THERMAL FATIGUE IN A DE-SUPERHEATER INDUCED BY THERMAL LOADS
Bakheet Al-Yami, Ali Babakr, Mohammed Al-Sonidah, and Ron Bradley Saudi Basic Industries Corporation (SABIC) SABIC Technology Center-Jubail, P.O. Box 11669, Al-Jubail, 31961 Saudi Arabia Raja Rizwan Imtiaz Arabian Petrochemical Company (PETROKEMYA) P.O. Box 10002-Jubail, 31961 Saudi Arabia ABSTRACT A failure had occurred in a petrochemical plant in a weld joint of a de-superheater only six months after being in service. System was commissioned after making necessary repairs using same metallurgy since all the needed resources were long deliveryscheduled items. Leaking of steam through the weld joint revealed the failure location. Analysis of the failed samples by metallurgical techniques, NDT, SEM, and EDX techniques indicated that the failure was caused by improper design of the injection of the BFW in the de-superheater that producing inner cyclic thermal differential loads leading to thermal fatigue. This paper will discuss the mechanism of the prevailing thermal fatigue failure was explored and explained. Keywords: Steam line; weld joint, de-superheater, thermal fatigue, beachmarks, and cyclic stresses.