If your company is planning an expansion, retro-fit, grass roots facilities, or simply modifying a process unit, and the process hazard analysis (PHA) indicates you need a safety instrumented system (SIS) as a protective layer, then you need to comply with ANSI/ISA S84.01. Why? Because in February 1996, the “Application of Safety Instrumented Systems for the Process Industries” was approved and will be enforceable by OSHA using 29 CFR Part 1910.119 and EPA’s 40 CFR Paert 68.