Which of the following are common methods used for corrosion control in piping systems?

The answer focusing on coatings, cathodic protection, and corrosion-resistant materials is the most relevant and common methods for controlling corrosion in piping systems.

Coatings provide a barrier between the metal surface and the corrosive environment, thereby preventing moisture and harmful substances from reaching the metal. This can include paints, powder coatings, or galvanization. Each of these methods applies a protective layer that can withstand the elements and chemicals found in various environments.

Cathodic protection is another vital method, particularly in underground or submerged applications. This technique involves making the metal structure the cathode of an electrochemical cell, which helps prevent corrosion by diverting corrosive activity to an anode made of a more easily corroded material. This is commonly implemented through impressed current systems or sacrificial anodes.

Corrosion-resistant materials are also used extensively in piping design and construction. These materials, such as certain alloys, stainless steel, or plastics, have inherent properties that resist corrosive reactions, thereby extending the life span of the piping systems.

In contrast, boiling, freezing, and filtering do not address corrosion prevention and are irrelevant to the context of maintaining and protecting piping systems. Welding, stitching, and folding are more focused on fabrication and repair rather than corrosion control.