The drive behind this research work cannot be
far-fetched from the quest to precisely predict how effectively welded low
carbon steel pipes will function in industrial service applications requiring
subjecting them to service use at elevated temperature as a function of
inferences drawn from a critical study of the corrosion behavior of these
welded steel pipes in both acidic and salty environment. To this end, a
particular low carbon steel pipe of known chemical composition was sectioned into
the required number of samples needed to carry out the corrosion experiment and
this finally amounted to twenty-four samples, out of which eight were
un-welded; the other eight samples were welded with tiny weld pool and the last
eight were welded with large weld pool. For adequate comparison and effective
corrosion evaluation, the samples were appropriately immersed into two
different corrosive media of 0.3M H2SO4 and 0.3M NaCl
respectively with special subjection of twelve samples to corrosion at the prevailing
room temperature and the other twelve samples were subjected to corrosion at a
controlled elevated temperature of 950C with the aid of the
blast-air oven. The corrosion behaviours of these welded steel pipes were
evaluated using the weight loss analysis method and the overall corrosion
exercise took 61 days. Subsequently, necessary readings including potential
difference; pH value and resulting weight losses were taken at four days
intervals. After the corrosion exercise, series of calculations were done with
the available data in order to compute the appropriate corrosion result through
the plot of different graphs and provide effective evaluation of the corrosion
behaviors of the aforementioned steel sample. Microstructural analyses of
pre-corrosion control samples X, Y and Z were undertaken as well as
macrostructural analyses of the as-corroded steel samples with the aid of the
optical metallurgical microscope. The results obtained revealed that corrosion
rates were much higher in 0.3M H2SO4 than in 0.3M NaCl at
both temperatures. Another notable point is the action of weldment against the
propagation of corrosion in H2SO4 and the anomaly in the
corrosion behaviours of welded samples in NaCl particularly at elevated
temperature. However, the corrosion rates of all samples reduced over time as a
result of the hygroscopic nature of the corrosive media used which resulted
into the loss in potency of the solutions as a function of reduction in the
concentration of the environments which also led to the decrease in potential
differences of the corrosive media with time and corresponding increase in
their pH values with time. Nevertheless, all samples immersed in H2SO4
experienced active corrosion between 22 mg/mm2/yr to 165mg/mm2/yr.
while samples immersed in NaCl experienced passive corrosion between 0.3mg/mm2/yr
to 1.97mg/mm2/yr. Therefore, the research work has been able to show
that welded low carbon steel will perform better in NaCl environment than in H2SO4
environment even at elevated temperature provided that there are no inherent
welding defects in the steel sample.
Seun, O (2018). INVESTIGATING THE CORROSION SUSCEPTIBILITY OF WELDED STEEL PIPES AT ELEVATED TEMPERATURE. Afribary.com: Retrieved April 23, 2021, from https://afribary.com/works/publication
Oyegunna, Seun. "INVESTIGATING THE CORROSION SUSCEPTIBILITY OF WELDED STEEL PIPES AT ELEVATED TEMPERATURE" Afribary.com. Afribary.com, 17 Apr. 2018, https://afribary.com/works/publication . Accessed 23 Apr. 2021.
Oyegunna, Seun. "INVESTIGATING THE CORROSION SUSCEPTIBILITY OF WELDED STEEL PIPES AT ELEVATED TEMPERATURE". Afribary.com, Afribary.com, 17 Apr. 2018. Web. 23 Apr. 2021. < https://afribary.com/works/publication >.
Oyegunna, Seun. "INVESTIGATING THE CORROSION SUSCEPTIBILITY OF WELDED STEEL PIPES AT ELEVATED TEMPERATURE" Afribary.com (2018). Accessed April 23, 2021. https://afribary.com/works/publication