Hot Work: Hidden Hazards

Summary

On November 9, 2010, a tragic explosion at DuPont's Tonawanda plant resulted in the death of a welder and injuries to another. The incident occurred during hot work on a tank that unknowingly contained flammable vinyl fluoride gas. Key safety failures included inadequate hazard analysis, lack of atmospheric monitoring inside tanks, and a failure to isolate process piping. The Chemical Safety Board (CSB) issued recommendations to improve safety procedures, including mandatory testing of tank atmospheres and better training. This incident highlights the need for rigorous safety protocols in industries involving flammable materials.

Takeaways

• 😀 A fatal explosion occurred at the DuPont Chemical Manufacturing Plant in Tonawanda, New York, on November 9, 2010, caused by welding near flammable gas in a tank.
• 😀 Hot work accidents, such as welding, cutting, or grinding near flammable vapors, were highlighted as a significant safety hazard in a 2010 CSB Safety Bulletin.
• 😀 The explosion was triggered by welding sparks falling into a tank containing flammable vinyl fluoride gas, which had traveled from adjacent tanks through an unisolated overflow line.
• 😀 Despite safety precautions such as valve locks and motor lockouts, DuPont failed to isolate the flow of flammable gas inside the overhead piping, leading to hazardous conditions.
• 😀 Testing for flammable gas in the atmosphere above the tank was done, but no testing was conducted inside the tank where the gas levels were dangerously high.
• 😀 DuPont’s failure to include slurry tanks in its Process Safety Management (PSM) program led to inadequate risk assessment and hot work permits being issued without proper safety evaluations.
• 😀 The malfunction of a compressor and the lack of a formal review of a liquid trap defect added to the potential danger, but these hazards went unrecognized and unaddressed.
• 😀 The CSB investigation revealed that there were similar incidents of hot work accidents at other facilities, where the lack of proper gas monitoring or isolation contributed to explosions.
• 😀 The CSB issued recommendations for DuPont to revise policies for atmospheric monitoring before and during hot work, and to require positive isolation of process piping before hot work is authorized.
• 😀 Hot work should not be treated as routine but with extreme caution due to the deadly potential of fire and explosion hazards when flammable vapors are overlooked.

Q & A

What event occurred at the DuPont Chemical Manufacturing Plant in Tonawanda, New York, on November 9, 2010?

On November 9, 2010, a powerful explosion occurred at the DuPont Chemical Manufacturing Plant in Tonawanda, New York, which killed a contract welder instantly and injured a second worker. The explosion was caused by welding sparks igniting flammable gas inside a tank.

What safety issue did the explosion at the DuPont plant highlight?

The explosion exposed weaknesses in how process hazards were analyzed and controlled, particularly with respect to hot work accidents, where welding, cutting, or grinding is done near flammable vapors.

What is 'hot work,' and why is it dangerous in chemical plants?

Hot work refers to activities like welding, cutting, or grinding that produce sparks or heat. It is dangerous in chemical plants because these activities can ignite flammable vapors, gases, or liquids, leading to explosions or fires.

What was the specific cause of the explosion at the DuPont facility?

The explosion was caused by welding sparks igniting flammable vinyl fluoride gas that had traveled from other tanks into Tank 1 through an open overflow line. The gas inside the tank had reached dangerous levels, which was not detected due to inadequate safety measures.

How did the DuPont personnel fail to properly assess the safety of the work being performed?

DuPont personnel failed to properly assess the safety of the work by not conducting atmospheric testing inside Tank 1, where flammable gas was present. They also mistakenly believed that flammable gas could not reach the slurry tanks in dangerous amounts.

What procedural failures contributed to the explosion at DuPont?

Key procedural failures included a lack of proper atmospheric testing inside the tanks, failure to isolate process piping connected to the tanks, and inadequate analysis of hazards related to a malfunctioning compressor and other equipment issues.

What are some factors that contributed to the presence of flammable gas in Tank 1?

Factors contributing to the presence of flammable gas in Tank 1 included the flow of vinyl fluoride gas from Tanks 2 and 3 through the open overflow line, as well as a malfunction in the compressor, which caused higher-than-normal levels of vinyl fluoride in the slurry.

What were some of the recommendations made by the CSB following their investigation of the DuPont explosion?

The CSB recommended that DuPont revise its policies to require atmospheric monitoring inside tanks before and during hot work, and to ensure that process piping, including vent lines, be positively isolated before hot work is authorized.

What was DuPont's oversight regarding its process safety management (PSM) program?

DuPont mistakenly did not include the slurry tanks in the facility's PSM program. As a result, the risks associated with flammable gas in these tanks were not properly assessed, despite the fact that the Tedlar production process was covered under OSHA's PSM standard.

What lessons can be learned from the DuPont explosion regarding hot work safety?

The lesson from the DuPont explosion is that hot work should always be preceded by thorough hazard analysis and monitoring of the atmosphere for flammable vapors. Proper safety procedures should be followed, including isolation of all related piping and tanks, and testing for dangerous gas levels before beginning any hot work.