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UW-Eau ClaireFacilities Planning & Management
Welding, Cutting and Brazing
29 CFR 1910.251 & 1926.350Subpart Q & J
By: Chou Lor, Safety Coordinator
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities 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
UW-Eau ClaireFacilities Planning & Management
Oxygen-fuel gas welding & Cutting
• The elements of Oxygen-fuel gas welding and cutting:– General Requirements– Cylinders– Service Pipe Systems– Pipe System Protection
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
• 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
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• 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
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• 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.
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• Service Pipe Systems– There are special requirements for service
pipe systems when using oxygen or acetylene.
• Oxygen• Acetylene or Acetylene Compounds
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• 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.
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• 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.
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities Planning & Management
• 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.
Oxygen-fuel gas welding and cutting
UW-Eau ClaireFacilities 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
UW-Eau ClaireFacilities Planning & Management
• 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.
Arc Welding & Cutting
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
• 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.
Arc Welding & Cutting
UW-Eau ClaireFacilities Planning & Management
• 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
Resistance Welding
Note: FP&M only does spot welding.
UW-Eau ClaireFacilities Planning & Management
• 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
Resistance Welding
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities 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.
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities Planning & Management
• 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
Tungsten Inert Gas Welding (TIG)
UW-Eau ClaireFacilities 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
positions
UW-Eau ClaireFacilities Planning & Management
• 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.
Gas Metal Arc Welding (MIG) Cont.
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
• Benefits•Simple, portable,& inexpensive•Self flux provided by electrode•Provides all position flexibility
• Shielding Gases•No shield gases added•Lower sensitivity to Wind
Shielded Metal Arc Welding (SMAW)/Stick Welding
UW-Eau ClaireFacilities Planning & Management
• 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).
Shielded Metal Arc Welding (SMAW)/Stick Welding Cont.:
UW-Eau ClaireFacilities Planning & Management
• 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:
Cutting
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities Planning & Management
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
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
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.
UW-Eau ClaireFacilities Planning & Management
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
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
UW-Eau ClaireFacilities Planning & Management
UW-Eau ClaireFacilities Planning & Management
Any Questions
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