IEC 61511 defines the Safety Life Cycle for Functional Safety Management. The initial Hazard and Risk Assessment (HRA) shall take place during the Analysis phase, based on an early version of the P&IDs and C&E chart. After completion of the initial HAZOP, MOC procedures should be applied to monitor and evaluate any changes during further design and implementation phases that might impact HAZOP assumptions or safeguards. HAZOP should be reviewed/updated prior to commissioning as part of a pre-startup safety review (PSSR) procedure and throughout the plant operating life, latest every five years.