CH 1 & 2 - INTRO & SAFETY IN WELDING

Chapter 1

Intro to Welding

• Way back in the day, casting was used to connect 2 pieces

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​Introduction

• Bronze goat statue in a temple in China was cast more than 1,500 years ago

• Repaired with braze welding about 1,000 years ago

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• 1750 to 1850: Industrial Revolution introduced forge welding or hammer welding

• 1886: developed the resistance welding technique (spot welding)

• 1930's: riveting was replaced by fusion welding

​More History

Welding Defined

• American Welding Society (AWS) weld defined: “a localized coalescence (the fusion or growing together of the grain structure of the materials being welded) of metals or nonmetals produced either by heating the materials to the required welding temperatures, with or without the application of pressure, or by the application of pressure alone, and with or without the use of filler materials.”

• In less technical language, a weld is made when separate pieces of material are joined and form one piece. This can be achieved when enough heat is applied or enough pressure is used.

• Tables & chairs

• Buildings & bridges

• Bikes, cars, planes

• & More!

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Uses of Welding

Welding & Cutting Processes

• Most popular weld processes: oxyacetylene welding (OAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), flux cored arc welding (FCAW), and torch or oxy-fuel brazing (TB).

•Most popular thermal cutting processes: oxy-acetylene cutting (OAC) and plasma arc cutting (PAC).

• Oxyacetylene welding (OAW) and torch brazing (TB) can be done with the same equipment; oxyfuel gas cutting (OFC) uses very similar equipment

• Common fuel gas: acetylene.

• Other gas combos for welding: hydrogen, MAPP, or propane.

• Base metal is melted and a filler metal may be added to reinforce the weld.

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Oxy-Fuel Welding & Cutting

(Gas welding or torch welding)

Multiple Choice

When using oxygen and acetylene cylinders, open the valves ___.

• quickly

• slowly

• with a pair of pliers

• none of the above

• Shielded metal arc welding (SMAW) uses a consumable stick electrode that conducts the welding current from the electrode holder to the work, the arc melts the end of the electrode away to become part of the weld metal.

• Welding transformer and 2 welding cables w/ a work clamp & electrode holder

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​SMAW

(Stick welding or rod welding)

Multiple Choice

For the safe operation of welding equipment, ___.

• shut OFF the power when welding is completed

• be sure the welding machine is equipped with a conveniently located power disconnect switch

• do not change the polarity when the machine is under load

• all of the above

• Gas tungsten arc welding (GTAW) uses non consumable electrode called Tungsten

• The arc between the electrode and the base metal melts the base and the end of the filler metal as you dip into the molten weld pool.

• Shielding gas flows from the gun nozzle to protect the molten pool from contamination

• GTAW = cleanest of all the weld processes

• GTAW = slower & higher skill level, but in high demand. It is used for extreme high-quality welds.

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GTAW

(Tig welding)

Multiple Choice

A welding machine that is not properly grounded can cause a severe shock.

• True

• False

• Gas metal arc welding (GMAW) uses solid wire that is fed from a spool, thru the cable assembly, and out thru the gun

• Shielding gas flows thru separate tube in the cable assembly, thru the gun nozzle, and around the wire

• GMAW = fast and economical, produces long welds fast that requires little-to-no post weld cleanup

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GMAW

(Mig or wire welding)

• Flux cored arc welding (FCAW) like GMAW, but with flux cored wire.

• Inside the molten weld metal, the flux gathers impurities and floats them to the surface where slag is formed covering the weld as it cools.

• GMAW & FCAW are the first choice for many welding fab shops b/c they are cost effective, produce high-quality welds, and are flexible & versatile

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FCAW

(Flux)

Multiple Choice

Before taking a bathroom break, you should turn OFF your welder.

• True

• False

• Plasma cutting (PAC) uses a stiff, highly ionized, extremely hot column of gas to almost instantly vaporize the metal being cut.

• Most ionized plasma is formed as high-pressure air is forced thru a small opening between a tungsten electrode and the torch tip

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Plasma Arc Cutting

Multiple Choice

Operating welding cables above their rated capacity results in faster welding speeds.

• True

• False

Occupational Opportunities

The following are general descriptions of the job classifications used in our profession; specific tasks may vary from one location to another:

• Welders ​

• Tack welders​

• Welding operators​

• Welders’ helpers​

• Welder assemblers, or welder fitters​

• Welding inspectors ​

• Welding shop supervisors ​

• Welding salespersons ​

• Welding shop owners ​

• Welding engineers ​

Chapter 2

Safety in Welding

Introduction

• There is no substitute for caution or common sense

• A safe job is not by accident, it takes work to make a job safe

• Each person must take personal responsibility for their own safety and the safety of others on the job.​

• If an accident does occur on a welding site, it can have consequences far beyond just the person injured.​

• Serious accidents can result in local, state, or national investigations. For example, if OSHA becomes involved, the job site may be closed for hours, days, weeks, months, or even permanently. ​

Burns...

• Most common & painful injuries in a weld shop

• Can be caused by UV rays & by contact with hot materials

• There is a high chance of infection from burns b/c of dead tissue

• All burns should receive proper treatment to reduce infection

• The three classifications include first-degree, second-degree, and third-degree burns. ​

• They occur when the skin is reddish in color, tender, and painful. No broken skin. Will occur around 130°F.

• Treatment: ​Start by putting the burn area under cold water (not iced) or compresses until the pain decreases and cover it with sterile bandages or clean cloth.

First Degree Burns

• The surface of the skin is severely damaged, blisters may form, and possible breaks in the skin. Will occur higher than 130°F.

• Treatment: Like 1st degree, use cold water compresses until pain decreases, may apply burn cream, then cover with a sterile bandage.

Second Degree Burns

• The surface of the skin and possibly the tissue below the skin appear white or charred. May occur around 480°F​.

• Nerve endings may be destroyed, so, little pain.

• Cold water compresses, don't remove any clothing stuck to the burn if any, cover the burn with thick sterile non-fluffy dressings.

Third Degree Burns

Multiple Choice

An accident should always be reported no matter how minor the accident.

• True

• False

Do we call 911 at COD?

• Emergency @ COD main campus? Call campus police.

  • Using your phone: Dial [phone]

  • Using COD phone: Lift the phone and dial 2000

• Emergency outside of COD? Call 911

Some types of light can cause burns...

• Light wave felt as heat

• Can cause burns

• You can feel it right away

• Should always wear protective equipment

Infrared Light

• Light that we see

• Varying quantities/colors when welding

• Too much = temp night blindness

• Too little = eyestrain

• Lay of the land

Visible Light

Ultraviolet Light (most dangerous)

• Can cause 1st & 2nd degree burns to the welder's skin and eyes

• Cannot see or feel UV light

• Most common areas to be burned are neck/wrists

• UV light can burn & injure either the white part or the retina (black part)

• Personal Protective Equipment (PPE)

• Different levels of protection in different parts of the lab

• Safety glasses in the lab

PPE

General Work Clothing

• Work clothing must stop UV light from passing through it

  • Dark color, thick, and tightly woven.

  • 100% wool, but difficult to find. 2nd best is 100% cotton clothing.

• Long sleeve shirt (expect holes...)

• Pants must have legs long enough to cover the top of the boots.

• No lighters or matches in any pockets to prevent fires and injuries

Special Protective Clothing

• For anyone in direct contact with hot material

• Leather is lightweight, flexible, and resists burning

  • Jackets, aprons, sleeves, gloves, etc.

• Hand protection

  • All leather gloves must be worn at all times when welding

• Body protection

  • Leather jackets or Fire retardant jackets

Face and Eye Protection

• Safety Glasses or Goggles

  • Must be worn at all times in the shop

  • Sunglasses ≠ safety glasses

• Full face shield

  • Grinding, cutting, overhead work

  • Tinted?

Welding Helmets

• Small undetectable UV leaks -> sore or itchy eyes after a welding day

  • Twist the plastic lens for cracks

  • Lens gasket installed correctly?

• Auto-darkening welding helmets

  • Recommended for welders

    • Auto on/off, multi-function, sensors, lens size +

  • 1/20,000th of a second

Shop Noise & Ear Protection

• The higher the sound level, the shorter the acceptable time of exposure

• Ear Plugs

  • In the ear canal

• Earmuffs

  • Outer ear

Respiratory Protection

• All welding/cutting processes produce harmful fumes, vapors, etc.

• Prevention

  • Clean off paint, oil, grease or any chemical before cutting or welding

• Protection

  • Powered air-purifying respirators

  • Half mask respirator

Multiple Choice

A respirator should be used in situations where welding metals give off toxic fumes.

• True

• False

Multiple Choice

___ gives off toxic fumes when welding.

• Aluminum

• Galvanized steel

• High carbon steel

• none of the above

Ventilation

• Areas with 10,000+ cu ft per welder, or have ceiling 16+ ft high, may not require forced ventilation unless fumes collect.

• Natural Ventilation

  • Outside air; garage door open, welding outside, etc.

• Forced Ventilation

  • Fume extractors; mobile or fixed.

Multiple Choice

A permit is required to enter confined spaces containing atmospheric hazards.

• True

• False

Material Safety Data Sheet (MSDS)

• Manufacturer of any product must provide their buyer/user a detailed sheet of info that includes possible hazards.

• The shop is the buyer, they must provide and update the MSDS book.

Cylinder Safety

• Oxygen & fuel cylinders (+ other flammable materials) stored...?

• O2 & C2H2 must be separated by a 5 ft wall or 20 ft

  • Wall/distance keeps heat away from the O2 cylinder safety valve

    • Small fire vs raging inferno

• Cylinders must be secured with a chain or device (no knock overs)

• Cylinder not in use? Protection cap on!

  • Why?

Multiple Choice

___ is NOT a basic rule that contributes to the safe handling of oxyacetylene equipment.

• Opening cylinder valves slowly

• Keeping heat, flame, and sparks away from combustibles

• Preventing oxygen and acetylene leaks

• Protecting the equipment from rust with a coating of oil

Acetylene

• Acetylene cylinders lying horizontally must stand upright for 4 hrs before use

• Acetylene -> Acetone -> Filler

  • Filler doesn't allow acetone to settle back away from valve quickly

• Too soon? Acetone draws out...

  • Acetone lowers flame temp, damages regulators or torch valve settings

Fire Protection

• Highly combustible materials must be 35ft away

  • Not able to be 35ft away? Then fire watch is needed.

• NEVER weld outdoors when drought = fire ban

• Fire watch can be provided by any person who can sound alarm & use extinguishers

Fire Extinguishers

• Type A: Ordinary combustible - wood, paper, rubber, etc.

• Type B: Flammable liquids/gases - gasoline, oil, grease, & propane

• Type C: Energized electrical equipment

• Type D: Combustible metals - magnesium, titanium, & sodium

Multiple Choice

A fire extinguisher should be accessible in locations where welding is done.

• True

• False

Multiple Choice

Accidents occur because of ___.

• indifference to regulations

• lack of information

• carelessness

• all of the above

Multiple Choice

To ensure a safe work site when welding, ___.

• report all injuries

• never attempt to operate any equipment without proper instruction

• always practice good safety habits

• all of the above

Multiple Choice

All welding equipment must be installed according to provisions of the ___.

• Code of Federal Regulations

• owner’s manual

• National Electrical Code®

• Occupational Safety and Health Administration

THAT'S IT!