FAILURE OF AUSTENITIC STAINLESS-STEEL COMPONENTS USED IN NITROGEN-OXIDE PLANT

Austenitic stainless steel components of a nitrogen oxide plant have b een found to leak in service. Thr failed components, namely pipe-to-pi pe joints and pipe-to-flange joints, have been studied through standar d metallographic techniques to analyse the cause of the failure. In ca se study I, involving the failure of pipe-to-flange joints, cracking w as observed in the pipe wall next to the pipe-to-flange weld. In case study II, involving the failure of a sight port flange, cracking was o bserved in the flange adjacent to the pipe-to-flange weld. In both cas es, cracking was by an intergranular mechanism, and carbon contents we re much higher than permitted for ''L'' grades of austenitic stainless steel. (C) 1997 Elsevier Science Ltd.