Corrosion of industrial furnace tubes in a chlorine contaminated environment

Tubes of a furnace where ethylene dichloride (EDC) was cracked into vinyl chloride monomer (VCM) in a petrochemical industry, lost their structural integrity and developed cracks after about five years of operation. Various sections of a failed furnace tube were metallurgically evaluated using scanning electron microscopy combined with energy dispersive X-ray spectroscopy and X-ray diffraction. The material of the furnace tube was 347H stainless steel. Experimental results indicated that the failure of the furnace tubes was caused by high-temperature corrosion due to a chlorine contaminated environment which greatly accelerated oxidation attack. It was recommended that alloys, such as the higher grade Fe-base alloys, should be used that are more resistant to a chlorinecontaminated environment.