Document QJge3EzddrmY6ZpaQZapKaejv

11 Test the container for the presence of flammable vapors, preferably with a com bustible gas indicator Test for toxic con taminants and for oxygen sufficiency if personnel are to enter 12 Make similar tests just before welding re pair operations are performed If the operations extend over an appreciable period of time, make repeated tests Precautions for employee protection during container cleanmg operations include 1 Wear head and eye protection, rubber gloves, boots, and aprons when handling steam, hot water, and caustic solutions When handling dry caustic soda or soda ash, wear approved respiratory protective equipment, long sleeves, and gloves 2 To handle hot drums, wear asbestos hand pads or gloves Steam irons or other hot surfaces which may be touched should be insulated or otherwise guarded 3 Dispose of residue m a safe manner. In each instance, the method of disposal should be checked for hazards 4. If a vessel must be entered, wear respira tory protective equipment approved for the exposure and a safety harness with attached lifeline tended by a helper who is similarly equipped and stationed outside the vessel Many containers which have held com bustible or explosive material present special problems Detailed information can be se cured from the manufacturer of such materi als For gasometers or gasholders for natural or manufactured gas, the American Gas As sociation should be consulted For cleaning and gas-freeing of tanks, bunkers, or compartments on board ship, refer to NFPA Standard No 306, Control of Gas Hazards on Vessels To Be Repaired Personal Protection Respiratory protection Dunng welding and cutting operations, toxic gases, fumes, and dusts may be evolved, depending on the type of electrode used, the base metal being welded or cut, and whether or not the base metal is coated with such materials as tar, paint, lead, or zinc Gases-- the oxides of nitrogen, carbon monoxide, ozone--and metallic dusts and fumes may, in varying degrees, present inhalation hazards if adequate respiratory protection is not pro vided American National Standard Z49 1, Safety m Welding and Cutting, gives specifications for local exhaust systems, general ventilation, and health protection of workers on various types of welding and cutting The following discussion is based on this standard, which should be consulted for further information In open-air welding or cutting or in large, well-ventilated areas, where clean carbon steel is welded or cut with bare or coated carbon-steel electrodes and without inert-gas shielding, minimum health hazards exist In confined areas, such as tanks, pressure vessels, and holds of ships, local exhaust or general ventilation systems should be provided to maintain concentrations of toxic gases, fumes, or dusts below maximum allowable concentrations (MAC) as defined in American National Standard Z37 Series "Maximal Ac ceptable Concentrations of Toxic Dust and Gases," or below threshold limit values (TLV) specified by the American Conference of Gov ernmental Industrial Hygienists For a com plete discussion, see Chapters 37 and 38, "In dustrial Hygiene" and "Industrial Toxicology " If gases, dusts, and fumes cannot be kept below the TLV because work is intermittent or for other reasons, welders should wear respiratory protective equipment approved for the exposure by NIOSH Where oxygen is also deficient, self-contained breathing ap paratus or hose masks with blowers are nec essary Coatings, fluxes, and base metals. When weldmg or cutting involves coatings or fluxes containing base metals that contain elements such as zinc, fluorine, beryllium, lead, or cadmium, and their compounds, local exhaust removal or general ventilation should be pro vided to maintain the concentration of any toxic fume generated below the MAC or TLV Outdoor welding and cutting involving lead, 969