‘Industry can do much better’ - US Chemical Safety Board

From the Industrial Fire Prevention blog editor:
These lessons learned, can also be applied to the Combustible Dust Industries:
  • Industry can do better
  • Propagation from processes not isolated from each other
  • Improperly designed engineering controls
  • Worker exposure
  • Building and process safety design needs improvement
  • Complex process-related accidents with tragic results are taking place across the country at companies of all sizes
  • If industry cannot police itself, AHJ's and government agencies will

From Industrial Fire Journal - Fire & Rescue - Hemming Group Ltd

‘Industry can do much better’

Published:  10 February, 2015
US Chemical Safety Board releases update on its ongoing investigation into the fatal methyl mercaptan release that took place at the DuPont facility in La Porte on November 15, 2014.

Four workers were killed during the release of what DuPont says were more than 23,000 pounds of methyl mercaptan, a highly toxic, flammable, and volatile liquid.

Four design issues have been identified by CSB investigators of the accident.

Firstly, the process included several interconnections between the methyl mercaptan supply line and a chemical vent system, which allowed a toxic leak into an unexpected location, where workers were
exposed with fatal consequences.

Secondly, the chemical vent system – which was intended to safely remove harmful vapor from process vessels – had a design shortcoming that allowed liquid to accumulate inside.  This liquid regularly caused pressure buildups in the vent, and the liquid needed to be manually drained by operators to prevent safety issues from interconnected equipment, such as reactors.

Thirdly, the vent drain that operators had to use was open to the atmosphere, meaning that workers were exposed to whatever chemicals were drained from the vent system.

Lastly, the building was designed in such a way that even had ventilation fans been working on the day of the accident, it could not necessarily protect workers from chemical exposure. ‘And we found that those vents were not, in fact, working at the time of the accident,’ said Moure-Eraso, adding that regulators and companies should place greater emphasis on making designs as safe and possible and updating them on a constant basis.

CSB Board Member Manuel Ehrlich said that the CSB had conducted approximately 50 interviews and had spent hundreds of hours reviewing documents and evaluating the incident scene.

‘Investigators had been inside the manufacturing building on numerous occasions evaluating the process equipment, building layout, and safety systems.  These systems include building ventilation, toxic gas detection, availability of emergency breathing air, and exit routes for workers, to name a few.’

methyl mercaptan tank

The investigation is approximately 50% complete, said Ehrlich:
‘In the coming weeks and months, testing of field equipment such as check valves, block valves, and interlock systems will take place as well as verification of critical instrumentation.’

According to CSB Chairperson Rafael Moure-Eraso, not only DuPont ‘but the industry as a whole must do much better.  Complex process-related accidents with tragic results are taking place across
the country at companies of all sizes.  This problem includes major corporations such as DuPont, not just smaller companies that some refer to as outliers. It is clear that the current process safety  regulatory system is in need of reform.’

Common factors found by CSB that contribute to major accidents such as the one in La Porte include lack of safe process designs; lack of risk reduction targets; degraded process safety systems; weak or
obsolete regulatory standards; inadequate regulatory resources and staffing; and overly permissive industry standards.

‘And the latest accident at DuPont is one of many incidents investigated by the CSB where we believe it will become clear that the process design was not as safe as possible.’

An audio of the briefing can be downloaded at:


release point


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