In process safety, primary containment refers to which concept?

• A. The emergency relief device
• B. The physical barrier that contains the material under normal conditions
• C. PPE used to protect workers
• D. The training program for operators

Answer: (B)

Primary containment is the physical barrier that holds the material under normal operating conditions. It refers to the walls, vessels, piping, valves, seals, and other equipment designed to contain the chemical during normal operation, preventing release to the surroundings. This first line of defense is what keeps the material contained inside the process system unless something goes wrong.

PPE protects workers, but it doesn’t stop a release from occurring in the system itself. A training program helps operators run the process safely, but it doesn’t physically contain the chemical. An emergency relief device is designed to relieve pressure and prevent vessel rupture, not to continuously contain the material during normal operation. Secondary containment, which isn’t described here, would come into play if a leak occurs, capturing any material that escapes primary containment.