Exam CCPSC Topic 1 Question 74 Discussion
Actual exam question for AIChE's CCPSC exam
Question #: 74
Topic #: 1
Question #: 74
Topic #: 1
A material had been oxidized many times, without incident, under an oxygen atmosphere in a small pilot plant vessel. While scaling up to a larger vessel, the plant engineers decided they could improve gas/liquid contact by using a more efficient feed dispersing system. This dispersing system filled the reactor ' s vapor space with a fine combustible mist. Several hours after startup, the vessel was ruptured by an internal mist explosion. The source of ignition was a small amount of catalyst left over from an earlier set of experiments. This was a phenomenon that the engineers had not considered. Which of the following risk based process safety elements could have helped prevent this incident? (Select all that apply)
Suggested Answer: B,D Vote an answer
The correct answers are B (Management of Change) and D (Process Knowledge Management) because this incident was caused by unrecognized hazards introduced during scale-up and process modification .
Option B (Management of Change - MOC) is critical because the engineers introduced a new feed dispersing system , which significantly altered the process by creating a combustible mist in the vapor space . According to CCPS, any change in equipment, process conditions, or technology must undergo a formal MOC review to identify new hazards, evaluate risks, and implement safeguards before startup. A proper MOC would likely have identified the explosion risk associated with mist formation in an oxygen-rich environment.
Option D (Process Knowledge Management - PKM) is also essential because the hazard resulted from insufficient understanding of the process chemistry and physical behavior , particularly mist explosibility and catalyst ignition potential. PKM ensures that organizations maintain accurate knowledge of chemical reactivity, flammability limits, and scale-up effects.
Options A , C , and E are not directly related to preventing this type of incident. Measurement and metrics track performance, contractor management is irrelevant here, and emergency management focuses on response rather than prevention.
This scenario highlights how scale-up changes can introduce new hazards , requiring both strong MOC and robust process knowledge.
Option B (Management of Change - MOC) is critical because the engineers introduced a new feed dispersing system , which significantly altered the process by creating a combustible mist in the vapor space . According to CCPS, any change in equipment, process conditions, or technology must undergo a formal MOC review to identify new hazards, evaluate risks, and implement safeguards before startup. A proper MOC would likely have identified the explosion risk associated with mist formation in an oxygen-rich environment.
Option D (Process Knowledge Management - PKM) is also essential because the hazard resulted from insufficient understanding of the process chemistry and physical behavior , particularly mist explosibility and catalyst ignition potential. PKM ensures that organizations maintain accurate knowledge of chemical reactivity, flammability limits, and scale-up effects.
Options A , C , and E are not directly related to preventing this type of incident. Measurement and metrics track performance, contractor management is irrelevant here, and emergency management focuses on response rather than prevention.
This scenario highlights how scale-up changes can introduce new hazards , requiring both strong MOC and robust process knowledge.
by Troy at Sep 27, 2026, 07:35 PM
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