During a shutdown for general maintenance of a catalytic cracking unit, intergranular cracks were observed to occur during welding of the regenerator’s standpipe component manufactured from 2 1/4 Cr-1Mo steel. The cracking was observed to be related to intensive carbide precipitation in grain boundaries. To overcome the problem it was decided to heat-treat the relevant section of the component to dissolve these carbides and make possible its welding to a new virgin section of the tube. Samples of the material in its various conditions (virgin, ex-service, heat-treated, and welded) were taken to check the efficiency of the thermal treatment in reducing the embattlement effects and to carry out a general assessment of the remaining life of the component related to creep behavior considering notched bar creep specimens. [S0094-4289(00)00503-X]

Issue Section:
Technical Papers
Keywords:
alloy steel, embrittlement, cracks, welding, precipitation, grain boundary segregation, creep fracture, notch strength, petroleum industry, heat treatment
Topics:
Creep, Embrittlement, Fracture (Materials), Fracture (Process), Grain boundaries, Heat, Petrochemicals, Precipitation, Steel, Temperature, Welding, Cracking (Materials), Heat treating (Metalworking)
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