This heater was severely damaged during startup as a result of a firebox explosion.

The correct answer is C because this incident clearly involves multiple failures across several RBPS elements , not a single-point breakdown. According to CCPS, major incidents typically result from combined weaknesses across systems .

Operating Procedures and Safe Work Practices were inadequate or not followed, as proper startup procedures should strictly prohibit bypassing safety interlocks and require verification of pilot ignition before introducing fuel gas. Management of Change (MOC) is relevant because bypassing interlocks constitutes a temporary change that should require formal authorization, risk assessment, and safeguards.

Training and Performance Assurance is critical, as the operator did not fully understand the hazard of gas accumulation in the firebox or the consequences of bypassing safeguards. Asset Integrity and Reliability also contributed, since instrumentation problems triggered the unsafe decision, indicating possible maintenance or reliability issues.

Additionally, Hazard Identification and Risk Analysis (HIRA) should have identified this scenario (fuel gas accumulation before ignition) as a credible hazard requiring strong safeguards. Finally, Process Safety Culture played a role, as bypassing interlocks suggests normalization of unsafe practices or production pressure overriding safety.

This event illustrates a classic breakdown of layers of protection , where both technical and organizational controls failed simultaneously, leading to a catastrophic explosion.