Abstract
-
The welding process is a crucial function in the oil and gas industry, and many companies,
including this Oman Oil and Gas Company, use this process in processes such as welding pipes,
pipelines, structures, spools, flanges, vessels, tanks, and tools. Welding arc temperatures reach
more than 4000°C and produce various welding fume components. Approximately 90% to 95%
of welding fumes generated are from the consumable electrodes of filler metals, and welders
who perform close thermal metal joining work are at an increased risk of airborne exposure to
welding fumes. In this study, an occupational hygiene survey was performed to assess the risk of
exposure to several welding fume compositions—respirable welding fumes (RWF), total welding
fumes (TWF), and metals such as vanadium, manganese oxide, iron oxide, nickel, cadmium
oxide, molybdenum, and hexavalent chromium. Personal exposure monitoring was undertaken
on welders working in permanent duplex stainless steel (DSS) and carbon steel (CS) workshops
when using two types of fusion welding: shield metal arc welding and gas tungsten arc welding.
The welding conducted in the CS workshop was determined to present the highest exposure risk to
RWF and TWF. Exposure to TWF in the DSS workshop was identified as high-risk with a geomean
well above the company action limit. Exposure monitoring of the metal compositions revealed that
the exposure of both groups was not significant and fell below the occupational exposure limits
(OEL). Biomonitoring for chromium and nickel revealed chromium levels significantly below the
biological limit, with one out of 14 urinary nickel samples slightly above the biological guidance
value set by the Scientific Committee on Occupational Exposure Limits (SCOEL).
A welding exposure questionnaire was administered, and responses suggest a lack of both
administrative control measures and respiratory protection programme. Participants’ spirometry
and body mass index medical records were examined and revealed no current decline in
respiratory function.
Reducing welder’s exposure below OELs requires a range of short- and long-term control
measures to ensure the welders’ health is protected. Several short-term improvements are
recommended, including:
• restricting access for those who are not welders or their supervisors,
• appropriate use of the screen board,
• installation of signs mandating the wearing of respiratory protection,
• provision of comprehensive training in welding fume hazards,
• establishment of a respiratory protection programme,
• appropriate positioning away from the fume direction,
• examination by a competent general practitioner of welders experiencing symptoms related
to welding fume exposure, and
• reinforcement of P2 disposable facepiece usage.
Proposed long-term solutions include:
• a feasibility study for exchanging electrodes or the welding process with a process that
produces fewer emissions,
• use of bolting for jointing whenever applicable,
• a feasibility study for using an on-torch extraction system or the installation of a portable or
fixed local exhaust ventilations system with a movable capture hood and air cleaner, and
• respirator fit testing as part of a comprehensive programme.
Once long-term control measures are applied, airborne TWF in both groups and RWF in the
CS group should be reassessed. All participants should also be resampled for urinary nickel to
confirm an acceptable total biological exposure.