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Arc Welding

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... vomiting, chest soreness, fatigue, gastrointestinal pain, weakness, and tiredness. ... was working inside a steel drainage pipe at a construction site at ... – PowerPoint PPT presentation

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Title: Arc Welding


1
Arc Welding
2
What is Arc Welding?
  • Generalized term used to describe welding that
    uses an electric arc between an electrode and the
    base material to melt and join the metals.
  • Common Names and Variations
  • Shielded Metal Arc Welding (SMAW) Stick Welding
  • Gas metal arc welding (GMAW) Metal inert gas
    (MIG), Flux-cored arc welding (FCAW), Submerged
    arc welding (SAW)
  • Gas tungsten arc welding (GTAW) or Tungsten inert
    gas (TIG) welding

3
  • Stick Welding Cut-Away

Photo Courtesy of Lincoln Electric
(http//www.lincolnelectric.com/knowledge/articles
/content/arcweldfund.asp)
4
Hazards
  • Welding is an inherently dangerous occupation.
  • Even without malfunction the process exposes
    those around it to heat, radiation, foreign
    objects (slag), gases, and high electrical
    current.
  • Malfunctions in equipment often leads to very
    dangerous situations.

5
Hazard Heat
  • The arc produced during welding can exceed 3000
    degrees Celsius.
  • Molten metal particles splash off the weld and
    can cause burns and fires.

6
Protection Heat
  • Personal Protective Equipment (PPE) is used to
    protect the worker from heat, light and slag.
  • Welding blankets are used to protect surrounding
    areas from slag.
  • Wearing PPE in hot climates poses the risk of
    overheating. Hydration and ventilation are a must.

7
Hazard Radiation
  • Welding exposes the welder and anyone around the
    work area to Ultraviolet (UV) Radiation. This
    exposure poses two risks
  • Flash Burn - A burning of the surface of the
    eyeballs and/or skin caused by the UV rays. Same
    effects as sun burn.
  • Retinal Burn - Burning of the retinal nerve
    caused by the projecting of the extremely bright
    arc on the back of the eyeball.

8
Protection Radiation
  • Flash burn and retinal burn can be prevented
    through the proper use of PPE. A high quality
    shade can prevent eye damage and is required
    (OSHA 1926.353(e)). The shade number used should
    correspond to the work being performed. Clothes
    that completely cover the body prevent flash burn
    to the skin.
  • Those working near the welder should be protected
    from flash burn by a welding barrier that is
    set-up around the area.

9
Hazard Gases
  • A welder is faced with different hazards related
    to the gases they are exposed to.
  • The welding process produces toxic fumes. The
    zinc oxide and magnesium oxide fumes can cause
    Metal Fume Fever. The symptoms of which can
    include headache, fever, chills, muscle aches,
    thirst, nausea, vomiting, chest soreness,
    fatigue, gastrointestinal pain, weakness, and
    tiredness. (American Welding Society)

10
Hazard Gases
  • The shielding gases used in welding, while inert,
    can cause asphyxiation in enclosed spaces. The
    gases are used in the welding process to displace
    oxygen from the area of the weld. If the gases
    are contained in a small area the workers oxygen
    levels will be depleted.
  • The gas cylinders used in the welding carry the
    same risks of rupture and explosion as any
    compressed gas cylinder.

11
Protection Gases
  • In order to protect the worker from toxic gases
    and from the displacement of available oxygen
    proper ventilation is required (OSHA
    1926.353(a)).
  • OSHA regulation (1926.353(b)) requires lifelines
    and full-time spotters to be used for welding in
    confined spaces.
  • Care should be taken in the transport and use of
    all gas cylinders.

12
Hazard Electrical Current
  • Arc welding draws a large amount of current and
    passes it through the piece of material in front
    of the worker. Anytime electricity is involved
    there is a risk of injury/death.

13
Protection Electrical Current
  • In order to avoid electrical shock welding should
    be done in a dry environment. Avoid moist
    conditions and standing water.
  • In hot climates there is the possibility of sweat
    soaked clothing becoming an electrocution hazard.
  • Electrical equipment should be inspected
    frequently. Splices must be rated at least as
    high as the conductors they are joining and no
    splices can be present in the 10 feet of
    conductor closest to the welding torch (OSHA
    1926.351(b)).

14
The Numbers
  • The risk from fatal injuries from welding is more
    than four deaths per 1,000 workers over a working
    lifetime.
  • For the construction industry, welders flash
    (burn to the eyes) accounts for 5.6 of all
    construction eye injuries.
  • 1/4 of all welding injuries are eye injuries.
  • Explosions and electrocutions are rare but tend
    to be very serious.

15
Specific Cases
  • A construction worker was killed on June 30, 2004
    in when a welding torch apparently ignited his
    clothes while he was working inside a steel
    drainage pipe at a construction site at Highway
    29 in Napa. The man was trapped inside the pipe
    and burned to death.
  • On August 21, 1989 in British Columbia a welder
    was discovered unconscious inside a titanium tank
    he had been finish welding valves. The argon gas
    used to shield the weld displaced the oxygen in
    the bottom of the tank and worker died of
    asphyxiation.
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