LOPA (Layer of Protection Analysis) is a simplified form of risk assessment and generally uses order-of-magnitude categories to start the frequency of events, severity of consequence, and probability of failure of independent layers of protection (IPLs) to approximate the risk of a scenario.
LOPA is an analysis tool that is usually based on information developed during a qualitative risk assessment, such as a HAZOP or other methodology included in a process risk analysis (PHA), and is implemented using a set of rules (guideline).
The main purpose of LOPA is to determine whether there are sufficient layers of protection against a specific accident scenario (risk).
For more information, talk to a specialist.