Welding, Cutting and Brazing
29 CFR 1910.251 & 1926.350
Subpart Q & J
By: Chou Lor, Safety Coordinator
UW-Eau Claire
Facilities Planning & Management
Welding, Cutting and Brazing
• Training Objectives
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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
UW-Eau Claire
Facilities Planning & Management
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:
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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
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The pressure adjusting screw:
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Turning clockwise allows the gas
allows to flow.
Turning counterclockwise
reduces or stop the gas flow.
• Blow out cylinder valve
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• 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
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Oxygen-fuel gas welding and cutting
• General Requirements Cont.:
– Safe Work Practices
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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
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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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Facilities Planning & Management
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: FP&M 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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Facilities Planning & Management
Welding/Cutting Hazards
• Potential Hazards Cont.:
– Metal fumes from vaporizing of the work with the
extremely hot arcs may be inhaled into the worker’s
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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Facilities Planning & Management
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
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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
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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:
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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 Manufacture’s
specifications.
• Avoid electrical shock DON’T 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
employee’s – DON’T 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:
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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:
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Fire
Burns
Shock
Toxic Exposure
– Follow proper procedures to prevent fires
– Use appropriate engineering controls
– Wear appropriate PPE
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Any Questions
??
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