scope:

This report presents the results of tests conducted on 554 specimens of carbon and carbon-molybdenum steel removed from petroleum refining equipment and examined for evidences of graphitization. Graphite formations were found in 33.8 per cent of these specimens. It has been established that some steels have a greater tendency to graphitize than others; and that high aluminum content (in excess of 0.015 per cent), high operating temperatures, and the steel-making process used in meeting certain specifications are factors which affect graphitization. Of the steels examined, ASTM A I06 pipe indicated the highest tendency to graphitize; and, of the carbon steels, ASTM A285 plate material indicated the highest resistance to graphitization. Connected nodules of graphite were found in both carbon and carbon-molybdenum steels. Although the carbonmolybdenum steel graphitized less frequently than the carbon steel, when it did graphitize, graphitization was of the more serious type.