(55ak) Human Error Limits Sil Rating

SIL Verification calculations that are required by IEC and ANSI/ISA do NOT include the probability of humans making mistakes, which they will, during human interventions such as during calibration checks. Therefore, the PFD of SIF calculated in such a way will omit the probability of these human errors, which are the largest terms for SIFs with PFDs of less than or equal to 0.01. A couple of papers have been published on this topic. This paper will reiterate this significant limitation on SIL rating for this panel discussion.