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Personal Safety For Automatic Pouring Systems
Because they hold and dispense molten metal, automatic pouring systems expose workers to most or all of the same hazards as melting and holding furnaces. Depending on the type of automatic pouring system, these hazards may include burns from metal splash, from contact with hot surfaces, from metal run-outs and from water/molten metal explosions. But automatic pouring systems also present their own hazards not normally associated with melt shop operations. The three major types of systems are: unheated tundish systems, heated pressure vessel systems and coreless pouring systems. Again, depending on the type of system and the metal being poured, these may include dangers such as magnesium flashes in pressure vessels and mold failures with resulting metal run-outs.
________________________________________________ Hazards Common to All Types of Automatic Pouring Systems Burns from contact with hot surfaces and materials and burns caused by molten metal splash are hazards associated with all types of automatic pouring systems. These burns can result in serious injury or death. Do not pour molten metal into molds that may contain water or other fluids. Molds should not be of a type that may react with the chemical composition of the melt. Do not overfill molds. Automatic pouring systems have numerous moving parts, including covers, positioning frames and stopper-rod mechanisms. These create trapping hazards if all or part of a worker’s body becomes caught between moving or moving and stationary machinery. Such entrapment can cause serious injury or death. Workers must be alert to the location and movement path of operating mechanisms and stay out of that path during the operating cycles of these mechanisms.
Hydraulic systems also create hazards in automatic pouring systems. Therefore, hydraulic systems must be inspected daily and any leaking components must be repaired. ________________________________________________ Safe Operation of Automatic Pouring Systems The safe operation of automatic pouring systems requires that operators and maintenance personnel follow safe practices as specified in their system manuals. Here is a review of some of those key practices: • In all types of systems, do not overfill the furnace or tundish. Molten metal may run over the pour spout or receiver and cause personnel injury or equipment damage. • In all types of systems, do not use an oxygen lance inside the furnace or tundish as this may cause metal run-outs, possible explosions and serious injury. • Failure to follow rigorous pressure line cleaning procedures on pressure pour systems used to hold and pour ductile iron can result in magnesium build-up in the lines. Magnesium, once exposed to oxygen (air), burns and can cause serious injury or death. • In a pressure pour furnace, do not pressurize the furnace when the metal held in the furnace is below the minimum level. Such pressurization could cause molten metal to erupt from the furnace siphons. This could cause severe burns or death to personnel in proximity to the siphon. • In a pressure pour furnace, if it is necessary to reheat the furnace internally, make certain that all pneumatic lines have been thoroughly cleaned and checked and that all water, water vapor or moisture have been removed from the piping. Remember, water vapor is one of the byproducts of oil or gas flames. Failure to properly inspect these lines can cause water, water vapor or moist air to enter the furnace and trigger a severe metal eruption from the furnace and/or furnace explosion, injuring or killing those working in proximity to the furnace vessel. • In a pressure pour furnace, do not increase the coil power to levels above the holding power (energy required to maintain the desired metal temperature) of the vessel without proper supervision. If energy that exceeds holding power is applied to the furnace, refractory lining failure resulting in metal penetrating the lining and breaching the steel furnace case could occur. A metal run out can present a deadly hazard to workers in the vicinity of the furnace or can result in a water/molten metal explosion that could cause injury or death over a wide area of the foundry. • In a pressure pour furnace, do not remove water flow to the inductor or coil while liquid metal is present in the furnace or while the power is on. Shutting off the cooling water will quickly cause a failure of the power coil and may cause a water leak. Metal run-out can also occur with the possibility of liquid metal trapping water. This is a very serious condition and can cause explosion, injury and death.
Shown above is an automatic iron pouring tundish system with Visipour® controls. Pressure Vessels Holding Ductile Iron Present Special Hazards
In ductile iron automatic pouring applications, magnesium buildup in a pressure vessel’s nitrogen lines creates a hazardous condition unless these lines are cleaned daily. Never allow these lines to operate longer than 24 hours between cleaning operations. This daily cleaning requirement is specified in the “Daily Maintenance” section of the Operation and Maintenance Manual for Pressure Pour Furnaces.
Personal Protective Equipment (PPE) is required when working with melting, holding or pouring equipment. You must use only dry nitrogen, an inert gas, to blow out the furnace’s pressure lines and clean the filter if used. Inevitably, however, when the furnace’s pressure lines are opened for cleaning, some air will enter the lines and any magnesium build-up in the lines can burn, producing a flare. Therefore, full body Personal Protective Equipment (PPE), including a full-facepiece chemical cartridge respirator approved for exposure to sulfur dioxide gas, must be worn when opening or cleaning nitrogen pressure lines and filters.
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