The U.S. Chemical Safety and Hazard Investigation Board (CSB) released an update on its investigation into a July 2023 explosion at the Dow Louisiana Operations’ Glycol II plant in Plaquemine, Louisiana, that resulted in the release of over 31,000 pounds of ethylene oxide (EtO). Multiple subsequent explosions and fires damaged nearby piping and equipment, including a reflux drum. In addition to the release of EtO, the incident resulted in substantial property damage at the facility, and local officials issued a shelter-in-place order for hundreds of nearby residents.
The CSB is continuing to gather facts and analyze several key areas involved in this incident, including:
- Emergency pressure-relief systems scenarios
- Reactive chemical hazards
- Reactive material emergency pressure-relief system design
- Maintenance procedures and practices
- Relevant facility, corporate, and industry standards
According to the CSB investigation update, the Glycol II plant contains multiple processing areas, including the EtO production unit. To produce EtO, Dow’s EtO production unit reacts ethylene and oxygen. The EtO is then further processed through finishing operations, which purify the EtO. The EtO finishing operations contain distillation columns to remove impurities from the final EtO product.
In the EtO finishing operations section of the Glycol II plant, purified EtO flows from the top of a distillation tower, is condensed, and then sent to a reflux drum. The EtO in the reflux drum flows to multiple locations through its reflux pumps. The EtO can be pumped back to the distillation column to be used as reflux, recycled back to the reflux drum or sent to storage tanks as a final product. EtO flow to the storage tanks also includes pumping the EtO through a heat exchanger, called the product cooler. Figure 1 provides a simplified graphical depiction of portions of the EtO finishing operations process related to this incident.
The CSB’s investigation of this incident is ongoing. Complete findings, analyses, and appropriate recommendations will be detailed in the CSB’s final investigation report.
