welding hazards mitigating the risk

8/13/2019 Welding Hazards Mitigating the Risk

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Welding HazardsWelding HazardsMitigating theMitigating theRiskRisk

Presented by Dave Hisey toPresented by Dave Hisey to

the WMEA Conferencethe WMEA ConferenceJune 12, 2003June 12, 2003


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Welding HazardsWelding Hazards

Electric ShockElectric Shock

Electric Shock from welding will killElectric Shock from welding will kill Province of Ontario StatsProvince of Ontario Stats

August 15, 1988August 15, 1988

Sept. 15, 1993Sept. 15, 1993

August 04, 1994August 04, 1994

Nov. 02, 2001Nov. 02, 2001 Each date represents a fatality involvingEach date represents a fatality involving

electric weldingelectric welding


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Electric ShockElectric Shock

Electric Shock from welding will killElectric Shock from welding will kill Recent US Mining FatalitiesRecent US Mining Fatalities

August 30, 2000August 30, 2000 Sept. 16, 2002Sept. 16, 2002

Both fatalities involved stick welding inBoth fatalities involved stick welding inconfined work areas while the welder wasconfined work areas while the welder was

lying on the base metallying on the base metal


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Electric ShockElectric Shock Welding machinesWelding machines

can and do operatecan and do operate

at up to 100 VDCat up to 100 VDC

We must prevent theWe must prevent the

welder fromwelder from

receiving electricreceiving electric

shockshock

John Richards isJohn Richards isgoing to explain howgoing to explain how

this device worksthis device works


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Shock Stop DesignShock Stop Design

CriteriaCriteria

Reduce the OCVReduce the OCVwhen the welderwhen the welderis not in use andis not in use andreturn power thereturn power theinstant an arc isinstant an arc isstuck.stuck.

SeamlessSeamlessoperation foroperation forwelder no impactwelder no impacton quality.on quality.


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Shock Stop ComponentsShock Stop Components MicroProcessorMicroProcessor

Based.Based.

Solid State SwitchingSolid State Switching

up to 720 Amps.up to 720 Amps.

Powered by thePowered by the

available OCV.available OCV.

Mounted in aMounted in a

Fibreglass Enclosure.Fibreglass Enclosure.


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Shock Stop Theory ofShock Stop Theory of

OperationOperation The human bodyThe human body

normallynormally provides aprovides ahigh resistancehigh resistancevalue.value.

A number of factorsA number of factorsreduce the effectivereduce the effectiveresistance.resistance. TemperatureTemperature

Humidity/MoistureHumidity/Moisture

DistanceDistance

Surface AreaSurface Area


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Shock Stop Theory OfShock Stop Theory Of

OperationOperation Shock Stop measuresShock Stop measures

the resistance of thethe resistance of thewelding circuit.welding circuit.

The ThresholdThe Threshold

Resistance is in theResistance is in theRange of 40Range of 40--5050Ohms.Ohms.

When the electrodeWhen the electrodeis struck on the workis struck on the workthe resistance dropsthe resistance dropsbelow the thresholdbelow the threshold

level and Shock Stoplevel and Shock Stopoutput is energized.output is energized.


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Shock Stop Theory OfShock Stop Theory Of

OperationOperation To allow the weld toTo allow the weld to

be established thebe established theoutput is energizedoutput is energizedfor a minimum of 3for a minimum of 3

seconds.seconds. The microprocessorThe microprocessor

is fast enough thatis fast enough thatthe turn on and offthe turn on and off

time is nottime is notnoticeable to thenoticeable to theuser.user.


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Shock Stop DiagnosticsShock Stop Diagnostics InternalInternal

SCR, Trigger Devices,SCR, Trigger Devices,

MPUMPU

ExternalExternal Welding Cables,Welding Cables,

Ground PathGround Path

Shock Stop is anShock Stop is an

additional Safetyadditional Safetydevice to be useddevice to be used

with existing safetywith existing safety

practices.practices.


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Shock Stop SummaryShock Stop Summary Welders acceptWelders accept

electric shock as partelectric shock as partof their job.of their job.

The risks associatedThe risks associated

with shock are notwith shock are notknown by weldersknown by weldersnor their supervisors.nor their supervisors.

Technology isTechnology isavailable to reduceavailable to reducerisk and improverisk and improveworking conditions.working conditions.


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Stray Welding CurrentsStray Welding Currents Cause damage toCause damage to

Pins and bushingsPins and bushings

BearingsBearings

Building structureBuilding structure

Building electrical systemsBuilding electrical systems ConduitsConduits

Ground/Bond wiresGround/Bond wires

Tech cable jacketsTech cable jackets Bonding screwsBonding screws

ElectronicsElectronics computer driven equipmentcomputer driven equipment

PeoplePeople


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Stray Welding CurrentsStray Welding Currents

Responsible forResponsible forfatalitiesfatalities

Nov. 02, 2001Nov. 02, 2001Cambridge OntarioCambridge Ontario


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Main

400 amp splitter

Welder

Failure point

Worker suffers fatal

shock when opening

a 600 volt attachment

device

Work Lead

30 amp

welderswitch

Service

Ground

Building Steel


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EMT Connector

which failed

Connection

to Splitter

The connector which the victim

was attempting to open when he

died


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Burn marks where

welding machinewas located


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Main

400 amp splitter

Welder

Failure point

Worker suffers fatal

shock when opening

a 600 volt attachment

device

Work Lead

30 amp

welderswitch

Service

Ground

Building Steel

d f ld bl


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Condition of Welding CablesCondition of Welding Cables

is Importantis Important

Unacceptabledamage

Unacceptable

risk!

E l f W ldi C tE l f W ldi C t


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Examples of Welding CurrentExamples of Welding Current

DamageDamage



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DamageDamage


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C t f W ldi C tC t f W ldi C t


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Costs of Welding CurrentCosts of Welding Current

DamageDamage

Engine overhaulEngine overhaulcosts can be as highcosts can be as high

as $350,000.00as $350,000.00

Destroy that engineDestroy that engine

due to weldingdue to welding

damagedamage

Costs can be as highCosts can be as high

as $600,000.00as $600,000.00

Wh D St W ldiWh D St W ldi


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Why Do Stray WeldingWhy Do Stray Welding

Currents OccurCurrents Occur

Because multiple parallelBecause multiple parallelcurrent paths existcurrent paths exist


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TYPICAL WELDER CIRCUIT600V POWER OUTLET

POWER SUPPLY

600V, 3PHASE

CABLE

3 POWER +GRND

CONDUCTORSSTRUCTURAL

GROUND

WELDER

MACHINE

FRAMEGROUND

WORK LEADTERMINAL

ELECTRODETERMINAL

DC OUTPUT

ELECTRODEWORKPIECE

TABLE

FLOOR/GROUND

DC WELDING CURRENT FOLLOWS CONTROLLED PATHTHRU THE CABLES


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FAULT CONDITION DC ELECTRODE TERMINAL


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FAULT CONDITION DC ELECTRODE TERMINAL(NO WELDING IN PROGRESS)

NOTE: ELECTRODENOT IN USE

WORK

TERMINALELECTRODE

TERMINAL

FAULT

POWER TOOL

When Using Steel asWhen Using Steel as


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When Using Steel asWhen Using Steel as

Current PathCurrent Path

The multiplier is XThe multiplier is X 77

4/0 welding cable = 14/0 welding cable = 1 5/85/8 round barround bar

This Major CompanyThis Major Company


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This Major CompanyThis Major Company

Experienced Serious StrayExperienced Serious StrayWelding Current ProblemsWelding Current Problems


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This flat bar is

only 22 gauge

material it gotvery hot!


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These mats were

melted by the heat

generated fromwelding current

passing through 22

gauge sheet metalstrip


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Clamp used here

only amplifies theproblems

Tack weld will not

carry the current


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Stopping the DamageStopping the Damage

Work Lead Position is KeyWork Lead Position is Key

W117.2W117.2--01 S 5.3.2.4 .. The work lead01 S 5.3.2.4 .. The work lead

shall be connected as close as practicable toshall be connected as close as practicable tothe location being welded uponthe location being welded upon

to ensure welding current returns directly toto ensure welding current returns directly tothe sourcethe source through the work leadthrough the work lead


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W117.2W117.2--0101 ....

The work lead shall be of the same crossThe work lead shall be of the same cross--sectional area as the greater portion of thesectional area as the greater portion of the

electrode cable.electrode cable.

Damaged cables shall be replacedDamaged cables shall be replaced

Cable length shall not exceed that specified byCable length shall not exceed that specified bythe welding equipment manufacturer.the welding equipment manufacturer.


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W117.2W117.2--0101 ....

Electrical grounds connected to a buildingElectrical grounds connected to a buildingframework or other locations remote from theframework or other locations remote from thework area increase the possibility of outputwork area increase the possibility of output

current passing through lifting chains, cranecurrent passing through lifting chains, cranecables, or other electrical paths.cables, or other electrical paths.

This passage of current through buildingThis passage of current through buildingsystems can cause extensive damage tosystems can cause extensive damage toequipment and electrical circuits if the workequipment and electrical circuits if the worklead isnlead isnt properly installed.t properly installed.

From ThisFrom This To ThisTo This


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From ThisFrom This To ThisTo This

Correct Work LeadCorrect Work Lead


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Correct Work LeadCorrect Work Lead

ConnectionsConnections

Note the amountNote the amountof steel containedof steel containedin the designedin the designedfor purpose 600for purpose 600amp weldingamp weldingclamp whenclamp when

compared withcompared withthe standard Cthe standard Cclampclamp


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Welding Fume DiseaseWelding Fume Disease

Manganese IssueManganese Issue

Relationship to ParkinsonsRelationship to Parkinsons

Pregnant Welder ConcernsPregnant Welder Concerns

No published studiesNo published studies


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Welding Fume DiseaseWelding Fume Disease ACGIH reduced Manganese TLV toACGIH reduced Manganese TLV to

.2mg/m.2mg/m33 in 1996in 1996

Notice of Change to .03mg/mNotice of Change to .03mg/m33

How it is measured has also changedHow it is measured has also changed

Relationship of manganese toRelationship of manganese to

Parkinson's under study at HarvardParkinson's under study at Harvard --

AWSAWS 2 year study Dr. Joseph Brain2 year study Dr. Joseph Brain


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Whats wrong withWhats wrong withthis picture?this picture?


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The Female WelderThe Female WelderAlberta StatisticsAlberta Statistics

3.67% of all licensed welders female3.67% of all licensed welders female

Over 200 weldersOver 200 welders -- femalefemale

59 steamfitters59 steamfitters -- female (additional) plusfemale (additional) plusapprenticesapprentices

13.37% of apprentice welders female13.37% of apprentice welders female

Currently there are over 5000 apprenticeCurrently there are over 5000 apprentice

welders in Albertawelders in Alberta 670 female670 female


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SyncrudeSyncrude Canada Ltd., CSA, The LAC, &Canada Ltd., CSA, The LAC, &


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SyncrudeSyncrude Canada Ltd., CSA, The LAC, &Canada Ltd., CSA, The LAC, &

Keyano College are working together toKeyano College are working together to

make this a reality.make this a reality.


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Thank YouThank YouAre there any questions forAre there any questions formyself or John Richards?myself or John Richards?

welding hazards mitigating the risk

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