(106a) Operation and Maintenance of Safety Instrumented System (SIS)

The use of Safety Instrumented Function (SIF) in Safety Instrumented Systems (SIS) and Burner Management Systems (BMS) is a crucial protection layer that helps to reduce process risk to acceptable levels. SIS follows IEC61511 which is a lifecycle standard. IEC61511 is a comprehensive lifecycle standard that covers all aspects of SIS lifecycle, starting from conception, design, engineering, commissioning, maintenance, and decommissioning. The operation and maintenance phase is the longest part of the SIS lifecycle, and it is the responsibility of the owner/operator to adhere to IEC61511 maintenance and documentation requirements to comply with OSHA PSM. Each SIF must be tested at an interval determined during the SIL calculations. This test interval usually matches the Turnaround interval as most SIFs cannot be tested while the plant is running. Many users inadvertently ignore the useful life of devices specified by manufacturers. A device in safety service must be replaced or refurbished at the end of its mission time. Management of Change, documentation, training, validating device failure rates in SIL certificates against the field failure rates, developing decommissioning plan are examples of the tasks every user must perform as part of the SIS maintenance stage of the lifecycle. This paper seeks to raise awareness among users of IEC61511 requirements to ensure compliance with OSHA PSM.