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New Data on Welding Fume –gFocus on Controls

Presented to: EEI Fall Health and Safety MeetingPresented by: Jeff Hicks Principal Presented by: Jeff Hicks, Principal Scientist, Exponent

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Highlights of What We Currently KnowDiff t f f ldi d diff t l l f f Different forms of welding produce different levels of fume exposures– Emphasis of exposure parameters is on Manganese and Hexavalent Chromium

Metals in consumables often dictates the composition and concentration of f fumes – Cr and Mn have no substitutes

The hierachery of fume production is SMAW>FCAW>GMAW>GTAWShielded Metal Arc Welding (SMAW) is the most popular type of welding –– it is relatively simple, it requires less skill and experience as compared to other types of

welding, – it has a short set-up time, and the equipment is relatively inexpensive– It is one of the most portable types of welding

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Highlights of What We Currently KnowSMAW t l t i i h i ( b 1%) SMAW on metals containing chromium (e.g. above 1%) will result in exposures above the PEL under many circumstancesThere are many variables that affect fume exposuresIndoor work results in higher fume levels as compared g pto outdoor workGMAW welding can result in overexposures to CrVI –b t t l t t d t SMAWbut to a lesser extent as compared to SMAWExposures to Mn are generally below the current PEL and TLV – there is a proposal to lower the TLV in and TLV – there is a proposal to lower the TLV, in which case many typical exposures will be above the TLVs

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Highlights of What We currently KnowG T t A W ldi (GTAW TIG) lt i Gas Tungsten Arc Welding (GTAW or TIG) results in the lowest fume exposures, but this welding process is considerably slower as compared to other types of y p ypwelding, like SMAW or GMAWGTAW rarely results in exposures to Mn and CrVI

b th PELabove the PELCarbon arc gouging gives rise to very high fume concentrations including high levels of CrVI on concentrations, including high levels of CrVI on chromium containing alloys, and Mn on all types of steel

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Highlights of What We Currently KnowTh f t l f i l i d The use of controls on fume exposures is evolving and becoming more commonplace - more and more welders (individuals and contractors) are beginning to use some form of fume exposure controlfume exposure controlRespirators are the most common method of controlThe use of local exhaust ventilation (fume extractors) can be The use of local exhaust ventilation (fume extractors) can be very effective at controlling exposuresThe use of LEV systems is time consuming, the inlet must be positioned very carefully our field observations show that it is positioned very carefully, our field observations show that it is rarely used properly or in a highly efficient wayMany contractors do not even try to use LEV – they claim that it i t tl d l d th t th ill i tis too costly and slow, and that they will use respirators

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H Cl D th E h t H d N d tHow Close Does the Exhaust Hood Need to Be? (Data from NIOSH)

Table 2: Capture Velocities for the Local ExhaustLocal Exhaust Ventilation Units

Di t f H d U it 1 (f ) U it 2 (f )Distance from Hood (in)

Unit 1 (fpm) Unit 2 (fpm)

6 120 3006 120 3009 60 220

12 30 50

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Portable LEV (Fume Extractors)

Air Velocity at the Weld Site Compared to CrVIC t ti I id th W ldi H l tConcentration Inside the Welding Helmet During SMAW on 308 Stainless Steel

Air Velocity (at inlet centerline) Compared to Distance from Exhaust Inlet

100

120

140

pm) High

Distance from Exhaust Inlet

20

40

60

80

Air V

elocit

y (fp g

Volume LEV

0

20

12 18 24 36

Distance from Inlet (inches)

120

140

160

Low

40

60

80

100

120

Air V

elocit

y (fp

m) Low

Volume LEV

0

20

40

4 5 8 12 18Distance from Inlet (inches)

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O ti i i th U f F E t tOptimizing the Use of Fume ExtractorsThe cross draft exhaust air velocity at the weld site should be greater than 50 feet per minute ideally near should be greater than 50 feet per minute, ideally near 100 fpm.High volume fume extractors should be kept within 18 g pinches of the weld site.Low volume fume extractors should be kept within 6 i h f th ld it inches of the weld site. If these parameters cannot be achieved, appropriate respiratory protection should be worn when respiratory protection should be worn when conducting SMAW on stainless steels.Train workers in these procedures.p

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Welding Fume Trends over TimeMi h l Fl d P S i t di d OSHA ldi Michael Flynn and Pam Susi studied OSHA welding fume data base information and examined it for exposure trends.pThey also examined how total fume exposures related to specific metals, like manganese.

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Flynn, M, and P. Susi, 2010, “Manganese, Iron, and total Particulate Exposures to Welders”, J. Occ. y , , , , g , , p ,Env. Hyg. 7:115-126.

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F C t l O ti Wh t Ab t thFume Control Options – What About the Welding Process

M dif i th ldi f h ld b Modifying the welding fume process should be considered in the options for fume control.OSHA has indicated that welding on high chromium OSHA has indicated that welding on high chromium alloys may need to be done with GTAWGiven what is known about fume generation by g ydifferent processes, other alternatives should be considered

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Cost and Feasibility Analysis of Welding Processes –focus on fume exposures, technical and financial feasibility

X l E h b i i th t d t h i l Xcel Energy has been examining the cost and technical feasibility of using welding processes other than SMAWAn initial study has been conducted by Jerome Spear, CIH, y y p(Spear Consulting, LP – Magnolia, Texas) and Arlen Siert, PhD, CIH (Xcel Energy, Denver, Colorado) – the information contained in the following slides were provided by these i di id lindividualsThey have examined issues such as technical feasibility, production rate, quality, cost and fume exposures levels –p , q y, pemphasis has been on CrVI– SMAW

FCAW– FCAW– GMAW (two different processes – spray, pulse)

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Welding Process Controlled Comparison Welding Process Controlled Comparison StudyStudy

Power Electric Generation Maintenance WeldingPower Electric Generation Maintenance Welding

SMAW, FCAW, SMAW, FCAW, and GMAWand GMAW

316L Stainless Steel (19% Cr)316L Stainless Steel (19% Cr)Horizontal/Vert. Butt WeldingHorizontal/Vert. Butt Welding

Production Rate Production Rate (or Travel Speed)(or Travel Speed)

Cr(VI), Cr(VI), MnMn, and Fumes (NOS), and Fumes (NOS) QualityQualityCostCost

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B il B tt St i l St l

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Boiler Bottom Stainless Steel Repair Welding Projectp g j

150 MW front wall coal-fired high pressure steam boilerhigh pressure steam boilerReplacement of boiler wet bottom ash drip platesStainless steel fillet weldingStainless steel fillet welding –mostly horizontal position, some verticalDivided into four portions toDivided into four portions to compare SMAW, FCAW, GMAW-spray mode, GMAW-pulsed modep

17Cost Comparison SMAW, FCAW, GMAW-S, GMAW-Pstainless steel butt welds – 50% horizontal / 50% vertical position

based on travel speed only- based on travel speed only

SMAW FCAWGas 9 1%SMAW

Labor

FCAWLabor

Consumable$1 25/LF$0.27/LFLabor

55 3%

Consumables44.7%

Gas 9.1%Labor 24.5%

Consumable

Consumable

ShieldingGas

$1.25/LF

$1.01/LF

$0.73/LF

$0.10/LF

55.3%

$1 10/LF

Consumables66.4%

$2 26/LF

GMAW-SL b

$1.10/LF$2.26/LF

Gas 12.9%Labor

GMAW-PGas 12.6%LaborLabor

Consumable$0.58/LF

$0.31/LF

Consumables58 1%

Labor 29% Labor

ConsumableConsumables59 2%

Labor 28.2%

$0.29/LF

$0.61/LF

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ShieldingGas$0.13/LF$1.05/LF

58.1% ShieldingGas

59.2%$0.13/LF

$1.03/LF

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Welding 316 (19% Cr) Stainless Steel

45

5045

Exposure Level and Travel Speed by Process

Hexavalent Chromium PEL 5 ug/m3

35

40

45

35

40

M)e PE

L / T

LV

PEL 5 ug/m3

Manganese TLV 0.2 mg/m3

42 IPM40 IPM

44 IPM

25

30

35

25

30

Min

ute

(IPM

el T

imes

the

Respirable Fume* TLV 3 mg/m3

Expected

30 IPM28 IPM

32 IPM

15

20

25

15

20

Inch

es /

xpos

ure

Leve IPM

vertical

IPM horizontal

Lower than normal due to stitch welding

24 IPM

5

10

15

5

10

Ex

IPM horizontal

Expected IPM horizontal

Mn 0.32 mg/m3 0.48 mg/m3

0.18 mg/m30.2 mg/m3 8 IPM

0

5

0GMAW-P GMAW-S FCAW SMAW

*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble

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Welding 316 (19% Cr) Stainless Steel (50/50% horizontal/vertical)

2.5

40

45

g ( ) ( )Exposure Level and Cost by Process -based on travel speed only

2

30

35

40

LF)

TLV

Hexavalent Chromium PEL 5 ug/m3

1.525

30

inea

r Foo

t (L

s th

e PE

L / T Manganese

TLV 0.2 mg/m3

$1.05$1.03 $1.10

115

20

$ Pe

r Li

Leve

l Tim

es Respirable Fume* TLV 3 mg/m3

0.5

5

10

Expo

sure

$ Per LF

11 µg/m320 µg/m3 27 µg/m3

00GMAW-P GMAW-S FCAW SMAW

Process

*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble

2020

Welding Process Controlled Comparison Welding Process Controlled Comparison StudyStudyStudyStudyPower Plant Coal Bunkers Wear Plate Installation Power Plant Coal Bunkers Wear Plate Installation P jP jProjectProject

SMAW, FCAW, SMAW, FCAW, and GMAWand GMAW

309L (24% Cr) Stainless Steel 309L (24% Cr) Stainless Steel Production Rate Production Rate (or Travel Speed)(or Travel Speed)( )( )

Horizontal WeldsHorizontal Welds QualityQualityCostCost

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Power Plant Coal Bunkers Wear Plate Installation Project400 LF of 0.25” SS horizontal butt welds on wallsC b t l l tCarbon steel wear plates on 60º sloping walls inside large coal bunkersC b t l j i d t 304Carbon steel joined to 304 (18% Cr) stainless steel plates below309L (24% Cr) consumables for dissimilar welds retain Cr with dilution

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Power Plant Coal Bunkers Wear Plate Installation Project4 experienced welders selected for proficiencyFastest production rate ppossible with acceptable qualityAlmost equal amounts of qFCAW and GMAW with a small amount of SMAWHalf-mask P100 respirators orHalf mask P100 respirators or single-use disposablesSamples collected inside welding hoodwelding hood

23Quality Problems: GMAW dripping in spray mode used for Quality Problems: GMAW dripping in spray mode used for penetration penetration penetration penetration –– tootoo high deposition rate out of positionhigh deposition rate out of position–– need to slow down wire feed speedneed to slow down wire feed speedpp

24Quality: better quality later, but some spatter Quality: better quality later, but some spatter –– need to fine tune voltageneed to fine tune voltageneed to fine tune voltageneed to fine tune voltage

25309 (24% Cr) Stainless Coal Bunkers Horizontal WeldsExposure Level and Production Rate by Process

12

14

10

12

)

10.6 IPM10.6 IPM61 µg/m3

10

e PE

L / T

LV

8

10

Min

ute

(IPM

)

HexavalentChromium PEL 5 ug/m3

M

.51 mg/m3 26

50% arc50% arc--on 100% arcon 100% arc--on 100% arcon 100% arc--onon

6

8

el T

imes

the

6

te In

ches

/ M Manganese

TLV 0.2 mg/m3

RespirableF *

6.3 IPM6.3 IPM

mg/m 6mg/m3

4

6

posu

re L

eve

4

duct

ion

Rat Fume*

TLV 3 mg/m3

IPM

3.3 IPM3.3 IPM 19.5 µg/m3

.23 mg/m3

11.5 mg/m3 11

µg/m3 9.2 / 3

2

Exp

2

Prod

CrVICrVI MnMn FumeFume

.35 mg/m3

mg/m3

0SMAW-S309 GMAW 309 FCAW 309

Process

0*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble(n=1) (n=2) (n=3)

CrVICrVI MnMn FumeFume

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Welding Process Controlled Comparison Welding Process Controlled Comparison StudyStudyStudyStudyCoal Fired Boiler Bottom Submerged Flight Conveyor E i P jExpansion Project

SMAW SMAW vsvs FCAW FCAW Production RateProduction Rate

308L (20% Cr) Stainless Steel 308L (20% Cr) Stainless Steel

Production Rate Production Rate (or Travel Speed)(or Travel Speed)QualityQuality( )( )

Vertical WeldsVertical Welds QualityQualityCostCost

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SMAW vs FCAW(308L, 20% Cr, Vertical Position)

SMAW (50% Arc Time)

1 23 IPM

FCAW (100% Arc Time)

4 7 IPM1.23 IPM 4.7 IPM

28308 Stainless (20% Cr) Vertical Butt Welds on 1/4" Plate 1/8" Gap

Exposure Level and Production Rate by Process

16

18

4.5

579 µg/m3 4.7 IPM

12

14

the

PEL

/

3.5

4

s / M

inut

e HexavalentChromium PEL 5 ug/m3

M

50% arc-on 100% arc-on

8

10

evel

Tim

es t

TLV

2.5

3

Rat

e In

ches

(IPM

)

ManganeseTLV 0.2 mg/m3

Respirable*

36 µg/m3

6

8

Expo

sure

Le

1.5

2

Prod

uctio

n R Fume*

PEL 5 mg/m3

IPM

1.23 IPM7.1 mg/m3

0.15 mg/m3 17 mg/m3

2

4E

0.5

1

P1.23 IPM

0.83 mg/m3

0SMAW 308 FCAW 308

Process

0*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble(median n=3)(n=1)

2929

Welding Process Controlled ComparisonWelding Process Controlled Comparison StudyW ld Sh C iWeld Shop Comparison

SMAW (50% Arc Time) FCAW (100% Arc Time)

316L (20% Cr) Stainless Steel Fillet Welds in Down-Flat

FCAW (100% Arc Time) Production Rate (or Travel Speed)

Position QualityCost

3030

Weld ShopSMAW vs FCAW (316L, 19% Cr, Down-Flat)

SMAW (50% Arc Time)n=3

4 85 IPM

FCAW (100% Arc Time)N=4

12 7 IPM4.85 IPM 12.7 IPM

31316 Stainless (19% Cr) Fillet Welds in Shop Flat Position

Median Exposure Level and Mean Production Rate by Process

70

80

12

14370 µg/m3

12.7 IPM

50

60

the

PEL

/

10

s / M

inut

e HexavalentChromium PEL 5 ug/m3

M50% 100%

40

50

evel

Tim

es t

TLV

6

8

Rat

e In

ches

(IPM

)

ManganeseTLV 0.2 mg/m3

RespirableF *

arc-on arc-on

20

30

Expo

sure

Le

4

6

Prod

uctio

n R Fume*

TLV 3 mg/m3

IPM73.7 µg/m34.85 IPM

33

10

20E

2

P.79 mg/m3

13.2 mg/m3.35 mg/m3

13 mg/m3

CrVICrVI MnMn FumeFume CrVICrVI MnMn FumeFume

0SMAW 316 FCAW 316

Process

0*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble(n=3) (n=4)

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Welding Process Controlled ComparisonWelding Process Controlled ComparisonWelding Process Controlled Comparison Welding Process Controlled Comparison StudyStudyLi Cl ifi T k P jLi Cl ifi T k P jLime Clarifier Tank ProjectLime Clarifier Tank Project

FCAW versusFCAW versusGMAW (ShortGMAW (Short--Circuit)Circuit)

309L (24% Cr) Stainless Steel 309L (24% Cr) Stainless Steel Butt Welds in Horizontal (2/3) Butt Welds in Horizontal (2/3)

GMAW (ShortGMAW (Short--Circuit) Circuit) Production Rate (or Production Rate (or Travel Speed)Travel Speed)( )( )

and Vertical (1/3) Positionsand Vertical (1/3) Positions QualityQualityCostCost

33309 Stainless (24% Cr) Horizontal Welds on 2 Lime ClarifierTanks

Exposure Level and Production Rate by Process

3.5

4

14

16

17 µg/m3

14 IPM 14 IPM

2 5

3

the

PEL

/

10

12

s / M

inut

e HexavalentChromium PEL 5 ug/m3

M

14 IPM 14 IPM

50% arc-on 60% arc-on

2

2.5

evel

Tim

es t

TLV

8

10

Rat

e In

ches

(IPM

)

ManganeseTLV 0.2 mg/m3

RespirableF *4 4 mg/m3

1

1.5

Expo

sure

Le

4

6

Prod

uctio

n R Fume*

TLV 3 mg/m3

IPM

6.1 µg/m3

.22 mg/m3

2.7 mg/m3

4.4 mg/m3

0.5

1E

2

4 P

.11 mg/m3

CrVICrVI MnMn FumeFume CrVICrVI MnMn FumeFume0

FCAW 309 GMAW 309Process

0*Respirable Particulates Not Otherwise Classified Insoluble or Poorly Soluble

CrVICrVI MnMn FumeFume CrVICrVI MnMn FumeFume

(n=1) (n=1)

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Conclusions/RecommendationsThis limited study indicates that SMAW does result in high fume

b t it b tl d t exposures, but it can be a more costly process as compared to procedures like GMAW and FCAWLabor is likely the largest cost of welding.– SMAW$ >> FCAW$ and GMAW$

This current study is strongly suggestive, but may not consider all of the direct and indirect costs associated with labor and all of the direct and indirect costs associated with labor and consumablesFour different welding projects were examined, additional projects need to be studied to ensure the data are validThis type of analysis can be very useful (and necessary) to push a large scale change in the selection of welding processesg g g p

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Conclusions/RecommendationsMinimize SMAW stainless steelMinimize SMAW stainless steel.Air currents have an effect on exposure that are difficult to control.difficult to control.LEV likely needed for SMAW, GMAW, and FCAW on Cr containing alloysg yAdditional research is needed to demonstrate the efficacy of the welding methods, and the positive y g pattributes– EPRI is considering such a study