Effect of Strain Rate on the Hot Tensile Behavior of Invar Alloy Failure analysis of clogging caused by corrosion of copper pipes containing chloride gas in the presence of moisture (case study)

This research report investigated investigates the causes and mechanisms of copper pipes clogging used in gas chlorination systems of drinking water. Clogging of the chlorine gas transmission pipes causes incomplete water disinfection process and may put the human health in dangerous. Comprehensive examinations of the destroyed copper pipes in some stations revealed that, the reason of frequent clogging of the pipes is corrosion phenomenon. The reasons and mechanism of the frequent clogging of the pipes were investigated in the present work. For this purpose, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to deduce the reasons and mechanism of the frequent clogging. The investigations of pipe clogging mechanism revealed that, the unwanted presence of the water inside the pipe when the system is out of service lead to pipes clogging in two stages (formation and growth of corrosion products). The simultaneous presence of water and chlorine inside the pipes cause the formation of corrosive electrolyte (Hydrochloric acid) which provides corrosion conditions inside the pipes. The XRD results identified the presence of the porous and voluminous corrosion product of paratacamite (Cu2(OH)3Cl). The SEM images demonstrated by providing the corrosive environment inside the pipe and as result, formation of porous corrosion products cause the rapid growth of non-protective layer of corrosion products. The growth of corrosion products scale and aggregation of separated parts of corrosion products in some parts of the pipes led to pipes clogging and as result the incomplete injection of sufficient amount of chlorine in drinking water.