uw-eau claire facilities planning & management welding, cutting and brazing 29 cfr 1910.251...

UW-Eau ClaireFacilities Planning & Management

Welding, Cutting and Brazing

29 CFR 1910.251 & 1926.350Subpart Q & J

By: Chou Lor, Safety Coordinator


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


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


Oxygen-fuel gas welding & Cutting

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


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.


• 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



• 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



• 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.



• Service Pipe Systems– There are special requirements for service

pipe systems when using oxygen or acetylene.

• Oxygen• Acetylene or Acetylene Compounds



• 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.



• 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.



• 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.



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


• 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


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.


• 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


• 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.


• 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


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.


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.


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


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


• 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)


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


• 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.


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.


• 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


• 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.:


• 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


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


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.


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.


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.


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


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


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.


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.


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



Any Questions

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uw-eau claire facilities planning & management welding, cutting and brazing 29 cfr 1910.251...

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