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This Presentation is provided to you by: Weld Canada .com Industry Standard Welding Procedures Software CSA, AWS, ASME and API Welding Codes. Welding fume Management. Welding fume Management. In what units is fume generation measured? What units apply to particulate TLV’s?

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slide1

This Presentation is provided to you by: WeldCanada.comIndustry Standard Welding Procedures Software CSA, AWS, ASME and API Welding Codes

welding fume management
Welding fume Management
  • In what units is fume generation measured?
  • What units apply to particulate TLV’s?
  • A FCAW welder produces how much fumes per year?
slide4

Fume emission level versus shielding atmosphere

Fumes (mg/min.)

1.000

Wire ER 70S3 dia.: 1,2mm

280 - 300 A

800

740

28 - 30 V

600

470

400

350

290

190

200

150

0

CO2

100

20

10

5

0

O2

0

0

5

5

8

1,5

0

80

85

90

92

98,5

Ar

slide5

Ar + 18% CO2

Ar + 13% CO2 + 5% He

Ar + 10% CO2

Ar + 6% CO2 + 2% O2

Ar + 5% CO2 + 4,5% O2

Ar + 3,5% O2

I

Wire ER 70S3

1,2mm

Wire = 10 m/min

I = 280 / 300 A U= 32 / 34 V

Influence of CO2 content in the shielding gas on CO emissions

CO content (ppm)

200

160

150

130

120

100

80

Ar + 3,5% O2

50

40

0

0

slide7

Very fine (10E-8 cm) Fine (10E-4 cm) Coarse (1 cm )

Airborne particulates

Typical size range

Atmospheric dust

Welding fume and dust

Tobacco smoke

Coal dust

Cement dust

Respirable particles

factors affecting fume generation rate
Factors affecting fume generation rate
  • Type of shielding gas if applicable to the process
  • Welding current
  • Welding voltage
  • Arc length
  • Polarity
  • Current density
  • Humidity
  • Base plate
  • Electrode angle
  • Electrode type
  • Formulation of the electrode and wire
fume emission testing device
Fume emission testing device
  • Filters weighed before and after test
  • Welding time known
  • 30 seconds/1 min exhaust
  • fume emission rate calculated: average of five readings
  • measurements in mg/minute
  • Air exhaust fan
  • Filters
  • Conical column
  • Observation window
  • Rotating table
  • FCAW gun mount
  • AWS F 1.2-92( Laboratory method for measuring fume generation rates
  • and total fume emission for Welding and Allied Processes)
  • 20mm plate, 20 inch dia, 4 inch efffective, 120 lbs .
slide10
Typical fume generation Rates

Process

Range g/min

SMAW

0.2 - 1.2

FCAW

0.5 - 3.5

GMAW

0.1 - 0.5

GMAW(AL)

0.1 - 1.5

the filter is about the size of a medium pizza
The filter is about the size of a medium PIZZA!
  • Clean and used filter, after 30 seconds!
slide15
Hexavalent Chromium
  • Hexavalent chromium is a known lung carcinogen
  • SMAW stainless steel electrodes produce high level of Cr VI ( 50% - 70% of total chromium)
  • Lithium compounds reduce Cr VI significantly
  • FCAW stainless steel electrodes produce high level of Cr VI ( 30% - 60% of total Chromium)
  • GMAW of stainless steel produces very little Cr VI ( < 10% of total Chromium)
  • ANSI/AWS F3.1 - 89 : Guide for Welding Fume Control
slide18
Welding fumes

?

fume

generation

g/min

Welding amperage

slide19

100 A

170 A

Influence of the shielding gas and parameter set up

on fume emission level in GMAW

(Wire: ER 70S3)

Fumes (mg/min)

1.000

300 A

800

600

350 A

400

200

Tension (V)

0

15

20

25

30

35

40

Ar + 10% CO2

Ar + 18% CO2

Ar + 3% CO2 + 1% O2

3 d representation of fume generation for non pulsed gmaw
3-D representation of fume generation for non pulsed GMAW
  • For a given wire feed speed or amperage:
    • Low fume generation in short circuit range
    • As voltage is increased, transfer transits through globular range causing a first maxima
    • Fine tuning of spray transfer gives a minima
    • As voltage increased beyond the optimum, fume generation rate increases
slide21
Fume Concentration

Fume concentration is measured in

Milligrams per cubic meter (mg/m3)

some terms used in the welding fume legislation
Some terms used in the welding fume legislation
  • OSHA: Occupational Health and Safety Administration
  • PEL: Permissible Exposure Limit (8 hours)
  • TWA: Time weighted average (8 hour exposure)
  • NIOSH: National Institute of Occupational Safety and Health
  • ACGIH: American Conference of Governmental Industrial Hygienists
  • OEL: Occupational Exposure Limits (8 hours)
  • TLV: Thresh hold Limit Value (8 hours)
  • TWAEV: Time Weighted Average Exposure Value (8 hours)
  • STEL: Short Term Exposure Limit ( TLV-STEL : 15 minutes)
  • C: Ceiling value ( TLV-C : instanteneous max value not to be exceeded)
  • General ventilation must move 2,000 cu feet per minute
  • Each welder should have 10,000 cu feet of barrier free work space
  • Serious violation : $ 7,000 per violation
  • Repeat violation: $ 70,000 per violation
slide25
Daily variation of Fume Concentration

Actual Exposure

Fume

concentration

mg/m3

Exposure limit

Time weighted

Average

08:00 12:00 16:00

fume weight per welder per year
Fume weight per welder per year ?
  • Fume generation rate of 1g/minute
  • 2000 hours/yr at 20% duty cycle = 400 hours welding time
  • 400 hours X 1 g/minute X 60 = 24,000 grams = 52.8 pounds
  • Equal to the weight of one coil of wire per year!
slide27

FUME GENERATION – 1.6 mm FCAW : 200,000 HOURS OF ARC TIMENOTE: 200,000 hours of arc time at 18% duty cycle translates to approximately 556 welders.

Through choice of gas and wire fumes reduced

Annually by 4.75 MT!!

test results of air quality

Sample

Location

Sampling time in minutes

Volume sampled in

liters

Lab results

(micro grams per sample)

Concentration

(mg/m3)

99V001

Welder under general exhaust fume hood, fume hood switched

OFF

61

122.1

3424

28.0

99V002

Welder under general exhaust, fume hood switched ON

61

122.1

1969

16.1

99V003

Welder under fume hood, with a smoke extracting gun

62

122.4

171

1.38

Ontario Ministry of Labour, TWAEV for welding fumes

5.00

Test results of air quality
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