Document DG7KVKEVLEZ7neOvDxObrnv2n

-32- "Stainweld" USS CR-;:i 18-8 "Rezistal" Silica (SiO )................................................ 11.0%,............... 19.6??.................. 10.0% Calcium fluoride (CaF )........................... 40.5&.............. 11.4;?.................. 23.4J? Oxides of Iron, Aluminum and Nickel. ZO.2%............ 52,1%.................. 36,67? The following is an interesting comparison between the compositions of dust formed vdien using bare mild steel eleotrodes and when using coated electrodes for welding galvanized steels Brand "Fleetweld" "Wilson" "Murex" Bare Electrodes % ZnO % Fe203 79.2 62.6 60.5 20.0 60.6 40.0 Coated Electrodes % ZnO % Fe203 67.5 78.8 72.0 31.9 21.5 28.0 Investigations have shown that there may be as much as a five per cent, varia tion in composition of dust produced by the same make and kind of electrode when used- _ tinder oonstant conditions but by different operators. Ferric oxide (FeD3) which emanates from all welding arcs, regardless of the type of coating, is disagreeable but not harmful. Concentrations of iron oxide of about ten milligrams per cubic meter are said to be entirely non-injurious to the respira tory organs. Breathing the dense clouds of fumes of zinc oxide, formed when the zinc of the galvanized coating is boiled off by the heat of the welding arc, oauses what is cammouly known as "fume fever". This is evidenced by nausea followed by chills and un pleasant fever. The fume fever does no lasting harm except after prolonged exposure, and the effects are not cumulative. Ordinary ventilation, which is necessary in any welding operation, is considered adequate to prevent fume fever. What Is The Amount And What Are The Characteristics of Dust Produced By The Various Electric Arc Welding Operations? There is a wide variation in the amount and character of dust produced by different types of rods on different materials under different operating conditions. FUME, OR DUST PRODUCED BY ARC WELDING Material Being Electrode Size of Particles Welded Used Electrode Per cu. ft. Rivets inside Cross Coil Drum. G-E W-20 Coated 6/32" 20,050,560 Mild Steel Blanks Inside Booth. G-E W-20 Coated 6/32" 14,839,680 Characteristics of Dust Particles. (Sizes and Per centages Estimated) About 98% angular crystal line, 5 microns or less in size; 2% rounded semi-opaque, 10 microns or more in size. About 80% round black or red dish brown specks, 1 microns or less in size; 20% slightly angu lar crystalline, 10 microns or less but mostly about 5 microns and large number reddish brown specks too small and numerous to count. EM001522