Which scenario is considered a realistic release?

• A. A release will occur from the disconnection of the largest pipe connected to a vessel
• B. A release occurs from a minor valve leak
• C. A release occurs only during maintenance shutdown
• D. A release occurs only when the vessel is completely full

Answer: (A)

In process safety, a realistic release is a credible release path that could reasonably occur during normal operations due to equipment failure or other typical faults, and it should be capable of producing a meaningful release rate for consequence analysis. Disconnection of the largest pipe connected to a vessel fits this idea well because it represents a plausible mechanical failure that can happen in the field—rupture or separation of a major conduit would allow product to vent rapidly, creating a substantial release. This scenario does not rely on special conditions like being in maintenance or the vessel being full; it reflects a credible failure mode that could occur during ordinary operation and lead to a significant release.

A minor valve leak, while possible, typically produces a much smaller release and may not be considered a realistic release for assessing major hazards. Releasing only during maintenance shutdown or only when the vessel is completely full are conditional scenarios that are less universally applicable as standard realistic release paths.