Plant Hazard Analysis and Safety Instrumentation Systems serves as a comprehensive guide to the development of safety instrumented systems (SISs), outlining the connections between SIS requirements, process hazard analysis, SIS lifecycle, implementation, safety analysis, and realization in control systems. The book also explores the impact of recent advances, such as SIL, SIS, and Fault Tolerance. This book facilitates the linkage between SIS requirements and process hazard analysis for the completion of SIS lifecycle implementation. The author, drawing from over 35 years of industrial experience, incorporates practical examples throughout the book. It covers safety analysis and realization in control systems, providing up-to-date descriptions of modern concepts like SIL, SIS, and SIF. The inclusion of security issues alongside safety issues is particularly relevant for the programmable systems used in modern plant instrumentation systems. Additionally, the book delves into discussions on cost impact, basics of statistics, and reliability. The impact of hazardous atmospheres on electrical enclosures is extensively discussed, especially in light of Atex. The new chapters in this updated edition address security concerns crucial for programmable systems in modern plants. Topics include the discussion of hazardous atmospheres and their impact on electrical enclosures, the use of IS circuits, and their links to safety considerations in major developmental areas, including IIoT, Cloud computing, wireless safety, Industry 4.0, and digital transformation. This book is a valuable resource for Process Control Engineers, Process Engineers, Instrumentation Engineers, Safety Engineers, and Mechanical/Manufacturing Engineers from various disciplines, helping them understand how instrumentation and controls provide layers of protection for basic process control systems, ultimately increasing overall system reliability. It also serves as a useful guide for researchers, students, and graduate-level professionals in process safety disciplines, Electrical and Industrial Engineers specializing in safety and area classifications, as well as plant managers and engineers in the industry.