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 embrittlement effects and to carry out a general assessment of the remaining life of the component related to creep behavior considering smooth bar creep specimens. [S0094-4289(00)00403-5]

Issue Section:
Technical Papers
Keywords:
cracks, welding, creep fracture, precipitation, grain boundary segregation, brittle fracture, embrittlement, alloy steel, petroleum industry, heat treatment
Topics:
Creep, Rupture, Steel, Fracture (Process), Heat, Welding, Fracture (Materials)
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