Validation and Maintenance of Independent Protection Layers (IPLs)

Companies are utilizing risk assessment methodologies to identify engineered and administrative independent protection layers (IPLs) credited with risk reduction toward achieving their tolerable risk criteria. Each IPL in the form of alarms, operating procedures, basic process control system interlocks, safety instrumented functions, relief devices, etc., requires validation that it is designed and maintained to meet the following criteria: independence, functionality, integrity, reliability, auditability, access security and management of change. Design documentation, reliability data and inspection results, and conditions related to demands (e.g. initiating events and conditional modifiers) on these safety functions must be retained in a manner that they can be used for periodic revalidations and risk profiling. This session invites papers that address IPL integrity management. Authors are encouraged to share: management philosophies; written management systems; related functional safety lifecycle management systems or case studies per ANSI/ISA 84.00.01/IEC 61511; bypass management protocols; change management methods; document control and data management methods; inspection and testing programs; conditional modifier management, and risk profiling. Sharing lessons learned with others at the conference on these subjects will result in a meaningful contribution to the overall process safety of the industry through improving the availability of safety functions and attainment of risk management criteria.