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Hydrofluoric Acid : The Worst Of All Acids?

Hydrofluoric acid : the worst of all acids?

  • Flash
Despite being produced 200 times less than sulphuric acid (1 M vs. 200 M tonnes/year), the ARIA database has recorded nearly 80 accidents involving hydrofluoric acid (HF) (vs. 220 for H2SO4). A series of recent accidents serves to recall its hazards, especially the serious consequences in the event of its release...
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47277

  • Accident report
  • FRANCE
The summary of this accident has not yet been translated. In the meantime, please refer to the French summary :

Compresseur n°1 accidenté : compresseur à double étage comprimant l'éthylène de 3 à 33 bar. Il fonctionne en alternance avec le compresseur principal. Le jour de l'accident, il totalisait 43 jours de fonctionnement depuis sa dernière maintenance 5 mois avant. Il jouxtait 2 autres compresseurs (n°2 et 3). Ces derniers étaient arrêtés et isolés automatiquement sur déclenchement des détecteurs gaz, ce qui n'était pas le cas [...]

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46801

  • Accident report
  • FRANCE

Two explosions ripped through a petrochemical complex at night

The blasts occurred around 3 am in the storage zone of a petrochemical plant: 2 tanks ignited and their floating roofs were damaged. The 1st tank contained 11,300 m³ of pyrolysis gasoline (a mix of diesel, butene, toluene and butadiene). The 2nd tank, located 300 m away, was holding 48,000 m³ of naphtha. On-site fire-fighters, backed up by neighbouring facilities' response teams, arrived on the scene in large numbers. The complex operator activated the internal emergency plan and n [...]

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  • Accident report
  • ALLEMAGNE
The summary of this accident has not yet been translated. In the meantime, please refer to the French summary :

Dans une usine chimique, une fuite d'effluents contenant de l'acétonitrile (solvant nocif et inflammable) provenant du réseau des eaux usées de procédé entraîne une contamination des eaux souterraines. En raison de l'utilisation sporadique de ce réseau, la durée de la fuite n'a pu être déterminée avec précision. Une estimation maximaliste a donné 557 jours. La perte potentielle est estimée à 61 t d'acétonitrile.

Des puits s [...]

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Mixing of incompatible products

  • Fact sheet
Transfer of chemicals between fixed and mobile tanks may cause mixtures of incompatible products. This risk is all the more pernicious as the mixture usually involves "classic" substances and widely used: bleach, acid ... This fact sheet presents some lessons learnt from the accidentology.
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Accidents Associated With Chlorine

Accidents associated with chlorine

  • Study
This summary report was established based on information collected from 557 French accidents (251 cases) or foreign accidents (306 cases) which took place between January 1917 and May 2003 and which are recorded in the ARIA database. This document should be of specific interest to installations implementing large quantities of chlorine (chemical plants, paper mills, metallurgy…), as well as companies involved in its transport.
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Mix Of Incompatible Products

Mix of incompatible products

  • Flash
The accidents presented in this flash involve chemical reactions between incompatible products inadvertently placed into contact with one another. Encountered in all types of activities, such accidents are frequent and occur not only during the delivery of chemical products (wrong destination reservoir, etc.), during handling or cleaning operations (mistaken chemical substance, simultaneous use of 2 incompatible products), but also when emergency interventions deploy inappropriate resources for the type of accident at hand (use of water on a fi [...]
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Prolonged rejection of mercaptans from a chemical plant

  • Accident report
  • FRANCE

On Monday around 8 am, a technician detected an odour of mercaptan (foul-smelling gas at < 1 ppb, toxic at high concentrations) in the dialkyl zinc dithiophosphate (ZDDP) unit of a chemical plant producing additives for lubricants. He was sampling a product scheduled for transfer since the previous Saturday in the adjustment tank when the tank's "high temperature" alarm went off in the control room. Around 9 am, analyses confirmed that the product had thermally decomposed. An inerting test conducted by adding a zinc oxide / water mix failed near 11 am due to technical difficulties that slowed preparation of the neutralising mix within a mobile mixer; namely by lack of an outlet connection, insufficient time allotted for mix preparation. Given the saturation of the unit's scrubber, foul-smelling cloud drifts beyond the site. The plant operator activated the internal emergency plan at 10 am and informed the Prefecture around 11:30; 33 municipalities were notified thanks to the phone alarm system. Other neutralisation tests conducted at the end of Monday evening also failed. Wind direction had changed; the odours spread throughout the county, then the Paris Metropolitan area and the southern part of England during the night. Tens of thousands of individuals felt discomforted, some complaining of vertigo, headaches and vomiting. Emergency services performed some 20 medical visits in and around Rouen. The Prefect assembled a public information team as of Tuesday morning and, as a precaution, activated the external emergency plan at 10:35 am Tuesday. From Wednesday morning through Friday evening, a new operating protocol allowed "safe" neutralisation of the decomposing product in batches of 12 and 36 tonnes prior to truck transfer to an incineration facility. According to a conservative assessment, this decomposition generated 95 kg of H2S, discharged via the stack of the scrubber system, and another 545 kg of mercaptans not entirely treated (accounting for a maximum discharge into the atmosphere of 272 kg). Given the geographic spread of the malodorous plume, this accident received heavy media attention both in France and abroad. Once the tank had been cleaned, the external measures were lifted on 6th February. Operating losses were initially estimated at several hundred thousand Euros due to plant shutdown for the duration of the incident and a ZDDP production line still idle 3 months later. Several causes were identified: - On Friday 18th January, a technician inadvertently started the adjustment tank stirrer and not the recirculation pump on the unit's control panel. Transferred to the tank on Saturday morning, a product batch at 94°C gradually heated until Monday morning, when the thermal decomposition was discovered (T > 110°C). Technicians on their rounds that weekend had not noticed the stirrer running despite the indicator light on the control panel and the shaft visibly rotating at the top of the tank; - The filling of a storage tank, combined with limited demand, led the operator to store product in an adjustment tank, whose transfer and recirculation mechanisms were only operable in manual mode following the implementation Friday of a software safety step that deact [...]

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Bursting Of A High-pressure Steam Pipe

Bursting of a high-pressure steam pipe

  • Accident report
  • FRANCE

At 11:15 pm, a violent and loud bursting occurs within an ammonia (NH3) synthesis unit at a SEVESO-classified nitrogenous fertiliser plant. The convex base welded to a heat-insulated, high-pressure water vapour pipe connected to catalytic reforming equipment had burst prior to ignition. The base, a 40-kg block of steel, was projected longitudinally. Inside the shop area, a walkway was ripped off its supports damaging an access ladder. The steel base crossed the ammonia confinement space 25 m further, without causing any damage, then flew over a [...]

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