Understanding IEC 61511 / ISA 84 and Developing a Safety Requirements Specification
Safety instrumented systems (SISs) play a key role in process control to achieve safety and productivity. Their purpose is to take a process to a safe state when predetermined set points are exceeded. SISs are also called emergency shutdown systems, safety shutdown systems, and safety interlock systems.
Several standards have been enacted to address the reliability of SISs. ANSI/ISA S84.00.01-2004, Functional Safety: Safety Instrumented Systems for the Process Industry Sector, first issued in 1996, has now been harmonized with IEC 61511 issued in 2003. In March 2000, OSHA issued a letter, reaffirmed in November, 2005, stating that the S84 standard is considered "good engineering practice" for safety instrumented system design. This effectively makes the S84 standard part of process safety management (PSM) since paragraph (d)(3)(ii) of the OSHA PSM standard specifies: "The employer shall document that equipment complies with recognized and generally accepted good engineering practices".
IEC 61511 / ISA 84 identifies three Safety Integrity Levels (SILs) for the process industries and specifies performance requirements for each level. Different levels of risk require different levels of safety system performance.
This course teaches the important concepts and terms needed to understand the IEC 61511 / ISA 84 standard and it describes its requirements and its relationship to PSM. The detailed requirements for a Process Hazard and Risk Assessment (PHRA) and the allocation of safety functions to protection layers are discussed. A key requirement of IEC 61511 / ISA 84 is the development of a Safety Requirements Specification (SRS). The course explains how to prepare the SRS and attendees develop a SRS in a workshop session.
A detailed manual is provided for use as a reference after you have completed the course. Also provided is a Microsoft Word template for preparing the SRS.
Understand the overall requirements of the IEC 61511 / ISA 84 standard for SIS. Understand the requirements for a PHRA and the allocation of safety functions and how they relate to PHA. Be able to prepare a SRS for each SIS.
Process safety personnel, control and instrumentation engineers, project engineers and others who need to apply the IEC 61511 / ISA 84 standard.
Experience in process safety is helpful.
- SIS concepts and terms
- Standards and regulations applicable to SIS
- PHRA and the allocation of safety functions
- Preparation of a Safety Requirements Specification (SRS)
Duration / Credits
- One day
- 0.7 CEUs awarded
- 1.17 CM Points, ABIH Approval #: 10-144
- 7 PDH or Technical Hours
- 0.7 COCs
- For USA Courses, see Schedule