An employee, 49, of a paint manufacturing company spent eight days in intensive care on life support and has been left with all-over body scarring, partial blindness to one eye, hearing damage, and damage to a knee and shoulder. He was off work for 16 months. The explosion at the company’s premises on August 4, 2020, also caused significant damage to the building. The employee was making paint in a large mixing vessel, which involved the use of flammable liquids. As he emptied resin pellets from a large bulk bag into the vessel, an electrostatic spark was generated, igniting flammable vapor within the vessel, and causing the large explosion. The Health and Safety Executive (HSE) investigation identified that the company failed to implement sufficient measures to control the risk. This included a failure to use a correctly working extraction system to remove the flammable vapors and effective bonding of the bulk bag to prevent the build-up of electrostatic charge that led to the static spark discharging. The company pleaded guilty to breaching Section 2(1) of the Health and Safety at Work etc. Act 1974 and was fined £800,000 with £14,032 costs at Newcastle upon Tyne Magistrates’ Court on November 30, 2022.
We have worked with many flammable liquid processes to design the safety systems intended to prevent this very accident. Years ago, a study showed that the #1 cause of flammable liquid flash fires in processing was the addition of solids to a mixing vessel and that the #1 ignition source for these events was static electricity. NFPA 77, Chapter 13 specifically covers the hazard of “Adding Solids” (13.5). We have two (2) options, although we design to both methods.
1) controlling the static generation and providing a path to ground for it
2) inerting the vessel atmosphere to below the MOC of the flammable atm
NFPA 77 WARNING! Even where the vessel is inerted, large additions of solids will introduce air into the vessel while expelling flammable vapor from the vessel.
This accident appears to be caused by the addition of solids into the mixing vessel. NFPA 77 suggests the following when we are analyzing the hazards associated with such a common task.