TY - JOUR
T1 - Corrosion of carbon steel and alloys in concentrated ammonium chloride solutions
AU - Toba, K.
AU - Ueyama, M.
AU - Kawano, K.
AU - Sakai, J.
PY - 2012/11
Y1 - 2012/11
N2 - Corrosion resistance and the behavior of carbon steel and alloys in high concentration ammonium chloride (NH 4Cl) solutions were investigated. This study was conducted to better understand material performance in severe NH 4Cl corrosive environments in refineries. Immersion tests were performed under boiling 20 wt% and 40 wt% NH 4Cl solutions. Sixteen materials commonly used in refineries and two new alloys were examined, including carbon steel; aluminized carbon steel; aluminum brass; Types 405, 410, 304L, 316L, and 321 stainless steels (UNS S40500, S41000, S30403, S31603, and S32100); 300-series stainless steel with 6% Mo; two types of super duplex stainless steels; Alloys 800, 625, and C-276 (UNS N08800, N06625, and N10276); Grade 2 and Grade 19 titanium (UNS R50400 and R53530); Alloy A (equivalent to a modified Type 317L [UNS S31703] stainless steel); and a modified Alloy 825 (UNS N06845). Significant corrosion was observed in carbon steel in both solutions. The corrosion rates of carbon steel were as high as 25.4 mm/y and 60.4 mm/y in 20 wt% and 40 wt% NH 4Cl solutions, respectively. However, neither general corrosion nor pitting was observed on titanium alloys and alloys with a pitting resistant equivalent number (PREN) of 40 and higher. The maximum pit depth had a close relationship with the PREN. In addition, an electrochemical study was used to investigate the corrosion behavior of carbon steel. The effects of the temperature and NH 4Cl concentration were determined from polarization curves and the corrosion potential.
AB - Corrosion resistance and the behavior of carbon steel and alloys in high concentration ammonium chloride (NH 4Cl) solutions were investigated. This study was conducted to better understand material performance in severe NH 4Cl corrosive environments in refineries. Immersion tests were performed under boiling 20 wt% and 40 wt% NH 4Cl solutions. Sixteen materials commonly used in refineries and two new alloys were examined, including carbon steel; aluminized carbon steel; aluminum brass; Types 405, 410, 304L, 316L, and 321 stainless steels (UNS S40500, S41000, S30403, S31603, and S32100); 300-series stainless steel with 6% Mo; two types of super duplex stainless steels; Alloys 800, 625, and C-276 (UNS N08800, N06625, and N10276); Grade 2 and Grade 19 titanium (UNS R50400 and R53530); Alloy A (equivalent to a modified Type 317L [UNS S31703] stainless steel); and a modified Alloy 825 (UNS N06845). Significant corrosion was observed in carbon steel in both solutions. The corrosion rates of carbon steel were as high as 25.4 mm/y and 60.4 mm/y in 20 wt% and 40 wt% NH 4Cl solutions, respectively. However, neither general corrosion nor pitting was observed on titanium alloys and alloys with a pitting resistant equivalent number (PREN) of 40 and higher. The maximum pit depth had a close relationship with the PREN. In addition, an electrochemical study was used to investigate the corrosion behavior of carbon steel. The effects of the temperature and NH 4Cl concentration were determined from polarization curves and the corrosion potential.
KW - Ammonium chloride
KW - Corrosion
KW - Corrosionresistant alloy
KW - Hydroprocessing
KW - Pitting resistant equivalent number
KW - Refining
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U2 - 10.5006/0587
DO - 10.5006/0587
M3 - Article
AN - SCOPUS:84868229441
SN - 0010-9312
VL - 68
SP - 1049
EP - 1056
JO - Corrosion
JF - Corrosion
IS - 11
ER -