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