The majority of Safety Instrumented System (SIS) failures are still due to improper engineering specifications. Care must be given to ensure that systematic failures do not enter into SIS Design.
In the attached Control Magazine article, Embracing the Safety Lifecycle, BP and Emerson safety experts offer tips for maintaining an effective SIS throughout its entire lifecycle, from FEED to installation, operation, and support.
Control_Nov2014_SafetyLifecycle.pdf
Have you experienced SIS failure? If so, how were you able to remedy the issue...