T.O. 1-1A-9
e.
Dispose of grinding sludge as soon as it is removed from the equipment. Do not store or allow to even partially
dry since it is extremely flammable. This may be done by spreading It on a layer of fire brick or hard burned paving brick
to a maximum depth of 3" to 4", then placing a combustible material on top of it and burning the entire lot. The sludge
will burn with intense heat, therefore, a safe location must be used. A method of rendering magnesium sludge
chemically inactive and non-combustible by reacting it with a 5% solution of ferrous chloride(FeC122H20) is detailed in
the National Fire Protection Association's Bulletin No. 48, Standards for Magnesium.
f.
The clothing of operators should be smooth and fire retardant without pockets and cuffs. Caps should be worn.
All clothing should be easy to remove and kept free of dust accumulations.
4-24. WELDING, BRAZING AND SOLDERING SAFETY PRACTICES . Other than the precautions for thorium alloy
welding previously discussed, no special safety practices are necessary for welding, brazing or soldering magnesium
than for other metals so long as the metal's characteristics of a low melting point and rapid oxidation are borne in mind
and allowed for. Partial melting of the metal must occur before it will burn and continued burning will occur only as long
as the melting temperature is maintained. If the remote possibility of fire does occur it can be controlled and
extinguished by the same means as detailed for machine chip fire in paragraph 4-21.
WARNING
Welding operations produce heat, highly toxic fumes, injurious radiation, metal slag and
airborne particles. Protection equipment, consisting of welding goggles with proper tinted
lenses, apron or jacket, and welder's boots is required. Good general ventilation is normally
adequate.
4-25. HEAT TREATING SAFETY PRACTICES . Heat treating of magnesium alloys requires the exercising of certain
definite rules, if safe and good quality workmanship is to result. The following rules should be closely followed:
a.
Use furnace equipment having two sets of temperature controls, operating independently of each other.
b.
Standardize checking procedures and adjustments of all equipment and of operating cycles.
c.
Load the furnace with castings of one identical alloy only. Insure the castings are clean.
d.
Use S02 (Sulfur Dioxide) atmosphere to control oxidation.
e.
Use the recommended time and temperature operating ranges at all times.
f.
Provide approved fire extinguishing equipment.
WARNING
Water and other extinguishers for Class A, B, AND C fires shall not be used.
4-26. If a fire should occur for any reason, as evidenced by excessive furnace temperature and omission of a light
colored smoke, proceed as follows:
a.
Shut off all power, fuel and S02 feed lines to the furnace.
b.
Notify fire marshal control crew at once.
c.
Begin fire extinguishing procedures using one of the following methods:
(1)
G-1 Powder Method.
Where it can be safely done, a small fire should be removed from the furnace, dumped into an iron container and then
extinguished by covering with G-1 powder which is a graphite base powder of the Pyrene C02 Company. Metal Fyr
Powder of the Fyr Fyter Company is the same material. In large furnaces or with fires of high intensity, the powder can
be applied to the burning parts with a shovel (assuming the furnace door can be opened safely). Paper bags filled with
the powder can be used if the fire is so located that such bags can be thrown in effectively. Remove parts not burning
with long. handled hooks. After all burning parts have been covered with the powder, the furnace load should be allowed
to cool with the door open. For the handling of large quantities of G-1 powder, pumps have been constructed which can
throw 75-100 lbs/minute onto the fire through a 30 foot hose and nozzle.
(2)
Boron Trifluoride (BF3) Gas Method.
WARNING
Boron trifluoride vapor or gas is toxic in the proportion of more than 1 part per million by
volume of air when exposures are prolonged or frequently repeated. Five parts per million by
volume of air or more are usually present in visible clouds of material resulting from the
release of the gas to atmosphere. Therefore, personnel must not enter such clouds or any
area where there is reason to believe the safe level is exceeded unless wearing a gas mask
with an acid gas canister containing a dust filler. Analysis of atmosphere in the worker's
breathing zone will be accomplished to assure personnel safety.
Change 14 4-15
