified and Enhanced Approach

An application of a more cost-effective, simplified, and enhanced approach for the design and evaluation of Safety Instrumented Systems (SIS) called funnel risk graph method (FRGM) is presented in this paper. This approach makes compliance more practicable and standards more useful, resulting to an equal degree of functional safety as compared with the traditional approach. A real-life case study utilizing industrial SIS devices are presented to demonstrate the benefits of this approach. In contrast with other complex schemes commonly used for safety assessment, the proposed FRGM gives benefits such that it is straightforward in steps and resource-efficient while achieving the same safety function. While safety is aimed at protecting the systems from accidental failures to eliminate or minimize hazards, security is focused on protecting the systems from deliberate malicious attacks. They share the same goal-protecting the SIS from failing. Industry cybersecurity has become more critical these days and to address such concern, risk assessment for the security of SIS is proposed to be included in the design and evaluation, as part of the enhancement process.