"fire was reported under the melting furnace....."

If molten metal escapes is holding location it will flow like any other liquid. Molten metal surprisingly has the same viscosity as water. So escape metal will flow rather quickly to the lowest point in the vicinity of its container. Here is an incident that is short in total words but to the point.

A fire was reported under the melting furnace at (an aluminium company name omitted) during one Sunday evening during the month of February. Crews found the building full of smoke when they arrived. The fire was put out.

To the best of our knowledge no one was injured in this incident. We are thankful for that. This aluminium plant is older. This age has served it well because it has a well-executed safety plan. We can assume that the fire department used fire fighting supplies provided by the aluminium plant. Why? Because the aluminium plant learned decades ago that their local fire departments did not have enough fire fighting supplies on hand to deal with the size of hazards that exist at the aluminium plant.

Back to the incident, we assume molten metal escaped and flowed to the maintenance pit under the furnace. Maintenance pits under furnaces were designed for a myriad of reasons including to have a large enough volume to collect the capacity of the furnace in case of leaks. Though we find that statement to be obvious. Some companies fail to understand the hazard associated with maintenance pits under furnaces, maintenance pits under or adjacent to casting pits (both d.c. and horizontal), any concrete trenching recessed in the floor (for conduit lines, water lines, etc.). The hazard is that molten metal can flow to these localized areas. If the substrate of the maintenance pit under a furnace has moisture on it (which almost all do). An explosion may result. We use may because as one of our mentors have said “you can do the same procedure incorrectly over and over with no explosion, then an explosion will occur”.

Twenty years ago the best practice toward safety was to properly coat the substrate in the localized areas that could collect molten metal with Wise Chem. Then overtime as our industry went through a never-ending series of recessions this practice by some companies was cut to save on costs. Only after explosions kept occurring did some of the aluminium companies restarted this best practice. Recently insurance companies have pointed out these localized areas during audits and insist that they get Wise Chem. We know of too many incidents that occur when molten metal flows into a maintenance pit under furnace, maintenance pit adjacent to a casting station and trenching. Please note, the practice by some in our industry to fill their trenches with sand to prevent the molten metal from filling or protecting is not recommended in our opinion. Why? Well sand can retain moisture, there can still be an explosion if molten metal enters and it will. Almost all trenches are covered with steel plates. The steel plates commonly have gaps between them. It is those gaps that the molten metal flows into. Also, note any steel plates around a casting station should be properly coated with Wise Chem. We know of explosions that have occurred on these plates.

The publication Aluminium Insight had an article on this topic. It can be found here.

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