ANSI/ISA-84.00.01-2004 Part 2 (IEC 61511-2 Mod) provides guidance on the specification, design, installation, operation and maintenance of Safety Instrumented Functions and related safety instrumented system as defined in ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod). This standard has been organized so that each clause and subclause number herein addresses the same clause number in ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod) (with the exception of the annexes).

For existing SIS designed and constructed in accordance with codes, standards, or practices prior to the issue of this standard (e.g., ANSI/ISA-84.01-1996), the owner/operator shall determine that the equipment is designed, maintained, inspected, tested, and operating in a safe manner.