Graduation Year

2018

Document Type

Thesis

Degree

M.S.P.H.

Degree Name

MS in Public Health (M.S.P.H.)

Degree Granting Department

Public Health

Major Professor

Steve Mylnarek, Ph.D.

Co-Major Professor

Thomas Bernard, Ph.D.

Committee Member

Rene Salazar, Ph.D.

Keywords

MIG Welding, Nanoparticle, Ultrafine particles, Exposure

Abstract

The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires.

Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder.

According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

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