Welding and Cutting Safety
It’s your responsibility
Safety Topics
• Welding safety
–
–
–
–
Arc rays
PPEs
Machines
Ventilation
• Oxyfuel cutting safety
–
–
–
–
–
Cylinders
Oxygen
Fuels
Equipment
Flame types
• Grinding safety
– Pedestal grinders
– Portable grinders
• General shop safety
–
–
–
–
–
Fire extiguishers
Burn treatment
First aid
MSDSs
General safety
Arc Rays
• Welding arcs are intensely brilliant lights.
• They contain a proportion of ultraviolet light
which may cause eye damage. For this
reason, the arc should never be viewed with
the naked eye within a distance of 50.0 ft
(15.2 m).
• The spectrum of the welding arc is similar to
that of the sun. Exposure of the skin and eyes
to the arc is the same as exposure to the sun.
• Due to the close proximity, the arc is more
dangerous than sun exposure.
Personal Clothing Requirements
• 100% cotton or wool clothing.
• To assess UV protection of materials, simply hold the the material up
to a light or window and see how much light gets through. Less light
filtering through means greater protection. In addition, darker colors
provide more protection than fabrics of the same material in light
colors.
• Clothing must not be frayed or torn or it can catch fire.
• No exposed open pockets.
• No synthetic (flammable) materials are to be worn, such as nylon,
polyester or rayon.
• Safety glasses are required at all times while working.
• High top, all leather boots.
• DO NOT carry matchers or lighter while welding, cutting or grinding.
Personal Protective Equipment
• A welding hood with
the proper filter shade.
• A welding cap,
optional, but
recommended.
• A welding jacket.
• Apron, optional.
• Leather welding
gloves.
Recommended Welding Filter
shades
Recommended Welding Filter
Shades
• A #10 shade lens is typically the
recommended shade for most arc
welding.
Reflected Arc Radiation
• Reflected UV light can cause the same burs as direct exposure.
• Where the work permits, the welder should be enclosed in an
individual booth painted with a finish of low reflectivity such as zinc
oxide (an important factor for absorbing ultraviolet radiations) and
lamp black, or must be enclosed with noncombustible screens similarly
painted. Booths and screens must permit circulation of air at floor
level. Workers or other persons adjacent to the welding areas must be
protected from the rays by noncombustible or flameproof screens or
shields or must be required to wear appropriate goggles.
Electric Shock
• The hazard of electric shock is one of the the most serious
and immediate risks facing a welder.
To avoid being shocked
• The maximum open circuit voltage for a welder is 80 volts.
• Wear dry gloves in good condition for welding.
• Do not touch the electrode or metal parts with skin or wet clothing
while the machine is turned on.
• Keep dry insulation between the body and any grounded metal.
• Do not stand in water while welding.
• Do not place liquids on or above welders/electrical equipment.
• Keep welding cables and electrode holders in good condition.
• Remember water conducts electricity. You are mostly water!
Welding Safety
• Never weld or flame cut directly on concrete, it
could explode from the heat.
• Be cautious when picking up metal, it could be
hot.
• Do not leave hot metal in areas other than those
designated or clearly mark the piece “HOT”
• Never pass current through a gas cylinder.
• Use screens to protect others from the arc light.
Welding Machine Care
• Welding machines should be cleaned and
maintained on a regular schedule.
• Never exceed the rated duty cycle of the
machine.
• The duty cycle is the % of time the machine
can be operated within a ten minute period.
Duty Cycle Chart Example
• The duty cycle is the
percentage of time a welding
machine can be used.
• The “use time” is based on a ten
minute time period.
• Example: a 60% duty cycle
means that it can be used for six
minutes and needs four minutes
of cool down time.
• If the duty cycle is exceeded,
the internal heat will damage
the machine.
Ventilation Safety
• Consider proper ventilation your most important safety
factor. Prior to welding or cutting, make sure you have
clean air to breath or wear the proper respirator.
• "CAUTION! Welding may produce fumes and gases
hazardous to health. Avoid breathing these fumes and
gases. Use adequate ventilation. See ANSI Z49.1 – 1967
Safety in Welding and Cutting published by the American
Welding Society.“
• If there is smoke on your welding hood after welding, then
your head is in the wrong place.
Proper Ventilation Requirements
•
•
•
•
•
Mechanical ventilation must be provided when welding or cutting is done in a
space of less than 1 0,000 cubic feet (284 m(3)) per welder-, in a room having
a ceiling height of less than 16 feet (5 m); or in confined spaces or where the
welding space contains partitions, balconies, or other structural barriers to the
extent that they significantly obstruct cross ventilation.
Ventilation must be provided be at the minimum rate of 2,000 cubic feet (57
m(3)) per minute per welder, except where appropriate local exhaust hoods
and booths a, or airline respirators
Natural ventilation is considered sufficient for welding or cutting operations
where the restrictions listed in the preceding paragraphs are not present.
Respiratory protective equipment shall be used when the methods above are
not feasible.
Improper Use of Welding Gases. Compressed gases used for welding and
cutting shall not be used for ventilation purposes, comfort cooling, blowing
dust from clothing, or cleaning the work area.
Ventilation Requirements
Minimum air flow/Duct diameter inches
•
•
•
•
•
Welding Zone
4 to 6 inches from arc to torch:
6 to 8 inches from arc or torch:
8 to 10 inches from arc or torch:
10 to 12 inches from arc or torch:
Cubic f/m
150 cfm
275 cfm
425 cfm
600 cfm
Duct Dia. inches
3
3½
4½
5½
Toxic Materials
• Local exhaust ventilation shall be used when potentially
hazardous materials are employed as base metals, fluxes,
coatings, platings or filler metals. These include, but are not
limited to, the following materials:
• Beryllium
Lead
• Cadmium
Mercury
• Chromium
Zinc
• Fluorides
• Inert-gas metal-arc welding or oxygen cutting of stainless steel
• Except for operations involving beryllium, cadmium, lead, or mercury,
respiratory protective equipment is not required when natural or
mechanical ventilation is sufficient to remove welding fumes from the
breathing zone of the workers.
Solvents/Cleaning Agents
• Chlorinated Hydrocarbons. Degreasing or other operations
involving chlorinated hydrocarbons shall be located or
controlled such that vapors from these operations will not
enter the atmosphere surrounding any welding or cutting
operations to prevent the degradation of such chlorinated
hydrocarbon vapors to more highly toxic gases by the
action of heat or ultraviolet radiation.
• These types of solvents shall be no closer than 200 feet
from welding activities.
Oxyfuel Cutting (OFC)
The oxyfuel cutting process uses a
combination of oxygen and a fuel to
provide a high temperature flame.
General Cutting Safety
• The light from cutting can be dangerous, a
#5 shade filter lens is recommended for
most cutting applications.
• There is not enough UV light created by the
flame to burn your skin.
• Sparks, molten metal and the flame can
burn you, wear protective clothing.
Oxyfuel Cutting (OFC)
• OFC can be a manual process in which the
welder must control the the torch movement
or a machine can control the movement.
• The term oxyfuel gas cutting outfit refers to
all the equipment needed to cut.
• Cylinders contain oxygen at extremely high
pressure and a fuel gas at a low pressure.
Oxygen Cylinders
• Oxygen is stored within cylinders of various
sizes and pressures ranging from 20002640 PSI. (Pounds Per square inch)
• Oxygen cylinders are forged from solid
armor plate steel. No part of the cylinder
may be less than 1/4” thick.
• Cylinders are then tested to over 3,300 PSI
using a (NDE) hydrostatic pressure test.
Oxygen Cylinders
• Cylinders are regularly
re-tested using
hydrostatic (NDE)
while in service
• Cylinders are regularly
chemically cleaned
and annealed to relieve
“jobsite” stresses
created by handling .
Oxygen Cylinder Storage
Requirements
•
•
•
•
Oxygen cylinders shall not be stored near highly combustable material
(especially oil or grease); near reserve stocks of carbide, acetylene, or other
gas cylinders; near any other substance likely to cause or accelerate fire; or in
an acetylene generator compartment.
Oxygen cylinders in storage shall be separated from fuel gas cylinders or
combustable materials a minimum of 20 feet or by a noncombustable barrier at
least 5 feet high having a fire-resistance rating of at least one-half hour.
Inside buildings, cylinders shall be stored in well protected, well ventilated
areas and shall be stored away from elevators, stairs, or gangways. Assigned
storage spaces shall be located where cylinders will not be knocked over or
damaged by passing or falling objects.
Valve protection caps, where cylinders are designed to accept a cap, shall
always be in place, hand-tight, except where cylinders are in use or connected
for use.
Cylinder Transportation
• Never transport cylinders without the safety
caps in place.
• Never transport with the regulators in place.
• Never allow bottles to stand freely. Always
chain them to a secure cart or some other
object that cannot be toppled easily.
• Never use cylinders as rollers or supports.
Oxygen Cylinders
• Oxygen cylinders
incorporate a thin metal
“pressure safety disk”
made from stainless steel
and are designed to
rupture prior to the
cylinder becoming
damaged by pressure.
• The cylinder valve should
be turned on all the way
for any high pressure
cylinder.
Pressure Regulators for
Cylinders
• Reduce high storage
cylinder pressure to
lower working
pressure.
• Most regulators have a
gauge for cylinder
pressure and working
pressure.
Pressure Regulators for
Cylinders
• Regulators are shut off
when the adjusting screw
is turn out completely.
• Regulators maintain a
constant torch pressure
although cylinder pressure
may vary.
• Regulator diaphragms are
made of stainless steel.
Regulator Hoses
• Hoses are are fabricated from
rubber.
• Oxygen hoses are green in
color and have right hand
thread.
• Acetylene hoses are red in
color with left hand thread.
• Left hand threads can be
identified by a grove in the
body of the nut and it may
have “ACET” stamped on it.
Check Valves &
Flashback Arrestors
• Check valves allow gas to
flow in one direction only.
• Flashback arrestors are
designed to eliminate the
possibility of an explosion
at the cylinder.
• Combination Check/
Flashback Valves can be
placed at the torch or
regulator.
Fuel Gas Types
•
•
•
•
•
•
Acetylene
Gasoline
Hydrogen
Mapp gas
Butane and Propane
Propylene
Acetylene Gas
• Virtually all the acetylene distributed for welding and cutting use
is created by allowing calcium carbide (a man made product) to
react with water.
• The nice thing about the calcium carbide method of producing
acetylene is that it can be done on almost any scale desired.
Placed in tightly-sealed cans, calcium carbide keeps indefinitely.
For years, miners’ lamps produced acetylene by adding water, a
drop at a time, to lumps of carbide.
• Before acetylene in cylinders became available in almost every
community of appreciable size produced their own gas from
calcium carbide.
Acetylene Cylinders
• Acetylene is stored in cylinders specially designed
for this purpose only.
• Acetylene is extremely unstable in its pure form at
pressure above 15 PSI. (Pounds per Square Inch)
• Acetone is also present within the cylinder to
stabilize the acetylene.
• Acetylene cylinders should always be stored in the
upright position to prevent the acetone from
escaping thus causing the acetylene to become
unstable.
Acetylene Cylinders
• Cylinders are filled with a
very porous substance
“monolithic filler” to help
prevent large pockets of
pure acetylene from
forming.
• Cylinders have safety
(Fuse) plugs in the top and
bottom designed to melt at
212° F (100 °C).
Oxygen and Acetylene Regulator
Pressure Settings
• Regulator pressure may vary with different
torch styles and tip sizes.
• PSI (pounds per square inch) is sometimes shown as
PSIG (pounds per square inch -gauge)
• Common gauge settings for cutting
– 1/4” material Oxy 30-35psi Acet 3-9 psi
– 1/2” material Oxy 55-85psi Acet 6-12 psi
– 1” material Oxy 110-160psi Acet 7-15 psi
• Check the torch manufactures data for
optimum pressure settings.
Regulator Pressure Settings
• The maximum safe working pressure for
acetylene is 15 PSI !
Gasoline
• Gasoline torches have been found to perform very
well, especially where bottled gas fuel is not
available or difficult to transport to the worksite.
• Tests showed that an oxy-gasoline torch cut steel
plate up to 0.5 inch thick as well as oxyacetylene;
and 0.5 to 4 inches thick better: 3 times better at
4 inches thick.
• The gasoline is fed from a pressure tank whose
pressure can be hand-pumped or fed from a gas
cylinder.
Hydrogen
• Hydrogen has a clean flame and is good for
use on aluminum.
• It can be used at a higher pressure than
acetylene and is therefore useful for
underwater welding and cutting.
• It is a good type of flame to use when
heating large amounts of material.
Mapp Gas
• MAPP gas is a registered product of the Dow
Chemical Company.
• It is liquefied petroleum gas mixed with
methylacetylene-propadiene.
• It has a heat value a little less than acetylene.
• It can be used at much higher pressures than
acetylene.
• It does not polymerize at high pressures - above
15 psi or so (as acetylene does) and is therefore
much less dangerous than acetylene.
Butane and Propane
• Butane, like propane, is a saturated hydrocarbon.
• Both are mixed together to attain the vapor
pressure that is required by the end user and
depending on the ambient conditions.
• Propane, however, has a very high number of
BTUs per cubic foot in its outer cone, and so with
the right torch (injector style) can make a faster
and cleaner cut than acetylene, and is much more
useful for heating and bending than acetylene.
• Propane is cheaper than acetylene and easier to
transport.
Propylene
• Propylene cuts similarly to propane.
• When propylene is used, the torch rarely
needs tip cleaning.
• There is often a substantial advantage to
cutting with an injector torch.
Fuel Gas Cylinder Valves
• Fuel gas cylinder shut off
valves should only be
opened 1/4 to 1/2 turn
• This will allow the
cylinder to be closed
quickly in case of fire.
• Cylinder valve wrenches
should be left in place on
cylinders that do not
have a hand wheel.
Typical torch styles
•
A small welding torch, with throttle valves
located at the front end of the handle. Ideally
suited to sheet metal welding. Can be fitted for
cutting.
•
attachment in place of the welding head
shown. Welding torches of this general design
are by far the most widely used. They will
handle any oxyacetylene welding job, can be
fitted with multi-flame (Rosebud) heads for
heating applications, and accommodate
cutting attachments that will cut steel 6 in.
thick.
•
A full-size oxygen cutting torch which has all
valves located in its rear body. Another style of
cutting torch, with oxygen valves located at
the front end of its handle.
Typical startup procedures
• Verify that equipment visually appears safe IE: Hose
condition, visibility of gauges.
• Clean torch orifices with a “tip cleaners” (a small wire
gauge file set used to clean slag and dirt form the torch
tip).
• Crack (or open) cylinder valves slightly allowing
pressure to enter the regulators slowly.
• Opening the cylinder valve quickly will “Slam” the
regulator and will cause failure.
Typical startup procedures
• Never stand directly in the path of a regulator
when opening the cylinder.
• Check for leaks by setting the regulators to the
working pressure and closing the cylinders for a
short time. When opening the cylinder valves,
watch for the regulators to increase in pressure, if
they do, there is a leak in the system.
• Using a soapy (non-petroleum based) “Bubble”
solution can reveal the leak location.
Typical startup procedures
• Always use a flint and steel spark lighter to light the
oxygen fuel flame.
• Never use a butane lighter or matches to light the flame.
Flame Settings
• There are three distinct types of oxy-fuel flames,
usually termed:
– Neutral
– Carburizing (or “excess fuel”)
– Oxidizing (or “excess oxygen” )
• The type of flame produced depends upon the
ratio of oxygen to acetylene in the gas mixture
which leaves the torch tip.
Pure Acetylene and Carburizing
Flame profiles
Neutral and Oxidizing Flame
Profiles
Flame definition
• The neutral flame (Fig. 4-1) is produced when the ratio of oxygen to
acetylene, in the mixture leaving the torch, is almost exactly one-toone. It’s termed ”neutral” because it will usually have no chemical
effect on the metal being welded. It will not oxidize the weld metal; it
will not cause an increase in the carbon content of the weld metal.
• The excess acetylene flame (Fig. 4-2), as its name implies, is created
when the proportion of acetylene in the mixture is higher than that
required to produce the neutral flame. Used on steel, it will cause an
increase in the carbon content of the weld metal.
• The oxidizing flame (Fig. 4-3) results from burning a mixture which
contains more oxygen than required for a neutral flame. It will oxidize
or ”burn” some of the metal being welded.
Pedestal or Bench
Grinder Safety
• Safety glasses with side shields and a face
shield must be worn. Hearing protection
should be worn.
• Remove loose fitting clothing, jewelry, and tie
back long hair.
• Gloves should not be placed near the
grinding stone.
• Never grind aluminum with a wheel designed
for steel. The wheel will overheat and could
explode.
Pedestal or Bench Grinder Care
•
•
•
•
•
•
•
Before working with a bench grinder, make sure the tool and it’s accessories are
in the proper working order.
“Ring Test” grinding wheels before mounting. Suspend the wheel on a pencil
held horizontally through the center of the hole. Tap the wheel lightly with a
plastic screwdriver handle, in spots 45 degrees from vertical. If it produces a
clear ringing tone it is in good condition. If it sounds dull, REPLACE it.
Inspect the wheels for a hairline crack before using. DO NOT USE A CRACKED
WHEEL.
Make sure the wheel housing guards are in place.
Don’t operate a grinder unless it is securely mounted to the solid surface.
Do not heavy grind on the side of the wheel.
Adjustments need to be made when the grinder is unplugged & stopped. Adjust
tool rests 1/8” from the wheels and slightly below center and spark or shatter
guards (at the top of the wheel housing guards) 1/16”away from the wheels. Readjust these as the wheels wear down to a smaller diameter.
Portable Grinder Safety
•
•
•
•
•
•
•
•
Safety glasses with side shields and a face shield must be worn.
Hearing protection should be worn.
Never use a portable grinder without the guard in place and correctly
adjusted.
Always have the auxiliary handle fitted; hold the grinder with both
hands and have a Never grind aluminum with a wheel designed for
steel. The wheel will overheat and could explode.
stable stance.
Ensure the workpiece is rigidly supported and firmly clamped.
Movement in the workpiece during grinding may result in disc shatter or
grinder kickback, with the potential for operator injury.
Ensure the grinder is turned off before plugging it in.
Check to make sure there are no flammable materials that may be hit
by sparks and check the area for any smouldering material when the
work is completed.
The maximum speed in revolutions per minute (rpm) is marked on
every wheel. Never exceed this limit.
Portable Grinder Care
• Inspect all wheels for cracks and defects before mounting
them.
• Ensure that the mounting flange surfaces are clean and flat
• Run nearly mounted wheels at operating speed for one
minute before grinding.
• Do not use a grinder that vibrates or makes unusual noises.
• If a grinder is dropped, you should inspect the grinding
wheel for cracks or defects.
• Be aware of where your sparks are going.
Fire Extinguisher Requirements
•
•
Suitable fire extinguishing equipment must be maintained in a state of readiness for
instant use. Such equipment may consist of pails of water, buckets of sand, hose or
portable extinguishers depending upon the nature and quantity of the combustible
material exposed.
Fire watchers are required whenever welding or cutting is performed in locations where
other than a minor fire might develop, or any of the following conditions exist:
– Appreciable combustible material, in building construction or contents, closer than
35 feet (1 0. 7 m) to the point of operation.
– Appreciable combustibles are more than 35 feet (1 0. 7 m) away but are easily
ignited by sparks.
– Wall or floor openings within a 35-foot (1 0. 7 m) radius expose combustible
material in adjacent areas including concealed spaces 'n walls or floors.
– Combustible materials are adjacent to the opposite side of metal partitions, walls,
ceilings, or roofs and are likely to be ignited by conduction or radiation.
Fire Watch Requirements
• Fire watchers must have fire extinguishing equipment
readily available and be trained in its use. They must be
familiar with facilities for sounding an alarm in the event
of a fire. They must watch for fires in all exposed areas, try
to extinguish them only when obviously within the
capacity of the equipment available, or otherwise sound the
alarm. A fire watch must be maintained for at least a halfhour after completion of welding or cutting operations to
detect and extinguish possible smoldering fires.
Fire Extinguisher Types
•
•
•
•
•
It is vital to know what type of extinguisher you are using. Using the
wrong type of extinguisher for the wrong type of fire can be lifethreatening.
Class A extinguishers are for ordinary combustible materials such as paper,
wood, cardboard, and most plastics. The numerical rating on these types of
extinguishers indicates the amount of water it holds and the amount of fire it
can extinguish.
Class B fires involve flammable or combustible liquids such as gasoline,
kerosene, grease and oil. The numerical rating for class B extinguishers indicates
the approximate number of square feet of fire it can extinguish.
Class C fires involve electrical equipment, such as appliances, wiring, circuit
breakers and outlets. Never use water to extinguish class C fires - the risk of
electrical shock is far too great! Class C extinguishers do not have a numerical
rating. The C classification means the extinguishing agent is non-conductive.
Class D fire extinguishers are commonly found in a chemical laboratory. They
are for fires that involve combustible metals, such as magnesium, titanium,
potassium and sodium. These types of extinguishers also have no numerical
rating, nor are they given a multi-purpose rating - they are designed for class D
fires only.
Fire Extinguisher Symbols
Using an Extinguisher
• To use an extinguisher, you pull out the
safety pin.
• Aim at the fuel, not the flames, and depress
the lever.
• Move the stream side to side with a
sweeping motion.
Burn Types and Treatment
• FIRST DEGREE BURNS
• The first-degree burn usually produces a pink to reddish color on the
burned skin. Mild swelling, tenderness and pain are also symptoms of
a first-degree burn. This is the least serious type of burn and involves
only the upper layer of skin, the epidermis. For these minor burns, the
victim should cool with plain water and use non-prescription antibiotic
creams. These burns usually heal on their own within a few days with
little or no scarring. However, if a first-degree burn is over a large area
of the body, seek emergency medical attention. Also, if an infant or
elderly person suffers any type of burn, even minor, obtain medical
assistance promptly.
Burn Types and Treatment
• SECOND DEGREE BURNS
• Second-degree burns involve the epidermis and the second skin layer,
the dermis. The epidermis is destroyed and burned-through in a
second-degree burn. There are the same symptoms of pain and
swelling but the skin color is usually a bright red and blisters are
produced. Usually second-degree burns produce scarring. Second
degree burns may take from one to three weeks to heal but are
considered minor if they cover no more than 15% of the total body
area in adults and 10% body area in children. These burns require
medical attention and medication to heal properly. Call for immediate
medical help as soon as the burn occurs and do not apply any type of
butter or greasy substance to the burn. This can hamper cooling of the
burn area and also do further damage. Consult medical personnel about
whether or not to administer fluids to victim before arriving at a
hospital.
Burn Types and Treatment
• THIRD DEGREE BURNS
• The third-degree burn may appear charred or have patches
which appear white, brown or black. Both the dermis and
epidermis are destroyed and other organs, tissues and
bones may also be involved. Third-degree burns are
considered the most serious. They produce deep scars that
many times require cosmetic or reconstructive surgery and
skin grafts. Pain may or may not be present since usually
nerve endings which transmit pain have been destroyed in
this type burn.
What if you catch on Fire
• Smother the flames with your welding gloves.
If the fire is large.
• STOP where you are. Moving or running feeds air to
the flames and worsens the fire.
• DROP to the ground. If you stand up, the fire can
burn your face. Fold your arms high on your chest to
protect your face.
• ROLL slowly on the floor or ground, or in a blanket or
rug, if you can.
• COOL off as soon as possible with water for first and
second degree burns.
Material Safety Data Sheets
• A Material Safety Data Sheet (MSDS) is required under the U.S.
OSHA Hazard Communication Standard.
• They are required as a part of any compliance obligation to be
available and displayed prominently in the workplace. The public
has a right to MSDS data upon request.
• A material safety data sheet (MSDS) is a form containing data
regarding the properties of a particular substance.
• it is intended to provide workers and emergency personnel with
procedures for handling or working with that substance in a safe
manner, and includes information such as physical data (melting point,
boiling point, flash point, etc.), toxicity, health effects, first aid,
reactivity, storage, disposal, protective equipment, and spill-handling
procedures.
General First Aid
• First-aid equipment must be available at all times. All
injuries must be reported as soon as possible for medical
attention. First aid must be rendered until medical attention
can be provided.
• Report all dangerous situations immediately.
If you feel faint or dizzy while welding
• Let someone know immediately. Go to a safe area and sit
down. Drink water as soon as possible.
General Safety Rules
• Do not use equipment you have not been trained
to use. Watching someone use it is not adequate
training.
• If a part becomes caught in a machine, do not grab
it until you have turned off the machine.
• Never throw anything unless you are sure it is safe
to do so.
• Call out a warning prior to throwing something or
when you drop something from a height that it
could hit someone.