Plant Hazard Analysis and Safety Instrumentation Systems, Second Edition 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. In addition, it 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. Other sections cover safety analysis and realization in control systems, providing up-to-date descriptions of modern concepts like SIL, SIS, and SIF. 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. Finally, 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 much more.