THE CORROSION PROBLEMS IN HOUSEHOLD WATER HEATERS OF SABRATHA CITY

Abstract

The corrosion destructive action can reach the home of millions of people, thus costing a tremendous amount of money and causing a great inconvenience. With the up rise of brackish water in Sabratha city, corrosion can damage water heaters, pipe network, refrigerators and many more items found at homes. In addition, in the absence of adequate specifications, major failures of water heaters have been reported in the recent years creating a great deal of concern. This study investigated the reasons of water heaters failure, and the methods needed to overcome or limit such a problem.

Three main components, which have a direct relationship with the corrosion phenomena of heaters, were studied namely water, heater storage tank and heating element cover. To achieve that a chemical analysis of water samples and an examination of the microstructure and the chemical composition of heater storage tank and the heating element cover were carried out. The results revealed that the likelihood of forming a scale of Ca CO₃ increases with increasing temperature, salt concentrations and the PH value.

The metallographic examination showed the presence of a ferrite-pearlite structure. The microstructural studies revealed the presence of un-equivalent distribution of carbon content responsible for galvanic corrosion. They also revealed that grain growth in Heat Affective Zone (H. A. Z.) was responsible for pitting type corrosion. The weld showed typical WIDMANSTAATEN structure. Chemical composition of the sample indicated that the structure belongs to the low carbon steel which is identical to ASM 1020, and that the cover of heating element is made of pure copper.