An Optimal Design Procedure based on the Safety Integrity Level for Safety-related Systems

Abstract

Safety-related systems (SRSs) has widely used in shipbuilding and power generation to prevent fatal accidents and to protect life and property. Thus, SRS performance is a high priority. The safety integrity level (SIL) is the relative performance level of an SRS with regard to its ability to operate reliably in a safe manner. In this article, we proposed an optimal design procedure to achieve the targeted SIL of SRSs. In addition, a more efficient failure mode and effects diagnostic analysis (FMEDA) process and optimization model were developed to improve cost efficiency. Based on previous IEC 61508 diagnostic analyses that revealed unnecessary costs associated with excessive reliability, the new approach consists of two phases: (i) SIL evaluation by FMEDA, and (ii) solution optimization for achieving the target SIL with minimal cost using integer-programming models. The proposed procedure meets the required safety level and minimizes system costs. A case study involving a gas-detection SRS was conducted to demonstrate the effectiveness of the new procedure.

Construction of methods for ensuring the required level of safety integrity in the automated systems of control over technological processes

“…However, it is possible, when the automated control system is represented by a full closed circuit from sensors and measuring devices, the structure of receiving and processing the signals and giving controlling signals up to executive devices and mechanisms [7]. In this case it is possible to interpret and analyze the hazards of the consequences of system faults or information misrepresentation in it [12]. The implementation of some aspects of the above-mentioned with the use of the SIL analysis was proposed in article [13], but the emphasis was placed on functional security.…”