: clean out operation of a sludge, as a batch still, was organized in order to remove residues. This vessel had never been cleaned since it was installed, 31 years ago. An operator dipped the sludge to examine it and reported the sludge as gritty with the consistency of soft butter to management. No sample was sent for analysis nor was the atmosphere inside the vessel checked for a flammable vapor. It was thought that the material was a thermally stable tar. In order to soften the sludge, which was estimated to have a depth of 34 cm, steam was applied to the bottom battery. Advice was given not to exceed 90C. Employees started the clean out operation using a metal rake. The material was tar-like and had liquid entrained in it. Approximately one hour into the cleaning process a longer steel rake was used to reach further into the still. No permit to work was ever issued for the task of raking out the still base. The vessels temperature gauge in the control room was reported to be reading 48C, instructions were given to isolate the steam.

At approximately 13:20 hrs a number of employees involved in the raking left the still base to get on with other tasks. One person left on the scaffold had stopped raking and noticed a blue light, which turned instantly to an orange flame. As he leapt from the scaffold an incandescent conical jet erupted from the manhole. This projected horizontally towards the control building. A vertical jet of burning vapors shot out of the top rear vent to the height of the distillation column nearby. The jet fire lasted for approximately one minute before subsiding to localized fires around the manlid and buildings nearby. The force of the jet destroyed the scaffold, in the process, propelling the manhole cover into the center of the control building. The jet severely damaged this building and then impacted on the north face of the main office block causing a number of fires to start inside the building. A total of 22 fire appliances and over 100 fire fighters attended the incident.

Answer the following questions:

(a) Give the main failure in the technical measures that lead to the accident?

(b) Reiterate the condition caused the fire? Explain you answer?

(c) What specific control measures should be implemented? Justify your answers?

(d) Explain how can this fire be extinguished?

(e) Is the rake a hand tool? Explain its role in the accident? Can you recommend alternative hand tool to be used instead?