Blocked In

Summary of the video’s main report (CSB case study: Williams Geismar Olefins explosion)

Incident overview (June 13, 2013, Geismar, Louisiana)

On June 13, 2013, at the Williams Geismar Olefins Plant in Geismar, Louisiana, a heat exchanger (reboiler) ruptured violently. The failure triggered a major explosion and fire that killed two workers: the plant’s operations supervisor and an operator.

The Chemical Safety Board (CSB) concluded the root cause was a set of process safety management (PSM) failures that left the system vulnerable to catastrophic overpressure.

Why the overpressure hazard existed

The plant’s propylene fractionator used reboilers (shell-and-tube heat exchangers) to heat and vaporize propane–propylene mixtures.

Key contributing factors:

• Fouling (tar buildup) reduced heat transfer efficiency, requiring periodic shutdown and cleaning.
• To avoid shutting down the entire unit, new valves installed in 2001 allowed the plant to run only one reboiler at a time, while the other remained on standby.

Critical design/operations failure

The CSB found that the valves used to provide operational flexibility unintentionally isolated the standby reboiler from its protective pressure release valve.

As a result, when pressure rose, the plant lacked an effective safeguard to prevent rupture.

Sequence leading to the explosion

During a daily meeting before the incident, the plant observed reduced water flow through the operating reboiler and began investigating.

The CSB determined that around 8:33 a.m., the operations supervisor likely opened the hot-water valves to the standby reboiler:

• The standby reboiler contained trapped flammable liquid propane that had accumulated while it sat idle.
• The incoming hot water heated the propane, causing pressure to increase rapidly.
• Because the standby reboiler was blocked off from its pressure relief path, it ruptured within minutes, producing a fireball explosion.

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How CSB said multiple layers of the safety system failed (program deficiencies)

1. Management of Change (MOC) failure (2001) Williams performed an MOC review for the reboiler valve installation, but the CSB found it did not identify that the new valves could block the reboiler from its pressure release valve.

   The CSB emphasized that MOC is intended to evaluate safety impacts before hazards are introduced.

2. Delayed or compliance-driven MOC The CSB concluded the MOC was handled primarily to satisfy regulatory requirements, rather than to thoroughly control new hazards.

3. Pre-Startup Safety Review (PSSR) incompleteness Although a PSSR was completed, the CSB found key questions—such as whether pressure release systems were in place and operational—were left blank, yet management still approved the form.

4. Process Hazard Analyses (PHAs) didn’t find/control the hazard (2001, 2006, 2011) The CSB found PHAs did not sufficiently identify or control the overpressure risk. Even when recommendations existed (e.g., ensuring valves allow access to pressure relief), the CSB found the intended actions were not implemented for both reboilers.

5. No adequate procedures for known fouling/switching operations The CSB said Williams failed to develop effective written procedures for handling fouling and switching reboilers on the day of the incident—despite fouling being a known issue.

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Key lesson emphasized

The CSB highlighted that small “details” missed in safety program steps—such as MOC, PSSR, PHA, and safeguard evaluation—can combine to create major hazards that may only become obvious years later.

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CSB recommendations and broader message

• Williams should perform safety culture assessments with workforce participation, and report findings with specific corrective actions.
• Build a safety indicators tracking program to support continuous improvement using relevant data.
• Conduct comprehensive process safety program assessments to confirm effectiveness.
• The CSB urges other companies to review and incorporate the lessons from the Williams investigation.
• The video stresses that managers must implement, monitor, and support strong process safety programs and culture to protect workers and the environment.

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Presenters / contributors

• Narrator
• Sutherland
• Grim