UWEau Claire

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Welding, Cutting and Brazing

• 29 CFR 1910.251 1926.350
• Subpart Q J
• By Chou Lor, Safety Coordinator

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Welding, Cutting and Brazing

• Training Objectives
• Three Specific Types of Welding Modules
• Methods of Arc Welding
• Welding Hazards
• Safe Work Practices
• Fire Protection Prevention
• Proper Ventilation for Welding
• Welding Operators Protection

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Three Specific Types of Welding Modules

• In this Welding, Cutting, and Brazing module,
  three specific types of welding are covered.
  These are listed below
• Oxygen-fuel gas welding and cutting
• Arc welding and cutting
• Resistance welding

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Oxygen-fuel gas welding Cutting

• The elements of Oxygen-fuel gas welding and
  cutting
• General Requirements
• Cylinders
• Service Pipe Systems
• Pipe System Protection

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Oxygen-fuel gas welding and cutting

• General Requirements
• Focuses on using Acetylene Safely
• Flammable
• Unstable
• Cannot be adjusted above 15 psi
• Safe Work Practices
• Blow out cylinder valve
• Turn on cylinder valve first and
  then adjust the regulator pressure screw.
• Never stand in front or behind
  a regulator when opening the cylinder valve
  
• Open cylinder valve slowly

• The pressure adjusting screw
• Turning clockwise allows the gas allows to flow.
• Turning counterclockwise reduces or stop the gas
  flow.

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Oxygen-fuel gas welding and cutting

• General Requirements Cont.
• Safe Work Practices
• Purge oxygen and acetylene passages
• Light the acetylene
• Never use oil or grease
• Do not use oxygen as a substitute for air
• Keep your work area clean

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Oxygen-fuel gas welding and cutting

• Cylinders
• Cylinder approval and marking
• marked for the purpose of identifying the gas
  content, with either the chemical or trade name
  of the gas
• Storage of cylinders
• Storage area must be well ventilated
• Cylinders must be at least 20 feet from
  combustibles
• Valves must be closed
• Valve protection must be in place
• Inside storage must be limited to 2,000 cubic
  feet.
• Cylinders must be stored in upright position
• Oxygen must be at least 20 feet from fuel gas
  or 5 feet with a 1/2 hour fire barrier
• Separate oxygen from fuel gas

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Oxygen-fuel gas welding and cutting

• Cylinders Cont.
• Operating Procedures
• Operation must emphasize the absence of oily or
  greasy substances. Follow these rules of
  operation
• Cylinders, cylinder valves, couplings,
  regulators, hose, and apparatus shall be kept
  free from oily or greasy substances.
• Oxygen cylinders or apparatus shall not be
  handled with oily hands or gloves.
• A jet of oxygen must never be permitted to strike
  an oily surface, greasy clothes, or enter a fuel
  oil or other storage tank.

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Oxygen-fuel gas welding and cutting

• Service Pipe Systems
• There are special requirements for service pipe
  systems when using oxygen or acetylene.
• Oxygen
• Acetylene or Acetylene Compounds

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Oxygen-fuel gas welding and cutting

• Pipe System Protection
• The entire service pipe system must be protected
  against build-up of excessive pressure and leaks.
  This protection is accomplished with
• Protective equipment
• Regulators
• Proper hose and hose connections.

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Oxygen-fuel gas welding and cutting

• Pipe System Protection Cont.
• Protective equipment is divided into the two
  categories listed here
• Pressure Relief Devices
• The pressure relief device should discharge
  upwards to a safe location.
• Pressure relief valves are required in fuel-gas
  piping systems to prevent excessive pressure
  build up within the system.

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Oxygen-fuel gas welding and cutting

• Pipe System Protection Cont.
• Approved protective equipment shall be installed
  in fuel-gas piping to prevent
• Backflow of oxygen into the fuel-gas supply
  system
• Passage of a flash back into the fuel-gas supply
  system
• Excessive back pressure of oxygen in the
  fuel-gas supply system.

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Arc Welding and Cutting

• Definition
• A fusion process wherein the coalescence of the
  metals is achieved from the heat of an electric
  arc formed between an electrode and the work.
• Application
• Installation
• Operation Maintenance

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Arc Welding Cutting

• Application
• Applies to a large and varied group of processes
  that use an electric arc as the source of heat to
  melt and join metals.
• Installation
• Arc welding requires proper installation of
  equipment.
• A critical part of installation is ensuring that
  proper grounding is completed.

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Arc Welding Cutting

• Operation Maintenance
• All connections to the machine shall be checked
  to make certain that they are properly made.
• The work lead shall be firmly attached to the
  work.
• Magnetic work clamps shall be free from adherent
  metal particles of spatter on contact surfaces.
• Coiled welding cable shall be
  spread out before use to avoid
  serious overheating and
  damage to insulation.

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Arc Welding Cutting

• Operation and Maintenance Cont.
• During welding operations, cables with splices
  within 10 feet (3m) of the holder shall not be
  used.
• Welders should not coil or loop welding electrode
  cable around parts of their body.
• Cables with damaged insulation or exposed bare
  conductors shall be replaced.
• Joining lengths of work and electrode cables
  shall be done by the use of connecting means
  specifically intended for that purpose.
• The connecting means shall have insulation
  adequate for the service conditions.

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Resistance Welding

• Definition
• This is a group of fusion welding processes that
  use heat and pressure to make the coalescence.
• The heat comes from electrical resistance to
  current flow at the site of the weld.
• The processes include
• Spot Welding
• Projection Welding
• Seam Welding

Note FPM only does spot welding.
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Resistance Welding

• Spot Welding
• A process typically used in high-volume, rapid
  welding applications.
• The pieces to be joined are clamped between two
  electrodes under force, and an electrical current
  is sent through them.
• The advantages of spot welding are many and
  include the fact that it is
• An economical process
• Adaptable to a wide variety of materials
  including low carbon steel, coated steels,
  stainless steel, aluminum, nickel, titanium, and
  copper alloys
• Applicable to a variety of thicknesses
• A process with short cycle times
• A robust process
• Tolerant to fit-up variations

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Welding/Cutting Hazards

• Potential Hazards
• Fires may start by hot materials igniting nearby
  combustibles.
• Burns to the operator may occur if unprotected
  skin comes into contact with the extremely hot
  work.

• Magnetic fields could easily destroy/disrupt
  electronic components, stored data if not careful.

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Welding/Cutting Hazards

• Potential Hazards Cont.
• Metal fumes from vaporizing of the work with the
  extremely hot arcs may be inhaled into the
  workers lungs.
• Certain metals and metal oxide fumes, including
  zinc, cadmium and beryllium, produce serious
  illnesses when inhaled.
• Fluxes used with welding to create inert
  atmospheres at the point of the weld also present
  inhalation hazards.
• All welding and cutting must have adequate
  ventilation to protect the person doing the
  welding and those working around the welding area.

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Methods of Arc Welding

• Three Types of Welding Methods
• Tungsten Inert Gas Welding (TIG)
• Gas Metal Arc Welding (MIG)
• Shielded Metal Arc Welding (SMAW)/ Stick Welding

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Tungsten Inert Gas Welding (TIG)

• Definition
• TIG welding is an arc that is formed between a
  non-consumable tungsten electrode and the metal
  being welded.
• Gas is fed through the torch to shield the
  electrode and molten weld pool.
• Benefits
• Welds with or without filler metal
• Precise control of welding
  variables (heat)
• Low distortion
• Shielding Gases
• Argon
• 2 to 5 Hydrogen
• w/Helium

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Tungsten Inert Gas Welding (TIG)

• Applications
• Most commonly used for aluminum and stainless
  steel
• For steel
• Slower and more costly than consumable welding
• Except for thin sections or where very high
  quality is needed

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Gas Metal Arc Welding (MIG)

• Definition
• The heat source is formed by creating an electric
  arc between the work piece and a wire, which is
  fed continuously into the weld pool.

• Benefits
• Long welds can be made without starts and
  stops
• Minimal skill required
• Minimal cleaning of surface before
  weld
• Allows welding in all positions

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Gas Metal Arc Welding (MIG) Cont.

• Shielding Gases
• Inert
• Argon, Helium
• Used for aluminum alloys and stainless steels.
• Active
• 1 to 5 Oxygen, 3 to 25 CO2
• Used for low and medium carbon steels
• Applications
• Gas Metal Arc Welding (MIG) is used to weld all
  commercially important metals, including steel,
  aluminum, copper, and stainless steel.

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Shielded Metal Arc Welding (SMAW)/Stick Welding

• Definition
• Consumable electrode coated with chemicals that
  provide flux and shielding
• The filler metal (here the consumable electrode)
  is usually very close in
  composition to the
  metal being welded.

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Shielded Metal Arc Welding (SMAW)/Stick Welding

• Benefits
• Simple, portable, inexpensive
• Self flux provided by electrode
• Provides all position flexibility
• Shielding Gases
• No shield gases added
• Lower sensitivity to Wind

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Shielded Metal Arc Welding (SMAW)/Stick Welding
Cont.

• Applications
• Construction, pipelines, shipbuilding,
  fabrication job shops.
• Used for Steels, stainless steels, cast irons.
• Not used for aluminum and its alloys, or copper
  and its alloys (energy density is too high).

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Cutting

• Definition
• A stream of oxygen is directed against a piece of
  heated metal, causing the metal to oxidize or
  burn away.
• Making a Cut
• Mark a line as a guide.
• Turn on acetylene as for welding and light.
• Turn on oxygen adjusting flame to neutral.
• Make sure the oxygen lever flame remains neutral.
• Place metal on the cutting table so metal will
  fall clear.
• Flame Types

Oxidizing
Carborizing
Neutral
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Brazing

• Definition
• A process which a filler metal is placed at or
  between the faying surfaces, the temperature is
  raised high enough to melt the filler metal but
  not the base metal.
• The molten metal fills the spaces by capillary
  attraction.
• Torch Brazing
• Oxy-fuel torch with a carburizing flame
• First heat the joint then add the filler metal

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Safe Work Practices

• Electric Gas Welding
• Safety Check
• Ensure electrical cord, electrode holder and
  cables are free from defects
• No cable splices within 10 feet of electrode
  holder.
• Ensure welding unit is properly grounded. This
  helps to avoid over heating.
• All defective equipment shall be repaired or
  replaced before using.

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Safe Work Practices

• Electric Gas Welding Cont.
• Safety Check
• Remove all jewelry rings, watches, bracelets,
  etc
• Ensure PPE e.g.. welding hood, gloves, rubber
  boots or safety shoes, apron are available and in
  good condition.
• Ensure fire extinguisher is charged and
  available.
• Ensure adequate ventilation and lighting is in
  place.
• Set Voltage Regulator to Manufactures
  specifications.
• Avoid electrical shock DONT wrap cables around
  any body part.
• Ensure fittings are tight.

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Safe Work Practices

• Electric Gas Welding Cont.
• Safety Check
• Inspect hoses for cuts and frayed areas.
• Set gauges to desired PSI.
• Ensure that sufficient PPE is made available.
• Locate welding screens to protect employees
  DONT block your exit.
• Ensure that adequate ventilation and lighting are
  in place.

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Fire Protection Prevention

• Fire hazards must be removed, or
• Guards installed, or
• Welding/cutting must NOT take place
• Hot work permit should be used outside designated
  areas to ensure that all fire hazards are
  controlled
• Use of fire watch
• 1/2 hour after operation ceases

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Fire Protection Prevention Cont.

• Welding areas should meet the following
  requirements
• Floors swept cleared of combustibles 35 ft.
  radius of work area.
• Flammable and combustible liquids kept 35 ft.
  radius of work area.
• At least one fire extinguisher on site
• Protective dividers to contain sparks
  and slag
• Welding curtains
• Non-combustible walls
• Fire resistant tarps blankets

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Proper Ventilation for Welding

•  Ventilation
• Proper ventilation can be obtained either
  naturally or mechanically.
• Natural Ventilation is considered sufficient for
  welding and brazing operations if the present
  work area meets these requirements
• Space of more than 10,000 square feet is provided
  per welder
• A ceiling height of more than 16 feet.
• Mechanical ventilation options generally fall
  into two basic categories.
• Low vacuum system which takes large volumes of
  air at low velocities.
• High vacuum system that are captured and
  extracted fumes as near to the work as possible.

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Proper Ventilation for Welding

• Ensure protection from fumes and
  gases by one or a combination of the
  following
• Good general ventilation.
• Use of a booth.
• Local exhaust ventilation
  on the hand piece.
• Air supply to the helmet.

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Welding Operators Protection

• Welding involves specialized personal protection
  that must be worn every time you perform welding
  operations. The following is a list of basic PPE
  
• Fire-resistant gloves
• Aprons
• Safety shoes
• Helmet
• Ultraviolet radiation filter plate (arc welding)
• Goggles with filter lenses

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Welding, Cutting and Brazing

• Summary
• Major hazards include
• Fire
• Burns
• Shock
• Toxic Exposure
• Follow proper procedures to prevent fires
• Use appropriate engineering controls
• Wear appropriate PPE

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Any Questions
??
Please visit FPM Website
(www.uwec.edu/facmgt./index.htm)
for additional information.