ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 9, pp. 1510−1516. © Pleiades Publishing, Ltd., 2015.
Corrosion Failure Analysis of 20# Steel in the Process
of Natural Gas Puriﬁ cation
, Chaoyue Yang
, Decai Long
, and Zhuo Chen
School of Chemistry and Chemical Engineering, Southwest Petroleum University,
Rd. 8, Xindu District, Chengdu City, Sichuan Province, P. R. China,
CNOOC-Fujian LNG Co., Ltd. Fuzhou City, Fujian Province, P. R. China
Received September 25, 2015
Abstract—The present work investigated the corrosion on 20# steel in the process of natural gas puriﬁ cation of
PG gas ﬁ eld. According to the analyzing the corrosion condition of the desulfurization device, the research found
that the main corrosion was caused by H
and there was also the obvious corrosive pitting caused by chloride
ion. The morphology and composition of the corrosion scale were characterized by scanning electron microscopy,
X-ray power diffraction, and energy-dispersive spectroscopy. Results showed that corrosion scale consists of FeS,
S, and FeCO
. The weight loss experiment was conducted to estimate the actual corrosion rate of 20# steel.
Electrochemical methods such as polarization curve and electrochemical impedance spectroscopy were used to
analyze the effects of chloride ion concentration and temperature on the corrosion. It can be found that the cor-
rosion rate increased with the increasing of chloride ion concentration and temperature.
Natural gas is an important clean energy and one
of the three major energy pillar of the world’s primary
energy . Generally, in most area, natural gas
contains hydrogen sulﬁ de (H
S) especially in China
Sichuan basin, such as the PG gas ﬁ elds whose H
content is as high as 17% (volume fraction), and it also
contains higher carbon dioxide(CO
), so it belongs to
the high sour gas ﬁ eld. The equipment and pipeline
of these high sour gas ﬁ eld are faced with the serious
corrosion problem in the process of exploitation .
So the puriﬁ cation of natural gas is very important.
In all kinds of desulfurization and decarburization
methods, solution absorption is the main method and
the alkanolamine solution is most widely used . In
PG gas ﬁ eld, which studied in this paper, alkanolamine
is used for desulfurization and MDEA solution is used
as the desulfurizing agent. Analyzing the corrosion
condition of the desulfurization device showed that the
main corrosion was due to H
and there were also
the obvious corrosive pitting caused by chloride ion.
Figure 1 demonstrates corrosion morphologies.
The aim of the present work is to investigate the
corrosion and the corrosion inhibition of the 20# steel.
The microstructure and composition of the corrosion
scale were investigated by scanning electron microscope
(SEM), X-ray power diffraction(XRD) and energy-
dispersive spectroscopy(EDS). Additionally, the factors
affecting the corrosion such as chloride ion concentration
and temperature were also described by weight loss
experiment and electrochemical methods.
THEORY: CORROSION MECHANISM
OF HYDROGEN SULFIDE
AND CARBON DIOXIDE
S ionization of acid after dissolving in water
The text was submitted by the authors in English.