#TITLE_ALTERNATIVE#

• Main Author: WASKITO HADI (NIM 13703014), EKO
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/7762
• Institution: Institut Teknologi Bandung

Most of the industrial boiler is usually use for Steam Power Generation Plant. The operating condition become more severe when the Steam Power Generation Plants located in marine atmosphere. The use of coal as a fuel will promote corrosion because the coal ash deposit contains corrosive substances, such as Na2SO4 and NaCl.<p>The objective of this research is to observe the corrosion behavior of boiler superheater tube materials (SA 213 T-22) due to both coal ash deposit and marine environment respectively. The corrosive substance for this research consists of Na2SO4 as a representative of the coal ash deposit, and NaCl to represent the marine environment. High temperature corrosion attack because of molten salt were simulated by applying 2.0 mm pre-coated synthetic deposit of Na2SO4 and NaCl onto the surface of boiler superheater tube specimens. The specimens were heated to 9500C that represent the flame temperature on the superheater tube surface. The exposure time was varied from 6, 12, to 18 hours. Weight gain of the specimens due to corrosion was observed, as well as the depth of corrosion attack (materialography method).<p>The experimental results show the increase in corrosion attack due to surface deposit. Sulfur in Na2SO4 salt can increase the severity of attacks; even it is not as severe as chloride in NaCl salt. The most severe attack was found on specimens which deposit consists of 40% Na2SO4 and 60% NaCl, and the exposure time of 18 hours. The weight gain for this specimen is 23,099 mg/cm2 and the depth of corrosion attack around 853 um.<p>The corrosion mechanisms were also observed. Metallography examinations of the metal/oxide interface revealed that there was a diferent corrosion mechanism between Na2SO4 molten salt and NaCl molten salt. The corrosion attack by Na2SO4 was initiated by sulfidation on the grain boundaries, followed by carbon difusion into the grains (carburation), and finally the oxidation. The molten Na2SO4 will dissolve the protective oxide layer on the specimen surface. High temperature corrosion caused by NaCl was initiated by carbon difusion into the grains, followed by oxidation. The chloride ions will act as the catalyst for the corrosion reaction.