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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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Welding HazardsWelding Hazards
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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Welding HazardsWelding Hazards
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
Examples of Welding CurrentExamples of Welding Current
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Examples of Welding CurrentExamples of Welding Current
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?