The Art of Welding. William Galvery
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Название: The Art of Welding
Автор: William Galvery
Издательство: Ingram
Жанр: Зарубежная деловая литература
isbn: 9780831191641
isbn:
•Remember not to cross-contaminate your wire brush, emery cloth, and flap wheels by using the same ones on both steel and stainless steel. Hint: If you will be working with both steel and stainless steel, paint the handles of stainless steel brushes red for use on steel, and green for use on stainless. This prevents cross-contamination.
Figure 2-11 As a final prep step, clean the area with alcohol or acetone
Protecting Metal
Preparation for welding removes mill scale, grease, and paint, thus exposing fresh, bare metal to the atmosphere, an ideal condition for rapid corrosion. This is particularly true for most steels and for aluminum in a salt atmosphere. A protective finish will prevent corrosion and enhance the part’s appearance.
The most common protective finishes for welded products include:
•Painting for all metals—No specialized equipment is needed, but spray painting may be best for complex shapes to reduce labor expense. Several coats may be needed to make the item weatherproof.
•A red Rust-oleum® brand primer and two more finish coats will provide at least five years of rust-free service outdoors. In general, products which are supplied in aerosol cans are less durable than those supplied in conventional cans.
•Powder coating for steel and aluminum—Provides a durable, professional-looking surface with many colors and surface textures available. May be nearly as inexpensive as painting for complex shapes as it is sprayed on. Holds up well outdoors.
•Anodizing for aluminum only—This coating is durable and very thin, typically from 0.5 to 6 thousandths of an inch (0.013 to 0.154 mm). Colors are available but tend to fade in the sun. Red is the least stable color, black is much more stable. A non-colored, clear anodizing is the most stable. This is not a do-it-yourself process; leave it to specialists.
Protective coatings should go on promptly after welding (or final surface prep) so the metal does not have a chance to react with the atmosphere. Ideally only a few hours should elapse.
Figure 2-12 After welding, metal should be protected with paint or some other type of coating
What are some basic safety requirements?
Safe Welding Areas
Some welding processes have specific safety requirements. But in general the welding area should
•Be clean and comfortable to work in.
•Allow you to position the work to avoid welding on the floor unless absolutely necessary; you will not do you best work there.
•Be free of drafts on the work from fans, wind, windows, and doors, yet still have adequate change of air ventilation to reduce weld fume inhalation.
•Provide bright light; welding in sunlight is better than in dim light as the non-glowing parts of the weld show up better.
•Be between 70 to 80°F (21 to 27°C) because better welds will result than welds made in cold temperatures; however, acceptable welds can be made at ambient temperatures in the 40 to 50°F (4 to 10°C) range except where the weld specifications call for preheating.
•Have tools positioned within easy reach of the weldor.
•Be clear of combustibles, puddles, and tripping hazards.
•Provide all necessary personal safety equipment for the processes to be used.
Figure 2-13 A welding fume extractor removes potentially harmful vapors from the welding area without contaminating the weld
Photo courtesy of Lincoln Electric.
Personal Safety
In addition to providing a safe working environment, the weldor should also take steps toward personal protection for themselves or anyone else in the welding area. Those steps include:
•Protection of face and eyes from sparks and radiation with a helmet and lens of appropriate shade number (darkness).
•Protection of all of the welders skin from arc and weld material radiation by covering it with cotton, wool, specially treated canvas jackets, or leather garments; ultra violet radiation is carcinogenic.
•Personnel in the welding area must be protected from the welding arc and sparks by protective screens. Never view the welding being performed through the protective screens alone; the only way to safely view welding is through the proper shade lens and welding helmet or goggles.
•Beware of hazards from gases and ensure adequate ventilation; inert shielding gases may cause suffocation in confined areas.
•Provide adequate ventilation from welding process smoke and the metal vapors, particularly heavy metals like zinc and cadmium that are toxic; keep your head out of the welding plume.
•Leathers or specially treated canvas jackets must be worn when welding vertically or overhead to protect the welder from the falling hot metal, sparks and slag.
•A welder’s hat will prevent both radiation burns to the head and hot sparks, falling slag, and hot metal burns.
•High-top boots can prevent hot sparks and slag from burning your feet.
•Never weld with pant cuffs; sparks falling into cuffs will burn pants.
•Make sure your welding gloves are dry and have no holes.
•Keep hands and body insulated from both the work and the metal electrode holder.
•Do not change the polarity switch position while the machine is under welding current load.
•Welding machines must be turned off when not attended.
•Do not stand on a wet surface when welding to prevent electric shock.
•Welding cables and electrode holders must be inspected for broken insulation regularly to prevent electric shock.
•Welding power supplies on AC lines must be properly grounded and emergency shut-off switch location known and accessible.
•Welding area must be dry and free of flammable materials.
•Protect your ears from welding and grinding noise with ear plugs or ear protectors.
•Any compressed gas cylinders must be properly secured and out of the spark stream.
•Avoid wrapping welding cable around your arm or body in case a vehicle snags the cables.
•Never СКАЧАТЬ