Toxic inhalation hazard (TIH) chemicals are widely used in the chemical process industries (CPI) and transported through communities. Fatalities can occur if these chemicals are not managed properly.
The workers within chemical plants and oil refineries, as well as the general population in surrounding communities, are at risk of exposure to toxic chemicals. Transportation of these chemicals by road, rail, marine vessel, and pipeline also poses risks to operators and the public, particularly when traveling through densely populated areas. As a result, it is paramount that hazards are properly managed.
Toxic inhalation hazard (TIH) chemicals are a class of toxic chemicals that act on the respiratory tract and can cause pulmonary injury. Many industrial TIH chemicals are regularly handled in process units and transported. Some of these chemicals, such as chlorine bleach and ammonia, are common in households. Certain TIH chemicals can be particularly hazardous, as they cannot be detected through sight or smell upon release. Case Study 1 (sidebar) describes a fatal incident in South Korea that involved the release of hydrofluoric acid, a colorless, volatile TIH chemical (1).
This article provides guidance for handling TIH chemicals, as well as a quantitative method for evaluating the risks associated with transporting TIH chemicals and selecting appropriate mitigative measures. It also describes how to use a risk-based process safety (RBPS) approach (2) for auditing TIH risks at chemical plants.
Case Study 1. 2012 Hydrofluoric Acid Release, Gumi, South Korea
Two workers at the Hube Global chemical plant climbed onto a road tanker to hook up an air hose, intending to unload the hydrofluoric (HF) acid cargo by air pressure into a storage tank. While one employee connected the air hose, the other, presumably to save time, began unscrewing the bolts of the end plate on the acid outlet valve. He inadvertently bumped the manual outlet valve arm, which partially opened the valve. When the valve opened, eight tons of HF acid was released under pressure (during transportation, the cargo had become pressurized due to thermal expansion) (1).
Neither of the workers were wearing appropriate personal protective equipment (PPE). Both workers and three others at a neighboring facility were killed. Another 18 workers were hospitalized, and 4,195 people, including 416 firefighters, were treated for nausea, skin rashes, and breathing difficulties. A significant area of arable land downwind of the release was contaminated, resulting in the loss of crops, death of more than 3,900 cattle, and corrosion of 1,200 vehicles.
Several factors contributed to the severity of the incident:
- Industry procedures were not followed. The tanker should have been depressurized and appropriate flexible hoses deployed before the workers began the unloading process.
- The workers should have worn proper acid suits with supplied-air hoods.
- Municipal firefighters arrived without proper PPE and sprayed water on the release, which increased the rate of vaporization of HF acid.
- Local authorities were slow to evacuate the residents in the vicinity of the release, and they deployed inadequate resources (e.g., neutralizing agents).
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