Failure analysis of overheated coil leakage in ethylene cracking furnace

The ethylene cracking furnace is the core equipment of ethylene production plants. The safe and efficient operation of the furnace is essential for the production of ethylene and other raw materials. This article analyses the finned tube cracking failure on the convection portion of the ethylene cracking furnace. In order to find out the radical causes of the failure, Metallography, microcracking, chemical composition, mechanical property testing, hardness testing, and finite element modeling were adopted. The original fracture shows a characteristic of columnar crystal cracks with the presence of discontinuous fatigue striations, which is consistent with corrosion fatigue cracks. The fracture area at the tip of the crack shows a dimple fracture pattern, which is a characteristic of plastic cracking. At the same time, a large amount of chromium carbide precipitates at grain boundaries, indicating the presence of intergranular corrosion. Moreover, it worked under conditions of thermal stress and corrosive media. These indicate that corrosion fatigue and intergranular corrosion lead to the cracking of the finned tubes.