Root Cause Analysis of Boiler Explosion in Pharmaceutical Manufacturing

Incident Overview

During routine maintenance operations, a major European pharmaceutical company experienced an explosion in one of their boiler houses. The blast caused significant damage to the boiler and nearby infrastructure, though no personnel were injured due to a scheduled work break. The explosion took the boiler, one of three supporting multiple production lines, out of operation, reducing the boiler house's overall efficiency. With the root cause unknown, there was concern that a similar event could occur with the remaining two boilers, which shared similar designs.

Envista Forensics was engaged to investigate the origin and root cause of the explosion, identify contributing factors, and recommend preventive measures.

Structural damage caused due to the explosion in the exhaust of the boiler.

Envista’s Investigation

Envista’s UK-based team conducted a comprehensive on-site investigation at the pharmaceutical facility to assess the explosion's origin and impact. Our fire investigator examined the structural damage and determined that the explosion began in the boiler's exhaust flue. Using burn pattern analysis, we identified the explosion as a Deflagration to Detonation Transition (DDT) event – a process where a fast-burning flame suddenly speeds up and turns into a powerful explosion.

Our mechanical engineering expert evaluated the boiler’s design and maintenance activities at the time of the incident. Since the boiler was operating on diesel fuel at the time of the explosion, we recommended isolating and testing the diesel fuel supply system, including hoses, pipes, and valves, for potential failures.

Envista then coordinated testing at the manufacturer's headquarters, where our team discovered that multiple diesel injection nozzles had developed coke build-up, causing fuel leakage into the burn chamber. This finding was supported by data from the boiler’s control system, and we collaborated with the manufacturer to develop recommendations to prevent recurrence.

Oil slicks within the burn chamber, a clue to the build-up of diesel within the burn chamber.

Outcome and Global Impact

Our investigation provided the client with a detailed root cause analysis of the explosion and actionable recommendations to prevent future incidents. In addition to enhancing safety at the client’s facility, Envista’s collaboration with the boiler manufacturer led to the implementation of safety changes across thousands of similar boilers worldwide, helping to mitigate risks for other users.