Hydrofluoric acid incident

A large oil refinery had a failure in their alkylation unit resulting in a significant release of hydrofluoric acid (HF). This incident and others in refineries during recent years prompted members of the hydrocarbon processors to turn to HAZOP to better understand their risks. 

See Alcohols, above Hydrofluoric acid, Lactic acid, below See other gas evolution incidents... 

Deaths occurred after accidental releases of uranium hexafluoride at uranium-processing facilities in 1944 and 1986, but these deaths were not attributed to the uranium component of this compound (Kathren and Moore 1986 Moore and Kathren 1985 USNRC 1986). These releases resulted in the generation of concentrated aerosols of highly toxic hydrofluoric acid and uranyl fluoride. In the 1944 incident exposure time was estimated to be only 17 seconds, deaths occurred in 2 of 20 workers within an hour and were attributed to severe chemical burns of the lungs. In the 1986 incident, 1 of 23 workers died from massive pulmonary edema, indicating that inhalation of hydrofluoric acid was responsible for death. Estimated airborne concentrations were 20 mg uranium hexafluoride/m for a 1-minute exposure and 120 mg uranium hexafluoride/m for a 60-minute exposure (15.2 and 91 mg U/m, respectively). 

When the reflux accumulator separates two liquid phases, excessive rise or fall of the interface level can carry over one phase into another, and/or reflux the column with the improper phase. In some situations, such carryover can be h2aardous. In one case (7), carryover of hydrofluoric acid into a propane product route from the reflux accumulator of an alkylation depropanizer caused multiple explosions in downstream equipment. The author is familiar with an almost identical incident that overpress u ed downstream equipment but stopped short of exploding. Refluxing an improper phase into a column can also be troublesome this is described in detail in Sec. 13.7. 

For vitrinite reflectance (Rq) measurements, coarsely crushed samples were acidified with hydrochloric and hydrofluoric acid to remove carbonate and silicate. The solution was then centrifuged with heavy liquid to separate kerogen. The kerogen was embedded in a resin plug and polished to a flat shiny surface. Measurements of the percentage of incident light reflected from vitrinite particles under oil immersion with a Carl Zeiss MPM-03 microspectrophotometry system were made. 

Successful treatment of severe exposures is dependent on rapid reactions by those responding to the incident and by the affected person(s). In the following sections, reference is made to various medications specific to the treatment of hydrofluoric acid exposure. It is unlikely that the typical rescue squad called to the scene will have these medications so they should be part of the first aid supplies maintained in the immediate area where exposures may occur. Have someone call for emergency medical assistance as soon as possible and direct them to arrange treatment with a physician or trauma center familiar with chemical bums. In all types of exposure, the first action recommended is prolonged flushing with copious amounts of water so an eyewash station, a shower and a source of potable water should be immediately available. 

Have on site the first aid equipment and trained persormel to deal with the expected range of incidents involving hazardous substances, e.g. refrigerated calciitm gluconate gel for hydrofluoric acid. 

Leonard et al. [187] reported a case series of 957 patients treated in a bum center in Boston, Massachusetts [187]. Of these, 35 (4 %) had chemical skin injuries. Involved chemicals were sulfuric acid, hydrochloric acid, hydrofluoric acid, phenol, chlorosulfonic acid, trichloroacetic acid, and cement. Sixteen of these patients had immediate water decontamination and 19 patients had delayed water decontamination. Those in the delayed water decontamination group had a fivefold greater incidence of full thickness chemical skin injuries and a significantly longer required period of hospitalization, even though these patients had approximately the TBSA involved compared to those who had immediate water skin decontamination [187]. 

A 13.8 - 17.9 mg/cm surface layer was removed by etching in a 1.2 % hydrofluoric acid solution at room temperature. The effective incident energy was about 20 MeV. 

During a 4-year time period from 1976 to 1980 in Boston, Massachusetts, USA, 857 inpatients were admitted to a specialized bum center [30]. Of these, 35 (4 %) had chemical injuries. Involved chemicals included acids (hydrochloric, sulfuric, hydrofluoric, chlorosulfonic, trichloroacetic, and undetermined acidic substances) (10 cases) and alkaline caustic substances (lye, cement) (9 cases). The chemical exposures were work related in 51 % of cases, and in 7 cases (20 %), they were due to deliberate chemical assaults. Some patients had relatively immediate copious water washing and some did not. Patients with delayed water decontamination had a fivefold greater incidence of fullthickness chemical skin injuries, but even immediate and copious potable water washing was unable to prevent chemical skin injuries in all cases [30]. 

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