(47l) Evolution of High Integrity Protection Systems (HIPS) and Using Risk Analysis Tools to Define Safety Integrity Levels (SIL) for Offshore Facilities

As Offshore Facilities operate in deeper waters, at higher pressures, and in more extreme environments; we push the limits of engineering, requiring higher pedigree safety systems to manage the increased potential for risk.  These higher pedigree safety systems allow us to push engineering limits even further.  This cycle mandates the application of more complex design standards and analytical tools to ensure that safety systems provide the necessary reliability.

The terms High Integrity Protection Systems (HIPS) and Safety Instrumented Systems (SIS) are often used interchangeably, and IEC 61511 (“Functional Safety - Safety Instrumented Systems for the Process Industry Sector”) provides design guidelines for achieving the necessary protection system reliabilities.  These reliabilities, which are driven by system architecture, component reliability, and application of redundancy/diversity, are characterized by a Safety Integrity Level (SIL).  This presentation will briefly review the evolution of design guidelines (e.g., RP 14C/J to IEC 61508/11), the evolution of protection systems from single element analog devices to contemporary high pedigree HIPS and SIS, and the various analytical tools that that have also evolved to characterize reliability.  A focal point will be one of the more common tools, Layer of Protection Analysis (LOPA), which facilitates the definition of SIL targets for critical protection systems.  Since LOPA is often over/mis-used, a key part of the presentation will be to convey sensible applications (e.g., defining SIL, acceptability of high risk scenarios, cost-benefit analysis of design options).  We will also discuss effective applications of the LOPA Guidelines, soon to be issued by the Center for Chemical Process Safety (CCPS).