In LOPA, what does an Independent Protection Layer (IPL) provide?

• A. It stands for Immediate Protective Layer and is integrated with normal control.
• B. It stands for Independent Protection Layer and provides an independent safeguard to reduce risk.
• C. It stands for Initial Process Layer and is part of design.
• D. It stands for Internal Protective Link and is a surveillance system.

Answer: (B)

Independent Protection Layer is an independent safeguard that reduces risk by stopping or mitigating a hazardous event after it starts, and it must operate independently from the initiating cause and from other protection layers to avoid common-cause failures. In practice, an IPL could be a safety instrumented system with its own sensors and logic, a relief valve or vent that can release pressure independently of the main control system, or a hard-wired interlock that trips equipment even if the normal process control fails. This independence and protective function are why it’s described as reducing risk beyond the normal controls. The other phrases either imply dependence on the normal control or use terms not aligned with LOPA concepts.