What type of piping is commonly used for underground gas installations?

The use of metallic piping for underground gas installations is primarily due to its durability, strength, and ability to withstand the pressures and environmental factors associated with buried applications. Metallic pipes, such as steel or iron, are designed to handle the stresses and potential impacts they may encounter underground. They also provide a level of security and reliability that is crucial for gas distribution systems, where leaks must be minimized and the integrity of the pipeline maintained.

Metallic piping is also not as susceptible to degradation from environmental conditions as some other materials might be. For instance, while PVC and CPVC are commonly used in plumbing applications, they have limitations regarding their temperature and pressure tolerance when used for gas services. Cast iron, although strong, is less commonly used due to its weight, potential for rust, and difficulty in installation compared to modern metallic options. Thus, metallic piping stands out as the preferred choice for underground gas installations.