Final answer:
All available options—coating, wrapping, and cathodic protection—are methods to protect underground gas piping from corrosion, with cathodic protection being an extremely effective approach.
Step-by-step explanation:
Gas pipe and tubing installed underground should be protected against corrosion using one or several methods to ensure their longevity and safety. The options for protecting these materials include: coating, wrapping, and cathodic protection. So, the correct answer to the question is 4) All of the above.
Cathodic protection is a particularly effective method for preventing corrosion. It involves connecting a more easily oxidized metal, known as a sacrificial anode (like magnesium or zinc), to the material that needs to be protected. This makes the pipeline act as a cathode with the sacrificial anode corroding instead, thus protecting the pipeline. Coatings and wrappings are also widely used to provide a physical barrier between the pipe and the environment, preventing exposure to elements that could cause corrosion.