Welding Fumes – Update on EPRI Research
Optimizing Local Exhaust Ventilation
Multi-metals Welding Fume Data Base
Presented to:
Edison Electric Institute
Presented by:
Jeff Hicks, CIH, QEP
Principal Scientist
Exponent
Ventilation Study: Purpose and Goals
To evaluate different portable local exhaust ventilation
systems designed for welding (called fume extractors)
in their ability to control airborne CrVI welding fumes.
To determine if these portable fume extraction systems
have a deleterious effect on weld quality.
To create a video that presents information about how
to properly use LEV systems. This is designed to be
shown to welders.
Methodology
Welding fume (total fume, CrVI and multiple metals) concentrations were
measured with and without ventilation, using different local exhaust systems,
operated at varying distances from the weld site.
Welding was performed in a shop environment.
SMAW welding on 308 stainless steel (with 308 rods).
GMAW welding on 308 SS (with 308 wire). This was a limited effort.
Evaluated low and high volume portable fume extractors.
Used direct reading equipment to measure total fume inside the welding
helmet. Collected air samples inside the welding helmet to measure total
fume (NIOSH 0500), CrVI by OSHA 215, and multiple metals by NIOSH 7300.
Conducted a series of experiments (26 separate experiments) with and
without ventilation equipment operating, and with the inlet to the ventilation
systems at various distances from the welding site.
Xray inspections of some welds were made to determine if there was a
negative effect on weld quality
Local Exhaust Ventilation Equipment
High Volume System
Loaned to us by Miller Electic
FILTAIRE MWX Fume Extractor
Weighs 300 lbs, exhausts 875 CFM through an
8” duct leading to a 14” diameter hood
Air velocity at face of inlet is
approx. 600 fpm
List price is $5,500 (with 10’ arm)
Local Exhaust Ventilation Systems
Low Volume System
Loaned to us by Lincoln Electric
Miniflex Portable Fume Extractor
Weighs 49 lbs , exhausts 135 CFM, 3” duct
with several optional hoods
Air velocity at face of inlet is
approx. 700 fpm
List price is $1,300
0
20
40
60
80
100
120
140
12 18 24 36
Air
Vel
oci
ty (
fpm
)
Distance from Inlet (inches)
0
20
40
60
80
100
120
140
160
4 5 8 12 18
Air
Vel
oci
ty (
fpm
)
Distance from Inlet (inches)
High
Volume
LEV
Low
Volume
LEV
Air Velocity (at inlet centerline) Compared to
Distance from Exhaust Inlet
SMAW on 308
Stainless, no LEV
High Volume Fume
Extractor Set-up
SMAW
at
varying
distances
from
weld site
Air Velocity at the Weld Site Compared to CrVI
Concentration Inside the Welding Helmet
During SMAW on 308 Stainless Steel
Air Velocity at the Weld Site Compared to Mn Concentration Inside
the Welding Helmet (based on a small number of samples)
0
0.005
0.01
0.015
0.02
0.025
0.03
2 18 35 37.5 65
Man
gan
ese
Co
nce
ntr
atio
n (
mg
/m3 )
Air Velocity at Weld Site (fpm)
Non-Destructive Testing of Welds
During selected experiments (when LEV was positioned close to the weld
site), xray inspections of the welds were used to determine if there was
porosity present – which would suggest that oxygen was present and weld
quality was poor.
Even at the highest cross-draft (120 fpm), there was no adverse effect on
weld quality. Note that only SMAW was evaluated, other types of welding
(e.g. GMAW, FCAW) were not evaluated.
Conclusions
When used properly, fume extractors can reduce
airborne CrVI concentrations by two orders of
magnitude (i.e. 100 fold reductions).
When used properly, fume extractors are the only
means of control that is necessary (no need for
respirators).
When SMAW welding on stainless steel (e.g. 308
stainless), airborne concentrations can exceed 500
µg/m3 without LEV.
Mn concentrations are usually below the current OSHA
PEL. LEV further lowers the airborne concentrations.
Optimizing the Use of Fume Extractors
The cross draft exhaust air velocity at the weld site
should be greater than 50 feet per minute, ideally near
100 fpm.
High volume fume extractors should be kept within 18
inches of the weld site.
Low volume fume extractors should be kept within 6
inches of the weld site.
If these parameters cannot be achieved, appropriate
respiratory protection should be worn when
conducting SMAW on stainless steels.
Train workers in these procedures.
Video Clip of LEV during Welding
Multi-metal Exposures during
Welding Activities in the Electric
Utility Industry
Welding Fume Data
We have gathered 555 welding fume air sample results from
electric utilities – samples were analyzed for several metals
Air samples were collected from inside the welding hood to best
reflect breathing zone exposures.
Sample durations ranged from 30 minutes (associated with
specific tasks) to 8 hr (full shift) – most of the data is from 4+ hr
sampling durations
Limited information was provided concerning other details,
such as the welding process and the types of consumables in
use. We were able to gather information about general
ventilation conditions
Metals Analyzed
15 metals analyzed for each sample by NIOSH 7300
Metal
Al Co Mo
As Cu Ni
Be Fe Ti
Cd Pb V
Cr Mn Zn
Summary of Data – Type of Welding Process
Type of welding process was not provided for many
samples
Type of Welding No. of Samples % of Total Samples
No Information (NI) 454 82.7%
TIG 33 6.0%
MIG 31 5.7%
CAC-A 10 1.8%
Torch Cutting 10 1.8% MIG / TIG / Plasma Cutting 1 0.2%
Plasma Arc Cutting 3 0.6% Welding and Torch cutting 2 0.4%
Welding & CAC-A 1 0.2%
SMAW 2 0.4%
SMAW / TIG 2 0.4%
Summary Statistics for Airborne Metal
Concentrations
Metal No. of samples Min (mg/m3) Max (mg/m3) Average * (mg/m3)
No. of Non-Detects (ND)
Al 549 0 7.7 0.11 104 (19%)
Be 549 0 0.00025 1.6E-06 542 (99%)
Cd 549 0 0.0017 1.4E-05 530 (97%)
Cr 548 0 0.98 0.016 76 (14%)
Co 548 0 0.011 0.00015 429 (78%)
Cu 548 0 0.50 0.0082 51 (9%)
Fe 548 0 30 0.67 21 (4%)
Pb 549 0 0.062 0.0012 449 (82%)
Mn 549 0 1.5 0.048 18 (3%)
Mo 544 0 2.4 0.0081 290 (53%)
Ni 548 0 0.55 0.011 113 (21%)
Ti 544 0 0.29 0.012 38 (7%)
V 548 0 0.94 0.0034 320 (58%)
Zn 446 0 3.0 0.056 80 (18%)
Average calculated using assigned value of 0 mg/m3 for ND
Occupational Exposure Limits for Common
Welding Fume Metals
Metal
OSHA PEL (TWA) NIOSH REL (TWA) ACGIH TLV (TWA)
Mn
5 mg/m3 (Ceiling)
1 mg/m3 TWA
0.2 mg/m3
ProposedTLV of
0.02 mg/m3
(respirable
fraction)
Iron Oxide Fume 10 mg/m3 5 mg/m3 5 mg/m3
Copper Fume 0.1 mg/m3 0.1 mg/m3 0.2 mg/m3
Ni 1 mg/m3 0.015 mg/m3 1 mg/m3
Be 0.002 mg/m3
0.0005 mg/m3
Ceiling 0.002 mg/m3
CrVI 0.05 mg/m3 0.001 mg/m3 0.050 mg/m3
Manganese Results Compared to OELs
N (excluding ND)
Minimum (mg/m3)
Maximum (mg/m3)
Arithmetic Average (mg/m3)
Geometric mean (mg/m3)
531 0.00013 1.5 0.050 0.016
# (%) > OSHA Ceiling of 5 mg/m3
# (%) > ACGIH TLV of 0.2 mg/m3
# (%) > Proposed TLV of 0.02 mg/m3
0 (0%) 26 (5%) 234 (44%)
Mn Concentration and Ventilation Conditions
During Welding
60% of Mn data had ventilation information (329 of 549)
Ventilation categories:
Ventilation Conditions Description
Low Confined work environment, low degree of
ventilation, visible fume accumulation reported
Medium Open indoor work areas with no report of
mechanical ventilation, no report of accumulating
fumes, limited or no active ventilation but no
obvious accumulation of airborne fumes
High Active dilution ventilation such as fans present to
disperse fumes, and outdoor work (except in
circumstances where the work area is confined)
Local Exhaust
Ventilation Highly localized exhaust ventilation systems to
extract fume at the the point of generation (often
called fume extractors)
Mn Air Concentrations and Ventilation Type
Type of
Ventilation
No. of
Samples
Mn
Minimum
(mg/m3)
Mn
Maximum
(mg/m3)
Mn
Average
(mg/m3)
Mn
Geometric
Mean (mg/m3)
LEV 58 0.00034 1.5 0.087 0.075
H 28 0.00034 0.17 0.033 0.074
M 233 0.00013 1.1 0.044 0.058
L 10 0.0012 0.39 0.071 0.14
NI 202 0.00014 0.59 0.047 0.056
NI No Information
Mn Geometric Mean and Ventilation
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
LEV H M L NI
Mn
Geo
met
ric
Mea
n
Air
Co
nce
ntr
atio
n (
mg
/m3 )
Ventilation Type
Mn Geometric Mean by Ventilation Type
NI No information
N = 58
N = 28
N = 233
N = 10
N = 202
OTHER METALS
Summary of Results for Selected Metals,
Excluding non-detects
Metal No. of
Detects
Minimum
(mg/m3)
Maximum
(mg/m3)
Arithmetic
Average
(mg/m3)
Geometric
Mean
(mg/m3)
# (%) >
OSHA
PEL
Fe 527 0.0059 30 0.69 0.27 1 (<1%)
Ni 435 0.00010 0.55 0.014 0.0020 0 (0%)
Cu 497 0.00016 0.50 0.0091 0.0030 3 (<1%)
Be 7* 0.000030 0.00025 0.00012 0.00010 0
Cr** 472 0.00026 0.98 0.018 0.0040
181
(38%)**
* 6 of 7 Be samples (where Be was detected, were above TLV of 0.00005 mg/m3
** Cr results were compared to CrVI PEL of 0.005 mg/m3 it is unlikely that all of
the detected Cr is CrVI
Exceedances of Occupational Exposure Limits,
including Non-detects
0
10
20
30
40
50
60
70
80
90
100
Mn Fe Be Cu Ni Cr
% o
f sa
mp
les
abo
ve O
EL
Occupational Exposure Limit (OEL) Exceedances including ND
% above PEL
% above REL
% above TLV
% above Proposed TLV
Note: We have assumed
Cr is all CrVI, - which is
Likely overstating
the CrVI concentration and
overstating the CrVI
exceedances
Conclusions – Multi-metal exposures during
typical welding activites
Most metal element exposures are below current OELs, most of the time – as
previously shown, CrVI overexposures can occur, especially when welding with Cr
containing consumables
If the TLV for Mn is lowered to 0.02 mg/m3 (respirable particulate), more than 40% of
typical exposure situations will exceed this value
Note that Mn is present in most welding consumable, and there is no known substitute
Complying with the new Mn TLV during many welding tasks will require that welding use ventilation and respiratory protection during many common welding tasks
A small but not insignificant fraction of samples exceeded the OEL for Nickel (about
10%), this is an important issue when welding with Ni containing consumables (e.g.
stainless steels) and in areas with limited ventilation
If you anticipate potential exposures to CrVI and Mn, and design controls for these
metals, exposures to welding fumes will be adequately controlled