Safety Integrity Level (SIL) Integrated with Human and Organizational Factors

Abstract

From many accident/incidents analysis, human and organizational factors have been identified as root causes or contributing factors. Therefore, in order to actuate preventively, many methodologies have been proposed for the quantification of these factors in organizations. Due to the advances of digital computing over the last decade, industries have increased the number of installed safety instrumented systems (SIS), which are instrumentation and controls installed in order to bring the process, or equipment to a safe state. However, after plant start up, these SISs may be adversely affected by human and organizational factors and may not reach, at the operation phase, the safety integrity level (SIL) calculated at the design phase. A methodology about the control of human and organizational factors in SIS operational phase is applied in a case study in a liquefied natural gas (LNG) plant. Through the case study the human and organizational factor(s) that most impacted the SIS in the unit could be identified and thus, these problems could be preventively eliminated. It was also possible to calculate the operational SIL and compare it with the design SIL.