Layer of protection analysis (LOPA) is a semi quantitative tool for analyzing and assessing risk. LOPA can be used in all phases of the process life cycle. LOPA helps to make consistent decisions on the adequacy of the existing or proposed layers of protection to prevent incidents. LOPA looks at the safeguards on a process plant to evaluate the adequacy of existing or proposed layers of protection against known hazards. It typically builds on the information developed during a qualitative hazard evaluation, such as a process hazard analysis, and can be used to meet the risk assessment requirements of IEC 61508 and IEC 61511.

The designer normally follows the sequence given below to eliminate hazards or to reduce the frequency of undesired consequences:
  1. Inherently safer concepts
  2. Basic process control system
  3. Safety instrumented systems
  4. Passive devices (such as dikes and blast walls)
  5. Active devices (such as relief valves)

Prism Consultants expertise facilitates Layers of protection analyses in the role of facilitator.

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