manufacturing processes lab (met 1321) prof s. nasseri manufacturing processes lab 1 welding safety

Manufacturing Processes lab (MET 1321)Prof S. Nasseri

Manufacturing Processes Lab 1Welding Safety


Safety• If we do not follow the safety

regulations, the welding may lead to– Serious injuries,– Permanent disabilities,– Death.

Welding safety procedures are developed to avid hazards that might be present from welding operations such as:Hazard of welding products (slag material may pop during welding), fumes and gases, electric shock, noise, heat, burns and radiation.


Heath risks

• The Ultra Violet (UV) rays of the welding arc can injure the eyes or the skin,

• Some gases produced by welding may be toxic and if breathed in may affect the lungs,

• Welding near flammable materials or welding on containers that have held combustible materials poses a fire risk.

OSHA= Occupational Safety and Health Administration is a federal agency that requires all employers to provide a safe environment for their employees.


Working in confined spaces• A confined space:

– is a workspace that is large enough and so configured that a person can bodily enter it and perform assigned work,

– has limited or restricted means for entry or exit,

– is not designed for continuous occupancy.

Examples:Tanks, silos, storage bins, hoppers, vaults, pits, and trenches.


A permit required confined space

• It contains or has the potential to contain a hazardous atmosphere,

• It contains a material that has the potential to engulf or flow over the entrant,

• It has an internal configuration such that an entrant could be trapped by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section,

• The confined space contains any other recognized serious safety or health hazard.


Ventilation• Welding should only be performed in well-ventilated areas. This is critical

for confined areas where fumes, smoke and dust are likely to collect.• Sometimes a respirator, fan or an exhaust system may be required.

Metals that produce toxic and hazardous fumes:• Zinc, Brass, Bronze, Lead, Cadmium, or Beryllium.

Also galvanized steel, metals painted with lead-base paint produce toxic fumes.

Remember that shielding gases are asphyxiants, and welding fumes are harmful.

asphyxia =a lack of oxygen or excess of carbon dioxide in the body that results in unconsciousness and often death


Rays generated in welding process

• Ultraviolet or UV (300 nanometer)

• Visible (600 nanometer)

• Infrared or IR (micrometer)

Radiation (UV and IR) can burn the skin and damage the eyes.


Eye protection• Eyes should be protected

against:– Radiation (UV, IR)– Sparks and hot slags that can

be projected.

• A welding arc should only be viewed through filter plates that meet the requirements of the American National Standard Institute (ANSI) Z87.1, Practice for Occupational and Educational Eye and Face Protection.


Helmets• Helmets have filter plates or filter glasses to protect against

injury and UV and IR.• Hand held helmets are used by observers.

• Various types of helmets:– Auto darkening (darkens in less than a hundred-millionth

of a second when arc light strikes the filter),– Flip front,– Fixed shade,– Compact.

• Shade 5 for Oxyacetylene Welding, • Shade 10 for 75A (amps) to 200A for ARC welding, • Shade 12 for 200A to 400A, • Shade 14 for over 400A.

Arc welding requires a No. 10 to 12 filter lens. MIG welding requires at least a No. 10 shaded lens. TIG welding requires a No. 11 or 12 shaded filter lens.


Safety glasses and goggles

• We have to remove the thin crust (slag) from the deposited bead, so safety glasses should be worn.

Because of the stresses that build up in the weld, slag may occasionally pop off the weld.


Proper clothingWork cloths should be made of natural materials

(leathers, wool, cotton).

Synthetic materials like polyester should never be worn, as they melt and burn easily. And can cause severe injury.

Coveralls or work cloths should be heavy enough to prevent IR and UV rays from penetrating to the skin.

No cuffs and pockets (to prevent molten metal

from catching in the clothes).


Proper clothingSleeves and collars should be kept buttoned.

Gloves (leather or gauntlet-type) for UV and IR rays and spattering hot metal. Gloves should be worn at all times.

Leather jacket and apron (spatter may cause injury).

Work boots (leather or other approved materials with a reinforced or steel toe). No Tennis or street shoes.


Ear ProtectionThese operations produce high levels of noise:• Chipping, Peening, air carbon gouging, plasma arc cutting.

Inserted to ear canals and are made of rubber, foam, or plastic. worn over the ears to reduce the level of noise.

NRR=27dB NRR=32 dB

• Safe noise levels are indicated by regulations developed by the Environmental Protection Agency (EPA) and OSHA.

• Noise Reduction Rating Number (NRR) is a number that indicates the noise level reduction in decibels (dB).– An NRR of 27 Noise level is reduced by 27 dB.


Hazardous substances• Hazardous substances:

– include those that are combustible, toxic, or corrosive. Examples are:

• Fumes and solid particles originated from the welding process.

• Gases that are generated during welding.

– May be present in a container having previously held:• A liquid that releases flammable, and/or toxic vapors at

atmospheric conditions,• An acid or alkaline material that reacts with metals to

produce hydrogen,• A liquid or solid that releases hazardous vapor if the

container is heated,• A dust cloud of finely divided airborne particles,• A flammable or toxic gas.


Avoid electrical shock!• Make certain that the electrode holder and all electrical connections

and cables are properly insulated.

• Check to see that the welder is properly grounded.

• Do not dip the electrode holder in water to cool it because this practice may result in electrical shock.

• Never weld in damp locations because of the shock hazard. When operating a MIG welder, never touch the electrical connection, bare wire, work, or a machine part which may cause electrical shock.


Avoid electrical shock!

Gloves help to insulate against possible shock. When TIG welding never touch the tungsten electrode with the filler rod.

The tungsten electrode is charged with electric current which may charge the filler rod and shock the person welding. The current potential at the tungsten electrode is at the arc voltage level or higher. A shock from the electrode could be deadly.


Safety Instructions

• Wear hearing protection with TIG pulsed power and high current settings. Power pulses cause the arc to emit sound waves. Because the noise produced may be loud at high current pulses, hearing protection should be worn.

• Adjust the TIG high frequency unit only within the limits recommended by the manufacturer. This will help reduce the possibility of shock and body burns.


Safety Instructions• Protect welding cables. Keep the cables from coming in

contact with hot metal and sharp edges. When welding, avoid wrapping electrode cables around your body.

• Use both hands. To reduce fatigue, use both hands for

welding.

• Handle hot metal with pliers or tongs. Submerge hot metal completely in water to prevent steam burns.

• Do not allow electrode to stick. If the electrode sticks, cut off the switch, allow electrode to cool, and then break it loose with your gloved hand.


Safety Instructions

• Prevent burns. Never allow the hot electrode or electrode holder to touch bare skin. Avoid letting the electrode touch the grounded cable. Remove hot metal from the work area when you are finished welding to prevent burns to others.

• Secure work. Use a welding table with a positioner to hold welds securely in place. Clamps and vises can be used to hold odd-shaped work or field work. Securing work will also prevent injury from accidental dropping of metal on your feet or body.

manufacturing processes lab (met 1321) prof s. nasseri manufacturing processes lab 1 welding safety

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