Formation of silified layer in areas of welded joint of reaction fired heaters coil

• Main Authors: Rubtsov, Aleksey, Shermatov, Djamshed, Seitzhaparov, Bexultan, Strokina, Ulyana
• Format: Conference Proceeding
• Language: English
• Subjects: Carburizing; Coils; Furnaces; Heat affected zone; High temperature; Mechanical properties; Progressions; Surface layers; Tubes; Welded joints
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0196744

Tubes of coils of reaction furnaces have a sufficiently long length of more than 10 meters and consist of several straight sections of conjugated welded joints. The number of welded joints in straight pipe sections is different and depends on the size and length of the sections to be replaced during repair. Numerous and long-term observations of failure statistics of reactor furnace coil elements during operation show that welds are the most vulnerable places. In welds, progressions and cracks, as well as a change in the structure of the metal, are most often observed. In welded joint zones, and most often in heat affected zones, premature destruction occurs due to deterioration of mechanical properties due to possible carburization of metal. All these operational defects are characteristic of high-temperature coils, since it is the elevated temperatures that trigger the mechanisms of their formation. Analysis of premature failure of coils of reaction furnaces showed that the prevailing rejection indicator is carburization of metal of welded joints of coil pipes along the inner surface. It is known that silicon and modified surface layers based on it can contribute to solving the problem of active saturation of metal with carbon. Therefore, the work on the study of the formation of a silicified layer in the areas of the welded joint of the reaction furnace coil when holding samples with welds for different periods of time in the silicizing mixture is relevant.