Fatigue, corrosion, and wear

This chapter is designed to discuss three causes of material deterioration—fatigue, corrosion, and wear. These aspects are related to various phenomena, which are caused by different mechanisms. The common feature of all three is the reduction of material qualities, which is partly responsible for failures and shortening of pipe service life. Fatigue is the loss of strength or other mechanical properties as the result of stressing over a period of time. Fatigue can be divided into several categories; these include cyclic fatigue and static fatigue. Wear is a general term implying the limits of material resistance or the loss of surface qualities. Wear can be an indication of the ageing of the material and end of life situation. Corrosion is the deterioration of a material as a result of reaction with its environment, especially with oxygen. All materials, including ceramics, plastics, rubber, and wood, deteriorate at the surface to some extent when they are exposed to certain combinations of liquids and/or gases. Plastics may react with some external environmental agents. The reaction may take place at the surface or may occur internally as a result of diffusion of external agents into the plastic body. This chapter discusses the aforementioned concepts along with preventive measures.