Procedure for assessing hardware safety integrity in legacy systems. (March 2016)

• Record Type: Journal Article
• Authors: Kim, Gi Young; Yoo, Ki Hoon; Ko, Byung Gak; Jang, Joong Soon
• Is Part Of: Journal of loss prevention in the process industries. Volume 40(2016:Mar.)
• Page Start: 461
• Page End: 470
• Publication Date: 2016-03
• Subjects: Hardware safety integrity -- Legacy system -- Safety integrity level -- Boiler control system -- IEC 61508; Chemical industries -- Safety measures -- Periodicals; 660.2804
• DOI: 10.1016/j.jlp.2016.01.019
• Languages: English
• ISSNs: 0950-4230

Abstract

Abstract: Functional safety is related to the safety functions of a safety-related system that uses electrical/electronic/programmable (E/E/PE) devices such as sensors, logic solvers, and final elements. A legacy system is a safety-related system which offers safety functions but which was not designed to comply with the IEC 61508 standard. This paper presents a procedure for assessing the hardware safety integrity of a legacy system so as to confirm its functional safety. The procedure defines the systematic relationship between the safety function and hardware system using a function-structure map (FSM) and assesses the hardware safety integrity centered on the safety function. The proposed procedure is applied to a boiler control system of a fossil-fuel power plant. Highlights: This research presents a procedure for assessing the hardware safety integrity of a legacy system. A function-structure map is used to respond effectively to the safety functions of the related hardware components and to prevent an error that an SIL evaluation is performed for safety-related systems. The proposed assessment procedure is applied to a boiler control system of a fossil-fuel power plant. The hardware SIL of each safety function is determined to be SIL3 in the boiler control system.