Back Draft

That job looks like a blast...NOT!

Molten metal splash is the most common cause of melt deck injuries and is caused by the addition of wet materials to the molten bath. It can be minimized by diligently inspecting and treating scrap. Metal run-out ranks among the most severe accidents.

An explosion occurs when moisture is confined by molten metal.
Wet charge materials, sealed scrap, and bridging are all safety hazards that can lead to catastrophic explosions in foundries. By diligently examining and treating scrap, following induction furnace safety procedures, properly training and retraining personnel, and use of automated melt shop equipment, founders can be confident their operations are as safe as possible.

Wet charge materials are a serious safety hazard in all foundries. Water, moisture, or any liquid-bearing material instantaneously turns to steam when coming in contact with molten metal — expanding to 1,600 times its original volume and producing a violent explosion. This occurs without warning and throws molten metal and possibly high-temperature solids out of the furnace, putting workers, the furnace itself, and nearby plant and equipment at risk.

A water/molten metal explosion can occur in any type of furnace. For an induction furnace, however, the aftereffects may be more serious, including the possibility of additional explosions caused by liquid in a ruptured cooling system coming in contact with molten metal in the bath. Molten metal need not be present in the furnace for a water/molten metal explosion to occur. Explosions also can occur if sealed drums or containers containing water are charged into an empty but hot furnace. In this case, the force of the explosion will eject the newly charged material and quite likely damage the refractory lining as well.

Appropriate Personal Protective Equipment (PPE) protects melt shop workers from both metal splash and radiant heat.
The violent and unpredictable nature of a water/molten metal explosion makes the wearing of appropriate Personal Protective Equipment (PPE) by melt shop workers imperative. PPE can help to prevent disfiguring, incapacitating or fatal burns.

Some foundries reduce the possibility of water/molten metal explosions by storing scrap under cover for a least one day and then carefully inspecting bales and containers for any residual moisture. But a more reliable solution employed by an increasing number of foundries is to use remote charging systems with charge dryers or preheaters. Remote charging systems permit the operator to stand safely back from the furnace or behind protective screens during charging. Dryers and preheaters maximize the removal of water and moisture before the scrap enters the bath.