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39 SHEET METALContents

- Accident Investigation

- Material Handling

- Welding and Soldering

- Ventilation

- Fire Safety

- Shop Safety

Accident InvestigationPurpose

Accidents that injure people or damage propertyon construction sites should be investigated. Insome cases, investigation is required by law.Refer to sections 51-53 of the OccupationalHealth and Safety Act.

The purpose of accident investigation is toidentify causes and prevent the accident fromoccurring again. The objective is not to blameanyone. The method is fact-finding.Investigation looks beyond the obviousimmediate causes to determine what other,underlying causes may have contributed to theaccident.

All concerned parties should be involved inaccident investigation. Depending on the sizeand duration of the project, that may include thehealth and safety representative, the joint healthand safety committee, the projectsuperintendent, and foremen.

Investigators understand that accidents don’t justhappen. They are caused by some failure inplanning, procedures, equipment, instruction,communication, or training. If the causes offailure aren’t identified and corrected, they canlead to similar accidents in the future.

It is recommended that accident investigationresults be discussed with all employees—in

particular, the steps being taken to prevent arecurrence.

What to investigate

After an accident, employers need to

• record the facts

• determine the immediate and underlyingcauses

• identify possible accident or illness trendsin order to counteract them

• substantiate a worker’s claim in the case ofpersonal injury

• take the steps necessary to prevent arecurrence.

When to investigate

Investigations should be conducted as soon afterthe accident as possible. There are severalreasons for doing this.

• With the passage of time the accidentscene will change, evidence may beremoved, and immediate and underlyingcauses will become harder to pinpoint.

• Details are quickly forgotten.

• Witnesses may move on to other sites.

• Employers need to demonstrate promptlytheir commitment to determine causes andprevent accidents from recurring.

How to investigate

An investigation is usually conducted right atthe accident scene. That helps to develop aclear picture and allow witnesses to show andpoint out things as well as describe and explain.

Witnesses should be interviewed separately.This helps to ensure that each witness recallsevents without being influenced by hearingsomeone else’s version. Investigators don’t wanteveryone buying into a newspaper version.They look for facts, evidence, and areconstruction of events that fits the differentpoints that witnesses recall.

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For instance, one witness may state, “There wasa sharp snap,” while another remembers “aripping noise.” The two reports are notnecessarily contradictory. The sharp snap mayindicate the sudden structural failure of anoverloaded component while the ripping noiseindicates a cable tearing apart following thefailure.

Investigators try to establish

• conditions before, during, and after anaccident

• activity being performed

• role of workers, supervisors, and witnesses

• involvement of machines or equipment

• factors such as weather, work surface, andground conditions

• the sequence of events

• any deficiencies or breakdowns in thesystem that allowed the events to occur

• how the system can be corrected toprevent the accident in future.

Investigators establish these facts by

• keeping an open mind and never jumpingto conclusions

• avoiding witch hunts, fault-finding, andblaming individuals

• contacting everyone involved

• sticking to the facts

• determining both immediate andunderlying causes

• recording the details and recommendationsso follow-up action can be taken

• ensuring that everyone understands thatthe purpose of the investigation is to gainthe knowledge and understanding neededto prevent a recurrence.

The worker’s role

Without the cooperation of workers,investigation will likely fail to disclose whatcaused the accident and how it can beprevented. Digging into the facts can be painful,but labour and management must work togetherto establish what happened, determineimmediate and underlying causes, and take theaction necessary to eliminate such accidents inthe future. The full cooperation of all parties istherefore essential.

For more information, contact the ConstructionSafety Association of Ontario at 1-800-781-2726and order the data sheet Accident Investigation(DS029), poster P103, and sticker S008.

Material HandlingWork areas

• Work areas should be laid out in advanceto ensure safe and efficient operation.

• When stockpiling material for fabricationor installation ensure that a good solidbase is provided for storage.

• If material is to be piled high, use sleepersto ensure a level and safe storage area.

• Keep work areas clear of clutter, debris,and scrap.

• Keep a box or barrel close by to disposeof scrap.

Preparing storage areas

• The area where the material is to be storedshould be as level as possible, dry, well-drained and with good access.

• Avoid storing materials under powerlines,especially if hoisting equipment is beingused to move it (O. Reg. 213/91, section37).

• Sleepers should be used to keep thematerial off the ground and to allow slings

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to pass freely under the load. Make surethere is adequate blocking available beforematerial is delivered.

• Storage areas should be as close to thework area as possible, whether materialwill be handled by crane or carried byworkers.

• The mechanical contractor and/or generalcontractor should be consulted beforesetting up site storage areas so that theyare aware of potential weights to be storedin each area. Ensure that material storedon floors does not overload the structure,and that sufficient support is in place onnewly poured slabs.

• To prevent accidents, all material shouldbe stored at least 1.8 metres (6 feet) awayfrom all open edges.

• Wherever practical, storage areas shouldbe well laid-out with clear and directaccess to work areas.

• Store so that material is free of mud, oil,grease, etc.

• In general, a clean work area is a safework area. Store materials away fromtravelled walkways

Ventilate storage areas

Storage areas need to be well ventilated. Thefumes given off by paint thinners, epoxies,acids, and other materials may be toxic orflammable.

Unloading and storage precautions

• Post DANGER signs and cordon offunloading areas as required.

• Serous accidents can occur if banding ortie-downs for bundles are released withoutcontainment and materials spill over.

• Be sure to communicate with the driverabout unloading procedures.

• Land and block the load before unhookingand unslinging it. Lower loads ontoadequate blocking to prevent damage toslings.

• Make sure identification tags are clearlyvisible in order to avoid extra handling.

• Space material so that it can be picked upwithout having to move other material. Ifmaterial must be stacked in layers, putsleepers between each layer.

• Immediately after cutting, dispose ofbanding material, waste wire, or any othergarbage in proper containers so that itdoesn’t become a hazard.

• Near openings, arrange material so that itcannot roll or slide in the direction of theopening.

Positioning the truck

• Position the truck as close to the craneunloading area as possible to avoidoverreaching by the crane.

• The truck should be positioned on terrainas level as possible.

• Keep the truck and crane away fromoverhead powerlines.

• A truck backing up should be directed bya competent signaller using establishedsignals (Figure 1).

• Truck wheels should be blocked orchocked during unloading.

Figure 1. Hand Signals for Traffic Control

Back up

Clearance

Stop

Change direction

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Mounting and dismounting from truck

beds

• Many accidents have occurred as the resultof workers getting on or off a flatbedtruck. Situations will vary, but acommonsense approach should befollowed.

• Before mounting the truck, scrape off yourboot soles to avoid slips.

• Mount the truck platform in full view ofthe crane operator or signaller so that youwill not be struck by the load or the cranehook.

• Climb up and down facing the truck,maintaining 3-point contract at all times(two hands and one foot, or two feet andone hand).

• If step and handrails are provided, usethem. Stepping on tires or hubs affordspoor footing.

Welding and SolderingThe following guidelines apply to welding,cutting, and brazing. For soldering, see the boxentitled “Soldering” a few pages ahead.

Wear protective clothing

• Cotton or wool fibres if possible. Syntheticfibres are flammable.

• High-top safety shoes laced up, with pantleg covering top of shoe. A spark inside ashoe can cause a serious burn.

• Welding gloves.

• No cuffs on pants or shirt to catch sparks.

• Long hair tucked under a cap.

• Long-sleeve shirt to protect your skin fromsparks and rays.

• Welding leathers if welding at highamperage for a long time.

• A welding cap and jacket if you arewelding overhead.

• No jewelry.

• Use the right shade number for weldinglenses. See Table 8.1. Both the welder andanyone assisting the welder must wear eyeprotection.

Table 8.1

Lens Shade Selection Guide for WeldingShade numbers are given as a guide only and may bevaried to suit individual needs.

Electrode Arc Minimum Suggested1

Size Current Protective Shade No.Operation mm (32nd in.) (Amperes) Shade (Comfort)Shielded Metal Arc less than 2.5 (3) less than 60 7 –Welding 2.5-4 (3-5) 60-160 8 10(SMAW) 4-6.4 (5-8) >160-250 10 12

more than 6.4 (8) >250-550 11 14

Gas Metal Arc Welding less than 60 7 –and Flux Cored 60-160 10 11(GMAW) >160-250 10 12

>250-500 10 14

Gas Tungsten Arc Welding less than 50 8 10(GTAW) 50-150 8 12

>150-500 10 14

Air Carbon (light) less than 500 10 12Arc Cutting (heavy) 500-1000 11 14

Plasma Arc Welding less than 20 6 6 to 8(PAW) 20-100 8 10

>100-400 10 12>400-800 11 14

Plasma Arc Cutting (PAC)Light2 less than 300 8 9Medium 300-400 9 12Heavy >400-800 10 14

Torch Brazing (TB) – – 3 or 4

Torch Soldering (TS) – – 2

Carbon Arc Welding (CAW) – – 14

Plate Thicknessmm in.

Gas Welding (GW)Light under 3.2 under 1/8 4 or 5Medium 3.2 to 13 1/8 to 1/2 5 or 6Heavy over 13 over 1/2 6 to 8

Oxygen Cutting (OC)Light under 25 under 1 3 or 4Medium 25 to 150 1 to 6 4 or 5Heavy over 150 over 6 5 or 6

Figure 20.17

1. Shade numbers are given as a general rule. It is recommended tobegin with a shade that is too dark to see the weld zone. Then oneshould go to a lighter shade which gives sufficient view of the weldzone without going below the minimum. In gas welding or oxygencutting where the torch produces a high yellow light, it is desirable touse a filter lens that absorbs the yellow or sodium line in the visiblelight of the operation (spectrum).

2. These values apply where the actual arc is clearly seen. Experiencehas shown that light filters may be used when the arc is hidden by theworkpiece.

Reproduced with the permission of the American Welding Society.

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Protect others

• Position yourself so that sparks go in thesafest direction.

• Warn others in the area before striking anarc.

• Set up a screen to protect others from thewelding flash.

• Check to see if sparks or molten particlescould fall to a lower level or roll along thefloor. Be especially careful about this whenyou are welding from a scaffold or ladder.

Avoid burns and fires

• Use a striker to ignite a torch flame. Usingmatches or a cigarette lighter can burnyour fingers.

• Don’t carry a butane lighter in your shirt orpants pocket. It may be ignited by sparks,splatter, or high heat.

• Clear the work area of flammable materialsor debris.

• Never lay down a torch while the flame isburning.

GAS SOURCE EFFECTS

Acetylene From acetylene not completely In very high concentrations, usually inused up in oxyacetylene welding. confined spaces, replaces oxygen in the

air possibly causing suffocation

Argon/Helium Used in gas-metal arc welding Same as above(GMAW) and gas tungsten arcwelding (GTAW) to shieldelectrode from oxygen.

Arsine Possible contaminants of Anemia (from breaking up red bloodcommercial acetylene cells), jaundice, pulmonary edema

Carbon Monoxide Welding arc changes carbon dioxide Headache, dizziness, concentrationin the air to carbon monoxide, problems, anemia, heart disorders,GMAW can be a primary source. and (in high enough concentrations)From incomplete burning during coma and deathwelding or soldering.

Nitrogen Oxides Welding arc changes nitrogen in Respiratory irritant, pulmonary edema(NO2) & NO in air to nitrogen oxides. (delayed onset)

GMAW and plasma arc weldingcan be a primary source.

Ozone Ultraviolet light caused by the Irritant to eyes, nose and throat, chestwelding arc changes oxygen in air pains, wheezing. Can lead to pulmonaryto another form of oxygen, edemacalled ozone. GMAW and plasma arcwelding can be primary sources.

Phosgene Ultraviolet radiation from welding Respiratory irritant, chest pains,arc decomposes chlorinated solvents pulmonary edema, death (if(degreasers) such as trichloroethylene concentrations are high enough)and 1,1,1, trichloroethane

Phosphine Possible contaminant of Fatigue, tremors, coma, convulsions,commercial acetylene pulmonary edema, and (with long-term

exposure) anemia, problems with thegastrointestinal system

Table 8.2WELDING EXPOSURES

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• If welding has to be done within 10 metres(30 feet) of flammable materials, provide afire watch with fire extinguishers. The firewatch must stay at the location for half anhour after welding is completed.

Use oxygen safely

• Never use oxygen to blow dust from yourclothes. It’s a fire hazard.

• Never oil the oxygen regulator.

• Never use any grease or oil around oxygen.Oxygen mixed with the slightest trace ofgrease or oil can cause a violent explosion.

Avoid toxic fumes

• Make sure you have proper ventilation.Keep as much distance as possiblebetween the welding plume and your face.Table 8.2 shows the effects of variousgases used for or produced by welding.

• Check the MSDS for the welding rod andcomponents to be used.

• Find out if the metal you are weldingcontains zinc, lead, cadmium, chromium,or nickel. These give off toxic fumes.

• Clean off any paint before welding,especially if it might be lead-based. Beforeremoving lead, see the Ministry of Labour’sguideline Lead on Construction Projects,available on www.labour.gov.on.ca.

• Remove any degreasers. When welded,chlorinated degreasers can producephosgene gas, which is extremely toxic.

Other hazards

• Never weld or cut directly on a concretefloor. The combination of heat andmoisture in the concrete can cause a smallarea of the concrete to spatter.

• Know the special hazards for each weldingprocess. See ITI Welding Book One formore information.

Electric arc welding/carbon arc welding

• Any moisture—even sweat—aroundelectric welding machines can cause ashock. Wear dry gloves and shoes withinsulated soles. Dry off the workbench orfloor if either is wet.

• Use the proper amp rating and duty cyclerating for the electric welding machine youare using. Overheating can damageinsulation and lead to shock.

• Make sure the grounding cable is properlyattached to the work or worktable.

• The leads that carry the welding currentshould not come in contact with chains,wire ropes, hoists, and elevators.

• Disconnect the power supply whenmoving the welding machine.

• Remove the electrode from its holderwhen the welding machine is not in use.

• Place electrode holders so that they do notcome in contact with people or flammablematerials.

• Never cool electrode holder by putting itin water.

• Make sure that the polarity switch, rangeswitch, or both are not moved while thepower source is being used. This cancause a fire and damage the machine.

Oxyfuel welding, cutting, and brazing

The compressed gas cylinders used for oxyfuelprocesses can be a hazard. They must be stored,handled, and used properly to avoid accidents.

Storing cylinders

Many gas cylinders, such as oxygen cylinders,are under high pressure. Damage to the valvecan turn the cylinder into a rocket.

• Avoid any sudden shock to cylinders.

• Store all compressed gas cylinders upright

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in a clean dry area away from oil, grease,flames, and flammable materials.

• Store cylinders upright and hold them inplace with chains or cables. Use a cylindercap to protect the valve, when applicable.

• Do not store oxygen cylinders within 20feet of fuel gas cylinders such as acetylene,propane, or butane unless they areseparated by a partition at least 5 feet highand having a fire resistance rating of atleast 30 minutes (Figure 8.1).

Handling cylinders

• Cylinders being transported should besecured in an upright position.

• Cylinder valves must be closed before thecylinder is moved.

• Never use cylinders as rollers or assupports, whether they are full or empty.

• Never remove cylinder caps with a pry bar.

Using cylinders

• Cylinders should be secured in an uprightposition while in use.

• Use positive action check valves at boththe regulators and torch. These valvesprevent the gas from flowing in reverse.

• Always use a regulator on a cylinder toreduce the pressure, unless the equipment isdesigned to withstand full cylinder pressure.

• Never force regulator fittings if they do notmatch the cylinder threads. Some regulatorfittings (such as acetylene) have left-handthreads.

• Before connecting a regulator to a cylindervalve, open the valve briefly to blow awayany dust.

• Never stand in front of the regulator whenturning on the cylinder valve. In case of amalfunction, the explosion or fire willblow out the front of the regulator.

• Before removing a regulator, close thecylinder valve and release the gas from theregulator.

• Never allow any oil on an oxygenregulator. Oxygen under pressure canexplode when it contacts oil.

• Use black iron pipe and fittings foracetylene. Never use copper pipe orfittings with acetylene. Copper andacetylene form acetylides which explodeviolently.

• Make sure that the fuel gas hose is red, theoxygen hose is green, and the inert gashose is black (U.S. only). Acetylene hosesusually have left-hand threads.

• Open the valve on oxygen cylinders all theway to prevent leakage around the valvestem.

• Close all cylinder valves when you areaway from work for any length of time.

Using acetylene

• Always keep acetylene hose pressure atless than 15 psi (pounds per square inch).Higher pressure creates a risk of fire.

• Leave a wrench on the acetylene cylindervalve for emergency turnoff.

• Open the acetylene cylinder valve only 1/4turn so that if can be turned off quickly incase of an emergency.

Figure 8.1

30 Minute Fire Rating

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• Breathing acetylene gas can causedizziness, a light-headed feeling, or loss orconsciousness. Acetylene is highlyflammable. You can recognize acetylene byits garlic-like odour.

Soldering

• Wear eye protection because flux orsolder can splatter.

• Ensure good ventilation while solderingor tinning a soldering iron. The salammoniac gives off irritating toxic fumes.

• Keep away from the soldering plume asmuch as possible because of the leadcontent in the plume.

• Rest a hot soldering iron in a holder. Donot put it on a workbench or onflammable material.

• When soldering outdoors, make sure thefirepot is clear of any combustiblematerial and is level and stable.

• Fill the propane tank for the firepotcarefully and away from open flames.The tank is full when gas begins escapingfrom the relief valve.

• Use a damp cloth to clean a solderedjoint. If water drops on the hot metal itcould cause the flux to splatter.

Working with acid

• Acid can blind you. Acid fumes cancause breathing problems. Acid on yourskin can burn. Use acid or other fluxcarefully.

• If acid gets in your eyes, wash immediatelywith cold running water. See a doctorimmediately.

• If acid gets on your skin, wash it off withcool tap water right away, until the

burning sensation subsides. See a doctorimmediately.

• Ensure good ventilation while you workwith acids.

• Acid on your clothing will rot the fabricand could contact your skin.

• Do not make cut acid near an open flame.The process gives off hydrogen gas thatcan explode.

• Do not fill a container for making cut acidmore than half full. The hydrogen gas cancause the acid to bubble vigorously.

• Never add water to raw acid (hydrochloricacid) when making a solution. Add theacid to water, and add it slowly over a 10or 15 minute period in a ceramic crockthat can stand the heat produced.

Plastic welding

Sheet metal workers make ductwork out ofplastic as well as sheet metal.

• PVC (polyvinyl chloride) ductwork iswelded using a PVC filler rod heated witha hot-air gun. The filler rod is used like thefiller for oxyacetylene welding.

• FRP (fibre-reinforced plastic) is chemicallywelded. A solvent dissolves the twosurfaces so that they melt together. Theprocess involves mixing a resin, promoter,and catalyst, which react together. Thereaction produces heat over 360° F. That’senough to start a fire.

• Follow safety precautions for FRP welding:

– Read the MSDS on any chemical or othermaterial you use.

– Check all chemical containers for leaksor cracks.

– Wear proper protective equipment whenworking with any chemical.

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– Follow the manufacturer’s guidelines formixing chemicals and their catalysts. Forsafety, many components must bemixed in a specific sequence.

• Make sure you have good ventilationwhen opening and using chemicals.

• When transferring resins from 55-gallondrums, make certain the drums areelectrically grounded to reduce sparkingfrom static electricity.

• When you transfer resin to a smallercontainer, label the new container with theproduct name, chemical family,flammability, and use.

• Never experiment with the chemicals,catalysts, or their mixing ratios.

• Make certain that the proper class of fireextinguisher is available.

• A sign should identify the area where FRPmaterials are being prepared.

• Never dispose of a mixing container untilthe reaction has been completed and is nolonger producing heat.

For more information, refer to the chapteron Welding and Cutting in this manual. Safepractices are also explained in the AmericanWelding Society’s ANSI Z49 publicationSafety in Welding and Cutting and in theCanadian Standards Association standardSafety in Welding, Cutting and AlliedProcesses (CAN/CSA-W117.2).

VentilationWhether you’re welding, cutting, fabricating, orinstalling, you need clean air on the job.

Air polluted by toxic gases and particles canmake breathing hazardous. If you work indoors,

you could be trapped in bad air if there is notenough ventilation.

Air may be a hazard even though there are nodanger signs. A toxic gas may be odourless (ascarbon monoxide is).

Some hazards have short-term effects that youfeel immediately such as burning eyes,dizziness, coughing, and headaches. Other airhazards have long-term effects that you mightnot feel for 20 years or more, such as cancer orasbestosis.

The first step is to control the source of aircontamination. Changing a process or using asafer material might do this.

If the air pollution cannot be avoided, someother step is needed to make breathing safe.One solution is better ventilation. Another is towear a respirator.

Ventilation takes care of most jobsite air hazards.It removes contaminated air and replaces it withoutside air. Ventilation may use natural airmovement or forced air.

Local exhaust ventilation

Local exhaust ventilation means removing air atthe source of the contaminant. Figure 9.1 showsthree different methods. A filter is added if theair contains solid particles such as dust, paints,or oils. Local exhaust is usually more effectivethan general ventilation, but it is not 100%effective.

• The process or equipment should beenclosed as much as possible.

• The airflow rate has to be high enough topull the contaminant into the airstream.

• Intake air must be equal to the air beingexhausted.

• Intake air must be free of contamination.Intake vents should not be close toexhaust vents.

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• Exhaust air must be filtered or otherwisetreated so that clean air is exhausted to theatmosphere. Filters should be cleaned orreplaced regularly.

Hazardous fumes

• Zinc from welding galvanized sheets cancause metal fume fever. Symptoms aresimilar to flu. Metal fumes can causenausea, fever, and shaking chills andshould be avoided.

• Welding stainless steel creates chromiumfumes, which can be hazardous.

• Hydrochloric acid used as a soldering fluxreleases chlorine gas when applied tometal. Chlorine is hazardous.

• Lead, found in solder and certain alloys,causes serious health problems. It is storedin the body for a long time.

• Solvents used for many operations can alsobe hazardous.

Ventilate storage areas

Storage areas need to be well ventilated. Thefumes given off by paint thinners, epoxies,acids, and other materials may be toxic orflammable.

Portable FumeExtractor

FumeExtraction Gun

Bench withPortable Hood

Figure 9.1: Local exhaust ventilation for welding

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Fire SafetyImportant!

• If your clothing catches fire, STOP, DROP,and ROLL.

• If you suspect a fire, sound an alarm.

• Applied as soon as possible, smotheringcan usually put out a small fire.

• Know the location of fire extinguisherswherever you work.

The construction regulation (O. Reg. 213/91)requires that workers be trained to use fireextinguishers.

Information in this chapter has been taken fromthe Occupational Health and Safety Act andRegulations for Construction Projects. Theintention is to provide a general summary of theduties required of various personnel.

Fire basics

• The words flammable and inflammableboth mean the same thing—burning easily.

• Some materials may have labels thatindicate a fire hazard Figure 11.1

• A fire needs three ingredients—fuel,oxygen, and heat.

• Most fires at a sheet metal shop or jobsiteare due to

–flammable vapours from solvents,adhesives, and fuel gas

–sparks and hot metal form grinding,cutting, welding, brazing, and soldering

–electrical overloads.

• These common causes of fire can beeliminated by good housekeeping, propermaintenance, and safe work practices.

• Know the four basic types of fire (Table11.1).

Table 11.1 – Classes of Fire

CLASS TYPE OF MATERIALSFIRE

A Common Wood, paper,

materials fabric, grass, grain, coal,rubbish

B Flammable Gasoline, oil, paint,

liquids and varnish, solvents,

vapours grease, wax, fat, oil

C Electrical Motors, switch boxes,

transformers,generators, wiring

D Combustible Magnesium, titanium,

metals zirconium, sodium,lithium, potassium

Fire classification

Fires are broken down into four different classes(Table 11.1). You should be familiar with eachclass in order to know which fire extinguisherto use and in order to take proper precautions.

Figure 11. 1 Hazardous materials should be identified

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Class A – Common materials such as wood,paper, fabric, grass, grain, coal, and rubbish.

• Keep storage and work areas free ofdebris.

• Do not leave portable heaters unattended.

• Do not block the sprinkler system withstacked goods.

• Use care when welding and cutting.

Class B – Flammable liquids and vapours suchas gasoline, oil, paint, varnish, solvent, grease,wax, fat, and oil.

• Store flammable liquids in tightly closedapproved containers.

• Keep these materials away from sparks.

• Spray cans, paint cans, and othercontainers for flammable liquids must bedisposed of as hazardous materials.

• Follow all safety procedures for gascylinders.

• Clean up flammable liquid spills promptly.

• Put rags used to clean up spills (andother oily rags) in airtight containersand dispose of them daily.

• Do not refuel gasoline-poweredequipment in confined spaces orwhile the equipment is hot.

• Use non-flammable solventswhenever possible.

• Do not weld near flammable liquids.

• Do not turn on electric switches oroperate electrical equipment if thereare vapours or unidentifiable odours.An electric spark can cause anexplosion.

• Check the MSDS to find the flash point —the temperature at which vapours willcatch fire.

Class C – Electrical equipment such as motors,transformers, switch boxes generators, andwiring.

• Do not overload fuses, circuits, motors, oroutlets.

• Do not install a fuse rated higher than thatspecified for the circuit.

• Clean and lubricate motors regularly.

• Inspect electrical equipment for old wiring,damaged insulation, and looseconnections.

• Install a wire guard around utility lights.

• Investigate strange smells around electricalequipment or appliances.

Class D – Combustible metals such asmagnesium, titanium, zirconium, sodium,lithium, and potassium (these are rarely aproblem for sheet metal workers)

A

B

C

D

Class “A” Extinguishers

For fires in ordinary combustiblematerials such as wood, paper, andtextiles where a quenching, coolingeffect is required.

Class “B” Extinguishers

For flammable liquid and gas fires, suchas oil, gasoline, paint and grease whereoxygen exclusion or flame interruption isessential.

Class “C” Extinguishers

For fires involving electrical wiring andequipment where the non-conductivity ofthe extinguishing agent is crucial.

This type of extinguisher should bepresent wherever functional testing andsystem energizing take place.

Class “D” Extinguishers

For fires in combustible metals such assodium, magnesium, and potassium.

How to Use the Extinguisher

Aim the extinguisher at the base of the fire to extinguishthe flames at their source.Figure 11.2

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• Use MSDSs to determine the hazards andstorage requirements of combustiblemetals.

• Place metal shavings in proper containers.

Fire extinguishers

Check the fire extinguisher label to see whichclass(es) of fires it can be used for (Figure 11.2).Some fire extinguishers can be used for morethan one class of fire. The label also coversoperating instructions and recharge procedures,first aid information, and general guidelines.

• Let your employer know if an extinguisheris damaged.

• One component of fire-extinguishertraining is the PASS procedure (Figure11.3):

– Pull the pin and break the seal.

– Aim the nozzle at the base of theflame.

– Squeeze the lever while holding theextinguisher upright.

– Sweep the nozzle from side to side.

• Do not try to fight a fire if

– the fire is spreading rapidly

– the fire is blocking the path of escape

– adequate fire-fighting equipment is notavailable.

P Pull the pin

A Aim the nozzle

S Squeeze the lever

S Sweep the nozzle

Figure 11.3 Learn the PASS procedure for using a fire extinguisher.

Evacuation procedures

To evacuate a burning building safely:

• Sound the alarm.

• Turn off electrical equipment (if safe to doso).

• Close windows that do not lead to fireescape routes.

• Close the door after everyone has left aroom. Do not lock the door.

• Notify anyone who may not have heardthe alarm.

• Leave the area quickly. Do not panic.

• Leave by an appropriate route. More firedeaths are caused by smoke and gasesthan by flames. Follow these rules:

– Feel a door to see if it is hot beforeyou open it.

– Stay low to avoid smoke and toxicgases; crawl if necessary.

– Cover your nose and mouth with adamp cloth.

– Use stairs instead of elevators.

– Report to an assigned, pre-determinedlocation outside the building.

• If you have no safe escape route:

– Seal cracks around doors, windows,and vents with wet towels.

– If a telephone is available, tell the firedepartment your exact location.

– Wait by the door or a window for firedepartment to arrive.

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Shop SafetySheet metal shops do not fall under theConstruction Regulation (O. Reg. 213/91).They are governed by the regulation forIndustrial Establishments (Reg. 851). Forresponsibilities of workplace parties andprocedures to follow, refer to theOccupational Health and Safety Act andRegulations for Industrial Establishments.

SAFETY BASICSAccidents are waiting to happen in a sheetmetal shop. The sharp edges of sheet metal canscratch you, gouge you, and even amputatefingers and hands. Equipment can easily crushyour hands or blind you if you don’t use itcarefully.

By following some simple safety rules, you cankeep yourself and your fellow workers safefrom most hazards.

• Watch your step! The shop has manythings you can trip on.

• Pick up scrap or other materials on thefloor before you or someone else tripsover it.

• Wear goggles or safety glasses as needed,especially around welding, grinding, orpolishing operations.

• Watch out for heavy moving carts. Don’tlet yourself get caught between a cart anda solid obstacle, such as a wall or piece ofmachinery.

• Don’t try to carry more than you can safelyhandle. Get help. You can avoid injury toyourself and to others as well. A largepiece of sheet metal that you drop couldinjure someone.

• Don’t try to catch falling materials.

• Don’t distract someone who is operatingmachinery. Don’t let yourself be distracted.

• Don’t wear loose clothes or jewelry on thejob. These items can easily get caught inpower equipment. Long hair should betied up or tucked under a cap.

SPECIFIC GUIDELINESAccess

Keep permanent aisles and passageways clean,clear, and in good repair. Aisles andpassageways should be marked by paintedlines, curbings, or other methods to distinguishthem from work areas.

Permanent roadways, walkways, and materialstorage areas in yards should be maintained freeof dangerous depressions, obstructions, anddebris.

Work areas

Permanent floors and platforms should be freeof dangerous projections or obstructions andshould be kept in good repair and reasonablyfree from oil, grease, or water. On slipperysurfaces, workers should be protected againstslipping by mats, grates, cleats, or equivalentmeasures. Floors and platforms should beconstructed and maintained to support the loadsto which they are subjected.

Storage

The maximum weight of materials stored ontemporary floors or load-carrying platformsshould not exceed their safe carrying capacity.

Wherever stored, material should be piled,stacked, or racked in a manner to prevent itfrom tipping, falling, collapsing, rolling, orspreading. Racks, bins, planks, sleepers, bars,strips, blocks, and sheets should be used wherenecessary to make the piles stable.

Sanitation

Safety devices, including protective clothing,should not be interchanged among employees

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unless the equipment is properly cleaned.Exception: safety devices worn over shoes orouter clothing, no part of which contacts theskin of the wearer, such as metal foot guards.

Toilets

Every place of employment should be providedwith a sufficient number of conveniently locatedwater closets for the use of employees. Toiletsshould be clean and provided with an adequatesupply of toilet paper.

Compressed air or gases

Compressed air or other gases should not beused to blow dirt, chips, or dust from clothingor protective equipment while it is being worn.

Compressed air or gases should not be used toempty containers of liquids where the pressureexceeds the safe working pressure of thecontainer.

The use of compressed air for cleaning machinesand tools should be controlled—or proper safetydevices or safeguards should be applied—toreduce or eliminate hazards to the eyes.

Flying particles or substances

Wherever the danger of injury from flyingparticles or substances cannot be eliminated bythe use of personal safety devices andsafeguards, then adequate shields, screens, chipguards, or enclosures should be provided. Theseshould be designed and constructed to deflector confine the flying particles or substances andthereby prevent injury to employees.

MACHINES AND EQUIPMENT — GENERALManagement must ensure

• that all supporting structures, foundations,and fastenings for machines andequipment are designed, constructed, andmaintained to support expected loadssafely and without dangerous vibration

• that equipment is of adequate design forexpected use

• that equipment isnot operated athazardous speeds,loads, or stresses

• that defective partsare repaired orreplaced

• that a record ofrepairs, replacements, and othermaintenance is kept for each machine andpiece of equipment

• that all machine operators and assistantsare properly trained in safe use of theequipment and conduct regularmaintenance checks

• that fire extinguishers are provided asrequired

• that personal protective equipment (PPE)to be used with machines and equipmentis available

• that periodic safety talks or meetings areheld for employees.

Operators must

• never eliminate or bypass any safetydevices installed on the machine

• wear all PPE required by law and by theemployer

• keep work areas clean, safe, anduncluttered

• report any defect or malfunctionimmediately

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• never operate equipment or machinery inexcess of capacity

• be certain that equipment is properlygrounded where required

• avoid becoming careless, overconfident, orcaught up in the rhythm of the operationat the expense of health and safety

• never remove warning plates or operator’sinstructions from machines and equipment

• never store anything in machines orequipment that may fall out into the workarea

• never stand or sit on anything whilefeeding machines that could cause you tofall, slip, or stumble into bending area

• never tie down or otherwise disarmactuating devices to provide continuousoperation.

MACHINES AND EQUIPMENT —LOCATIONPermanently installed machines should bearranged or guarded so that

• they and their operators cannot be struckby moving equipment and material

• product, waste stock, or material beingworked or processed will not endangeremployees.

Skirt guards or similar devices should be usedwherever there are shear hazards between pitedges and the machinery or equipment installedand operating there.

CLEANING, REPAIRING AND ADJUSTINGPRIME MOVERS1)Use extended swabs, brushes, scrapers,and other tools where machinery cannotbe locked or blocked against movementduring cleaning, adjusting, and otheroperations.

2)Every machine driven by a prime moverand equipped with lockable controls, orreadily adaptable to lockable controls,should be locked in the OFF positionduring repair work.

3)Machines or prime movers not equippedwith lockable controls, or readily adaptableto lockable controls, should bedisconnected from the power source toprevent inadvertent start-up and operation.

4) In all cases, warning signs or tags withadequate wording should be placed on thecontrols of machines and prime moversduring repair work.

5)The employer must provide enough signs,padlocks, and similar devices for useduring emergency repairs. Signs must beequipped with a means of attachment thatcan be secured to the control.

MACHINE GUARDSGuards are required on any shop equipmentthat could cause injury or accident.

• Never remove a guard unless it isnecessary to adjust the machine.

• If you must remove a guard, never do sowhile the machine is running.

• Never start a machine if the guards are notin place.

• Protect the treadle on foot-controlledpresses. Use a guard designed to preventaccidental tripping or a specially designedtreadle.

• Make sure that openings in treadle guardsaren’t more than twice the width of thefoot. The only exception is for the longbar that extends across the machine.

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SHEET METAL

SHOP EQUIPMENT — SPECIFIC TYPES

Press Brakes

Power press brake – This is a power-drivenmachine fitted with rams or dies for the purposeof blanking, trimming, drawing, punching,stamping, forming, or assembling cold materials.

• Post a sign on the front of every powerbrake. “Warning: Never place your handsor any part of your body under the ramwithin the point of operation.”

• Many operations performed on powerbrakes in sheet metal shops allow the useof point-of-operation guards and/or two-handed actuators. Use them wheneverpossible.

• Where no point-of-operation guard (two-handed actuating devices, presence-sensingdevices, etc.) can be used, it is still yourresponsibility to see that safe operatingprocedures are followed.

• Presence-sensing guards are available forpower brake operations.

• Where thenature of theworkprevents theapplication ofguards, usehand toolsappropriateto the job.

• Keep a safedistance from the point of power brakeoperation.

• Never place fingers, hands, arms, elbows,head, or feet in the dangerous bendingarea or near any moving part.

• Guards and area obstructions should beplaced over various power brakecomponents such a flywheels, gears,

sprockets and chain belts, or other movingparts.

• Always use safety tools, fixtures, andsupporting devices for loading andunloading.

Hand brake – This is a machine actuated byhand power only. It is used for formingmaterials.

• Take precautions to prevent injury tohands and fingers.

• When more thanone person isworking on thisequipment,coordinate theoperation. Makesure your partner’shands are clearbeforeclamping thehandles.

• Never put yourhand betweenthe upper leafand the bending leaf.

• Place safety barriers to limit access aroundcounterbalance weights.

Bar folder – This machine is actuated by handpower only and used for forming materials.Take precautions to prevent injury to hands andfingers.

Shears

Power shear –This is a power-driven machineused to shearplate and sheetmetal.

• Post a signon every

Power Press Brake

Hand Brake

Bar Folder

Power Shear

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power shear. “Warning: Do not extendfingers or hands beyond guard or barrier.”

• Power shears must be equipped withguards to keep hands and fingers out ofthe point of operation and the materialhold-down.

• Place personnel barriers with warningsigns at the rear of the machine to preventanyone from entering this area duringoperation.

• Never place fingers, hands, arms, elbows,head, or feet in the dangerous cutting areaor near any moving part.

Foot shear – This is a manually poweredmachine.

• Never try to hold narrow pieces of materialat the front ofthe shear.

• Do not holdshort pieces ofmetal in back ofthe blade.

• Keep your footout from underthe treadle soyou don’t stepon your own toes.

• No one should stand behind the shearunless necessary. A worker behind theshear should

– know when the shear is coming down

– stand clear of the shearmechanism and gauge bar

– watch out for the shear metalas it falls.

Beverly shear – This is hand-operated equipment used to cut ornotch light gauge metal. Takeprecautions to prevent injury tohands and fingers.

Forming Rolls

Power rolls – These are power-drivenmachines used to form round shapes of sheetmetal.

• The feed side of the rolls should beprotected with a fixed or self-adjustingbarrier to prevent the operator’s fingersfrom getting caught between the rolls orbetween the guard and the rolls. Thecontrol device should be of the constant-contact type, located to keep the operatorout of danger.

• The prime mover should be equipped withan effective brake. Across the front of therolls at knee height, a control bar, lever, orother device should be installed. Whenactivated, this device should stop themotor and apply the brake.

• Never wear gloves or loose clothingaround a power roll.

BeverlyShear

Foot Shear

Power Roll

TurningMachine

Easy Edger

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Hand rolls – These are hand-operated machines used to form andshape sheet metal. Operators shouldnot wear gloves or loose clothingand should take precautions toavoid injury to fingers and hands.

Cutting Equipment

Plasma cutter

• Ensure the area is properly exhausted.

• Take care when lifting to load the table.

• Ensure that all scrap pieces are removedbefore starting a new operation.

• Shield the cutting head.

• Wear gloves when loading and removingmaterial.

Laser cutter

• Ensure the area is properly exhausted.

• Take care when lifting to load the table.

• Ensure that all scrap pieces are removedbefore starting a new operation.

• Shield the cutting head.

• Wear gloves when loading and removingmaterial.

Water cutter

• Ensure the area is properly exhausted.

• Take care when lifting to load the table.

• Ensure that all scrap pieces are removedbefore starting a new operation.

• Wear gloves when loading and removingmaterial.

• Keep hands well clear of the water jet.

• Do not put hands in waste water.

Slitter – This is a power-driven machine usedto cut strips of sheet metal. When you run metalthrough the slitter, don’t let the metal slidethrough your hands.

Laser Cutter

Water Cutter

Slitter

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Saws

Cut-off saw – This device is a powered circularsaw that normally uses a friction cut-off wheel.It comes in both stationary and portable models.

Band saw – This is a power-operated saw thatuses a continuous circular band blade forcutting.

Power hack saw – This device is powered,base-mounted, and usually self-oiling to easecutting.

• Before using, make sure that

– all guards are in place

– blade travels true

– guard comes to within 1/4" of metalbeing cut

– tension control device is properly set.

• Never load stock while the blade isoperating.

• Always support long and heavy stock infront of and behind the saw.

• Never attempt to dislodge or move stockwhile the blade is operating.

• Always wear eye protection.

• Always hold the workpiece firmly againstthe table.

• Do not remove jammed cut-off pieces untilthe blade has stopped.

• Never wear loose clothing and gloveswhile operating the saw.

Ironworker –This poweredmachine is used tocut, punch, andform steel angle,channel, and barstock of all shapes.

• Take care toprevent injuryto hands andfingers.

• Always wear safety goggles.

• Make sure that punch and die are aligned.

Other Equipment

Power roll-former– A power rollformeris used to form locksand seams on sheetmetal.

• When you runmetal throughthe former,don’t let themetal slidethrough yourhands. Sharp edges and fishhooks cancause deep punctures.

Spiral pipe machine – This powered machineis used to form spiral duct.

• Take precautions against flying debris.

• Wear safety goggles and leather gloves.

PortableChop Saw

StationaryCut-off Saw

BandSaw

Power Hack Saw

Power Roll-Former

Ironworker

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Decoiling machine – This powered machineuncoils steel coils to produce sheets.

• Never stand under or in front of a coilwhile it is being moved.

• Do not stand in front or in back of a coilwhile aligning the coil roller onto the take-off holder.

• Hold the coil band firmly so that it cannotsnap out and cut you.

• Wear leather gloves.

Drill press – a power drill is bolted to a benchand the chuck is lowered by an operating wheelor lever.

• Centre-punch the work to keep the bit inplace when starting to drill.

• Remove chuck key beforedrilling.

• Always where safetygoggles.

• Never wear gloves whendrilling.

• Securely clamp short piecesof material before drilling.

Stationary grinders – A powered machineused to grind or de-burr metal components asrequired.

• Secure to prevent dangerous vibration.Mount on substantial floors, benches,foundations, orother solidstructures.

• Equip grinderwith adjustablework rest ofrigidconstruction.Adjust workclose to wheelwith maximumclearance of1/8".

• Always wear hearing protection, gloves,and goggles.

• Provide abrasive wheels with protectivehoods designed and constructed to protectemployees against flying fragments from aburst wheel.

• Never use defective wheels.

• Only use wheels clearly marked withspeed limitations.

• Dress wheels on a regular basis.

Spot welders – These devices use electricalresistance to generate theheat necessary to spot-weldmaterial. Always weargloves, face shield, andclothing that will protectyou from sparks. Makeevery effort to screenoperations from otherworkers.

Pneumatic riveter –This air-driven tool isused to draw rivets.

Spiral PipeMachine

DecoilingMachine

StationaryGrinder

DrillPress

Hand-controlledSpot Welder

StationarySpot Welder

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• Take care to prevent injury to hands andfingers.

• Always wear safety goggles.

• Ensure that rivet is properly set.

Paint shop – This is a separate building ordesignated area of an occupied building usedspecifically for painting.

• Ensure that paint shop is well ventilated.

• Wear adequate and proper clothing,respirators, and eye protection.

• Secure and check all couplings.

• Ensure that paint operations are a safedistance away from sparks or other sourcesof ignition.

Power forklifts – The operator must becertified.

Manual forklifts – With hand-operated palletlifters, make sure the load is centred and thefloor free of debris.

Overhead Cranes

Overhead cranes are generally used for indoorhoisting. They are often installed for specific

repetitive tasks. The capacity of these cranes iswide ranging. Contractors may use them forspecialized hoisting operations such asremoving or installing major plant equipment.

Safe operation of overhead cranes requiresoperators to have the knowledge andcompetence to employ safe rigging practices.The rigger must rig the load to ensure itsstability when lifted.

Power drive runway or monorail cranes areused to move heavy materials and to holdmaterials during the fabrication process. All suchequipment must be maintained in good workingorder and inspected annually to ensure that allcomponents operate properly and show nosigns of undue wear or damage.

All overhead cranes must be inspected annuallyby a competent person.

Ensure that the load is free to move. If itbecomes stuck and the crane begins orcontinues to lift, the crane may reach its fullcapacity quickly. There may be little or nowarning of this condition and riggingcomponents may fail.

PneumaticRiveter

Paint Shop

Paint Shop

PowerForklift

ManualForklift

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SHEET METAL

• The operator must be a competent person.

• Ensure that the sound alarm worksproperly.

• Before use, ensure that the crane issuitable for the planned hoisting task(s).Confirm it has appropriate travel, lift, andcapacity.

• Inspect the crane before use. Check fordamage, wear, and proper operation of allfunctions.

• Confirm the load weight. Check thecapacity of all equipment includinghardware, rope, and slings. Do not exceedthese capacities.

• Select the right sling for each lift. Beforeuse, inspect slings and other rigginghardware for wear, stretch, or otherdamage. Do not use damaged or defectiveslings. Use softeners around sharp corners.Do not splice broken slings.

• When communicating with a craneoperator, use clear agreed-upon signals.Except for the stop signal, the craneoperator should follow instructions onlyfrom a designated signaller. Where a wired

or remote controller is used, the operatorshould become familiar with all of itsfunctions before lifting the load.

• Warn all people in the lift area beforestarting the lift. Ensure that the path of theload is clear of persons and obstructions.Do not lift a load over anyone.

• Centre the crane hoist over the load beforehoisting to prevent the load from swinging.

• Slide the sling fully onto the hoisting hookand ensure the safety catch is fully closed.Do not load the hook tip or hammer asling into place.

• Secure unused sling legs. Do not dragslings or leave loose material on a loadbeing hoisted.

• Keep hands and fingers from beingtrapped or pinched between the sling andthe load when the slack is taken out of thesling. Step away before the lift is made.

• Move the load and controls smoothly.Minimize load swing.

• Walk ahead of the load during travel andwarn people to keep clear. Use a tag lineto prevent rotation or uncontrollablemotion. Raise the load only as high asnecessary to clear objects. Do not ride onthe hook or the load.

• Set the load down on blocking, neverdirectly on a sling. Do not pull or push theload out from under the hoist.

• Do not leave the load or the craneunattended while a load is suspended.

• Where crane operation by other personnelmust be restricted, employ tag and lockoutprocedures.

• Store slings off the floor in a clean drylocation on hooks or racks. Do not leaveslings, accessories or blocking lying on thefloor.

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HAND AND POWER TOOLSChainsaws

Each year in Ontario, construction workersare injured while using chainsaws. Generallythe injuries result from two types ofaccidents:

1) the operator makes accidental contact withthe revolving chain

2) the operator is struck by the object beingcut, usually a tree or heavy limb.

Many of these injuries are serious.

While the chainsaw is relatively easy tooperate, it can be lethal. As with all high-speed cutting tools, it demands the fullattention of even the trained andexperienced operator.

Requirements

Chainsaws can be powered by electric motors(Figure 155) or gasoline engines (Figure 156).

Both saws are designed to provide fast cuttingaction with a minimum of binding in the cut,even though wood may be sap-filled or wet.Both afford about the same performance interms of horsepower and they are equippedwith similar controls and safety devices.

Regulations require thatchainsaws used in constructionmust be equipped with achain brake. Make sure thatthe saw is equipped with achain brake mechanism, andnot simply a hand guard,which is similar in appearance.

Regulations require thatchainsaws used in constructionmust be equipped with “anti-kickback” chains. Called safetychains (Figure 157) by themanufacturers, these chainsincorporate design features

intended to minimize kickback whilemaintaining cutting performance.

Protective clothing and equipment

• Eye protection in the form of plasticgoggles is recommended. A faceshieldattached to the hard hat will not providethe total eye protection of close-fittinggoggles.

• Leather gloves offer a good grip on thesaw, protect the hands, and absorb somevibration. Gloves with ballistic nylonreinforcement on the back of the hand arerecommended.

• Since most chainsaws develop a highdecibel rating (between 95 and 115 dBAdepending on age and condition),adequate hearing protection must be worn,especially during prolonged exposure.

• Trousers or chaps with sewn-in ballisticnylon pads provide excellent protection,particularly for the worker who regularlyuses a chainsaw.

Kickback

Kickback describes the violent motion of thesaw that can result when a rotating chain isunexpectedly interrupted. The cutting chain’sforward movement is halted and energy is

Front HandleFront Hand Guard

(activates chain brake)

Guide Bar

Chain

Drive Sprocket

Rear Handleand Guard

Scabbard-TypeChain Guard

TriggerLock

Throttle TriggerFuel CapFigure 156

Gasoline Chainsaws

Figure 157Safety ChainDrive Tang

Low-Profile Cutter

Guard Link

DepthGauge

Figure 155 — Electric Chainsaw

Figure 158 — Kickback Zone

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transferred to the saw, throwing it back from thecut toward the operator.

The most common and probably most violentkickback occurs when contact is made in the“kickback zone” (Figure 158).

Contact in this zone makes the chain bunch upand try to climb out of the track. This mostoften happens when the saw tip makes contactwith something beyond the cutting area such asa tree branch, log, or the ground.

To minimize the risk of kickback

- use a low-profile safety chain

- run the saw at high rpm when cutting

- sharpen the chain to correct specifications

- set depth gauges to manufacturers’ settings

- maintain correct chain tension

- hold the saw securely with both hands

- don’t operate the saw when you are tired

- know where the bar tip is at all times

- don’t allow the cut to close on the saw

- make sure the chain brake is functioning.

Starting

When starting, hold the saw firmly on theground or other level support with the chainpointing away from your body and nearby

obstructions. Use a quick, sharp motion on thestarter pull (Figure 159). Never “drop start” thesaw. This leaves only one hand to control arunning saw and has resulted in leg cuts. Usethe proper grip (Figure 160).

Site hazards

• Take extra care when making pocket cuts(Figure 161). Start the cut with theunderside of the chain tip, then work thesaw down and back to avoid contact withthe kickback zone. Consider an alternativesuch as a sabre saw.

• Be particularly careful to avoid contactwith nails, piping, and other metallicobjects.

Maintenance

Well-maintained cutting components areessential for safe operation. A dull or improperlyfiled chain will increase the risk of kickback.

• Inspect and maintain your saw accordingto the manufacturer's recommendationsregarding chain tension, wear,replacement, etc. Check for excessivechain wear and replace chain whenrequired. Worn chains may break!

Saw withStep-In Handle

Figure 159 — Correct Starting Position

Note thumbposition

Figure 160 — Proper Grip

Note thumbposition

Before moving from placeto place, shut off the sawand walk with the guide barpointed backwards. A tripor a stumble with a runningsaw can cause seriousinjury.

RIGHT WRONG

Figure 161 — Pocket Cuts

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• Select the proper size files for sharpeningthe chain. Two files are necessary:

1) a flat file for adjusting depth gauge

2) a round file of uniform diameter forsharpening cutters and maintainingdrive links.

• You must choose the correct round file foryour chain to avoid damaging the cutters.Consult the owner's manual or the supplierto be sure of file size.

• A round file used in combination with afile holder or, better yet, a precision filingguide will give the best results (Figure162).

Adjusting chain tension

• Follow the manufacturer's instructions onchain tension.

• In general, the chain should move easilyaround the bar by hand without showingnoticeable sag at the bottom (Figure 163).

• Be generous with chain lubricating oil. It isalmost impossible to use too much. Mostlate model saws have automatic oilers. Butoperators must still remember to fillthe chain-oil reservoir.

Bench Stakes

• Lift safely to place the stake on the table.

• Make sure that stake is secure.

Slating Hammer

Safe practices withslating hammers aresimilar to those withother hammers (see thechapter on Hand andPower Tools in thismanual).

Precision Filing GuideChain

File HolderCheck the owner's manualfor recommended filingangle

Figure 162 — Sharpening Tools

RoundFile

Too Tight

Too Loose

Correct Tension

1/8 inch

Figure 163 — No Noticeable Sag

BenchStake

SlatingHammer

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Riveters

Lazy tong riveters and pop riveters (hand andair) are used to insert fasteners (rivets) betweentwo or more pieces of material to hold themtogether. Pop riveters are generally used forlighter-gauge material while lazy tongs are usedfor heavier-gauge material.

When using these tools, keep hands and fingersaway from hinged parts (pinch points) andareas around the rivet.

For more information on a variety of tools, seethe chapter on Hand and Power Tools in thismanual.

Hand Pop Riveter

Lazy Tong Riveter

Air Pop Riveter