Damage mechanisms anticipated on chemical plants include the following.
- Fatigue
All materials will fail when subjected to cyclic stress, even if the stress is at a level that would not cause failure under static loading. This is called fatigue. - Creep
Even if a material is under stress that does not semi-permanently deform or break at room temperature (below a certain temperature determined for each material), at high temperatures the material gradually deforms and breaks after a certain period of time. This phenomenon is called creep. - Natural Corrosion
Metals exist on earth as compounds (oxides, sulfides, etc.), but they are reduced (refined, etc.) and used industrially. Therefore, in the natural world environment where oxygen exists, it will return to an oxide. This phenomenon is called natural corrosion. - Dry corrosion
Metal reacts directly when it comes into contact with reactive gases such as oxygen, water vapor (gaseous state), and carbon dioxide gas, and the metal is consumed while forming a solid film of reaction products (oxides) on the metal surface. This is called dry corrosion. - Wet corrosion
In contrast to dry corrosion, in which the material dissolves in a gas, wet corrosion refers to the solution of the material in a liquid. The degree of corrosion varies depending on the combination of liquid components and materials (including anti-corrosion measures such as coatings). - Stress Corrosion Cracking
Corrosion is a phenomenon in which materials are dissolved into the environment. In normal corrosion, material dissolved generally or locally and the wall thickness decreases, but a phenomenon in which corrosion progresses in a crack-like manner in a very narrow area under constant stress is called stress corrosion cracking. . This occurs when three conditions are met: environment, material, and stress. - Wear
When solid materials are used in a state where they rub against each other, one (or both) wears out and the wall thickness decreases, a phenomenon called wear. - Erosion
Erosion is a phenomenon in which a material is mechanically worn down due to repeated collisions (or impacts) with fluid, and a portion of it is detached. It is called erosion - Property deterioration
Metals are used after being conditioned (e.g. by heat treatment) so that they exhibit optimal properties at the time of initial use. At room temperature, properties do not change because atoms do not move, but at high temperatures, properties change because atoms difuse to an energetically stable state. This change is often inconvenient in use (for example, decreases in material strength, ductility, and corrosion resistance) and can cause accidents after long-term use. This property deterioration is called property (metallurgical) deterioration.