Title: Fire Safety for Magnesium Processing and Finishing Operations
1Fire Safety for Magnesium Processing and
Finishing Operations
2Enabling Objectives
- After completing this section of the course
students should be able to - Discuss magnesium melting and casting operations
and the precaution for carrying out these
operations safely.
Explain procedures for fire and explosion
prevention for melting and casting, heat
treating, machining and finishing, dust
collection, cleaning procedures, electrical
equipment, personal protective equipment, spark
producing operations, grinding wheels, stamping
and drawing, fugitive dust, vacuums, storage and
fire prevention
3Magnesium!
4Magnesium Melting Casting
- Buildings non-combustible
- Melt rooms access to fire control
- Floors free of moisture standing water
- Storage below magnesium no depressions where H2O
could accumulate
Pouring magnesium castings
5Magnesium Melting Casting
- Solid metals thoroughly dried by pre-heating gt
250F or higher if impurities are present - Fuel supply lines to melt pots remote shutoffs
Ovens for preheating ingots
6Magnesium Melting Casting
- Turnings, powders etc. can ignite at lower
temperatures than the solid metal and should be
avoided - Keep solid magnesium free of dust, grindings and
swarf
7Magnesium Melting Casting
- Concrete always contains water!
- Contact with molten magnesium and concrete will
cause a violent explosion!
8Magnesium Melting Casting
- Keep the furnace and the surrounding area free of
moisture and iron oxide in the event of a runout
Area around the furnace is kept clean and dry
9Magnesium Melting Casting
- Molten magnesium systems to have 110 secondary
containment of largest expected failure - Install barriers or shields to prevent contact
with incompatible materials - Iron scale and magnesium possible thermite
reaction
10Magnesium Melting Casting
- Crucible interiors and covers free of iron oxide
scale to avoid thermite reaction - Inspect crucibles and melting pots regularly!
- Use of protective atmospheres can cause formation
of iron scale above
11Crucible Maintenance
- Repair or discard damaged crucibles
- Preheat ladles, skimmers sludge pans and molds
- Vigilant for avoiding spilling magnesium
12Crucible Maintenance
- FR clothing no pockets or cuffs
- Foundry boots
- Safety glasses and faceshields when handling
molten magnesium
Shields over metatarsals
13Magnesium Melting Casting
- Practice Quiz
- 1. Where the melting of magnesium takes place
- A. There should be no standing water on the
floor. - B. There should be no depressions under the
magnesium where water could collect. - C. Buildings should be non-combustible
construction. - D. All of the above
14Magnesium Melting Casting
- Practice Quiz
- 2. Concrete always contains water, therefore
contact with molten magnesium and concrete will
likely cause - A. A housekeeping problem
- B. A violent explosion
- C. A minor nuisance
- D. None of the above
15Magnesium Melting Casting
- Practice Quiz
- 3. Damaged crucibles can create a safety hazard,
crucibles should therefore - A. Be inspected for damage regularly
- B. If damaged, be discarded or repaired
- C. Used until there is a definite problem
- D. Only choices A B above.
16Magnesium Melting Casting
- Practice Quiz
- 1. Where the melting of magnesium takes place
- A. There should be no standing water on the
floor. - B. There should be no depressions under the
magnesium where water could collect. - C. Buildings should be non-combustible
construction. - D. All of the above
17Magnesium Melting Casting
- Practice Quiz
- 2. Concrete always contains water, therefore
contact with molten magnesium and concrete will
likely cause - A. A housekeeping problem
- B. A violent explosion
- C. A minor nuisance
- D. None of the above
18Magnesium Melting Casting
- Practice Quiz
- 3. Damaged crucibles can create a safety hazard,
crucibles should therefore - A. Be inspected for damage regularly
- B. If damaged, be discarded or repaired
- C. Used until there is a definite problem
- D. Only choices A B above.
19Magnesium Heat Treating
- Poses fire risks!
- In furnaces gt 750F use a special atmosphere
inside the furnace to retard the ignition of
magnesium - Procedure needed to check for furnace hot spots,
check prior to the heat and at regular intervals
- sulfur dioxide (SO2)
- sulfur hexafluoride with carbon dioxide (SF6/CO2)
- helium (He)
- argon (Ar)
20Magnesium Heat Treating
- Combustion safety controls
- One set maintains operating temperature
- High set control to shut fuel or power if max op
temp is exceeded even by a small amount!
21Magnesium Heat Treating
- Only clean parts free of swarf turnings placed
in furnace! - No combustible or aluminum separators or any
other Al in furnace load of Mg - Furnaces for Mg cleaned as necessary to remove
any accumulation of iron oxide scale
22Magnesium Heat Treating
- When heat treating it is critical to identify Al
containing Mg alloys - Aluminum and magnesium can form a eutectic alloy
which can cause furnace fires! - Same effect if Al contact Mg at elevated
temperatures - Use alloy manufacturer heat treating
specifications
23Magnesium Heat Treating
- Ensure magnesium alloys are never immersed into
salts used for aluminum - Mg in nitrate salt baths may cause an explosion!
- Mg and Al parts easily distinguished
- Magnesium and aluminum together forms an alloy
which has a lower melting and auto-ignition
temperature of either parent metal
24Magnesium Heat Treating
- Practice Quiz
- 1. Heat treating of magnesium
- A. Poses potential fire risks
- B. Should be done using a special atmosphere that
retards ignition of magnesium - C. Include procedures to check the furnace for
undesirable hot spots. - D. All of the above
25Magnesium Heat Treating
- Practice Quiz
- 2. A second set of temperature controls on
magnesium heat treating furnaces is needed
because - A. The first set of controls may fail.
- B. To shut down the furnace if the maximum
operating temperature is exceeded. - C. For convenience and to speed heating treating.
26Magnesium Heat Treating
- Practice Quiz
- 3. Nitrate salt baths if used for magnesium
- A. Will likely cause an explosion.
- B. Is the preferred solution.
- C. Is sometimes use to reduce processing time.
27Magnesium Heat Treating
- Practice Quiz
- 1. Heat treating of magnesium
- A. Poses potential fire risks
- B. Should be done using a special atmosphere that
retards ignition of magnesium - C. Include procedures to check the furnace for
undesirable hot spots. - D. All of the above
28Magnesium Heat Treating
- Practice Quiz
- 2. A second set of temperature controls on
magnesium heat treating furnaces is needed
because - A. The first set of controls may fail.
- B. To shut down the furnace if the maximum
operating temperature is exceeded. - C. For convenience and to speed heating treating.
29Magnesium Heat Treating
- Practice Quiz
- 3. Nitrate salt baths if used for magnesium
- A. Will likely cause an explosion.
- B. Is the preferred solution.
- C. Is sometimes use to reduce processing time.
30Machining, Finishing Fabricating Magnesium
- Cutting tools must not ride on the metal without
cutting frictional heat can ignite the fines! - Back the tool off as soon as the cut is finished
- Cutting tools kept sharp, ground with sufficient
clearance - Drilling holes gt 5X diameter of drill, use high
helix bits (45) to prevent packing
31Machining, Finishing Fabricating Magnesium
- Use only high flash tapping fluid
- Dont use water, water soluble oils and oils gt
0.2 fatty acids (hydrogen gas hazard) - Use water-oil emulsion fluids that inhibit
hydrogen gas formation
32Machining, Finishing Fabricating Magnesium
- Machines provided with pan to catch turnings and
chips - Pan designed to be pulled out quickly in case of
fire - Pan arranged so fire can be quickly extinguished
33Machining, Finishing Fabricating Magnesium
- Machine to keep chip size large
- Maintain good housekeeping around magnesium
machining operations - Remove chips regularly
- Avoid accumulation of more than 3 lbs of chips
- Chips stored in covered containers
34Magnesium Machining Finishing
- Practice Quiz
- 1. Machine magnesium so as to keep the size of
chips generated - A. A consistent size.
- B. Large.
- C. Small to reduce scrap volume.
35Magnesium Machining Finishing
- Practice Quiz
- 2. Tapping fluids for magnesium must be approved
for use with magnesium and - A. Prevent the formation of explosive hydrogen
gas. - B. Have a very low flash point.
- C. Have a high concentration of fatty acids.
36Magnesium Machining Finishing
- Practice Quiz
- 3. Machines that produce chips and turnings
should be provided with a catch pan that - A. Will catch the chips and turnings.
- B. Can be removed quickly in case of fire.
- C. Is arranged so the fire can be put out
quickly. - D. All of the above.
37Magnesium Machining Finishing
- Practice Quiz
- 1. Machine magnesium so as to keep the size of
chips generated - A. A consistent size.
- B. Large.
- C. Small to reduce scrap volume.
38Magnesium Machining Finishing
- Practice Quiz
- 2. Tapping fluids for magnesium must be approved
for use with magnesium and - A. Prevent the formation of explosive hydrogen
gas. - B. Have a very low flash point.
- C. Have a high concentration of fatty acids.
39Magnesium Machining Finishing
- Practice Quiz
- 3. Machines that produce chips and turnings
should be provided with a catch pan that - A. Will catch the chips and turnings.
- B. Can be removed quickly in case of fire.
- C. Is arranged so the fire can be put out
quickly. - D. All of the above.
40Dust Collection for Magnesium Operations
- Machines fitted with enclosures or hoods to
capture dust produced - Use wet-type collectors or cyclone collector
located outdoors - Do not use bag-type collectors for magnesium
41Wet-Type Collectors
- Any hydrogen generated from contact with water
must be properly vented - Remove sludge from the tank if the collector will
be inoperable for longer than a day - Use a secondary blower to ensure venting of the
sludge tank whenever the main exhaust is not on
42Wet-Type Collectors
- Use good collector housekeeping!
- Sludge build up in the collection tank should not
exceed 1/20 of the tank capacity - Remove sludge whenever the collector will be shut
down for extended periods greater that a day. - Wet collectors must be dedicated to the
collection of magnesium type materials only - Aluminum especially containing copper is
incompatible
43Cyclone Dust Collectors
- Locate collectors outdoors!
- Vent exhaust outside to a safe location
- Do not recycle air back into the building
44Dust Collection for Magnesium Operations
- All components of the dust collector should be
conductive and the system should be bonded and
grounded - Ensure no water can leak into the collector
45Dust Collection for Magnesium Operations
- Separate the collector from the machines that
feed it with duct that is at least 15 feet long - Explosion venting can be used on cyclone dust
collectors - Vent away from personnel and other equipment
46Cyclone Dust Collection for Magnesium Operations
- Air movement should be such to keep the
concentration of magnesium dust below ¼ of the
minimum explosive concentration for machines
feeding a cyclone dust collection system - Fast air movement helps keep concentration of
dust at safe levels
FAST!!
KEEP AIR MOVEMENT
47Cyclone Dust Collection for Magnesium Operations
- Keep duct tubes as short as possible
- Eliminate any unnecessary bends in ductwork
- No dead end section or unused caps where dust can
accumulate - Interlocked equipment power supply with exhaust
blower
Explosion venting in short duct run
48Dust Collectors
- Practice Quiz
- 1. Wet dust collectors must be.
- A. Vented to prevent the accumulation of hydrogen
gas. - B. Located outdoors.
- C. Fitted with duct runs that incorporate bends.
49Dust Collectors
- Practice Quiz
- 2. Insufficient air movement in a dust collection
system could cause - A. A high concentration of dust that approaches
the minimum explosive concentration. - B. Helps keep the concentration of dust below ¼
of the explosive range. - C. Will prevent dust from collecting in ducts.
50Dust Collectors
- Practice Quiz
- 3. For cyclone dust collectors
- A. Keep the duct runs as short as possible.
- B. Eliminate unnecessary bends in the ductwork.
- C. Eliminate dead ends and unused caps.
- D. Interlock the collector to the machines that
feed into it. - E. All of the above.
51Dust Collectors
- Practice Quiz
- 1. Wet dust collectors must be.
- A. Vented to prevent the accumulation of hydrogen
gas. - B. Located outdoors.
- C. Fitted with duct runs that incorporate bends.
52Dust Collectors
- Practice Quiz
- 2. Insufficient air movement in a dust collection
system could cause - A. A high concentration of dust that approaches
the minimum explosive concentration. - B. Helps keep the concentration of dust below ¼
of the explosive range. - C. Will prevent dust from collecting in ducts.
53Dust Collectors
- Practice Quiz
- 3. For cyclone dust collectors
- A. Keep the duct runs as short as possible.
- B. Eliminate unnecessary bends in the ductwork.
- C. Eliminate dead ends and unused caps.
- D. Interlock the collector to the machines that
feed into it. - E. All of the above.
54Cleaning Procedures for Magnesium Operations
- A thorough cleaning plan must be put in place
that includes the entire production area, beams
joists, pipes, etc. - Use conductive non-sparking tools for cleaning
- Vacuums listed for magnesium dust
You do not want too much dust up here!
55Cleaning Frequency
- Every effort must be made by management to
prevent the accumulation of hazardous levels of
dust - Perform regular cleaning
- Turn machines off
- Clean regularly and as often as necessary to keep
accumulations of dust below hazardous levels - Cover all portions of the building
56Electrical Equipment for Magnesium Operations
- Dust producing equipment and associated areas
inspected and cleaned regularly - Other portable electrical equipment approved for
Classified Location
Class II Approved Flashlight
57Electrical Considerations
- Electrical equipment and wiring in magnesium
production, processing, handling and storage
areas comply with the NEC - Processing equipment used in magnesium operations
grounded and bonded to dissipate static
electricity
NEC
58PPE Safety for Magnesium Operations
- Clothing flame retardant
- Clean and dust-free
- Dust easily brushed off
- No pockets or cuffs
- No wool or silk (static electricity)
- No exposed steel on shoes (spark generating)
59Cleaning Operations
- Practice Quiz
- 1. A thorough cleaning plan should be put in
place that includes - A. Beams, ducts, and tops of equipment.
- B. Incorporates the use of conductive
non-sparking hand tools. - C. Uses only vacuums approved for magnesium dust.
- D. All of the above.
60Electrical Equipment
- Practice Equipment
- 2. Portable electrical equipment for operations
that produce ignitable magnesium - A. Must only be operated by battery
- B. Must be safe and approved for use for the
hazard class involved. - C. Does not require a grounding conductor.
61Personal Protective Equipment
- Practice Quiz
- 3. Clothing used around magnesium operations
should be - A. Wool or silk.
- B. Cuffed to prevent tripping.
- C. Flame retardant.
62Cleaning Operations
- Practice Quiz
- 1. A thorough cleaning plan should be put in
place that includes - A. Beams, ducts, and tops of equipment.
- B. Incorporates the use of conductive
non-sparking hand tools. - C. Uses only vacuums approved for magnesium dust.
- D. All of the above.
63Electrical Equipment
- Practice Equipment
- 2. Portable electrical equipment for operations
that produce ignitable magnesium - A. Must only be operated by battery
- B. Must be safe and approved for use for the
hazard class involved. - C. Does not require a grounding conductor.
64Personal Protective Equipment
- Practice Quiz
- 3. Clothing used around magnesium operations
should be - A. Wool or silk.
- B. Cuffed to prevent tripping.
- C. Flame retardant.
65Safety for Magnesium Operations
- Control spark producing operations where
magnesium dust producing equipment is used - No flames, cutting or welding in areas where
machines that produce magnesium dust are in
operation
66Grinding Wheels
- Remove grinding wheels to a safe location for
dressing - Or, remove hoods
- Or, clean thoroughly
- Remove all deposits of dust around wheel before,
during and after dressing
Dressing the wheel is a problem! Do it right.
67Grinding Wheels
- Use only non-sparking tools to make repairs
- dust collectors that contain magnesium dust
- grinding wheel hoods that serve them
Non-sparking box wrench set
68Stamping and Drawing
- Take precautions to prevent overheating magnesium
- Collect trimmings and clippings at frequent
intervals - Place into dry and clean steel or non-combustible
receptacles
69Fugitive Dust
- Prevent the accumulation of fugitive dust
- Use only conductive, non-sparking shovels and
scoops - Brush bristles must be soft
- Brushes and brooms natural bristles
- Never use compressed air for cleaning magnesium
dust
Non-sparking tools for cleaning
70Fugitive Dust Vacuums
- Use hand cleaning to pick up as must dust as
feasible - Only vacuum dust that is spread out
- Scoop up or sweep bigger piles
- Vacuum used must be bonded and grounded
- Design, installation and use of vacuum systems
for magnesium dust must be properly engineered
due to the great potential hazard of fire or
explosion - Listed, labeled and approved
Class II approved vacuum
71Vacuums
- Hoses and attachments conductive and non-sparking
- System is to grounded and bonded where necessary
- Test for continuity to ground
- Locate fixed collection receptacle outside
72Grinding Wheels
- Practice Quiz
- 1. When dressing grinding wheels used for
grinding magnesium parts, which of the following
would be unacceptable - A. Remove the wheel to a safer location for
grinding. - B. Remove the hood.
- C. Leave the hood in place and dress the wheel
quickly.
73Fugitive Dust
- Practice Quiz
- 2. A responsible program for the management of
fugitive dust would not include - A. Use of conductive non-sparking tools.
- B. A procedure that prevents excessive
accumulation of dust anywhere in the plant. - C. Plant air reduced to 30 psi.
74Vacuums
- Practice Quiz
- 3. Requirements for vacuums used to collect
magnesium dust include - A. Vacuums should only be used where dust is too
dispersed or too small or spread out to sweep or
scoop up. - B. Periodically tested for continuity to ground.
- C. Have only hoses and attachments that are
conductive and non-sparking. - D. All of the above.
75Grinding Wheels
- Practice Quiz
- 1. When dressing grinding wheels used for
grinding magnesium parts, which of the following
would be unacceptable - A. Remove the wheel to a safer location for
grinding. - B. Remove the hood.
- C. Leave the hood in place and dress the wheel
quickly.
76Fugitive Dust
- Practice Quiz
- 2. A responsible program for the management of
fugitive dust would not include - A. Use of conductive non-sparking tools.
- B. A procedure that prevents excessive
accumulation of dust anywhere in the plant. - C. Plant air reduced to 30 psi.
77Vacuums
- Practice Quiz
- 3. Requirements for vacuums used to collect
magnesium dust include - A. Vacuums should only be used where dust is too
dispersed or too small or spread out to sweep or
scoop up. - B. Periodically tested for continuity to ground.
- C. Have only hoses and attachments that are
conductive and non-sparking. - D. All of the above.
78Storage of Magnesium
- Limit the size of piles of magnesium stored
- Piles should not exceed 20 feet in height
- Aisles should be at least 10 feet wide
- Do not store magnesium below grade
79Outdoor Storage
- Store on level and firm ground
- Stack to prevent toppling
- Keep the storage yard free of overgrowth of
vegetation - Ensure proper drainage is maintained
- Quantities of stored piles kept to a minimum
- No combustibles underneath ingots
Magnesium for the war effort in WW II
80Outdoor Storage
- Up to 100,000 pounds of magnesium may be stored
if - Proper drainage moves water away from stored
material - Aisles at least ½ the pile height plus 10 extra
feet - Piles kept to less than 10 feet wide
- Combustible materials not stored closer than 25
feet to ingots - Refer to NFPA 484 7.7.1.2.6 regarding property
lines
81Castings Storage
- Magnesium castings must be free of chips and fine
particles when stored - Floors non-combustible and well drained
- Buildings non-combustible unless full sprinkler
protection - Light castings piles lt 1000 ft³
- Stored away from heat combustibles
82Magnesium Rack Storage
- Aisles in front of racks equal in width to the
height of the racks - All aisle space kept clear and unobstructed
- Do not lean or stack separators or metal sheets
on edge so as to prevent heat from a fire
activating a sprinkler system - Combustible materials or rubbish not allowed to
accumulate in the rack space
83Scrap Magnesium Storage
- Buildings of noncombustible construction
- Dry magnesium kept away from other combustibles
- Scrap kept in covered containers and managed so
they will not become wet. - Wet magnesium submerged and stored outside in
covered, vented steel containers (check
frequently) - Do not stack scrap containers
84Storage of Magnesium
- Practice Quiz
- 1. Magnesium storage should conform to all of the
following except - A. Limit the size of piles of magnesium stored.
- B. Leave adequate aisle room between piles.
- C. Store magnesium in basements.
- D. Pile height should not exceed 20 feet high.
85Storage of Magnesium
- Practice Quiz
- 2. Storage of castings must be
- A. Free of chips and fines.
- B. In piles that do not exceed 1000 ft³.
- C. Well away from heat and combustibles.
- D. A C above only.
- E. A, B C above.
86Storage of Magnesium
- Practice Quiz
- 3. Magnesium stored outdoors must be
- A. Stacked to prevent toppling.
- B. Protected from vegetation overgrowth.
- C. Not closer that 25 feet to combustibles.
- D. All of the above.
87Storage of Magnesium
- Practice Quiz
- 1. Magnesium storage should conform to all of the
following except - A. Limit the size of piles of magnesium stored.
- B. Leave adequate aisle room between piles.
- C. Store magnesium in basements.
- D. Pile height should not exceed 20 feet high.
88Storage of Magnesium
- Practice Quiz
- 2. Storage of castings must be
- A. Free of chips and fines.
- B. In piles that do not exceed 1000 ft³.
- C. Well away from heat and combustibles.
- D. A C above only.
- E. A, B C above.
89Storage of Magnesium
- Practice Quiz
- 3. Magnesium stored outdoors must be
- A. Stacked to prevent toppling.
- B. Protected from vegetation overgrowth.
- C. Not closer that 25 feet to combustibles.
- D. All of the above.
90Fire Prevention Hot Work
- Permits required in areas that contain exposed
magnesium chips, dust or sponge - All areas requiring a Hot Work Permit are to be
thoroughly cleaned of magnesium chips, dust or
sponge prior to work
Hot work cannot proceed under these conditions
91Fire Prevention Hot Work
- Containers to receive molten magnesium thoroughly
cleaned and dried - Good housekeeping mandatory
- Supplies stored orderly, with separation of
incompatible materials and aisles maintained - Supplies of magnesium limited to those needed for
normal operations
92Fire Prevention Other Materials
- Regular combustibles like paper and wood are not
allowed to accumulate in magnesium processing
areas - What is necessary to be in the area for
production is allowed but they must be stored in
designated areas
- Clean chips and dust from buildings whenever
necessary and as frequently as conditions require - Chips and dust are to be removed to safe storage
or disposal areas
93Fire Prevention - Inspections
- Documented inspections
- detect build up of magnesium dust on all parts of
buildings - equipment not cleaned during daily operations
- No ordinary combustibles commingled with
magnesium dust, chips or sponge - No smoking and signs posted where chips or dust
is present
94Fire Prevention - Inspections
- Where smoking is prohibited in the entire plant
no smoking signs are optional - Consider the risks of using tools and utensils in
areas where magnesium dust is handled that could
generate static electricity or impact sparks - Where magnesium is collected or stored in
containers material handling equipment able to
remove any container from the area is readily
available
95Fire Prevention
- Practice Quiz
- 1. Hot work around ignitable magnesium requires
- A. A permit.
- B. That the area be thoroughly cleaned.
- C. Chips, dust and sponge removed.
- D. All of the above.
96Fire Prevention
- Practice Quiz
- 2. Inspections for fire prevention must be
- A. Mandatory only if a fire occurs.
- B. At the discretion of management.
- C. Documented.
- D. None of the above.
97Fire Prevention
- Practice Quiz
- 1. Hot work around ignitable magnesium requires
- A. A permit.
- B. That the area be thoroughly cleaned.
- C. Chips, dust and sponge removed.
- D. All of the above.
98Fire Prevention
- Practice Quiz
- 2. Inspections for fire prevention must be
- A. Mandatory only if a fire occurs.
- B. At the discretion of management.
- C. Documented.
- D. None of the above.
99Summary
In this section we covered the potential hazards
and risks associated with
- Melting and Casting
- Heat Treating
- Machining and Finishing
- Dust Collection
- Cleaning Procedures
- Electrical Equipment
- Personal Protective Eq.
- Spark Producing Operations
- Stamping and Drawing
- Fugitive Dust
- Use of Vacuums
- Storage of Magnesium
- Fire Prevention
And the controls needed for these potential
hazards and risks