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13 T
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Bridging “Bridging” occurs when cold charge materials in the top portion of an induction furnace are not in
contact with the molten metal in the bottom of the furnace. Bridging can cause superheating of the molten metal and lead to refractory failure and coolant system rupture. Bridging can be minimized by using proper charge materials, by ensuring different size charge materials are added correctly to the furnace and vigilant operator awareness. If bridging occurs, all power must be turned off until the bath temperature is known. Follow the furnace manufacturer’s bridging safety procedures.
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Melting Pit Area Always keep the furnace pit area clean and dry. Do not allow water
or other liquids (e.g. hydraulic fl uid) to accumulate. Furnace melting pits are designed to hold molten metal in case of an emergency and must be kept dry and free of trash at all times.
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he violent and unpredictable nature of a water/metal explo- sion makes safety clothing and
equipment imperative for melt shop workers. Such clothing can prevent disfi gurement and incapacitating burns, as well as fatalities. Personal protective equipment (PPE)
requirements for your operation should be determined by preparing a hazard assessment of each job as required by U.S. Occupational Safety and Health Ad- ministration Standard 29CFR1910.132.d. Basic PPE worn by melters and pourers may include a hard hat, safety glasses with side shields, face shield, tinted lenses, fl ame resistant and/or aluminized coat and pants, gloves, spats, chaps, leggings and smooth-toed safety shoes. PPE for pouring areas should always be
Furnace Maintenance Good furnace maintenance is essential to protect furnace cooling
coils from rupturing and causing an explosion. Special attention should be given to newly installed refractory material. Suffi cient drying time should be allotted to ensure that all moisture is eliminated prior to use. Always follow the furnace manufacturer’s and refractory supplier’s maintenance and sintering procedures.
Outside Municipal Emergency, Firefi ghting
Personnel and First Responders Emergency professionals must be informed of the presence of molten
metal areas, the types of metal being melted in the plant and the associ- ated hazards. Plant operations should be reviewed periodically with all emergency personnel, including outside municipal emergency departments, fi refi ghters and fi rst responders.
Don’t Skimp on Personal Protective Equipment
worn over 100% cotton undergarments. Synthetic or polyester clothing should never be worn around molten metal operations. All personnel (including furnace op-
erators, supervisors, metallurgists, etc., and all visitors) must wear full PPE as designated by the hazard assessment when entering the hazard zone for such operations as charging, sampling, tem- perature taking and metal pouring. MC
For More Information
The American Foundry Society’s “Guide for Selection and Use of Personal Protective
Equipment and Special Clothing
for Foundry Operations” offers more tips and guidelines. (This publication is available as a free download at:
www.afsinc.org/estore. Enter EC0601DL in the search fi eld).
MODERN CASTING / July 2010
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