FAILURE ANALYSIS OF SCREEN TUBES AND CYCLONE CANS OF BOILERS INPETROCHEMICAL INDUSTRY

摘要

This paper presents results of the failure analysis of carbon steel screen tubes and cyclone cans forrnseparation of wet steam. Site inspection showed severe abrupt multiple bulges with a hole on the top ofrnfirst screen tube with a thickness of 3.5 mm (0.14 in.) and OD of 76.2 mm (3.0 in.). The investigationsrnfound that the cleanliness of the tubes should be considered as “very dirty”. In other cases, the carbonrnsteel cyclone cans with thickness of 3 mm (0.12 in.) were gradually thinned and completely perforatedrnonly in the front portions located opposite to the wet steam inlet. The results of metallographic, X-rayrnand SEM/EDS analysis are presented and discussed. It was found that the screen tubes failed due torncreep rupture as a result of local overheating caused by the presence of excessive amounts of deposit.rnCyclone cans mainly experienced severe impingement type of damage. Remedial actions werernrecommended in each case and were implemented.