Are SIS requirements new?
No. SIS has been implemented for many years in all process industries. The issue has recently gained importance as government agencies have pushed regulatory codes for safety management. The emergence of microprocessors and critical software in logic solvers and field instruments is also a factor. Each process plant already has in place a detailed Company Procedures and Policies for SIS loop identification, engineering, specification, commissioning and maintenance. When a process plant decides to implement IEC 61511, additional requirements will be needed for compliance. These requirements are primarily in the methodologies and documentation of how the safety loop was designed and how it will be maintained through the life of the plant.
